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Preliminary report on a clutch of six dinosaurian eggs from the Upper Triassic Elliot Formation, Northern Orange Free State
... The first clutch of Mesozoic eggs containing embryos was collected more than twenty years ago from the Rooidraai locality in Golden Gate Highlands Park, South Africa. 1 The Elliot Formation crops out throughout the area, and although the sediments exposed at Rooidraai were once thought to be Late Triassic in age, 1 they are now regarded as Early Jurassic. 2 The Elliot Formation preserves a rich terrestrial vertebrate fauna, with the remains of the prosauropod dinosaur Massospondylus carinatus found to be relatively common at Rooidraai. 1 The Rooidraai embryos were originally attributed to dinosaurs on the basis of cranial features of one of them. 1 The eggs were later identified as 'probably prosauropod', 3 but more interestingly, the eggshell structure was described as sharing characteristics with the eggs of crocodilians. ...
... The first clutch of Mesozoic eggs containing embryos was collected more than twenty years ago from the Rooidraai locality in Golden Gate Highlands Park, South Africa. 1 The Elliot Formation crops out throughout the area, and although the sediments exposed at Rooidraai were once thought to be Late Triassic in age, 1 they are now regarded as Early Jurassic. 2 The Elliot Formation preserves a rich terrestrial vertebrate fauna, with the remains of the prosauropod dinosaur Massospondylus carinatus found to be relatively common at Rooidraai. 1 The Rooidraai embryos were originally attributed to dinosaurs on the basis of cranial features of one of them. 1 The eggs were later identified as 'probably prosauropod', 3 but more interestingly, the eggshell structure was described as sharing characteristics with the eggs of crocodilians. ...
... 2 The Elliot Formation preserves a rich terrestrial vertebrate fauna, with the remains of the prosauropod dinosaur Massospondylus carinatus found to be relatively common at Rooidraai. 1 The Rooidraai embryos were originally attributed to dinosaurs on the basis of cranial features of one of them. 1 The eggs were later identified as 'probably prosauropod', 3 but more interestingly, the eggshell structure was described as sharing characteristics with the eggs of crocodilians. The shells were described as consisting of 'broadly wedge-shaped and ill-defined units' 3 and so were thought to be 'seemingly more similar to crocodilian than to avian eggs'. ...
Some of the oldest known dinosaur eggs with embryos were reported from Lower Jurassic sediments of South Africa's Elliot Formation. The osteological data from the embryos suggest that the eggs were laid by dinosaurs, and the presence of skeletal materials of the sauropodomorph Massospondylus carinatus at the egg-producing locality prompted the tentative hypothesis of a prosauropod parentage for these eggs. Original analysis of eggshell microstructure, however, suggested that they shared crocodilian characteristics. Re-evaluation of eggshell microstructure suggests that the 'crocodilian' characteristics of the eggshell are instead artefacts of diagenesis. The available data from the eggs and embryos suggest that the clutch is probably dinosaurian in origin, but no particular dinosaurian lineage can be identified as the egg-layer.
... In 1976, a clutch of seven subspherical eggs (BP/1/5347a) was discovered by Prof. James Kitching in the early Jurassic upper Elliot Formation of Golden Gate Highlands National Park, South Africa 34,[45][46][47] . Two partially exposed embryos in the clutch were quickly identified as being dinosaurian 47 , making them among the oldest known dinosaur eggs and embryos in the world. ...
... In 1976, a clutch of seven subspherical eggs (BP/1/5347a) was discovered by Prof. James Kitching in the early Jurassic upper Elliot Formation of Golden Gate Highlands National Park, South Africa 34,[45][46][47] . Two partially exposed embryos in the clutch were quickly identified as being dinosaurian 47 , making them among the oldest known dinosaur eggs and embryos in the world. These eggs were later identified as belonging to the basal sauropodomorph dinosaur species Massospondylus carinatus 34 and the visible embryonic remains were described. ...
