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Triassic-Jurassic dinosaurs from India, their ages and palaeobiogeographic significance

Historical Biology

April 2024

DOI:10.1080/08912963.2024.2336992

Authors:

Ashu Khosla

Panjab University

Spencer G. Lucas

New Mexico Museum of Natural History and Science

We review the record of Late Triassic and Jurassic dinosaurs from India to determine their geological ages and palaeobiogeographic significance. The oldest Indian dinosaur, the basal saurischian Alwalkeria maleriensis, is from the early Late Triassic (Otischalkian/Carnian) lower Maleri Formation. The archosaur-dominated Upper Maleri Formation (Adamanian/late Carnian?) contains two sauropodomorph clades. The Indian Jurassic record of dinosaurs from the Pranhita-Godavari Valley is more extensive but has poor age constraints, whereas fragmentary, and better dated dinosaur remains are known from the Early Middle Jurassic of Kachchh, Gujarat and Rajasthan. The Indian Late Triassic dinosaurs fit into a picture of some degree of dinosaur cosmopolitanism across Late Triassic Pangaea, with primitive saurischians and/or theropods and primitive sauropodomorphs found in eastern Gondwana (India), western Gondwana (South America) and Euramerica. The well-known non-neosauropods Kotasaurus and Barapasaurus from the Middle Jurassic Kota Formation provide substantial evidence that India was a major centre of the early evolution of neosauropods. Tharosaurus indicus, from the Middle Jurassic strata of the Jaisalmer Basin, is a relic of a lineage that likely originated in India and swiftly expanded throughout the rest of Pangaea. This lineage further stresses the significance of Gondwanan India in elucidating the origin and early evolutionary history of neosauropod dinosaurs.

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Triassic-Jurassic dinosaurs from India, their ages

and palaeobiogeographic significance

Ashu Khosla & Spencer G. Lucas

To cite this article: Ashu Khosla & Spencer G. Lucas (28 Apr 2024): Triassic-Jurassic dinosaurs

from India, their ages and palaeobiogeographic significance, Historical Biology, DOI:

10.1080/08912963.2024.2336992

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Triassic-Jurassic dinosaurs from India, their ages and palaeobiogeographic signicance

Ashu Khosla

and Spencer G. Lucas

Department of Geology, Panjab University, Chandigarh, India;

New Mexico Museum of Natural History, Albuquerque, NM, USA

ABSTRACT

We review the record of Late Triassic and Jurassic dinosaurs from India to determine their geological ages

and palaeobiogeographic signicance. The oldest Indian dinosaur, the basal saurischian Alwalkeria maler-

iensis, is from the early Late Triassic (Otischalkian/Carnian) lower Maleri Formation. The archosaur-dominated

Upper Maleri Formation (Adamanian/late Carnian?) contains two sauropodomorph clades. The Indian

Jurassic record of dinosaurs from the Pranhita-Godavari Valley is more extensive but has poor age con-

straints, whereas fragmentary, and better dated dinosaur remains are known from the Early Middle Jurassic

of Kachchh, Gujarat and Rajasthan. The Indian Late Triassic dinosaurs t into a picture of some degree of

dinosaur cosmopolitanism across Late Triassic Pangaea, with primitive saurischians and/or theropods and

primitive sauropodomorphs found in eastern Gondwana (India), western Gondwana (South America) and

Euramerica. The well-known non-neosauropods Kotasaurus and Barapasaurus from the Middle Jurassic Kota

Formation provide substantial evidence that India was a major centre of the early evolution of neosaur-

opods. Tharosaurus indicus, from the Middle Jurassic strata of the Jaisalmer Basin, is a relic of a lineage that

likely originated in India and swiftly expanded throughout the rest of Pangaea. This lineage further stresses

the signicance of Gondwanan India in elucidating the origin and early evolutionary history of neosauropod

dinosaurs.

ARTICLE HISTORY

Received 20 December 2023

Accepted 26 March 2024

KEYWORDS

Triassic; Jurassic; dinosaurs;

India; palaeobiogeography

Introduction

The intricate palaeogeographic history of India, which includes

a protracted period of physical isolation during India’s gradual tran-

sition by continental drift from being part of Gondwana to joining

Laurasia, is still hotly debated today. Important biotic remnants of

this complex history are preserved in the Indian Triassic and Jurassic

fossil records (Khosla and Bajpai 2021). The history includes the

origin, evolution, and distribution patterns of various dinosaur clades

in the Indian Triassic-Jurassic strata. India thus offers a unique

chance to study dinosaurs in space and time, both in the Pangaean

context and throughout India’s northward drift after it split from

Gondwana. When considered in this light, the fossil record of Indian

dinosaurs offers a remarkable chance to investigate their diversity

and palaeobiogeographic dispersion over space and time.

The last eight decades have seen a very productive period for the

history of dinosaur research in India, and numerous dinosaur clades of

Triassic and Jurassic ages have been identified in the Maleri,

Dharmaram and Kota formations of the Pranhita-Godavari valley

(e.g. Huene 1940; Colbert 1958; Jain et al. 1964, 1975, 1979; Roy-

Chowdhury 1965; Kutty 1969; Chatterjee 1967, 1974, 1978, 1980,

1982, 1987; Chatterjee and Roy-Chowdhury 1974; Yadagiri 1982;

Jain and Roy-Chowdhury 1987; Yadagiri and Rao 1987; Yadagiri

et al. 1979; Yadagiri 1988, 2001; Kutty et al. 1987, 2007; Kutty and

Sengupta 1989; Chatterjee and Creisler 1994; Bandyopadhyay and

Roy-Chowdhury 1996; Loyal et al. 1996; Bandyopadhyay 1999; Nath

et al. 2002; Bandyopadhyay and Sengupta 2006; Spielmann et al. 2006;

Bandyopadhyay et al. 2002, 2010; Novas et al. 2010, 2011; Kammerer

et al. 2016; Chatterjee et al. 2017; Galton 2019; Chatterjee 2020;

Bandyopadhyay and Ray 2020; Prasad and Parmar 2020; Khosla and

Bajpai 2021). Middle Jurassic dinosaurs have also been discovered in

western peninsular India (Figure 1). These dinosaur records are less

diverse and less abundant but have better age constraints than the

Triassic-Jurassic dinosaurs from the Pranhita-Godavari Basin, Andhra

Pradesh.

Thus, apart from the Pranhita-Godavari Basin, fragmentary

remains of dinosaurs are also known from the earliest Middle

Jurassic (?Aalenian to Bajocian) Dingy Hill Member of the

Kaladongar Formation of Kuar Bet, Patcham Island, in the Rann of

Kachchh (Ghevariya and Srikarni 1992; Pandey and Dave 1993;

Satyanarayana et al. 1999), Middle Jurassic (Callovian) marine

Chari Formation, Jumara, Kachchh Mainland (Jana and Das 2002),

the Middle Jurassic (Bajocian) strata of Khadir Island (Kachchh,

Gujarat, Western India, Moser et al. 2006) and the Middle Jurassic

(early-middle Bathonian) strata of Jaisalmer District in Rajasthan

(Bajpai et al. 2023; Sharma et al. 2023a, 2023b). Indian dinosaur

records, while still incomplete for several geologic periods

(e.g. Triassic and Jurassic) and taxa (Bandyopadhyay and Ray 2020;

Khosla and Bajpai 2021), have provided important information for

research on the phylogeny and evolution of the group during the

early and middle part of the Mesozoic.

Throughout the Mesozoic Era, the Earth’s topography saw

a number of notable changes (e.g. Holtz et al. 2004; Dunhill

et al. 2016). Pangaea’s super continental aggregation reached its

apex in the Middle Triassic, after which it began to break apart

during the Jurassic into the landmasses of Laurasia (North

America, Asia and Europe) and Gondwana (South America,

Africa, Antarctica, Australia, India and Madagascar).

Throughout the Cretaceous, continental fragmentation persisted

(Upchurch 2008), coinciding with sea level rise to approximately

240 m above current levels (Haq et al. 1987; Miller et al. 2005;

Dunhill et al. 2016). As a result, by the end of the Cretaceous, all

major landmasses were isolated (Smith et al. 1994; Dunhill

et al. 2016). The dinosaurs emerged during the Late Triassic

(c. 230 Ma) and dominated terrestrial ecosystems throughout the

CONTACT Spencer G. Lucas spencer.lucas@dca.nm.gov New Mexico Museum of Natural History, 1801 Mountain Rd. NW, Albuquerque, NM 87104, USA

HISTORICAL BIOLOGY

https://doi.org/10.1080/08912963.2024.2336992

Published online 28 Apr 2024

Jurassic and Cretaceous (Sereno 1999; Brusatte et al. 2008). Since

continental fragmentation dominated during the non-avian dino-

saurs’ existence (e.g. Holtz et al. 2004; Butler et al. 2011; Dunhill

et al. 2016), increased endemism, regional extinction, and

decreased migration between continental landmasses should be

expected in their biogeographical history (Sereno 1999; Dunhill

et al. 2016; Krause et al. 2019).

Biogeography is one of the many facets of dinosaur research that

has gained prominence recently (Pitman et al. 1993; Storey et al.

1995; Loyal et al. 1996; Sereno 1997, 1999; Bonaparte et al. 1999;

Forster 1999; Chatterjee and Scotese 1999; Upchurch et al. 2002;

Briggs 2003; Holtz et al. 2004; Isabel and Ronquist 2004; Butler et al.

2006; Ali and Aitchison 2008; Smith et al. 2008; Nesbitt et al. 2009;

Bittencourt and Langer 2011; Chatterjee et al. 2013; Dunhill et al.

2016; Krause et al. 2019; Khosla 2021; Khosla and Bajpai 2021). As

a field, biogeography is expanding, and a large portion of its con-

ceptual framework is well established (e.g. Lomolino et al. 2006;

Morrone and Guerrero 2008; Bittencourt and Langer 2011; Krause

et al. 2019). However, as many authors have noted (e.g. Lieberman

2002, 2003; Dunhill et al. 2016; Krause et al. 2019), dependable

assumptions of endemic ranges – the foundation for all palaeobio-

geographic hypotheses – need to be built upon accurate interpreta-

tions of the fossil record.

The present communication represents the first detailed

review of the Triassic and Jurassic dinosaurs from western and

southern peninsular India (Figures 1 and 2), with respect to

their geological ages and palaeobiogeographical significance.

We also discuss the importance of this record in light of recent

theories regarding dinosaur biogeography in the Mesozoic

(Upchurch et al. 2002; Sereno et al. 2004; Krause et al. 2006,

Figure 1. Distribution of Mesozoic sedimentary basins in India, showing the Triassic and Jurassic successions including the dinosaur bone-bearing localities (modiﬁed after

Chinnappa et al. 2019).

2A. KHOSLA AND S. G. LUCAS

2019; Kutty et al. 2007; Nesbitt et al. 2009; Dunhill et al. 2016;

Khosla and Bajpai 2021). The main objective and purpose of

this paper is to first present an overview of the Triassic and

Jurassic dinosaur fossil record from India by providing addi-

tional stratigraphic and age data from these much-neglected

terrestrial dinosaur fossils and to provide an up-to-date status

of dinosaur studies.

We also investigate in what way the palaeogeography of the

Indian supercontinent influenced dinosaur biogeographical struc-

ture/routes and whether fewer biogeographical links between dino-

saurs resulted from less linked landmasses. Throughout the

Mesozoic, we compare biogeographical and geographical network

models proposed by different workers. The succeeding discussion is

aimed largely at establishing the geological ages and correlation of

the dinosaur fossils, and the goal of this summary of earlier research

on dinosaur remains from India’s Gondwana sedimentary deposits

is to accentuate the palaeobiogeographic relevance of these fossil

records and to highlight the present status of the Indian fossil

record.

Triassic dinosaurs

Maleri Formation

The Pranhita-Godavari Valley of Andhra Pradesh preserves a succession

of continental strata dating from the early Permian to the Early

Cretaceous (Tables 1 and 2, e.g. Chatterjee 1978; Bandyopadhyay and

Sengupta 2006; Kutty et al. 2007; Bandyopadhyay and Ray 2020; Khosla

and Bajpai 2021). Triassic and Jurassic dinosaur fossils are known from

this succession, namely from the Maleri, Dharmaram and Kota forma-

tions (Figure 2).

The Maleri Formation is composed of 300 m of red clays, fine-

medium sandstone, and limestone (Table 1, Kutty and Sengupta

1989; Chinnappa and Rajanikanth 2017; Chinnappa et al. 2019).

The Lower Maleri Formation (Chatterjee 1987) is the oldest of the

Indian dinosaur-bearing formations, with a diverse fossil vertebrate

fauna that includes dipnoans, xenacanthids, dicynodonts, cyno-

donts, metoposaurs, rhynchosaurs, ‘protorosaurs’, aetosaurs, para-

suchians, and dinosaurs (e.g. Roy-Chowdhury 1965; Kutty 1969;

Chatterjee 1974, 1978, 1982, 1987; Kutty et al. 1987, 2007; Kutty and

Sengupta 1989; Hungerbühler et al. 2002; Sengupta 2002, 2003;

Langer 2005; Bandyopadhyay and Sengupta 2006; Novas et al.

2010; Khosla and Bajpai 2021).

The vertebrate fossil assemblage from the upper Maleri Formation

includes an aetosaur, the sauropodomorph dinosaurs Nambalia and

Jaklapallisaurus and a large dicynodont. Chigutisaurid amphibians

(Compsocerops and Kuttycephalus: Sengupta 1995) and a ‘Rutiodon-

like’ phytosaur are also present (Bandyopadhyay and Sengupta 2006).