Dinosaur embryos are among the rarest of fossils, yet they provide a unique window into the palaeobiology of these animals. Estimating the developmental stage of dinosaur embryos is hindered by the lack of a quantitative method for age determination, by the scarcity of material, and by the difficulty in visualizing that material. Here we present the results of a broad inquiry, using 3D reconstructions from X-ray computed tomography data, into cranial ossification sequences in extant saurian taxa and in well-preserved embryos of the early branching sauropodomorph dinosaur Massospondylus carinatus. Our findings support deep-time conservation of cranial ossification sequences in saurians including dinosaurs, allowing us to develop a new method for estimating the relative developmental percentage of embryos from that clade. We also observe null-generation teeth in the Massospondylus carinatus embryos which get resorbed or shed before hatching, similar to those of geckos. These lines of evidence allow us to confidently estimate that the Massospondylus carinatus embryos are only approximately 60% through their incubation period, much younger than previously hypothesized. The overall consistency of our results with those of living saurians indicates that they can be generalized to other extinct members of that lineage, and therefore our method provides an independent means of assessing the developmental stage of extinct, in-ovo saurians.
... As a result of these discoveries, M. carinatus is potentially one of the best-represented early dinosaurs and has formed the basis for numerous palaeobiological studies on locomotion (Bonnan & Senter 2007), growth rates (Chinsamy 1993;Erickson et al. 2001), tooth replacement (D'Emic et al. 2013), ontogeny (Gow 1990;Gow et al. 1990;Reisz et al. 2005Reisz et al. , 2010 and nesting behaviour (Kitching 1979;Zelenitsky & Modesto 2002;Reisz et al. 2012). It has also been an important exemplar in broader studies of early dinosaur herbivory, palaeoecology and faunal studies (e.g. ...
... Other recent studies on Massospondylus carinatus have included descriptions of the clavicle in BP/1/5241 (Yates & Vasconcelos 2005) and those of eggs, nests and embryos (e.g. BP/1/5347 : Kitching 1979;Zelenitsky & Modesto 2002;Reisz et al. 2005Reisz et al. , 2010Reisz et al. , 2012. The referral of the latter to M. carinatus requires confirmation, however, as the single autapomorphy used to support this suggestion has been shown to be unreliable (Chapelle & Choiniere 2018; see below); moreover, reliance upon provenance arguments to verify this identification are no longer tenable in light of our new understanding of upper Elliot Formation sauropodomorph diversity (see above). ...
Massospondylus carinatus Owen, 1854, from the earliest Jurassic upper Elliot Formation of South Africa, was one of the first dinosaurs to be described from Gondwana. It has been incorporated into numerous phylogenetic, palaeobiological and biostratigraphic analyses, is often viewed as an exemplar for understanding sauropodomorph anatomy and is a key taxon in studies of early dinosaur evolution. Since its initial description, numerous specimens have been referred to this species, ranging from isolated postcranial elements to complete skeletons with three-dimensional skulls. In addition,M. carinatus has been identified in areas outside of the main Karoo Basin. Surprisingly, however, there have been few attempts to define the taxon rigorously, so that the basis for many of these referrals is weak, undermining the utility of this abundant material. Here, we provide the first detailed postcranial description of the neotype specimen of M. carinatus, use it as a basis for diagnosing the species on the basis of cranial, axial and appendicular characters, demonstrate that it represents an adult individual on the basis of osteohistology, and discuss ways in which these data can assist in providing a better
understanding of Karoo-aged African dinosaur faunas.
... As a result of these discoveries, M. carinatus is potentially one of the best-represented early dinosaurs and has formed the basis for numerous palaeobiological studies on locomotion (Bonnan & Senter 2007), growth rates (Chinsamy 1993;Erickson et al. 2001), tooth replacement (D'Emic et al. 2013), ontogeny (Gow 1990;Gow et al. 1990;Reisz et al. 2005Reisz et al. , 2010 and nesting behaviour (Kitching 1979;Zelenitsky & Modesto 2002;Reisz et al. 2012). It has also been an important exemplar in broader studies of early dinosaur herbivory, palaeoecology and faunal studies (e.g. ...
... Other recent studies on Massospondylus carinatus have included descriptions of the clavicle in BP/1/5241 (Yates & Vasconcelos 2005) and those of eggs, nests and embryos (e.g. BP/1/5347 : Kitching 1979;Zelenitsky & Modesto 2002;Reisz et al. 2005Reisz et al. , 2010Reisz et al. , 2012. The referral of the latter to M. carinatus requires confirmation, however, as the single autapomorphy used to support this suggestion has been shown to be unreliable (Chapelle & Choiniere 2018; see below); moreover, reliance upon provenance arguments to verify this identification are no longer tenable in light of our new understanding of upper Elliot Formation sauropodomorph diversity (see above). ...
Massospondylus carinatus Owen, 1854, from the earliest Jurassic upper Elliot Formation of South Africa, was one of the first dinosaurs to be described from Gondwana. It has been incorporated into numerous phylogenetic, palaeobiological and biostratigraphic analyses, is
often viewed as an exemplar for understanding sauropodomorph anatomy and is a key taxon in studies of early dinosaur evolution. Since its initial description, numerous specimens have been referred to this species, ranging from isolated postcranial elements to
complete skeletons with three-dimensional skulls. In addition,M. carinatus has been identified in areas outside of the main Karoo Basin. Surprisingly, however, there have been few attempts to define the taxon rigorously, so that the basis for many of these referrals is weak, undermining the utility of this abundant material. Here, we provide the first detailed postcranial description of the neotype specimen of M. carinatus, use it as a basis for diagnosing the species on the basis of cranial, axial and appendicular characters, demonstrate that it represents an adult individual on the basis of osteohistology, and discuss ways in which these data can assist in providing a better understanding of Karoo aged African dinosaur faunas.
... The clutch of eggs he discovered at the Rooidraai locality in the Free state was of particular interest since the eggs contained partially preserved embryos. Kitching (1979) tentatively suggested that they could be dinosaur embryos on the basis of the very short parietal region, the position of the postorbital, the parietal/supraoccipital suture, and the position and shape of the lacrimal of one of the exposed skulls. If this conclusion were correct, this find would not only mark the first amniote (taxon pertaining to reptiles, birds and mammals) eggs discovered in Africa, but also the first baby dinosaurs to be discovered in Africa. ...
... 3), which is approximately 0:16Â what it should be, giving the impression that the embryological material in the Rooidraai egg is much larger than it actually is. In the text of his article, Kitching (1979) mentions the correct dimensions of the eggs, i.e., 65 mm along the long axis and 55 mm in diameter, making these eggs approximately as big as goose eggs, and just big enough to house a archosaur embryo of approximately 150 mm in length. Weishampel and Horner (1994) calculated that both Massospondylus and Mussaurus hatchlings measured approximately 0.2-0.4% of the adult's length. ...
Recently discovered juvenile dinosaur remains from the Lower Elliot Formation (Upper Triassic) of South Africa can be assigned to Euskelosaurus browni (Huxley), an early prosauropod dinosaur. The oldest known juvenile prosauropods, before this discovery, were those from the Upper Triassic of Patagonia in Argentina. Although a satisfactory age correlation between the Lower Elliot Formation of the Karoo Supergroup of South Africa and the El Tranquilo Formation of Argentina has not been done yet, the South African juvenile dinosaurs remain the oldest reported from Africa. This latest discovery contributes to the understanding of the development and reproductive behaviour of early dinosaurs.
... Massospondylus carinatus is the most abundant non-avian dinosaur known from southern Africa, and hundreds of specimens have been referred to this taxon since its description in 1854 (Kitching, 1979;Kitching & Raath, 1984;Gow, Kitching & Raath, 1990;Sues et al., 2004). Massospondylus carinatus has been found in the upper Elliot and Clarens formations of the Stormberg Group in South Africa and Lesotho as well as in the corresponding Forest Sandstone and Mpandi Formations in Zimbabwe (Cooper, 1981;Kitching & Raath, 1984;Munyikwa, 1997;Catuneanu, Hancox & Rubidge, 1998;Bordy & Catuneanu, 2002;Rogers et al., 2004;Barrett et al., 2019). ...