Huene (1940) worked on the Upper Triassic Maleri Formation

of the Pranhita-Godavari Valley and recovered incomplete dino-

saur material and reported two fragmentary vertebrae of

a sauropodomorph (Colbert 1958; Roy-Chowdhury 1965;

Chatterjee 1987). The basal saurischian Alwalkeria maleriensis was

named for fossils from the Lower Maleri Formation (Chatterjee

Figure 2. The basal sauropodomorph localities with geological map showing the exposures of the Maleri, Dharmaram and Kota formations in the Pranhita-Godavari Valley

of Andhra Pradesh. Basal sauropodomorph ISI R257, R258, R261, R262, and R265 were found between the villages of Dharmaram and Krishnapur (map modiﬁed from Kutty

and Sengupta 1989; Kutty et al. 2007; Khosla and Bajpai 2021).

HISTORICAL BIOLOGY 3

1987; Chatterjee and Creisler 1994). Five dinosauriform/dinosaur

taxa have been reported from the Upper Maleri Formation,

Nambalia roychowdhurii (a basal sauropodomorph),

Jaklapallisaurus asymmetrica (a plateosaurian), an unnamed mem-

ber of Guibasauridae and two Dinosauriformes indet (Table 3,

Kutty 1969; Novas et al. 2011).

Parts of the front ends of the upper and lower jaws, many

fragmentary and incomplete vertebrae (Figures 3 and 4) from all

parts of the spinal column, the majority of a femur, and an astra-

galus (ankle bone) make up the only known specimen of Alwalkeria

maleriensis (holotype ISI R306, Chatterjee 1987; Chatterjee and

Creisler 1994). According to recent studies by Novas et al. (2011),

Alwalkeria is a legitimate and valid species due to autapomorphies

that include its unique femur and astragalus morphology.

According to Chatterjee (1987), the important characteristics of

Alwalkeria maleriensis include: the maxilla is a large, three-sided

bone, deeply emarginated posteriorly by an elongate antorbital

fenestra; the lower boundary of the fenestra is smooth without

a longitudinal alveolar edge; the dentary is thin and marked by an

outer longitudinal alveolar furrow, and a long, medial symphysis;

the teeth are unserrated, and the anteriormost teeth are tapered,

whereas the posterior teeth are medio-laterally compressed; the

neural arches are excavated by chonoses; the femur is well preserved

with a very extended proximal head and articulated fourth trochan-

ter; the calcaneum and astragalus are isolated.

Although the material of Alwalkeria is limited, the spacing and

morphology of the teeth closely resemble those of Eoraptor from the

Upper Triassic of Argentina. It is well known that in Eoraptor, a gap

(diastema) separates the teeth of the premaxillary and the maxillary

teeth of the upper jaw. The Maleri dinosaur A. maleriensis has

a heterodont dentition in the upper jaw, similar to Eoraptor and

basal sauropodomorphs, in that the teeth anteriorly are thin and

straight, whereas the teeth in the sides of the jaw are recurved like

those of theropods, though none of these teeth are serrated. This

Table 1. Lithostratigraphy and ages of various lithostratigraphic units in the Pranhita-Godavari Basin.

Formation Lithology

Thickness in

meters Characteristic fossils Age References

Chikiala Sandstones and

conglomerates

400 Plant fossils Early

Cretaceous

Lakshminarayana (2002); Chinnappa and

Rajanikanth (2017); Chinnappa et al. (2019)

Gangapur Sandstones,

clays, basal part

conglomeratic with

pebbles of quartz,

quartzite, chert,

mudstones and shale.

Red clays with

interbedded siltstones

500 Fossil wood, plant fossils Early

Cretaceous

Yadagiri 2001; Lakshminarayana (2002);

Chinnappa and Rajanikanth (2017);

Chinnappa et al. (2019)

Kota Upper: Sandstone,

siltstone, bedded

limestone, and

claystone

Middle: Red and green

clays , siltstone,

mudstone with

interbedded sandstones

and limestone

Lower: Sandstone with

pebbles of banded chert

and quartzite

100

Basal sauropod (Barapasaurus tagorei,

Kotasaurus yamanpalliensis) and

thyreophoran ornithischian, Early

mammals, ﬂying reptiles, ﬁshes, and

bivalved crustaceans.

Early to

Middle

Jurassic

Sinemurian-

Pliensbachian

Jain et al. 1975, 1979; Kutty et al. 1987;

Lakshminarayana 1994; Loyal et al. 1996;

Yadagiri 1988, 2001; Nath et al. 2002;

Sengupta 2003; Bandyopadhyay and

Sengupta 2006; Kutty et al. 2007;

Bandyopadhyay et al. 2010; Khosla and

Bajpai 2021

Dharmaram Coarse sandstone and red

clays at places indurated

mudstones

500 Sauropodomorphs:

Lamplughsaura dharmaramensis,

Pradhania gracilis

Indeterminate form.

Theropods: aﬀ. Dilophosaurus

Sphenosuchid: aﬀ. Dibothrosuchus

Phytosaurids: aﬀ. Nicrosaurus

Stagonolepidids:

aﬀ. Paratypothorax

aﬀ. Desmatosuchus

Late Triassic

to Early-

Middle

Jurassic

Yadagiri 2001; Bandyopadhyay and Sengupta

2006; Kutty et al. 2007; Novas et al. 2011;

Khosla and Bajpai 2021

Maleri Red clays, ﬁne-medium

sandstone and

limestone

300 Basal sauropodomorphs:

Nambalia roychowdhurii,

Jaklapallisaurus asymmetrica,

unnamed small guaibasaurid.

Dinosaur indet.

Dinosauriformes indet.

Theropod: Alwalkeria maleriensis

Temnospondyl: Metoposaurus

Prolacertilian: Malerisaurus

Rhynchosaur: Paradepedon

Phytosaurids:

Parasuchus

aﬀ. Rutiodon (‘“Angistorhinus”’)

Traversodont: Exaeretodon

Late Triassic

(Late

Carnian)

Otischalkian/

Carnian

Kutty (1969); Chatterjee (1987); Kutty and

Sengupta (1989); Yadagiri 2001; Novas et al.

(2011); Chinnappa and Rajanikanth (2017);

Chinnappa et al. (2019); Khosla and Bajpai

(2021); Ezcurra et al. (2024)

4A. KHOSLA AND S. G. LUCAS

tooth structure is not obviously herbivorous or carnivorous, which

suggests that this dinosaur might have been an omnivore. As

a whole, other similarities in the skulls of the two dinosaurs such

as the tooth form and spacing in Alwalkeria closely match those of

Eoraptor, despite the limited material. Thus, the teeth of the pre-

maxillary and maxillary bones of the upper jaw are divided by a gap,

much as in the Eoraptor. Morphologically, the two species are

linked by further similarities in their skulls (Langer 2004).

In an abstract, Remes and Rauhut (2005) argued that Alwalkeria

is a chimera: the front of the skull is that of a crurotarsan, and the

vertebrae belong to other reptiles. However, this conclusion has not

been widely accepted, and the astragalus and the femur of

Alwalkeria are clearly dinosaurian, with the latter having saur-

ischian features. Alwalkeria has also been considered to be a basal

theropod (Chatterjee 1987; Loyal et al. 1996), a connection between

the putative ‘bird’ Protoavis and herrerasaurids, and thus assigned

to Herrerasauridae based primarily on features of the femur (Paul

1988). However, recent workers have concluded that Alwalkeria is

too primitive to be a theropod and consider it a basal saurischian

(Langer 2004; Martinez et al. 2009).

Some undescribed specimens from the Upper Maleri

Formation had previously been the extent of the Indian

Triassic dinosaur record (Kutty 1969; Kutty et al. 1987; Novas

et al. 2011). The uppermost part of the Maleri Formation has

yielded two basal sauropodomorphs, Nambalia roychowdhurii

and Jaklapallisaurus asymmetrica (Novas et al. 2011). The non-

plateosaurian N. roychowdhurii is known from a right ilium, left

femur, and the distal half of the left tibia and fibula with an

articulated astragalus and calcaneum (Figure 5). The diagnostic

features are in the mid-caudal vertebrae, which are fairly elon-

gated, with round and hollow anterior and posterior articular

facets and low neural arches (Novas et al. 2011). The ilium has

a well-developed supra-acetabular crest as well as a totally per-

forated acetabulum (Novas et al. 2011). The femur has

a diagonally unexpanded distal end and a narrow distal anterior

intercondylar groove. From the posterior point of view, the

distal end of the tibia has a fairly developed posterolateral

projection that somewhat covers the ascending process of the

astragalus. The astragalus has a pit on the anterior surface

(astragalar ascending process), and, in anterior aspect, the med-

ial condyle is sub-triangular (Novas et al. 2011).

The other Upper Maleri Formation sauropodomorph,

Jaklapallisaurus asymmetrica (Novas et al. 2011), is known

from fragmentary dorsal and caudal vertebrae, a sacrum, right

Table 3. Updated list of dinosaur taxa from Late Triassic-Middle Jurassic of India (JF = Jaisalmer Formation; KK = Kaladongar Formation, Kuar Bet, Kachchh; LD = Lower

Dharmaram Formation; LK = Lower Kota Formation; LM = Lower Maleri Formation; UD = Upper Dharmaram Formation; UK = Upper Kota Formation; UM = Upper Maleri

Formation).

References

Middle Jurassic:

Sauropoda Camarasauromorpha gen et sp. indet. (KK) Moser et al. (2006)

? Spinosaurid (JF) Sharma et al. (2023b)

Tharosaurus indicus (JF) Bajpai et al. (2023)

Theropoda Dromaeosauridae indet. (UK) Prasad and Parmar (2020)

Ornithischia Ankylosauria indet. Galton (2019)

Ornithischia indet. (UK) Nath et al. (2002)

Early-middle Jurassic

Sauropoda Barapasaurus tagorei (LK) Jain et al. (1975, 1979); Bandyopadhyay and Ray (2020).

Kotasaurus yamanpalliensis (LK) Yadagiri (1988, 2001)

Ornithischia Ankylosauria indet. (LK) Nath et al. (2002)

Early Jurassic

Sauropodomorpha Lamplughsaura dharmaramensis (UD) Kutty et al. (2007)

Pradhania gracilis (UD) Kutty et al. (2007)

Indeterminate form (UD) Kutty et al. (2007)

Neotheropoda Indet. (LD) Novas et al. (2011)

Late Triassic (late ?Norian):

Nambalia roychowdhurii (UM) Novas et al. (2011)

Jaklapallisaurus asymmetrica (UM) Novas et al. (2011); Ezcurra et al. (2024)

Guibasauridae indet. (UM) Novas et al. (2011)

Dinosauriformes indet. (ISI R282) (UM) Novas et al. (2011)

Dinosauriformes indet. (ISI R284) (UM) Novas et al. (2011)

Late Triassic (Late Carnian):

Saurischia Alwalkeria maleriensis (LM) Chatterjee (1987; Chatterjee and Creisler 1994)

Table 2. Generalized Gondwana stratigraphy

showing the Triassic-Jurassic fossil bearing hori-

zons in the Pranhita-Godavari Basin (modiﬁed

after Bandyopadhyay and Sengupta 2006;

Bandyopadhyay and Ray 2020).

Basin

Age Pranhita-Godavari

Jurassic Middle Kota

Lower Dharmaram U

Rhaetian L

Norian

Maleri

Carnian L

Bhimaram

MLadinian

Anisian Yerrapalli

LOlenekian Kamthi

Induan

Permian

Lopingian Kundaram

Cisuralian-

Guadalupian

Barren Measures

HISTORICAL BIOLOGY 5

Figure 3. Alwalkeria maleriensis (Chatterjee 1987) incomplete skull and jaw in (A) left lateral, (B) right lateral and (C) ventral views (modiﬁed after Chatterjee 1987).

Figure 4. Alwalkeria maleriensis (Chatterjee 1987) Vertebrae: (A, B), cervical; (C – I), dorsals; Abbreviations: ch, chonoses (modiﬁed after Chatterjee 1987).

6A. KHOSLA AND S. G. LUCAS

pelvic girdle (Figure 6), a distal right femur, a complete right

tibia and astragalus, right metatarsals I – IV and two pedal

phalanges (Novas et al. 2011). The distal femur has

a diagonally-open popliteal fossa, straight anterior margin and

is slightly more than 1.5 times broader diagonally than the

anteroposterior depth of the medial condyle. A well-developed

cnemial crest on the proximal end of the tibia is somewhat bent

laterally (Novas et al. 2011). The tibia’s distal end is diagonally

broader than anteroposteriorly deep, with a protuberant lateral

notch that divides the anterior articular facet for the reception

of the astragalar ascending process from that of the poster-

olateral process. From an anterior point of view, the astragalar

body is sub-rectangular, with a modest ascending process

(Novas et al. 2011).

Another fragmentary saurischian belonging to the family

Guaibasauridae (sensu Ezcurra 2010), was also recovered from

the Upper Maleri Formation. The material includes a right

ilium, a fragment of the left iliac blade, partially preserved left

femur, left tibia, tarsus, and almost complete pes and three

sacral vertebrae (Novas et al. 2011). This material is currently

regarded as generically indeterminate.

Lower Dharmaram Formation

Stratigraphically above the Maleri Formation, the Dharmaram

Formation consists of coarse sandstone and red clays and, in places,

indurated mudstones (Khosla 2014; Khosla and Bajpai 2021). The

basal strata of the Dharmaram Formation are thick-bedded, coarse-

grained gritty sandstone, mudstones and claystone beds (Table 1,

Kutty et al. 1987; Loyal et al. 1996). The Dharmaram Formation

contains vertebrate fossils of Late Triassic-Early Jurassic age.

Fragmentary fossils of fish (Ceratodus and Xenacanthus), phytosaurs

(‘Nicrosaurus’), sauropodomorphs (Lamplughsaura dharmaramensis

and Pradhania gracilis), and aetosaurs have been reported, but most

of the reported taxa from the basal part of the Dharmaram Formation

are fragmentary, and more research is needed (Kutty and Sengupta

1989; Kutty et al. 2007).