Massospondylus carinatus Owen, 1854 is an iconic basal sauropodomorph dinosaur from the Early Jurassic of southern Africa. Over 200 specimens have been referred to this taxon, spanning the entire ontogenetic series from embryo to adult. Consequently, it provides an ideal sample for investigating dinosaur developmental biology, including growth patterns and growth rates, through osteohistological analysis. Massospondylus carinatus was the first early-branching sauropodomorph dinosaur for which a femoral growth series was sampled. Since then, growth series of other non-avian dinosaur taxa have shown that growth plasticity, interelemental variation, and ontogenetic locomotory shifts can complicate our understanding of growth curves and patterns. To investigate these questions further, it is necessary to sample multiple skeletal elements from multiple individuals across a large range of sizes, something that is often hindered by the incompleteness of the fossil record. Here, we conducted a broad, multielement osteohistological study of long bones (excluding metapodials) from 27 specimens of Massospondylus carinatus that span its ontogenetic series. Our study reveals substantial variations in growth history. A cyclical woven-parallel complex is the predominant bone tissue pattern during early and mid-ontogeny, which transitions to slower forming parallel-fibred bone during very late ontogeny. The bone tissue is interrupted by irregularly spaced cyclical growth marks (CGMs) including lines of arrested growth indicating temporary cessations in growth. These CGMs show that the previously recorded femoral growth plasticity is also visible in other long bones, with a poor correlation between body size (measured by midshaft circumference) and CGM numbers. Furthermore, we found that the growth trajectory for an individual can vary depending on which limb element is studied. This makes the establishment of an accurate growth curve and determination of the onset of reproductive maturity difficult for this taxon. Finally, we found no evidence of differential growth rates in forelimb vs hindlimb samples from the same individual, providing further evidence falsifying hypothesised ontogenetic postural shifts in Massospondylus carinatus .
... In this review we classified individuals interpreted as being in utero (that is, fossilized within a maternal body cavity), as well as individuals truly recovered in ovo, under the single term 'found in egg', because some saurian reptiles give live birth. Individuals found within the confines of an eggshell are rare but are known in pterosaurs (Chinsamy et al., 2008), sauropodomorphs (Kitching, 1979;Chiappe et al., 1998;Chiappe, Salgado & Coria, 2001;Reisz et al., 2005Reisz et al., , 2010Reisz et al., , 2012Reisz et al., , 2013Chapelle, Fernandez & Choiniere, 2020b;Norell et al., 2020), and coelurosaurs Yasumiba et al., 2016). In utero individuals are most commonly reported in marine reptiles [ichthyopterygians (e.g. ...
Morphology forms the most fundamental level of data in vertebrate palaeontology because it is through interpretations of morphology that taxa are identified, creating the basis for broad evolutionary and palaeobiological hypotheses. Assessing maturity is one of the most basic aspects of morphological interpretation and provides the means to study the evolution of ontogenetic changes, population structure and palaeoecology, life‐history strategies, and heterochrony along evolutionary lineages that would otherwise be lost to time. Saurian reptiles (the least‐inclusive clade containing Lepidosauria and Archosauria) have remained an incredibly diverse, numerous, and disparate clade through their ~260‐million‐year history. Because of the great disparity in this group, assessing maturity of saurian reptiles is difficult, fraught with methodological and terminological ambiguity. We compiled a novel database of literature, assembling >900 individual instances of saurian maturity assessment, to examine critically how saurian maturity has been diagnosed. We review the often inexact and inconsistent terminology used in saurian maturity assessment (e.g. ‘juvenile’, ‘mature’) and provide routes for better clarity and cross‐study coherence. We describe the various methods that have been used to assess maturity in every major saurian group, integrating data from both extant and extinct taxa to give a full account of the current state of the field and providing method‐specific pitfalls, best practices, and fruitful directions for future research. We recommend that a new standard subsection, ‘Ontogenetic Assessment’, be added to the Systematic Palaeontology portions of descriptive studies to provide explicit ontogenetic diagnoses with clear criteria. Because the utility of different ontogenetic criteria is highly subclade dependent among saurians, even for widely used methods (e.g. neurocentral suture fusion), we recommend that phylogenetic context, preferably in the form of a phylogenetic bracket, be used to justify the use of a maturity assessment method. Different methods should be used in conjunction as independent lines of evidence when assessing maturity, instead of an ontogenetic diagnosis resting entirely on a single criterion, which is common in the literature. Critically, there is a need for data from extant taxa with well‐represented growth series to be integrated with the fossil record to ground maturity assessments of extinct taxa in well‐constrained, empirically tested methods.
... They applied the first parataxonomic names to fossil eggs (Oolithes bathonicae and Oolithes sphaericus) found in the Bathonian Great Oolite Formation, Cirencester, England, of Jurassic age. Other notable work on fossil eggshells was from Portugal (de Lapparent and Zbyszewski 1957;Dantas 1991) and the Upper Triassic of South Africa (Kitching 1979;Grine and Kitching 1987). Meyer (1860) studied the megascopic characters of the fossil avian and turtle eggs from Offenbach, Germany. ...
Hundreds of Indian Late Cretaceous sauropod and theropod nests, eggs and eggshells have been recorded from a specific lithologic unit (Lameta Limestone) at Jabalpur, Bagh, Kheda–Panchmahal and in the Dongargaon-Pisdura areas of peninsular India. This chapter discusses in detail the current status and parataxonomic classification of Indian Late Cretaceous dinosaur eggshells. On the basis of morphological, micro- and ultrastructural studies, a total of 14 eggshell oospecies belonging to five different oofamilies and oogenera such as Megaloolithidae (Megaloolithus), Fusioolithidae (Fusioolithus), Elongatoolithidae (Ellipsoolithus), Laevisoolithidae (Subtiliolithus) and ?Spheroolithidae (Spheroolithus) have been chronicled from Indian infra- and intertrappean localities. The Indian eggshells have been revised, synonymized and described systematically. The majority of the Indian eggshells belong to the oofamilies Megaloolithidae (fan-shaped separated shell units) and Fusioolithidae (fused spheroliths and external nodes) of tubospherulitic morphotype. Three of the oofamilies—Megaloolithidae, Fusioolithidae and Elongatoolithidae—dominate the Indian eggshell assemblage and show distinct affinities with Peruvian, Romanian, French-Spanish, African and Argentinean localities. The oofamily Laevisoolithidae displays Mongolian and Argentinean affinities.
... Angular clasts are less common and often very fine to fine sandstone derived (Bordy et al., 2004c). This paedogenic glaebule conglomerate, apart from being a distinct marker unit, is palaeontologically unique as it also hosts the vast Tritylodon Acme (or Assemblage) Zone (TAZ), originally identified by Kitching (1979) and later discussed in biostratigraphic detail in Kitching and Raath (1984). This marker is thought to present a period of mass-wasting and general accumulation of distal reworked bone fragments, mostly comprising of Tritylodon sp. ...
The Elliot and Clarens formations (Stormberg Group) of the Karoo Supergroup famously preserve not only a dynamic suite of depositional environments spanning the Late Triassic to Early Jurassic, but also boast a diverse assemblage of trace and body fossils. Due to the nature of these assemblages spanning the globally correlative Triassic-Jurassic Boundary (TJB) and end-Triassic Extinction Event (ETE), the accuracy of temporal placement and correlation via the stratigraphic framework is paramount. Yet, a distinct lack of robust temporal framework and inconsistencies between the bio-, magneto- and lithostratigraphic records persist. This project sought to provide localized context for three key fossil-bearing localities (southwestern Lesotho), which could thereafter be applied both at a regional and global scale. In-depth facies, palaeocurrent and architectural element analyses illustrated an overall increase in palaeoclimatic aridity, as evidenced by the change in depositional system from the meandering fluvial dominated lower Elliot Formation to the aeolian Clarens Formation. Detrital zircon geochronology ascertained a temporal framework ranging from the Norian to Pliensbachian (216.7-190.5 Ma) Elliot Formation to the Sinemurian to Pliensbachian (190.5-186.7 Ma) Clarens Formation. These temporal constraints also support the presence of a regional paraconformity at the lower and upper Elliot contact. The geochronology additionally indicated a shared source provenance of recycled grains from the Cape Supergroup and older Karoo strata, interspersed with direct source inputs from proximal magmatic/metamorphic provinces. Ultimately, the greater temporal and palaeoecological resolution provided by this study promotes the better understanding of the early Mesozoic history of southern Gondwana and lays the foundations for future geochronological investigations.