Based on isolated postcranial material, the Lower Dharmaram

Formation, which overlies the Upper Maleri Formation, contains

a minimum of two dinosaur taxa. These include: (1) The dinosaur

Jaklapallisaurus asymmetrica represented by a distal femur with an

extensively and diagonally open popliteal fossa and straight margin in

distal view and (2) Neotheropoda identified by a femur with an inverted

head that makes an angle of less than 90° (with the main axis of the

shaft) and a well-developed and pyramidal anterior trochanter (Rauhut

2003). Because this femur lacks a proximally well-developed anterior

trochanter that extends over the level of the ventral border of the

femoral head (Rauhut 2003; Ezcurra 2006; Novas et al. 2011; Khosla

and Bajpai 2021), it can be eliminated from Averostra (sensu Ezcurra

and Cuny 2007). So, it represents a non-averostran neotheropod.

Age of India’s Triassic dinosaurs

As noted above, Upper Triassic vertebrate assemblages from India

with dinosaur fossils come only from the Pranhita-Godavari Valley.

Several summaries of the Upper Triassic tetrapod assemblages from

the Pranhita-Godavari Valley have been published (Jain et al. 1964;

Kutty 1969; Kutty and Roy-Chowdhury 1970; Sengupta 1970; Jain

and Roy-Chowdhury 1987; Yadagiri and Rao 1987; Kutty and

Sengupta 1989; Bandyopadhyay and Roy-Chowdhury 1996;

Bandyopadhyay and Sengupta 2006; Kammerer et al. 2016;

Bandyopadhyay and Ray 2020), but, other than the lower Maleri

assemblage, relatively few of the fossils have been adequately docu-

mented in print. This makes correlations of most of these assem-

blages tentative at best.

Sohn and Chatterjee (1979) documented ostracods from

a coprolite collected from the Maleri Formation near Achlapur

Village but provided no data on its precise stratigraphic position

in the Formation. The ostracod taxa are a cypridacean? and

Darwinula spp., temporally long-ranging taxa that offer no insight

into the precise age of the Maleri Formation.

Vijaya et al. (2009) documented palynomorphs extracted from

coprolites collected in red clays of the Maleri Formation south of

Mallidi (Maleri) Village but did not specify what part of the forma-

tion the palynomorphs came from. The numerous palynomorph

taxa were assigned a Norian-Rhaetian age in the abstract of Vijaya

et al. (2009) but a Rhaetian age in the text based largely on correla-

tion to an Australian palynological zonation (Helby et al. 1987).

However, as Helby et al. (1987) acknowledged, the age constraints

of the Australian palynological zonation with respect to marine

stages such as the Norian and Rhaetian are weak. Furthermore,

the Maleri palynomorphs reported by Vijaya et al. (2009) include

Camerosporites secatus (mis-spelled C. caecatus by Vijaya et al.),

a taxon of well established Ladinian-Carnian age (e.g. Visscher and

Krystyn 1978; Kuerschner and Herngreen 2010; Lucas et al. 2012).

Therefore, we reject a Norian or Rhaetian age for the Maleri

Formation palynomorphs and infer that a Carnian age is a more

supportable correlation.

The most reliable age constraints on the Lower Maleri fossil

assemblages are the tetrapods themselves, which can be corre-

lated within the land-vertebrate faunachron scheme of Lucas

(1998, 2010, 2018). The Lower Maleri Formation produces

a tetrapod assemblage that includes the amphibian

Metoposaurus (also assigned to Buettneria or Panthasaurus; we

prefer the original generic assignment; cf. Lucas 2020), the

rhynchosaur Paradepedon, the phytosaur Parasuchus, the arch-

osaur ‘Malerisaurus,’ an aetosaur, the theropod dinosaur

Alwalkeria, a prosauropod, a large dicynodont, and the cynodont

Exaeretodon (e.g. Huene 1940; Jain et al. 1964; Roy-Chowdhury

1965; Chatterjee 1967, 1974, 1978, 1980, 1982, 1987; Chatterjee

and Roy-Chowdhury 1974; Jain and Roy-Chowdhury 1987;

Chatterjee and Creisler 1994; Bandyopadhyay and Sengupta

2006; Spielmann et al. 2006; Kammerer et al. 2016). This is the

only well-described Upper Triassic tetrapod assemblage from the

Pranhita-Godavari Valley. It includes Parasuchus and

Metoposaurus, taxa indicative of an Otischalkian (middle-late

Carnian) age (Lucas 2010, 2018, 2020). Based primarily on its

stratigraphic position and a ‘Rutiodon-like’ phytosaur, the Upper

Maleri tetrapod assemblage may be Adamanian (late Carnian),

but needs further documentation for a definite age assignment

(Lucas 2010, 2018; Lucas et al. 2012).

The overlying Dharmaram Formation yields two stratigraphi-

cally discrete vertebrate fossil assemblages (lower and upper). The

lower assemblage has not been published, and it includes

a phytosaur that Kutty and Sengupta (1989, Table 2) list as

Nicrosaurus, aetosaurs, including a so-called ‘Paratypothorax-like’

form, and prosauropod dinosaurs. Based primarily on the potential

Nicrosaurus record, Lucas (2010, 2018) considered the lower assem-

blage of the Dharmaram Formation a possible Revueltian (early-

middle Norian) correlative, but this is a very tentative conclusion.

A similar tentative conclusion is to assign the lower Dharmaram

assemblage a younger, late Norian-Rhaetian age (Novas et al. 2011).

HISTORICAL BIOLOGY 7

The upper assemblage from the Dharmaram Formation is also

tentatively assigned an Early Jurassic age (see below).

Jurassic dinosaurs

Upper Dharmaram Formation

As noted above, the Dharmaram Formation contains two vertebrate

fossil assemblages, a lower assemblage of Late Triassic age (see

above) and an upper assemblage assigned an Early Jurassic age

(Bandyopadhyay and Sengupta 2006). The invertebrate fauna and

the flora of the Upper Dharmaram Formation include ostracods,

charophytes and pollen, and the vertebrate fauna includes semio-

notid fishes (Lepidotes, Parapedium, and Tetragonolepis),

a coelacanth (Indocoelacanthus robustus), teleosaurid crocodiles,

turtles, lizards, sauropod dinosaurs, a fish (‘Campylognathoides

indicus’), and mammals (Jain et al. 1975; Rudra 1982; Loyal et al.

1996; Nath et al. 2002). The Upper Dharmaram Formation has

yielded three sauropodomorph dinosaurs, Lamplughsaura dhar-

maramensis, Pradhania gracilis, and an indeterminate taxon

(Tables 2, 3, Kutty et al. 2007).

Lamplughsaura dharmaramensis (Kutty et al. 2007) is a heavily

built quadruped measuring about 10 m in length (with a small head,

long neck, large appendages, and a long tail) known from an incom-

plete postcranial skeleton of an adult individual and partially preserved

skulls of four individuals (Kutty et al. 2007). Also included are a nearly

complete vertebral column (all cervical vertebrae, eight dorsal neural

arches and four centra, a sacral neural arch, eleven caudal vertebrae),

four dorsal ribs, five chevrons, the shoulder girdle (scapulae, left sternal

plate), much of the fore-limb (left and right humeri, left radius, right

ulna, two metacarpals, manus), pelvic girdle (right ilium, left and right

ischia), and hindlimb (right femur, left tibia, fibulae, astragalus, calca-

neum and metatarsal III) (Kutty et al. 2007). The diagnostic features

include teeth with coarse denticles that are few or missing on the mesial

edges, as well as the caudal cervical neural spines that bear an upward-

directed ligamentous wrinkle on the cranial and caudal surfaces and

a transversely protracted spine table (Kutty et al. 2007). The caudal

neural spines are shorter than the transverse processes. The descending

caudal flange at the distal end of the tibia covers 66% of the astragalar

transverse width (Kutty et al. 2007).

Kutty et al. (2007) established Lamplughsaura (Figure 7) and

described it as a large, robust sauropod with a small head, a long

and flexible neck, an unbending and curved trunk, deep ribs, long,

vertically held appendages, and a long tail. The humerus is huge

with a strong yet low deltopectoral crest. The sturdy ulna and

manus are robust and short. Lamplughsaura’s forelimb was stout

and long, equivalent to about 74% of the length of the hindlimb.

This indicates that Lamplughsaura had the long forelimbs charac-

teristic of sauropods (Upchurch 1998; Upchurch et al. 2004). To

create a narrow trackway, the elbow was perhaps turned back and

the knee forward. Lamplughsaura’s graviportal posture is associated

with the development of a straight shaft in both the femur and the

humerus (at least in caudal view), with the limbs offering direct

vertical support (Kutty et al. 2007). The long and robust forelimb

shows that Lamplughsaura was most likely a habitual quadruped,

with graviportal parasagittal appendages and a digitigrade posture,

yet not a runner (Kutty et al. 2007). Phylogenetically, initial results

indicated that Lamplughsaura is either a basal sauropod or, more

uncertainly, a stem sauropodomorph (Kutty et al. 2007). It bridges

a morphological gap between bipedal plateosaurids like Pradhania,

and four-legged, long-necked sauropods such as Barapasaurus and

Kotasaurus (Chatterjee 2020).

Pradhania gracilis is a relatively small (4 m long) sauropodomorph

known from fragmentary material consisting of a couple of cranial

elements, vertebrae (two cervicals, one sacral), and an incomplete left

manus (Kutty et al. 2007). The maxilla has a prominent longitudinal

ridge medially that is wide rostrally, and isolated from the premaxillary

suture by a deep, vertical groove. There are 20 alveoli, all empty except

three in which small, erupting teeth are present (Kutty et al. 2007).

Phylogenetically, the precise position of Pradhania gracilis is

currently uncertain, but it is certainly a stem sauropodomorph

(Kutty et al. 2007). Chatterjee (2020) recently concluded that

P. gracilis is a massospondylid sauropodomorph similar to

Massospondylus of South Africa, and more derived than

Riojasaurus of Argentina.

Additional dinosaur skeletal material from the Upper

Dharmaram Formation belongs to Sauropodomorpha incertae

sedis (indeterminate genus and species). Phylogenetically, this saur-

opodomorph, represented by the proximal portion of a femur, is

more derived than Saturnalia (Brazil) and Thecodontosaurus (Great

Britain) from the Upper Triassic (Kutty et al. 2007).

Age of the Dharmaram Formation

Previously, the Upper Dharmaram was considered Late Triassic in

age (Kutty and Sengupta 1989). However, Bandyopadhyay and

Roy-Chowdhury (1996) proposed that the Upper Dharmaram is

Early Jurassic because it lacks typical Triassic tetrapods (e.g. phy-

tosaurs, aetosaurs, metoposaurs), and is similar to other faunas of

Early Jurassic age.

The tetrapod assemblage of the Upper Dharmaram Formation

has even been assigned ages of Hettangian (Bandyopadhyay and

Sengupta 2006; Bandyopadhyay and Ray 2020) or Sinemurian

(Bandyopadhyay and Roy-Chowdhury 1996; Kutty et al. 2007),

but these stage-level age assignments lack justification. The age

assignments are very much based on the stage of evolution of

a few taxa in the Upper Dharmaram assemblage –

a sphenosuchid, plateosaurid and possible ornithischian – none of

which have been documented. We tentatively assign an Early

Jurassic age to the Upper Dharmaram vertebrates, but no more

precise age assignment is possible with current data.

Kota Formation

The Dharmaram Formation is overlain by the Kota Formation

(Tables 1 and 2). Various workers, such as King (1881), Kutty

(1969), Rudra (1982), Bandyopadhyay and Rudra (1985),

Raivarman et al. (1985), Kutty et al. (1987), Lakshminarayana

(1994, 2002), Sengupta (2003) and Bandyopadhyay and Sengupta

(2006), have provided geologic and stratigraphic information about

the dinosaur-rich Kota Formation. The Kota Formation is a tripartite

stratigraphic unit composed of marl and limestone on top of silt-

stone-mudstone beds, followed by mudstone and ferruginous shale

interbedded with sandstone.

Thus, Lakshminarayana (1994), divided the Kota Formation

into three members: lower, middle, and upper. The lower member

is made up of sandstone and red clays with banded chert pebbles,

and Bandyopadhyay and Sengupta (2006) stated that the lower

portion of the Kota is composed of a thick, hard, compact, and

coarse pebbly sandstone that grades laterally and vertically into

finer siltstone and mudstone. Limestone makes up the middle

member (Lakshminarayana 1994; Chinnappa et al. 2019). The

upper member is sandstone, siltstone, and claystone (Chinnappa

8A. KHOSLA AND S. G. LUCAS

Figure 5. Line drawings of selected bones from the Late Triassic Upper Maleri Formation of India, including the holotype (G – J), small (L – M), and large (A – F, K) paratype

specimens of Nambalia roychowdhurii (Novas et al. 2011). Right lateral images of the mid-caudal vertebra (A), posterior caudal vertebrae (B, C), left manual digits I (D) II (E)

and III (F) in medial views (D – F); right ilium in lateral view (G), left femur in anterior (H) and distal (I) views; left tibia, ﬁbula, astragalus, and calcaneum in anterior view (J);

left foot in anterior view (K); and left astragalus in ventral (L) and anterior (M) views. Abbreviations: X-#=phalanx X-#; aig=anterior intercondylar groove; apa=ascending

process of the astragalus; at=anterior trochanter; aw=acetabular wall; ca=calcaneum; clg=collateral groove; dIV=digit IV; fh=femoral head; ﬁ=ﬁbula; ft=ﬂexor tubercle;

isp=ischial peduncle; mttI–V=metatarsals I – V; ns=neural spine; pap=pit on the anterior surface of the ascending process; poap=postacetabular process; prap=pre-

acetabular process; prz=prezygapophysis; sac= supraacetabular crest; stc=sub-triangular medial condyle; ti=tibia; tp=transverse process. Scale bars = 2 cm (A – F); 5 cm

(G – M, modiﬁed after Novas et al. 2011. All the abbreviations are after Novas et al. (2011).