... Dinosaur nests dominate the literature on fossil tetrapod nests, which date back to the Late Triassic of Argentina (Bonaparte and Vince, 1979). Jurassic dinosaur nests are few in number (Hirsch et al. 1979;Kitching 1979;Mateus et al. 1997;Carpenter 1999), and most known dinosaur nests are of Cretaceous age (Carpenter and Alf 1994). Dinosaur nests are sometimes recognized by the preservation of a nest structure, such as bowl-shaped patches of green mudstone (Horner and Makela 1979) or a raised rim of sediment that is preferentially cemented (Varricchio et al. 1999). ...
The diverse ichnofaunas of the Late Triassic have been studied for almost 200 years. During the Late Triassic, facies favorable for the preservation of trace fossils were the result of low sea levels, monsoonal climates and the development of extensive depositional basins as Pangea began to fragment. The most abundant vertebrate trace fossils in the Late Triassic are tetrapod tracks, including Brachychirotherium, Chirotherium, “Parachirotherium,” Synaptichnium, Atreipus, Grallator, Eubrontes, Banisterobates, Trisauropodiscus, Evazoum, Tetrasauropus, Pseudotetrasauropus, Eosauropus, Apatopus, Batrachopus, Rhynchosauroides, Gwyneddichnium, Procolophonichnium, Chelonipus, Brasilichnium and Dicynodontipus. There are five tetrapod footprint biochrons of Triassic age that can be identified across the Pangaean footprint record. Coprolites are the second most abundant vertebrate trace fossils in the Late Triassic and include Heteropolacopros, Alococoprus, Dicynodontocopros, Liassocoprus, Saurocoprus, Strabelocoprus, Malericoprus, Falcatocoprus and Revueltobromus. Coprolites are useful in biochronology in the Late Triassic. Consumulites, dentalites (new term for bite marks), and burrows are moderately common in the Late Triassic. Nests and gastroliths are rare. All groups of vertebrate trace fossils demonstrate different diversity and abundance patterns through the Phanerozoic. Most vertebrate trace fossils have their earliest occurrences in the Devonian. The early Permian is an acme for both tracks and coprolites. The Late Triassic yields abundant tracks and coprolites, and tracks are also common in the Early Jurassic. The Jurassic and Cretaceous represent the times with the greatest diversity of vertebrate traces (tracks, coprolites, consumulites, dentalites, nests and gastroliths). The Quaternary also represents a time of vertebrate ichnological diversity (tracks, coprolites, regurgitalites, nests and burrows).
... The Elliot formation breaks down easily with mudstones and siltstones weathering rapidly to a poor soil which forms the negative slopes on the mountain sides (Groenewald, 1986). This formation is well known in the GGHNP for its vertebrate fossil remains (Kitching, 1979;Kitching & Raath, 1984;Reisz et al, 2005). ...
A variety of mass movement and depositional geomorphic phenomena in the Golden Gate Highlands National Park have been described in the literature over the past few decades, yet notably, the prominent rockfalls remain understudied. The objective of the MSc study is to undertake detailed mapping of the GGHNP rockfalls, and in so doing ascertain a better understanding of their macro-morphologies, associated spatial-size dynamics and relationships to lithology, using both field-based and desktop image processing techniques.
Ground truthing, using the highest possible resolution achievable through differential GPS (DGPS) and field measurements with an accuracy of cm to mm, serves to quantify the accuracy of mapping rockfall phenomena through 0.5 m GSD colour aerial imagery. In addition, field measurements are used as inputs for feature extraction, such that rockfalls associated with the Clarens, Elliot and Molteno Formation Sandstones may be defined using object orientated classification techniques. The dimensions, orientation and absolute coordinates of rockfalls for select representative sites were captured using both field based and desktop techniques. The rockfall coordinates were taken at the midpoint of each measured rock using a DGPS, with an accuracy of ~ 2 cm on the x, y and z axis.
Object Based Image Analysis (OBIA) of Clarens and Molteno Fm. rockfalls was performed successfully using ground-truthed rockfall measurements to guide the creation of segmentation and classification rulesets. Multiple linear regression modelling can be used to model rockfall characteristics from ground-truthing with remotely sensed imagery, albeit to a very limited extent. Elliot Formation rockfalls could not be mapped and analysed mainly due to resolution limitations. Uni- and bi-variate statistics show promise in interpreting rockfall distribution and weighting with environmental variables derived from a DEM and geological vector.