HISTORICAL BIOLOGY 9

Figure 6. Line drawings of few bones from the dinosaur specimens found in India’s Upper Maleri Formation during the Late Triassic. (A – D) Jaklapallisaurus asymmetrica

(Novas et al. 2011), ISI R274:(A) Anterior view of the right hindlimb; (B) distal view of the femur; (C) proximal view of the tibia; and (D) distal view of the astragalus. (E) ISI

R277, lateral view of the right ilium. (F) ISI R277, anterior view of the right femur; (G) ISI R282, lateral view of the right pelvic girdle, and sacrum. Abbreviations: 1sa=ﬁrst

sacral vertebra; 3sa=third sacral vertebra; X-#=phalanx X-#; amc=anterior projection of the medial condyle; apa=ascending process of the astragalus; as=astragalus;

at=anterior trochanter; aw=acetabular wall; bf=brevis fossa; bs=brevis shelf; cc=cnemial crest; fc=ﬁbular condyle; fe=femur; fh=femoral head; isp=ischial peduncle;

mc=medial condyle; mttI+IV=metatarsals I+IV; obf= obturator foramen; p=pubis; pf=popliteal fossa; poap=postacetabular process; pp=pubic peduncle; prap=preace-

tabular process; sac=supraacetabular crest; tc=tibial condyle; ti=tibia. Scale bars = 5 cm (A – D, G); 2 cm (E, F, modiﬁed after Novas et al. 2011. All abbreviations are after

Novas et al. (2011).

10 A. KHOSLA AND S. G. LUCAS

et al. 2019). According to Rudra and Maulik (1994), the lower part

of the Kota Formation was formed by a meandering river system,

while the upper part was formed by a braided river system, whereas

the limestone facies were construed as a lacustrine deposit.

The lower member of the Kota Formation produced the basal

sauropods Barapasaurus tagorei (Jain et al. 1975, 1979;

Bandyopadhyay et al. 2010) and Kotasaurus yamanpalliensis

(Yadagiri 1988, 2001), and a thyreophoran ornithischian, regarded

by some as an ankylosaur (Table 3, Nath et al. 2002; Galton 2019),

as well as mammals such as Kotatherium haldanei (Datta 1981) and

Indotherium pranhitai (Yadagiri 1984) (=Indozostrodon simpsoni

Datta and Das 2001, Prasad and Manhas 2007). Semionotid fishes,

Table 5. Generalized stratigraphic table of Kachchh area (Gujarat, western India) showing the dinosaur-bearing formations (modiﬁed after Karanth and Gadhavi 2007).

Age

Series (Biostratigraphic

units)

Formation (Lithostratigraphic units)

with references Lithology

Upper Cretaceous- Early

Palaeocene

Deccan Traps

Lower Cretaceous Umia Bhuj Sandstone and shale

Upper Jurassic Katrol Jhuran Sandstone and shale

Middle Jurassic Chari

Patcham

Khadir

Jumara (Sauropod bone, Jana and

Das 2002)

Jhurio

Khadir (Camarasauromorph sauropod,

Moser et al. 2006)

Dinosaur bones (Satyanarayana et al.

1999)

Coral limestone, oolitic limestone, shale, marl, sandstone, conglomerate

Shale, limestone

Variegated to dark red argillaceous siltstone, ﬁne- to medium- grained

crossbedded sandstone, clay and marl

Sandstone, shale, limestone, conglomerate

Precambrian basement

not exposed

Table 4. Generalized stratigraphic table of Jaisalmer area showing the dinosaur-bearing formations in Rajasthan (modiﬁed after Pandey and Fürsich 1994; Rai and Garg

2007; Bajpai et al. 2023; Sharma et al. 2023a, 2023b).

Age Formation Member with references Lithology and facies

Cretaceous Habur Marine coquinoidal limestone and sandy limestone

Cretaceous Pariwar Sandstone and shale alternation with plant fossils and fossilised tree trunk

Upper

Jurassic

Bhadasar Mokal

Kolar Dunger

Coarse to ﬁne-grained sandstone, marine in the lower part grading into nonmarine

sequence at the top

Upper

Jurassic

Baisakhi Rupsi

Ludharva

Baisakhi

Marine shale and sandstone alternations

Middle to

Upper

Jurassic

Jaisalmer Kuldhar

Badabag (Spinosaurid pedal ungual

phalanax, Sharma et al. 2023b)

Fort (Tharosaurus indicus, Theropod teeth,

Bajpai et al. 2023; Sharma et al. 2023a)

Joyan

Hamira

Marine carbonate facies: Lithology: Shale, sandstone, siltstone, argillaceous marl,

arenaceous limestone, siliceous limestone, calcareous sandstone and mudstone,

limestone, bioclastic intraformational conglomerate

Lower

Jurassic

Lathi Thaiat

Odania

Sandstone with plant fossils

Proterozoic Older

sediments

Figure 7. Skeletal reconstruction of Lamplughsaura dharmaramensis (Kutty et al. 2007). Note that the majority of dorsal and caudal vertebrae, ribs and chevrons, upper

piece of ilium, and distal ischium are reinstated and based on those bones in close relatives (line drawing of the skeleton, modiﬁed from Kutty et al. 2007; Khosla and Bajpai

2021). Bones are well-preserved and are shaded.

HISTORICAL BIOLOGY 11

pterosaurs, crocodiles, and turtles are also present. The upper

member’s claystones yield plant fossils, whereas the lower member’s

siltstones and fine-grained sandstones yield fossil wood.

Thus, three distinct dinosaur species have been found in the

Kota Formation. Numerous postcranial bones from at least six

individuals of the large basal sauropod Barapasaurus tagorei make

up the best-known Kota dinosaur (Figures 8 and 9). Bones were

first found in 1958, but the majority of the specimens were dis-

covered in 1960 and 1961 (Bandyopadhyay et al. 2010). Jain et al

(1975, 1979) described the initial discoveries, and Bandyopadhyay

et al. (2010) provided a thorough osteological description. To date,

the skeletal material is kept at the Indian Statistical Institute’s (ISI)

palaeontological collection, whereas the majority of the bones are

on display at the ISI’s Geological Museum as part of a mount

(Figures 8 and 9, Bandyopadhyay et al. 2010).

Barapasaurus is known only from the Kota Formation. More

than 300 bones have been collected in a layer associated with huge

fossilised tree trunks at the interface of mudstone and sandstone

layers occupying an area of about 277 m

(Bandyopadhyay et al.

2010). Although one of the specimens was partially articulated, the

majority of the bones were found to be disarticulated. The mini-

mum number of individuals in the fossil assemblage is at least six

because there are six left femora (Bandyopadhyay et al. 2010).

Taphonomically, this assemblage is interpreted as a ‘herd’ that

died as a result of a catastrophic event, almost certainly a flood

(Bandyopadhyay et al. 2002, 2010). This flood may have exhumed

the trees and transported them and the Barapasaurus bones a long

distance before decomposition occurred. The bones began to dis-

articulate as decomposition progressed. Because of the disarticula-

tion of the relatively small and light skull bones, the current

removed them, leaving only the massive postcranial bones at the

location, which explains why no skull bones were recovered

(Bandyopadhyay et al. 2010).

Barapasaurus achieved a large size (an estimated length of 14 m)

and was completely quadrupedal, with graviportal and columnar

appendages (Figures 8 and 9). The teeth are spoon-shaped with

coarse denticles and are characterised by bulbous pits and grooves

with respect to the anterolabial and posterolingual sides of the

crown (Jain et al. 1975; Bandyopadhyay et al. 2010). Coarse tuber-

cles are present on the carina. It has cranial and dorsal vertebrae.

The dorsal neural spines are composed of spino-postzygapophyseal

and spinodiapophyseal laminae. The neural canal (mid-dorsal ver-

tebrae) opens dorsally through a restricted cut into an enormous

hole, and the sacrum has four co-ossified vertebrae

(Bandyopadhyay et al. 2010). The scapula is well preserved with

a high and thin blade. The coracoid is subcircular, and the ilium

possesses a well-developed anterior process and subrectangular

ischial peduncle (Bandyopadhyay et al. 2010). The ischium is rela-

tively slender and rod-like distally, and the pubis has a well-

developed terminal expansion (Bandyopadhyay et al. 2010). The

tibia is short and stout (Jain et al. 1975; Bandyopadhyay et al. 2010).

The humerus expands equally at the distal and proximal ends with

a protuberant deltopectoral crest and the ulna more robust than the

radius; the triradiate proximal end of the ulna has a deep radial

fossa (Jain et al. 1975, 1979; Bandyopadhyay et al. 2002, 2010;

Gillette 2003).

Barapasaurus shows numerous primitive characters that are

absent in later sauropods (Chatterjee 2020). However, the rela-

tionship of Barapasaurus within the Sauropoda has been a point

of contention. It was not assigned to any sauropodomorph group

when it was first identified by Jain et al (1975), despite the

presence of many primitive, prosauropod-like characteristics.

Barapasaurus has also been associated with another early saur-

opod, Vulcanodon. Initially, Barapasarus was considered similar

to the Middle Jurassic Shunosaurus from China and Patagosaurus

from Patagonia (Bandyopadhyay 1999). However, Upchurch

(1995) deemed the Vulcanodontidae to be polyphyletic. Except

for some very primitive taxa, Upchurch (1995) created the clade

Eusauropoda, which comprises all recognised sauropods.

Vulcanodon was placed outside the Eusauropoda, whereas

Barapasaurus was placed within it, indicating that Barapasaurus

is more derived than Vulcanodon (Upchurch et al. 2007).

Figure 8. Diagram showing the left side of the mounted skeleton of Barapasaurus tagorei (Jain et al. 1975, 1979) at the Indian Statistical Institute in a modern stance with

an extended tail (adapted and modiﬁed from Bandyopadhyay et al. 2010).

Figure 9. Barapasaurus tagorei (Jain et al. 1975). Mounted manus in anterior view

(adapted from Bandyopadhyay and Ray 2020).

12 A. KHOSLA AND S. G. LUCAS

However, a more recent phylogenetic investigation indicates that

Barapasaurus is a basal sauropod with Vulcanodon, so it has been

removed from Eusauropoda (Bandyopadhyay et al. 2002, 2010).

The Kota Formation has also yielded bones of a second saur-

opod, Kotasaurus yamanpalliensis (Yadagiri et al. 1979; Yadagiri

1988, 2001). It is a basal sauropod that is more modest in size (body

length 9 m) and more primitive than Barapasaurus tagorei

(Upchurch et al. 2004; Chatterjee 2020). Initially, Kotasaurus was

described based on dorsal vertebrae and an iliac blade (Yadagiri

1988). The sauropod dinosaur K. yamanpalliensis is represented by

fossils of more than 12 individuals (Figures 10 and 11) and known

to have been a large, quadrupedal herbivore with a long neck and

tail like all sauropods (Yadagiri 2001).

With the exception of two teeth, the majority of the skeleton of

Kotasaurus is known, although the skull is not known (Yadagiri

1988, 2001). It is known primarily from 12 individuals and includes

well preserved, isolated cervical vertebrae, dorsal vertebrae, and the

limb girdles. The sacrum is well preserved, and the second sacral rib

is extensive; dorsally, it has a wing-like robust projection that arises

from the neural arch. The rib is much expanded in distal view

(Yadagiri 2001). Other diagnostic characteristics include the pre-

sence of a thin proximal surface to the scapula, comparatively

slender appendage bones, and, in the caudal vertebrae, ‘v’- shaped

chevrons with sharp articular facets on their dorsolateral corners.

The humerus shows a contracted shaft with extended ends. The

proximal end is more extended than the distal (Yadagiri 2001).

A solid deltopectoral crest is well developed and encompasses the

upper portion of the lateral edge of the anterior face of the humerus.

The radius is long and slender with an oval proximal articular

surface. The incomplete left pubis has the iliac symphyseal region

and shaft preserved (Yadagiri 2001). The femur retains the lesser

trochanter and is a comparatively thin, columnar bone measuring

130 cm in length. It has a straight shaft that is oval in cross-section

(Yadagiri 2001). The comparatively short and somewhat twisted

humeri, on the other hand, as well as the retention of a lesser

trochanter on the femur, are basal sauropod traits (Yadagiri

2001). The vertebral centra are enormous, in contrast to those of

the coeval Barapasaurus, which display more hollowing of the sides

as a weight-saving technique, though without pneumatisation

(Yadagiri 2001).

Kotasaurus is one of the most primitive sauropods yet discov-

ered. The body plan was that of a normal sauropod, yet it resembled

prosauropods in numerous plesiomorphic traits (Yadagiri 2001).

According to Glut (1997) it was once unclear if Kotasaurus was

a sauropod or a basal sauropodomorph that needed to be placed

outside of Sauropoda. However, some palaeontologists group it

with Barapasaurus and the fragmentary Zizhongosaurus and

Ohmdenosaurus in the Vulcanodontidae. This family is now

thought to be paraphyletic (Yadagiri 2001; Upchurch et al. 2007).

Kotasaurus is more basal phylogenetically than Barapasaurus and

Vulcanodon but more derived than Chinshakiangosaurus,

Antetonitrus, and Jingshanosaurus, according to the analysis by

Bandyopadhyay et al. (2010).

The third Kota Formation dinosaur is a thyreophoran

ornithischian (Nath et al. 2002) assigned to Ankylosauria by Galton

(2019). The recovered material includes parts of a skull (mandible),

which does not display sutures, and its external surface exhibits pitted

ornamentation. The symphysis of the mandibles is closely placed due

to compression. The material also includes teeth, a large number of

body armour plates, dorsal and caudal vertebrae and parts of pectoral

girdle bones (Nath et al. 2002). Wilson and Mohabey (2006) regarded

these bones as crocodilian, but Galton (2019) considered the armour

to be ankylosaurian, and we accept Galton’s conclusion.