Point density analyses found that for the entire GGHNP ~2 and ~4 rockfalls are found per Km² of Clarens and Molteno Formation rockfall areas.
... Reproductive and body mass data were collected for the nine dinosaur taxa for which reliably identified, well-described clutches have been described. These comprise four maniraptoran theropods (Troodon formosus, Byronosaurus jaffei, Machairasaurus philoceratops, and Citipati osmolskae), and five additional dinosaur taxa: the early Jurassic prosauropod Massospondylus [72][73]; two Late Cretaceous ootaxa, Megaloolithus patagonicus and Megaloolithus sirugei, assigned to titanosaur sauropods on the basis of embryos in the former [74][75]; and two hadrosaurs, an unknown lambeosaurine and Maiasaura peeblesorum [76][77]. Note that the Jurassic allosauroid theropod, possibly Lourinhanosaurus, with well described eggs from Portugal [78][79] was excluded due to significant ambiguity in clutch size among published accounts. ...
Diapsids show an extremely wide range of reproductive strategies. Offspring may receive no parental care, care from only one sex, care from both parents, or care under more complex regimes. Young may vary from independent, super-precocial hatchlings to altricial neonates needing much care before leaving the nest. Parents can invest heavily in a few young, or less so in a larger number. Here we examine the evolution of these traits across a composite phylogeny spanning the extant diapsids and including the limited number of extinct taxa for which reproductive strategies can be well constrained. Generalized estimating equation(GEE)-based phylogenetic comparative methods demonstrate the influences of body mass, parental care strategy and hatchling maturity on clutch volume across the diapsids. The influence of polygamous reproduction is not important despite a large sample size. Applying the results of these models to the dinosaurs supports the hypothesis of paternal care (male only) in derived non-avian theropods, previously suggested based on simpler analyses. These data also suggest that sauropodomorphs did not care for their young. The evolution of parental-care occurs in an almost linear series of transitions. Paternal care rarely gives rise to other care strategies. Where hatchling condition changes, diapsids show an almost unidirectional tendency of evolution towards increased altriciality. Transitions to social monogamy from the ancestral state in diapsids, where both sexes are polygamous, are common. In contrast, once evolved, polygyny and polyandry are very evolutionarily stable. Polygyny and maternal care correlate, as do polyandry and paternal care. Ancestral-character estimation (ACE) of these care strategies with the character transition likelihoods estimated from the original data gives good confidence at most important nodes. These analyses suggest that the basalmost diapsids had no parental care. Crocodilians independently evolved maternal care, paternal care evolved in the saurischian line, prior to derived theropod dinosaurs, and the most basal neognaths likely exhibited biparental care. Overall, the evolution of parental care among diapsids shows a persistent trend towards increased care of offspring, and more complex care strategies and behaviors with time. Reversions to reduced care are infrequent.
... This sample represents nearly all the taxonomically identifiable eggs and eggshell currently available for the Mesozoic. Exceptions include dendroolithid eggs with therizinosaur embryos (Manning et al., 1997), Lower Jurassic eggs with embryos from the Elliot Formation of South Africa (Kitching, 1979), egg material associated with an adult Deinonychus antirrhopus (Makovicky and Grellet-Tinner, 2000), and three purported avian egg types from the Cretaceous of Mongolia (Mikhailov, 1997). Eggshell and eggs associated with the therizinosaur embryos (Manning et al., 1997) have not been described in detail nor were they available to the authors. ...
... Discussion. A clutch of six subspherical eggs with mineralized shells was collected from the Late Triassic Elliot Formation at Rooidrai, South Africa (Kitching 1979). Poorly preserved remnants of embryos found in three of the six eggs permitted the certain assignment of these eggs to dinosaurs. ...
This first attempt to summarize knowledge on the eggshell structure in amniotic vertebrates, and in particular, the global diversity of the fossil remains, is based on original observations, and employs advanced microscopic techniques. The nomenclature, terminology, nature of eggshell biocrystalline matter and regularities of biomineralization are discussed in detail. Various classifications, based on different levels of eggshell matter organization (ultrastructure, microstructure and general morphology), are also considered. It is argued that basic (ultrastructural) types, microstructural morphotypes, types of pore system and types of surface ornamentation should be employed as the main structural categories in systematic description. A systematic section includes descriptions of all main fossil egg groups. Fourteen parafamilies and 32 paragenera of dinosaur and Cretaceous avian egg remains are considered, and a comparative review is provided for all the material (18 paragenera and 42 paraspecies) known from Asia. A full listing of known fossil egg parataxa is given in an appendix.