Prasad and Parmar (2020) documented various morphotypes of

ornithischian and theropod (mostly dromaeosaurid) teeth from the

Kota Formation. Based on qualitative morphological examinations

of isolated teeth, they recorded five morphotypes: a Richardoestesia-

like form, Dromaeosauridae indet. and ornithischians, and one

morphotype of Theropoda indet. Prasad and Parmar (2020) noted

similarities in the teeth they described to Middle Jurassic teeth from

the United Kingdom to advocate a Middle Jurassic age for the Kota

Formation.

Yadagiri (1982) described, in an unpublished Geological Survey

of India progress report, fragmentary material from the Early

Jurassic Kota Formation, including an isolated tooth referred to as

the new taxon Dandakosaurus indicus (Yadagiri 1982; Sharma et al.

Figure 10. Kotasaurus bone distribution at the Yamanpalli excavation site. Scale = 1 m (adapted from Yadagiri 2001).

HISTORICAL BIOLOGY 13

2023a). The other material includes a proximal pubis and referred

lateral tooth, dorsal vertebra, proximal caudal vertebra and prox-

imal ischium (Yadagiri 1982). The theropod dinosaur

Dandakosaurus (meaning ‘Dandakaranya lizard’) comes from the

Kota Formation in Andhra Pradesh, India. Currently categorised as

Averostra incertae sedis, there have been conflicting suggestions

that it is a primitive tetanuran or a ceratosaur. The fragmentary

pubis, GSI 1/54Y/76, which was found between 1958 and 1961 and

classified as a carnosaur in 1962, is the holotype. Yadagiri desig-

nated the type species, D. indicus, in 1982. The genus is poorly

understood due to nondiagnostic material, and some palaeontolo-

gists even regard it as a nomen dubium. Its pubis is noteworthy in

and of itself since it seems to have a vertical pubis as opposed to

forward-facing, as in the ‘saurischian’ hip type, or backward-facing,

as in the ‘ornithischian’ hip type. Given that ‘ornithischian’ hip

types evolved more than once within the group, it may not be

possible to classify ‘Dandakosaurus’ beyond identifying it as

a theropod closely connected to megalosauroids.

Age of the Kota Formation

The Kota Formation contains two vertebrate assemblages, lower and

upper. The dinosaurs are known only from the lower assemblage,

together with mammal fossils. The upper assemblage is much more

diverse, consisting of semionotid, pholidophorid and coelacanthid

fishes, a turtle, a pterosaur, sphenodonts, lepidosaurs, and diverse

mammals (see Bandyopadhyay et al. 2010, Table 3). The Kota

Formation tetrapod assemblages have been assigned an Early Jurassic

age based largely on the associated fish fossils or to the Middle Jurassic

based on the stage of evolution of some of their tetrapods. Specific age

assignments for the lower Kota are Sinemurian-Pliensbachian, and for

the upper Kota are Toarcian-Aalenian (Bandyopadhyay and Ray

2020), but we see no basis for stage-level age assignments. Other age

assignments, some as young as Early Cretaceous, are also in the

literature (see Chinnappa et al. 2019, Table 2 for a listing of the diverse

ages assigned to the Kota Formation).

Most vertebrate palaeontologists regard the Kota Formation verte-

brate assemblages as of the Early Jurassic age (Nath et al. 2002; Gillette

2003; Weishampel et al. 2004; Lucas 2009). Apparent support for this

comes from the supposed presence of the fish Campylognathoides, also

known in Liassic strata in Holzmaden, Germany, but the Indian

material assigned to Campylognathoides belongs to a fish, not

a pterosaur, e.g. Alarcón-Muñoz et al. (2021). Evans et al. (2001)

described the rhynchocephalians from the upper Kota as two new

endemic genera. They noted that rhynchocephalians were widely dis-

tributed across Pangaea during the Late Triassic, including Gondwana

records in Brazil and South Africa. Evans et al. (2002) described

a primitive acrodont iguanian lizard from the upper Kota (also see

Yadagiri 1986). The other oldest known lizard is from the Middle

Jurassic (Bathonian) of England, but Middle Jurassic lizard diversity

indicates the likely presence of older lizard records. The triconodont

Dyskritodon from the Kota Formation (Prasad and Manhas 2007) is

also known from the Lower Cretaceous of Morocco (Sigogneau-

Russell 1995).

Kota Formation palynomorphs have been considered Early

Jurassic (Prabakhar 1989) or Middle Jurassic-Early Cretaceous

(Callovian-Barremian) age (Vijaya and Prasad 2001). Kota macro-

floras have been considered Late Jurassic to Early Cretaceous (?) in

age (Chinnappa et al. 2019). Charophytes have been considered

Early Jurassic (Bhattacharya et al. 1994), and ostracods Middle

Jurassic (Govindan 1975; Misra and Satsanji 1979).

The upper Kota Formation fish have been compared to Early

Jurassic fish assemblages from Europe that share the genera

Tetragonolepis, Lepidotes and Pholidophorus (Yadagiri and Prasad

1977; Jain 1980, 1983). Patterson and Owen (1991) argued that they

may reflect a Toarcian transgression in Tethys that enabled similar fish

to live in the United Kingdom.

The Kota sauropod Barapasaurus has been compared to the

Middle Jurassic sauropods Patagosaurus from Argentina and

Shunosaurus from China (Bandyopadhyay 1999; Gillette 2003),

leading Bandyopadhyay (1999) to suggest that the age of the Kota

may extend into the Middle Jurassic. At the stage of evolution of the

theropod and ornithopod teeth, the sauropods Barapasaurus and

Kotasaurus are considered compared to Cetiosaurus, and the sphe-

nodonts have also been suggested to indicate a Middle Jurassic age

(Evans et al. 2001; Prasad and Parmar 2020). Outside of India, the

oldest ankylosaur fossils are of Middle Jurassic age. Wills et al.

(2023) recently argued that the oldest maniraptoran dinosaur fossils

Figure 11. Mounted skeleton of Kotasaurus yamanpalliensis (Yadagiri 1988, 2001).

Adapted from Bandyopadhyay and Ray (2020).

14 A. KHOSLA AND S. G. LUCAS

are of Middle Jurassic age, and they included the Kota Formation

dromaeosaurids documented by Prasad and Parmar (2020) in that

age assignment. Prasad and Manhas (2007) described a Kota doc-

odont tooth that, if Early Jurassic, would be the oldest docodont.

A Middle Jurassic age thus seems the most defensible assign-

ment for the Kota Formation vertebrate-fossil assemblages. The

vertebrates support such an age assignment, though their support

comes primarily from correlations based on stage of evolution, not

on shared low-level taxa. Thus, we consider the Kota Formation

tentatively to be of Middle Jurassic age but make no more precise

age assignment.

Other Indian Jurassic dinosaur records

Apart from the Pranhita-Godavari valley, fragmentary remains of

dinosaur skeletal material of Middle Jurassic age have been found in

two locations in the Rajasthan’s Jaisalmer region (Figure 12) and

four locations in Gujarat’s Kachchh region. The only Indian

Jurassic dinosaur tracks were published by Pieńkowski et al.

(2015), who documented theropod tracks they assigned to

Eubrontes and Grallator from tidal sediments of the Thaiat

Member of the Lathi Formation at Thaiat Ridge on the Jaisalmer-

Jodhpur Highway. Overlying marine strata have the Bajocian coral

Isostrea bernardiana, so it is likely these tracks are Bajocian. These

are the oldest dinosaur tracks reported from India.

Mathur et al. (1985) reported Middle Jurassic dinosaurs from the

Jaisalmer District in Rajasthan (Western India), but Weishampel

et al. (2004) listed them as of Late Jurassic age (cf. Moser et al.

2006). Earlier, Pandey and Fürsich (1994) stated that those frag-

mentary remains of dinosaurs were likely recovered from the

Kuldhar Oolite Member of the Jaisalmer Formation (of Callovian

age, based on its ammonite fauna).

Sharma et al. (2023a) recently documented an incomplete

theropod tooth they identified as a non-coelurosaurian averos-

tran (turiasurian, Table 4). This fossil came from the Fort

Member of the Jaisalmer Formation 20 km east of Jaisalmer

City, strata of likely early-middle Bathonian age, as the overlying

Badabag Member has late Bathonian ammonites (Pandey et al.

2012). Nonetheless, the sedimentary succession in the fossil area

more likely belongs to the Lathi Formation of Bajocian or pre-

Bajocian age (Moser et al. 2006). A cladistic analysis performed

by Sharma et al. (2023a) of a dentition-based data matrix

revealed that the isolated crown was most likely from a non-

coelurosaurian averostran, and may be from the mesial dentition

of a ceratosaurid, allosauroid, or a non-spinosaurid megalosaur-

oid. This tooth demonstrates the existence of at least one species

of medium- to large-sized theropod on the Tethyan coast of

northwest India during the Middle Jurassic.

Sharma et al. (2023b) also recently reported the discovery of

a single, complete pedal ungual phalanx from the Middle Jurassic

marine carbonate rocks of Rajasthan, in northwest India’s Jaisalmer

Basin (Tables 3, 4). The ungual bone has a shallow semi-circular

excavation, is almost straight in lateral view, is triangular in form,

pointed, elongated, asymmetrical, dorsoventrally compressed, and

ventrally flat. The diagnostic characteristics and proportions have

a striking resemblance to the pedal ungual phalanges of spinosaurid

theropods, which are mostly recognised from the Cretaceous. The

results of bivariate and multivariate analysis support the connection

to spinosaurids (Sharma et al. 2023b). Thus, classified as

Megalosauroidea, the ungual phalanx is hypothesised to be

a basally branching Jurassic spinosaurid. Given the geographical

and stratigraphic provenance, this recent discovery by Sharma et al.

(2023b) is likely the earliest known example of a spinosaurid.

The skeletal components from the Jaisalmer area include

a couple of large bones and a number of scutes that were identified

as dinosaurian based on bone histology, structure and sedimentary

facies. According to Moser et al. (2006) the scutes (?) might indicate

a basal thyreophoran dinosaur, or they could be from sauropods or

crocodylomorphs. Mathur et al. (1985, p. 61) also noted the pre-

sence of a crocodilian vertebra, though the huge size of some of the

osteoderms (for instance, 15 cm across and 2 cm thick) is likely

indicative of a dinosaurian affinity (Moser et al. 2006).

Kachchh (Gujarat) is the traditional site for studying Jurassic

dinosaurs in western India. The coarse-grained sandstone and

conglomeratic strata of the Dingi Hill Member of the Kaladongar

Formation at Kuar Bet, Patcham Island, have been found to include

fragmentary dinosaur skeletal remains, including vertebrae and

limb parts, as well as huge petrified trees, and are of Middle

Jurassic age (Table 5, Ghevariya and Srikarni 1992; Pandey and

Dave 1993; Satyanarayana et al. 1999). The Kaladongar Formation

is a 450-m-thick succession consisting of mixed siliciclastic-carbo-

nate sediments intercalated with shales, and this formation encom-

passes six different facies such as micritic mudrock, micritic

sandstone, muddy micrite, sandy micrite, allochemic sandstone

and sandy allochemic limestone (Joseph et al. 2012). The deposi-

tional environments of the dinosaur-bearing strata of the

Kaladongar Formation are nearshore marine and foreshore to off-

shore under varying wave and current energy conditions, according

to sedimentological and trace fossil studies (Satyanarayana et al.

1999; Joseph et al. 2012). The dinosaur bones are found in marine

strata with ammonites of Middle Jurassic age.

From Bathonian strata of the Patcham Formation on Patcham

Island, Ghevariya and Srikarni (1994) reported sauropod caudal

vertebrae and a pelvic girdle and indeterminate teeth, bones, and

eggshell. The overlying Middle Jurassic (Callovian) Chari

Formation, which is 200 m thick and largely made of sandstone,

shale, and limestone, has yielded the proximal part of a sauropod

tibia from Jumara, Kachchh Mainland (Figure 13 and Table 5, Jana

and Das 2002). The bone was discovered in marine strata together

with ammonites in what is interpreted as warm, shallow marine

shelf facies (Jana and Das 2002). The ammonites belong to the

Reineckeia anceps Zone of middle Callovian age.

Fragmentary postcrania of large (up to 20 m long or more)

sauropods of Middle Jurassic (Bajocian) age have also been recov-

ered from the Khadir Formation of Khadir Island in Kachchh

(Table 5, Figure 14, Moser et al. 2006). The bone-bearing stratum

is in the Haibhalange Shale Member, strata with Bajocian bivalves

and ammonoids and about 150 m below strata with the late

Bajocian ammonite Leptosphinctes (Fürsich et al. 2001). The dino-

saur material consists of a metacarpal, a first pedal ungual and

a fibula, which can be assigned with certainty to the

Camarasauromorpha (Tables 3, 5) and is the best-established

record of that dinosaur group in India.

The findings from the Gujarat area close a temporal and geo-

graphical gap in our insight into sauropods and add to our under-

standing of their early phylogenetic relationships (Moser et al.

2006). The nine dinosaur bones recovered from Khadir Island

belong to sauropods, and three of them can be compared to parti-

cular sauropod genera more closely. The metacarpal shows simi-

larity to three sauropods, namely, Camarasaurus, Brachiosaurus,

and Janenschia, whereas the claws look like the claws of

Brachiosaurus. The fibula is similar to that of Camarasaurus.

Current phylogenetic analyses of sauropods, Brachiosauridae,

Camarasauridae, and Titanosauria have been grouped together in

the Camarasauromorpha (e.g. Salgado et al. 1997; Upchurch et al.

2004; Moser et al. 2006), and the Khadir Island fossils can be

referred to this group. The Indian Middle Jurassic record of

HISTORICAL BIOLOGY 15

Camarasauromorpha is well dated and may be the earliest record of

that taxon.

Bajpai et al. (2023) recently named Tharosaurus indicus, the

first known dicraeosaurid sauropod fossil from western India

(Tables 3 and 4), for fossils from the Middle Jurassic (early-

middle Bathonian) strata of the Jaisalmer Basin, Rajasthan.

Fossils were collected from a shale block at the base of the early-

middle Bathonian Fort Member. The fossils comprise disarticu-

lated but related axial skeleton specimens collected over an area

spanning about 25 m

(Bajpai et al. 2023). The incomplete anterior

Figure 12. (A) Location map of the dinosaur-bearing Jaisalmer area, Rajasthan; B) Geological map of the Mesozoic rocks of Jaisalmer Basin, Rajasthan, India (adapted and

modiﬁed after Sharma et al. 2023b); Chandoo Village Quarry Section (CVQS) is marked as a star; C) Lithostratigraphic section of Chandoo Village Quarry Section (modiﬁed

and adapted from Sharma et al. 2023b), showing vertebrate (dinosaur) fossil-bearing bioclastic rudstone horizons. Abbreviations: Mb, Member.

16 A. KHOSLA AND S. G. LUCAS

dorsal neural arch, middle/posterior neural spines, anterior dorsal

ribs, partial anterior and middle caudal vertebrae, and partial

anterior and middle cervical anterior condyle and right prezyga-

pophyses are all included in the holotype (RWR-241) material

(Bajpai et al. 2023).

Bajpai et al. (2023) established Tharosaurus founds based on

a combination of the following traits: The lamina of the middle/poster-

ior cervical centro-prezygapophyseal lamina is divided into two parts;

the medial branch connects to the intraprezygapophyseal lamina,

which is shared by all dicraeosaurids (Bajpai et al. 2023); the elliptical

middle/posterior cervical centroprezygapophyseal fossa is bordered by

pillar-like centropostzygapophyseal lamina, which is shared with the

dicraeosaurids Brachytrachelopan, Pilmatueia and Lingwulong (Bajpai

et al. 2023); the deep bifurcation of the cervical neural arch extends to

the dorsal margin of the neural canal and is shared by the dicraeosaur-

ids Pilmatueia and Amargasaurus (Bajpai et al. 2023); shared by the

Figure 13. Geographic location of Kutch (Kachchh) with Jumara (highlighted with a marked box) from which a sauropod bone from the Chari Formation was described. The

Rann of Kutch (Kachchh) is the patterned region (adapted from Jana and Das 2002).

Figure 14. Kachchh geographic map indicating the locations of Middle Jurassic dinosaur localities, including Khadir Island (adapted from Moser et al. 2006).

HISTORICAL BIOLOGY 17

dicraeosaurid Katedocus, the anterior condyle of the middle/posterior

cervical vertebrae is more rugose than the remainder of the centrum

(Bajpai et al. 2023); the bifid middle/posterior cervical neural spine, the

divided lateral fossa or pleuroceol on the cervical centra, and the paired

ventral fossae that extend up to the posterior margin of the centrum are

all shared with Flagellicaudata (Bajpai et al. 2023).

Tharosaurus offers fresh perspective on the variety of sauropods

found in India’s Gondwana strata and has significant ramifications

for the genesis and distribution of Neosauropoda. The new taxon,

which can be identified by parts of the axial skeleton, is phylogen-

etically related to the earlier-diverging dicraeosaurids and is the

world’s oldest diplodocoid. Palaeobiogeographic investigations of

Tharosaurus reveal that the new taxon is a relic of a lineage that

originated in India and rapidly expanded over the rest of Pangaea,

in contrast to the other Indian Jurassic sauropods.

Palaeobiogeographical implications of Indian Triassic and

Jurassic dinosaurs

At the genus and species level, all of India’s Triassic and Jurassic

dinosaurs are endemic taxa. Partly, this may be an artefact of the

alpha taxonomy of fragmentary material, but the taxonomic differ-

ences do appear significant in the more completely known dinosaurs.

Thus, inferences about biogeography of India’s Triassic-Jurassic

dinosaurs have to be made at the family level or higher taxonomic

levels. Furthermore, uncertainty about the precise geological ages of

many of India’s Triassic-Jurassic dinosaurs also hinders palaeobio-

geographical interpretation. Even so, some clear inferences can still

be drawn.

Triassic

There have been at least two views of tetrapod palaeobiogeography

across Late Triassic Pangaea. The traditional view is one of cosmo-

politanism, and whatever provinciality existed was the difference

between Laurasian archosaur-dominated assemblages and

Gondwanan therapsid-dominated assemblages (e.g. Romer 1966;

Cox 1973). More recent studies argue for a distinction between

Laurasian and Gondwanan tetrapod assemblages largely predicated

on floral differences or for provinciality driven by palaeolatitude

(zonal climate belts) (e.g., Ezcurra 2010; Whiteside et al. 2011).

Shubin and Sues (1991) inferred tetrapod cosmopolitanism dur-

ing the Middle Triassic followed by latitudinal variation that corre-

lated to long-recognised palaeofloral differences (e.g. Dobruskina

1995; Artabe et al. 2003). However, their correlation with tetrapod

assemblages (see especially Shubin and Sues 1991, Figure 3) is

fraught with inaccuracies (see Lucas 2018 for a detailed discussion

of the correlations). Furthermore, their analysis identifies India and

Madagascar as having affinities with the tetrapod assemblages of

Europe and North America, even though the floras of India and

Madagascar are Gondwanan (Dicroidium-dominated).

Whiteside et al. (2011) claimed latitudinal differences between

Late Triassic tetrapod faunas due to the differences between areas in

which sedimentation was driven by ~ 10 kyr cycles (cynodont-

dominated) and those driven by ~ 20 kyr cycles (procolophonid-

dominated). Their analysis was based on the tetrapod record of the

Newark Supergroup in which there is essentially no temporal over-

lap between older, cynodont-dominated assemblages and younger

procolophonid-dominated assemblages. Clearly, the differences

between these assemblages could be due to their different geological

ages, not to palaeolatituidinal differences.

Ezcurra (2010) analysed the palaeobiogeography of Triassic

tetrapods for three time slices: Middle Triassic, ‘Ischigualastian’

and ‘Coloradan’. Like Shubin and Sues (1991), his analysis

identified Middle Triassic cosmopolitanism. Interestingly, his ana-

lysis of the ‘Ischigualastian’ linked India and Europe but not North

America, despite the great similarity between North American and

European tetrapod assemblages at this time. In general, his analysis

employs too coarse of temporal resolution to identify meaningful

palaeobiogeographic differences.

The correlations advocated by Lucas (2010, 2018) indicate that

the strikingly distinct Late Triassic tetrapod assemblages are those

from the Berdyankian-Adamanian of South America. Whether or

not these assemblages, dominated by dicynodonts, represent dis-

tinct provinces or distinct facies, however, is difficult to determine.

Given the inland nature of deposition in the South American basins

that produce these assemblages, the possibility that they are just

representatives of the dicynodont-dominated biofacies seen earlier

in the Triassic needs to be entertained. Otherwise, the Late Triassic

tetrapod record seems to demonstrate much cosmopolitanism.

The Indian Triassic dinosaur record begins with Alwalkeria,

a basal saurischian of the Carnian age. If the correlations advocated

by Lucas (2010, 2018) are accepted, Alwalkeria is one of the oldest

dinosaurs, older than the South American Late Triassic dinosaurs

and the same age, within resolution, as the oldest North American

dinosaurs. It is part of a group of basal saurischians that evidently

had a Pangaean distribution. Despite claims that the oldest dino-

saurs are in South America and that dinosaurs originated there

(Langer et al. 2014), diverse data identify older dinosaurs outside

of South America (Lucas 2018).

Palaeobiogeographically, Alwalkeria is a small theropod, similar

to Syntarsus from Zimbabwe and North America, Coelophysis of

North America and Procompsognathus of Germany (Chatterjee

1987). India was an integral part of Gondwana during the Late

Triassic, thus a solid faunal connection among India and the

other Gondwana landmasses existed in Late Triassic time. But,

opposed to this, the Maleri fauna is clearly ‘northern’ in its affi-

nities. The Indian Late Triassic tetrapod assemblages, thus, are

more similar to coeval assemblages in North America, Europe and

Morocco (Chatterjee 1984, 1987; Ezcurra 2010). Thus, they support

a level of cosmopolitanism across much of Late Triassic Pangaea,

with South America as a distinct province or facies (cf. Ezcurra

2010; Lucas 2018). The Maleri Formation has yielded primitive

sauropodomorphs, Nambalia and Jaklapallisaurus, Alwalkeria is

the lone named Late Triassic omnivorous dinosaur species from

India, and the lower Dharmaram Formation has also yielded pri-

mitive sauropodomorphs.

All of the Indian Late Triassic tetrapod families known from the

Maleri Formation are also present in North America. The Chinle

Group fauna of North America is quite similar to the Maleri fauna,

and some genera (Malerisaurus, Parasuchus, Metoposaurus and

‘Typothorax’) are shared, further demonstrating a palaeontologic

and biogeographic connection among Late Triassic India and

Laurasia. Conceivably, the course of faunal dispersal between

India and North America during the Late Triassic was through

northern Africa (Figure 15, Chatterjee 1984, 1987). Indian Upper

Triassic vertebrate fossils show less resemblance to South American

fossils.

The earliest known Gondwanan dinosaur assemblages

(Ischigualastian) are not identical to those found in India, but

rather more diversified in South America (Novas et al. 2011).

Moreover, the Upper Maleri and Lower Dharmaram dinosaur

assemblages resemble putative coeval European and South

American dinosaur assemblages in terms of primitive sauropodo-

morph occurrence. Accordingly, the available data from the

Triassic beds of the Pranhita–Godavari Basin implies that dinosaur

diversity and abundance rose in this region of Gondwana in the

Late Triassic (Novas et al. 2011).

18 A. KHOSLA AND S. G. LUCAS

Together with Unaysaurus tolentinoi and Macrocollum itaquii,

the new study by Ezcurra et al. (2024) revealed Jaklapallisaurus

asymmetricus to be a member of Unaysauridae, at the base of

Plateosauria, from the early Norian of southern Brazil. Because of

the length of their ghost lineage, this phylogenetic conclusion

suggests that the spread of early plateosaurian sauropodomorphs

between the Southern Hemisphere and modern-day Europe would

have happened soon after Ischigualatian time (Ezcurra et al. 2024).

The reduction of a previously inferred diachrony between the

biogeographic dispersals of theropods and sauropodomorphs dur-

ing post-Ischigualatian periods is therefore caused by the presence

of early plateosaurians in the early Norian of South America and

India (Ezcurra et al. 2024).

The Maleri and Dharmaram dinosaurs fit into a picture of at

least some degree of dinosaur cosmopolitanism across Late Triassic

Pangaea, with primitive saurischians and/or theropods and primi-

tive sauropodomorphs found in eastern Gondwana (e.g. India),

western Gondwana (South America) and Euramerica. However,

the Indian Late Triassic dinosaur genera are endemic to India,

which suggests that the beginnings of dinosaur endemism had

already begun in Pangaea during the Late Triassic.

Jurassic

Palaeobiogeographically, the Kota Formation vertebrate fauna is

quite comparable to that from Middle Jurassic deposits of the

United Kingdom. Euramerican species outnumber Gondwanan

species, indicating close biogeographic ties between India and

Laurasia in the Middle Jurassic, with limited faunal interchanges

between India and other Gondwanan landmasses (Prasad and

Parmar 2020). According to these authors, many of these vertebrate

families have a Pangaean distribution, and restricted sampling on

the Gondwanan continents obscures actual intra-Gondwanan bio-

geographic links. Only by sampling the Gondwanan Jurassic sites

extensively and exhaustively will a clearer picture emerge.

It is now well established that during the Late Triassic and Early

Jurassic, Pangaea was integrated when sauropodomorphs were

developing and dispersing into what became various continents

(Figure 16). The most basal sauropodomorph, Saturnalia (Langer

et al. 1999), has been found to have originated in Gondwana and

supports a Gondwanan origin of sauropodomorphs. This is sup-

ported by the discovery of other less known basal sauropodo-

morphs from Madagascar (Flynn et al. 1998); Zimbabwe (Raath

Figure 15. Late Triassic reconstruction of western Pangaea. The potential routes of land vertebrate dispersal are depicted (modiﬁed after Chatterjee 1987).

HISTORICAL BIOLOGY 19

Figure 16. A reconstruction of Gondwana’s palaeogeography illustrates India’s location during the Early Jurassic Period (200 Ma), the time when basal sauropodomorphs

were present (adapted and modiﬁed from Chatterjee and Scotese 1999; Kutty et al. 2007).

Figure 17. The palaeogeographic and spatio-temporal distribution of diplodocoids over Pangaea, species of various ages are shown together in a simpliﬁed Middle Jurassic

(170 Ma) map. The families of diplodocoid and fossil occurrences are. The following numbers next to sauropod silhouettes show the age of the fossils: 1—Middle Jurassic

(early-middle Bathonian); 2—Late Jurassic; 3—Cretaceous; 4—Middle Jurassic (Callovian). (Map modiﬁed after Scotese 2016 and source of information on sauropod

distribution adapted from Ren et al. 2023; Bajpai et al. 2023).

20 A. KHOSLA AND S. G. LUCAS

1996), and a form that is not similar to Azendohsaurus from

Morocco (Gauffre 1993) and is most likely nondinosaurian (Jalil

and Knoll 2002) during the Carnian (Kutty et al. 2007). Thus, these

dinosaurs suggest that Gondwana may have served as the sauropo-

domorph centre of origin (Kutty et al. 2007).

The worldwide dispersal of basal sauropodomorphs shows

that geology and the environment were not critical obstructions

to their movement. Various workers (Chatterjee and Scotese

1999; Kutty et al. 2007) considered that the India-Madagascar-

Seychelles block was a mainland in Gondwana during the

development of basal sauropodomorphs. The primary phase of

the break-up of Pangaea occurred in the Middle Jurassic (180

Ma) between Africa and North America, with India likely still

a part of Gondwana around this time (e.g. Kutty et al. 2007).

During the Jurassic, shallow seas with humid biomes occupied

much of western India and Europe (Smith et al. 1994; Sharma

and Singh 2021). The Jaisalmer theropod is roughly concurrent

with the megalosaurids Megalosaurus, Dubreuillosaurus and

Poekilopleuron (Bathonian), and the possibly averostran

Cruxicheiros (Bathonian) from Europe, the megalosaurid

Afrovenator (?Bathonian-Oxfordian) from Northern Africa, the

basally-branching tyrannosauroids Kileskus and Proceratosaurus

(Bathonian) from central Russia and Europe, respectively, along

with the metriacanthosaurids Sinraptor and Yangchuanosaurus

(Bathonian-Callovian) from China (Rauhut et al. 2016; Sharma

et al. 2023a, 2023b). An incomplete theropod shed tooth crown

from the Bathonian Fort Member of the Jaisalmer Formation

was recovered, by cladistic analysis, as a megalosaurid theropod.

If confirmed, this specimen would be the first non-avian teta-

nuran and megalosaurid discovered in India. This lost tooth is

proof that at least one species of medium- to large-sized ther-

opod existed on the Tethyan coast of northwest India during

the Middle Jurassic.

Given the presence of hybodont sharks in the theropod-yielding

bed of the Fort Member of the Jaisalmer Formation, which are

similar to those discovered at contemporaneous Bathonian sites in

Europe, a Laurasian affinity of this specimen is also conceivable.

This discovery establishes the Jaisalmer Basin as one of the signifi-

cant Bathonian sites in Gondwana, which contain dinosaur fossils,

and is the sole clear Middle Jurassic (Bathonian) theropod record in

India. With this contribution, the Jaisalmer Basin is now recognised

as a promising location in India for the discovery of dinosaur

skeletons from the Jurassic of Gondwana (Sharma et al. 2023a).

Sharma et al. (2023b) reported on the discovery of a single, very

intact pedal ungual phalanx in the Jaisalmer Basin, Rajasthan,

northwest India, from the Middle Jurassic marine carbonate

rocks. Bivariate and multivariate analysis support its connection

to spinosaurids. Under Megalosauroidea, the ungual phalanx is

hypothesised to be a basally branching Jurassic spinosaurid.

Considering the geographical and stratigraphic provenance, this

record might be the earliest known instance of a spinosaurid.

Apart from the biogeography of the theropod tooth from the

Middle Jurassic (Bathonian) of the Jaisalmer Formation, the recent

discovery of Tharosaurus indicus (Bajpai et al. 2023), the first

known dicraeosaurid sauropod fossil from western India, in the

Middle Jurassic (early-middle Bathonian, Table 4) strata of the

Jaisalmer Basin is of palaeobiogeographic significance. The earlier

stratigraphic age of Tharosaurus suggests that migrations from

India to Asia may have gone through western Gondwana and

North America via Europe (Figure 17, Bajpai et al. 2023). The

Chinese sauropod Lingwulong, however, still presents

a biogeographic challenge because it predates all other western

Gondwanan and Euramerican diplodocoids. According to Bajpai

et al. (2023), the biogeographic conundrum caused by the two

Middle Jurassic dicraeosaurids found in China and India suggests

that neosauropods originated prior to the Middle Jurassic and then

achieved a worldwide distribution (Xu et al. 2018; Mannion et al.

2019; Ren et al. 2023). Geological and sampling biases appear to be

the cause of the absence of corroborative fossils representing chron-

ologically and phylogenetically intermediate taxa (Xu et al. 2018),

which highlights the necessity for more stringent collecting efforts

in these areas (Bajpai et al. 2023).

Bajpai et al. (2023) further stressed how crucial Gondwanan

India is for understanding the early evolutionary history and origin

of neosauropod dinosaurs. Tharosaurus is still the oldest known

diplodocoid despite the fragmentary material that is now available

and the likelihood that the taxonomic attribution within

Flagellicau-data may potentially alter with the recovery of further

material/character sampling. The finding of Tharosaurus elevates

India to a significant hub for diplodocoid and neosauropod radia-

tion, together with the probable Bajocian camarasauromorph from

Kachchh (Moser et al. 2006; Bajpai et al. 2023). When compared to

the other Indian Jurassic sauropods, Tharosaurus’ palaeobiogeo-

graphic analyses indicate that the new taxon is a remnant of

a lineage that began in India and quickly spread throughout the

remainder of Pangaea.

The most recent common ancestors (MRCAs) of neosauropods

may have originated and spread over Asia and North-South America

in the late Early/early Middle Jurassic (Wilson and Upchurch 2009;

Xu et al. 2018). This study highlights the significance of the pre-

Bathonian Indian sauropodomorph record in tracking the origins of

Neosauropoda, even if previous authors have focused on America

and Asia as the places inhabited by the MRCAs of these clades (Xu

et al. 2018; Ren et al. 2023). The well-known early-diverging non-

neosauropods Kotasaurus and Barapasaurus from the Middle

Jurassic Kota Formation of India provide substantial evidence for

this assertion (Bandyopadhyay and Ray 2020; Khosla and Bajpai

2021). To sum up, the finding of Tharosaurus highlights the necessity

for more research into India’s Bathonian and older Jurassic horizons

in order to find ancestral taxa that are transitional between neosaur-

opods and Barapasaurus-like eusauropods (Bajpai et al. 2023).

Conclusions

(1) The earliest record of dinosaur remains from India are from

the Late Triassic (late Carnian) Lower Maleri Formation

(Pranhita-Godavari Basin, Andhra Pradesh), which has yielded

fragmentary bones assigned to the basal saurischian Alwalkeria

maleriensis. The Upper Maleri Formation contains a younger

and more diverse Late Triassic dinosaur fauna, including two

basal sauropodomorphs, Jaklapallisaurus asymmetrica and

Nambalia roychowdhurii.

(2) Alwalkeria, a tiny theropod from the phylogenetic perspective,

is comparable to Procompsognathus from Germany,

Coelophysis from North America, and Syntarsus from

Zimbabwe (Chatterjee 1987). Since India was a fundamental

component of Gondwana throughout the Late Triassic, there

was a strong faunal link between India and the other

Gondwana landmasses at that time. In contrast to this, the

Maleri fauna, has ‘northern’ connections. Nambalia and

Jaklapallisaurus, perhaps transitional prosauropods, have

been found in the Maleri Formation, while Alwalkeria is the

only known species of Late Triassic carnivorous dinosaur from

India (Chatterjee 1984, 1987; Novas et al. 2011).

Palaeobiogeographically, the presence of primitive

HISTORICAL BIOLOGY 21

sauropodomorphs makes the Upper Maleri and Lower

Dharmaram dinosaur assemblages resemble purportedly con-

temporaneous South American and European beds. As a result,

the data now available from the Triassic beds of the Pranhita-

Godavari Basin implies that dinosaur diversity and abundance

increased in this part of Gondwana from the late Carnian to the

Rhaetian.

(3) The dinosaurs of Maleri and Dharmaram formations, along

with primitive sauropodomorphs and theropods found in

western Gondwana (South America), eastern Gondwana

(India), and Euramerica, provide evidence for at least some

degree of dinosaur cosmopolitanism throughout Late Triassic

Pangaea. However, the Indian Late Triassic dinosaur genera

are endemic to India, and a better record of the earliest

dinosaurs may reveal that the beginnings of dinosaur ende-

mism had already begun in Pangaea during the Late Triassic

(though many more discoveries will be needed to test this).

(4) Well-preserved Indian Jurassic dinosaurs have been

reported from two horizons (Upper Dharmaram

Formation and the overlying Kota Formation) of the

Pranhita- Godavari Basin. The Dharmaram fauna includes

three sauropodomorphs, Pradhania gracilis, Lamplughsaura

dharmaramensis and an indeterminate taxon. The Kota

Formation of likely Middle Jurassic age has yielded three

types of dinosaurs, two sauropods (Kotasaurus yamanpal-

liensis and Barapasaurus tagorei) and a third, a possible

ankylosaur. Two recent data matrices for primitive sauro-

podomorphs included codes for the dinosaurs from India

(Novas et al. 2011). According to the findings of this early

investigation, Lamplughsaura is either a stem sauropodo-

morph or, less likely, a basal sauropod. The second sauro-

podomorph from the Upper Triassic is more derived than

Saturnalia (Brazil) and Thecodontosaurus (Great Britain). It

is represented by the proximal half of a femur. This is also

true for the smaller Pradhania gracilis (Kutty et al. 2007),

which is outside of the Sauropoda clade and is undoubtedly

a stem sauropodomorph (adult body length: 4 m, Kutty et al.

2007). The only known specimen of Pradhania has a very

noticeable medial longitudinal ridge on the maxilla, which is

an autapomorphy. The well-known non-neosauropods

Kotasaurus and Barapasaurus from the Middle Jurassic

Kota Formation provide substantial evidence that India

was a major centre of the early evolution of neosauropods.

(5) Fragmentary remains of dinosaurs are also known from the

earliest Middle Jurassic of Kuar Bet, Patcham Island (Gujarat),

Jaisalmer District in Rajasthan; Jumara, Kachchh Mainland;

and the Khadir Formation of Khadir Island (Kachchh,

Western India).

(6) Theropod dental remains from the Middle Jurassic marine

carbonate rocks of the Jaisalmer Basin, northwest India, were

described for the first time by Sharma et al. (2023a). A partial

shed fossil tooth crown was found in a bioclastic intraforma-

tional conglomerate bed of the Bathonian Fort Member

(Jaisalmer Formation). The isolated crown most likely

belonged to a non-coelurosaurian averostran, potentially

from the mesial dentition of a ceratosaurid, allosauroid or

a non-spinosaurid megalosauroid, according to a cladistic

study of a dentition-based data matrix (Sharma et al. 2023a).

This tooth’s loss provides proof that at least one species of

medium- to large-sized theropods existed on northwest

India’s Tethyan coast during the Middle Jurassic. The

Jaisalmer Basin is currently recognised as a potential area in

India for the finding of dinosaur bones from the Jurassic of

Gondwana as a result of this discovery (Sharma et al. 2023a).

More recently, a single, well-preserved pedal ungual phalanx

was found in the Middle Jurassic marine carbonate rocks of

the Jaisalmer Basin, Rajasthan, northwest India, according to

Sharma et al. (2023b). Bivariate and multivariate analysis

support the link to spinosaurids. The ungual phalanx is

thought to be a basally branching spinosaurid from the

Jurassic Period, and it is classified under Megalosauroidea.

The geographic and stratigraphic provenances of this contri-

bution suggest that it might be the earliest example of

a spinosaurid yet discovered. Tharosaurus indicus, from the

Middle Jurassic strata of the Jaisalmer Basin, is the first known

dicraeosaurid sauropod fossil from western India. It is a relic

of a lineage that likely originated in India and swiftly

expanded throughout the rest of Pangaea in contrast to the

other Indian Jurassic sauropods such as Barapasaurus and

Kotasaurus. Bajpai et al. (2023) emphasise the significance of

Gondwanan India in understanding the early evolutionary

history and genesis of the neosauropod dinosaurs.

(7) Even though it is somewhat sparse, the dinosaur record

during the lower and middle Mesozoic in India has greatly

expanded our understanding of dinosaur palaeobiogeogra-

phy. The paucity of Triassic and Jurassic forms in western

India may be due to inadequate fieldwork, inaccessibility to

the fossiliferous strata, absence of strata of the proper age, or

a real biogeographic trend. This record is inconsistent with

the continental size of the nation. However, 70% of the

Indian Triassic-Jurassic dinosaur discoveries took place

and have been published in the last 17 years (i.e. 2007

onwards), indicating that this record will likely continue to

rise in the near future. There is a chance that fresh dinosaur

discoveries will be made in Gondwana. Questions about the

mechanisms that led to dinosaur dispersal throughout

Gondwana both during and after its fragmentation will

continue to be explored as this record expands.

Acknowledgments

Ashu Khosla is appreciative of the financial assistance provided by the

Department of Science and Technology (DST), Government of India, New

Delhi [grant number SR/S4/ES-382/2008]. The comments of the editor Prof.

Gareth Dyke, reviewer Prof. J. Lallensack and critical comments of the two other

anonymous reviewers, which have considerably improved the content and

clarity of this article.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Funding

Ashu Khosla expresses gratitude for the funding support given by the DST

PURSE project (Panjab University, Chandigarh) and the Department of

Science and Technology (DST), Government of India, New Delhi [grant number

SR/S4/ES-382/2008].

ORCID

Ashu Khosla http://orcid.org/0000-0002-6237-7765

Spencer G. Lucas http://orcid.org/0000-0002-4594-3024

22 A. KHOSLA AND S. G. LUCAS

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FIRST JURASSIC EVIDENCE OF A POSSIBLE SPINOSAURID PEDAL UNGUAL, FROM THE JAISALMER BASIN, INDIA

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RIV ITAL PALEONTOL S

We describe an isolated, almost complete pedal ungual phalanx from the Middle Jurassic marine carbonate rocks of the Jaisalmer Basin, Rajasthan, north-western India. The ungual bone is triangular shaped, pointed, elongated, asymmetrical, dorsoventrally compressed, ventrally flat, bearing a shallow semi-circular excavation, and almost straight in lateral view. The morphological features, as well as its proportions closely resemble the pedal ungual phalanges of spinosaurid theropods, presently known dominantly from the Cretaceous. The affinity to spinosaurids is supported by bivariate and multivariate analyses. The ungual phalanx is tentatively identified as a basally branching Jurassic spinosaurid under Megalosauroidea. Considering the stratigraphical and geographical provenances, this contribution may represent the oldest record of a spinosaurid.

Fossils of the oldest diplodocoid dinosaur suggest India was a major centre for neosauropod radiation. https://rdcu.be/diyrR

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Aug 2023

The Early Jurassic and Cretaceous deposits of India are known for their diverse sauropod fauna, while little is known from the Middle and Late Jurassic. Here we report the first ever remains of a dicraeosaurid sauropod from India, Tharosaurus indicus gen. et sp. nov., from the Middle Jurassic (early–middle Bathonian) strata of Jaisalmer Basin, western India. Known from elements of the axial skeleton, the new taxon is phylogenetically among the earlier-diverging dicraeosaurids, and its stratigraphic age makes it the earliest known diplodocoid globally. Palaeobiogeographic considerations of Tharosaurus, seen in conjunction with the other Indian Jurassic sauropods, suggest that the new Indian taxon is a relic of a lineage that originated in India and underwent rapid dispersal across the rest of Pangaea. Here we emphasize the importance of Gondwanan India in tracing the origin and early evolutionary history of neosauropod dinosaurs.

Machine learning confirms new records of maniraptoran theropods in Middle Jurassic UK microvertebrate faunas

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Full-text available

Apr 2023

Current research suggests that the initial radiation of maniraptoran theropods occurred in the Middle Jurassic, although their fossil record is known almost exclusively from the Cretaceous. However, fossils of Jurassic maniraptorans are scarce, usually consisting solely of isolated teeth, and their identifications are often disputed. Here, we apply different machine learning models, in conjunction with morphological comparisons, to a suite of isolated theropod teeth from Bathonian microvertebrate sites in the UK to determine whether any of these can be confidently assigned to Maniraptora. We generated three independent models developed on a training dataset with a wide range of theropod taxa and broad geographical and temporal coverage. Classification of the Middle Jurassic teeth in our sample against these models and comparison of the morphology indicates the presence of at least three distinct dromaeosaur morphotypes, plus a therizinosaur and troodontid in these assemblages. These new referrals significantly extend the ranges of Therizinosauroidea and Troodontidae by some 27 myr. These results indicate that not only were maniraptorans present in the Middle Jurassic, as predicted by previous phylogenetic analyses, but they had already radiated into a diverse fauna that pre-dated the break-up of Pangaea. This study also demonstrates the power of machine learning to provide quantitative assessments of isolated teeth in providing a robust, testable framework for taxonomic identifications, and highlights the importance of assessing and including evidence from microvertebrate sites in faunal and evolutionary analyses.

FIRST THEROPOD RECORD FROM THE MARINE BATHONIAN OF JAISALMER BASIN, TETHYAN COAST OF GONDWANAN INDIA

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Full-text available

Mar 2023

Middle Jurassic theropods have a scanty record worldwide, especially from Gondwana. In India, where Jurassic theropods are particularly rare and only represented by a few isolated teeth and some badly preserved bones, there is currently no record of theropods from the Middle Jurassic of western India. Here we report the first theropod dental material from Middle Jurassic marine carbonate rocks of the Jaisalmer Basin, northwestern India. The specimen consists of an incomplete shed tooth crown recovered from bioclastic intraformational conglomerate bed of the Bathonian Fort Member of the Jaisalmer Formation. A cladistic analysis performed on a dentition-based data matrix revealed that the isolated crown likely pertained to a non-coelurosaur averostran possibly from the mesial dentition of a ceratosaurid, a non-spinosaurid megalosauroid, or an allosauroid. This shed tooth provides evidence that at least one taxon of medium to large-bodied theropod lived on the Tethyan coast of NW India during the Middle Jurassic. This contribution marks the Jaisalmer Basin as a new promising area in India for dinosaurian remains from the Jurassic Gondwana.

Dinosaur fossil records from India and their palaeobiogeographic implications: an overview

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Full-text available

Sep 2021

ABSTRACT Khosla A & Bajpai S 2021. Dinosaur fossil records from India and their palaeobiogeographic implications: an overview. Journal of Palaeosciences 70(2021): 193–212. The complex palaeogeographic history of India involving a gradual transition from Gondwana to Laurasia with an intervening phase of prolonged physical isolation, and the biotic signatures of this complex history as preserved in India’s Mesozoic fossil record are of much current interest and continue to be debated. Seen in this context, the fossil record of dinosaurs from India provides a unique opportunity to study their diversity and palaeobiogeographic distribution in time and space. The Indian fossil record, as currently documented, is patchy and restricted mainly to three intervals of the Mesozoic era: Late Triassic, Early/Middle Jurassic and Late Cretaceous. The Late Triassic–Jurassic record, representing a Pangean setting, is known primarily from the Gondwana formations of Pranhita–Godavari (P–G) Valley in the southern Indian state of Andhra Pradesh, although sporadic Jurassic occurrences are also known from Kutch (Gujarat) and Rajasthan. The earliest Late Triassic dinosaur fauna of India comes from the rhynchosaur–dominated Lower Maleri Formation of Carnian age. Known from fragmentary and isolated specimens, the Late Triassic dinosaur fauna is currently represented by the sole species Alwalkeria maleriensis, which is possibly a basal saurischian with uncertain relationships. A slightly younger dinosaur fauna from the archosaur–dominated Upper Maleri Formation of late Norian–earliest Rhaetian age consists of a more diverse assemblage including the two named basal sauropodomorphs (Nambalia roychowdhurii and Jaklapallisaurus asymmetrica). In contrast to the Late Triassic, the Early Jurassic record of Indian dinosaurs described from the Upper Dharmaram and Lower Kota formations of P–G Valley, is far more abundant, diverse and based on more nearly complete material that is currently referred to four named taxa of stem sauropodomorphs or basal sauropods (Lamplughsaura dharmaramensis, Pradhania gracilis, Kotasaurus yamanpalliensis, Barapasaurus tagorei) plus an ornithischian (Ankylosauria). Kotasaurus, one of the earliest known sauropods, is more primitive than Barapasaurus and shared numerous plesiomorphic characteristics with prosauropods. Together, the Late Triassic and Early Jurassic sauropods dinosaurs of India document the early radiation of this group. Amongst the other important records of Jurassic dinosaurs in India is the oldest known camarasauromorph sauropod whose identification is based on a metacarpal, a first pedal paw and a fibula from the Middle Jurassic (Bajocian) strata of Khadir Island, Kutch. Fragmentary postcranial skeletal material of an unidentified Middle Jurassic dinosaurs is also known from Kuar Bet (Patcham Island) in the Rann of Kutch and the Jumara area of Kutch Mainland. Post–Gondwana, the Late Cretaceous dinosaurs of India occur in a different geodynamic setting in which the Indian Plate, as traditionally considered, was a northward drifting island continent in the middle of the Indian Ocean. Apart from the solitary record of a Cenomanian–Turonian sauropod from Nimar Sandstone, Cretaceous dinosaurs from India are documented mainly by skeletal remains and eggs/eggshells from the Maastrichtian infratrappean (=Lameta Formation) and intertrappean deposits in the Deccan Volcanic Province of eastern, western and central peninsular India, and from broadly coeval Kallamedu Formation of Cauvery Basin, southern India. Skeletal remains of the Lameta dinosaurs belong to two major groups, titanosaur sauropods and abelisaurid theropods, plus a possible ankylosaur, whereas the Cauvery records include fragmentary titanosaur bones and a solitary tooth of a troodontid theropod. Apart from bones and teeth, a number of dinosaur egg–bearing nesting sites are also known to occur in the Lameta Formation of east–central and western India, extending for more than 1,000 km across the states of Madhya Pradesh, Gujarat and Maharashtra. Close phylogenetic relations of the Lameta titanosaurs and theropods with corresponding taxa from the Maastrichtian of Madagascar (Vahiny, Majungasaurus) and the rare occurrence of Laurasian elements such as a troodontid, pose interesting palaeobiogeographic problems in the context of India’s supposed oceanic isolation, especially after its separation from Madagascar at ~ 88 Ma. Key–words—Triassic, Jurassic, Cenomanian–Turonian, Cretaceous, Dinosaurs, India, Palaeobiogeography.

First record of a Late Jurassic rhamphorhynchine pterosaur from Gondwana

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Full-text available

Sep 2021

We describe partial remains of a non-pterodactyloid pterosaur from Upper Jurassic levels of the Atacama Desert in northern Chile. The material includes a left humerus, a possible dorsal vertebra, and the shaft of a wing phalanx, all preserved in three dimensions and likely belonging to a single individual. The humerus has a hatchet-shaped deltopectoral crest, proximally positioned, and its shaft is markedly anteriorly curved, which are characteristic features of the clade Rhamphorhynchidae. In addition, the presence of a groove that runs along the caudal surface of the phalanx, being flanked by two asymmetric crests, is a distinctive feature of the clade Rhamphorhynchinae, which includes such genera as Rhamphorhynchus and Nesodactylus. Previous to this research, known records of Rhamphorhynchinae were restricted to Laurasia; thus, the specimen studied here represents the first evidence of this group found to date in Gondwana. Associated ammonoids allow us to assign the material to a middle Oxfordian age, which makes this specimen the oldest known pterosaur found in Chile, and the first of Oxfordian age in Gondwana. This discovery suggests that the clade Rhamphorhynchidae had a global distribution during the Late Jurassic.

Osteology of the sauropodomorph dinosaur Jaklapallisaurus asymmetricus from the Late Triassic of central India

Article

Dec 2023
ANAT REC

The Gondwana formations exposed in the Pranhita‐Godavari Valley of central India include Middle Triassic to Lower Jurassic continental deposits that provide essential information about the tetrapod assemblages of that time, documenting some of the oldest known dinosaurs and the first faunas numerically dominated by this group. The Upper Maleri Formation of the Pranhita‐Godavari Basin preserves an early‐middle Norian dinosaur assemblage that provides information about the early evolutionary history of this group in central‐south Gondwana. This assemblage comprises sauropodomorph dinosaurs and an herrerasaurian, including two nominal species. Here, we describe in detail the anatomy of one of those early dinosaurs, the bagualosaurian sauropodomorph Jaklapallisaurus asymmetricus . The new anatomical information is used to investigate the position of the species in an updated quantitative phylogenetic analysis focused on early sauropodomorphs. The analysis recovered Jaklapallisaurus asymmetricus as a member of Unaysauridae, at the base of Plateosauria, together with Macrocollum itaquii and Unaysaurus tolentinoi from the early Norian of southern Brazil. This phylogenetic result indicates that the dispersal of early plateosaurian sauropodomorphs between the Southern Hemisphere and what nowadays is Europe would have occurred shortly after Ischigualastian times because of the extension of their ghost lineage. Thus, the presence of early plateosaurians in the early Norian of South America and India reduces a previously inferred diachrony between the biogeographic dispersals of theropods and sauropodomorphs during post‐Ischigualastian times.

Re-examination of Dashanpusaurus dongi (Sauropoda: Macronaria) supports an early Middle Jurassic global distribution of neosauropod dinosaurs

Article

Nov 2022
PALAEOGEOGR PALAEOCL

Neosauropods were the dominant sauropod clade with a global distribution as early as the Late Jurassic. However, its distribution and biogeography in the Middle Jurassic are unclear due to the paucity of phylogenetic evidence for neosauropod taxa of this age. In China, the only reported Middle Jurassic neosauropod, the diplodocoid, has challenged the traditional East Asian Isolation Hypothesis for dinosaur paleobiogeography. Here, based on phylogenetic analysis including Dashanpusaurus dongi from the early Middle Jurassic of southwest China, we demonstrate that this taxon represents the earliest diverging macronarian as well as the stratigraphically lowest neosauropod globally. Our biogeographic analysis together with other geological evidence further indicates that neosauropods achieved a global distribution at least in the early Middle Jurassic while Pangaea was still a coherent landmass.

Contribution to the stratigraphy and vertebrate fauna of Lower Jurassic Kota Formation, Pranhita-Godavari Valley, India

Article

Dec 1987

Gondwana Sequence of the Pranhita-Godavari Valley represents a thick succession of sediments ranging in age from Early Permian to Early Cretaceous. The Mesozoic Gondwana sediments contain a number of vertebrate bearing zones which are important for correlation and for assigning age to different units. New data on the vertebrate fossils of Kota Formation help trace the evolutionary history of early Jurassic mammals and dinosaurs and palaeogeographic configuration. The status of Gangapur Formation, as a unit, overlying Kota Formation and underlying Chikiala Formation is elaborated. Its lithological identity is established in the Yamanpalli area. Measured lithostratigraphic column of the limestone zone of the Kota Formation is described with the lithological variations and fossil contents. The data is useful for the correlation of limestone members in delineating the Kota Formation along its strike. Analysis of the geochemical data and vertebrate fossil community of Mesozoic sediments with particular emphasis on the Kota Formation, provide overwhelming evidences for freshwater environment of deposition of the Kota Formation. The evolutionary status of vertebrate fauna consisting of early mammals, dinosaurs and pholidophorid fishes is described which supports the Jurassic age of the Kota Formation.

A small assemblage of marine hybodont sharks from the Bathonian of the Jaisalmer Basin, India

Article

Sep 2021
Neues Jahrbuch Geol Palaontol Abhand

We are describing a small assemblage of marine hybodont sharks from the Middle Jurassic (Bathonian) carbonate rocks of the Jaisalmer Basin, North-western India. The assemblage is represented by both cuspidate and crushing dental remains of the genus Planohybodus and Strophodus (previously Asteracanthus), respectively. This is the first record of Planohybodus sp., Strophodus magnus, Strophodus medius and Strophodus indicus sp. nov. from the Jurassic of India or any other Gondwanan continent. This is the most diverse Jurassic marine chondrichthyan faunal record from the Jaisalmer Basin to date. This chondrichthyan faunal record from the Bathonian of India has close affinity to the European forms. This study reveals a much wider paleogeographic distribution of hybodont sharks and corroborates their cosmopolitan presence in the Mesozoic seas. The discovery of a new species, Strophodus indicus sp. nov. from India demonstrates a greater diversity in the genus Strophodus.

Triassic-Jurassic dinosaurs from India, their ages and palaeobiogeographic significance

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