... Indeed, the first description of fossil tetrapod eggs by Buckman (1859) was of a clutch of turtle eggs from marine Middle Jurassic strata and is still one of the oldest records of evidence of a fossil tetrapod nest. However, dinosaur nests dominate the literature on fossil tetrapod nests in the Triassic (Bonaparte and Vince, 1979), Jurassic (Hirsch et al., 1979;Kitching, 1979;Mateus et al., 1997;Carpenter, 1999) and Cretaceous (e. g., Carpenter and Alf, 1994). ...
... Babies have been reported for Hadrosaurinae (see Sternberg, 1955), Bagaceratops rozhdestvenski, Protoceratops andrewsi, ?P. kozlowskii (see Maryanska and Osmolska, 1975;Sochava, 1972), cf. Maiasaura peeblesorum (see Horner and Makela, 1979), Mussaurus patagonicus (see Bonaparte and Vince, 1979), an unidentified dinosaur (Kitching, 1979) Psittacosaurus mongoliensis (see Coombs, 1980), ? Tar The reasons for the scarcity of bones of baby dinosaurs may be threefold: (1) some of the small bones, because of their size and delicate construction, were easily destroyed by scavengers, preburial transportation, low environmental pH, and postburial erosion (before and after fossilization); (2) the small size of some bones makes them easy to overlook in the field (this may also apply to dinosaur egg shell fragments); or (3) without some knowledge of dinosaur osteology, small broken fragments may go unrecognized in the field or among microvertebrates collected by screen-washing. ...
... 33,34 Lower Jurassic A clutch of six dinosaurian eggs of uncertain taxonomic affinity were found in a sandstone block derived from the Elliot Formation (Red Bed Stage), northern Orange Free State, South Africa. The initial report stated that these 104 sediments were Upper Triassic in age, 35 but more recent publications assign the Elliot Formation to the Lower Jurassic. 36 Kitching's preliminary account noted that three of the eggs clearly contained foetal remains in an advanced stage of development, while one juvenile appeared to have hatched prior to fossilisation, leaving a collapsed and shapeless eggshell embedded in the matrix. ...
There is currently no consensus among creationists about the location of the Flood/post-Flood boundary in the geological record, although most consider the Mesozoic sediments to have been deposited by the Flood. However, a study of the palaeontological literature reveals that in situ dinosaur nests occur at multiple levels throughout the Mesozoic. These nests stratigraphically overlie thousands of metres of Flood-deposited Palaeozoic sediments. Creationist arguments that attempt to accommodate multiple periods of nest building and nurture of juveniles within the limited time available during the Flood have not proven convincing. The nests are strong evidence that the Mesozoic host sediments are post-Flood.
... ,49 R e f e r e n c e s Reproductive behaviors may have been similar to those of later generations of dinosaurs, but only two Late Triassic dinosaur nests (containing dinosaur egg clutches) have been found so far.50,51 Thus, much is still unknown about whether dinosaur parents brooded or cared for their young, behaviors proposed for some Late Cretaceous dinosaurs (see Horner, page 71).52 ...
3 he rhetorical and two-part question "From where did dinosaurs come and where did they go?" encourages the asking of many more questions, but such questions will inevitably relate to two intertwined phenomena expe-rienced by all life: evolution and extinction. Dinosaurs, like all living things, originated through evolutionary processes, diversified as a result of those very same processes, and most of their lineages went extinct. In this chapter, I will focus on the processes and products of evo-lution in dinosaurs, but with emphasis on the beginning of that history. Hypotheses for dino-saur extinctions 65 million years ago and the evolution of some dinosaur lineages into birds are discussed in detail by other authors in this volume (see Currie, page 89; and Archibald, page 99). Scientific studies of dinosaur evolution ex-emplify that science is a work in progress. Its practitioners often acknowledge that once-stated certainties are liable to be proven wrong, once-outlandish ideas may be closer to reality than originally thought, or, alternatively, only minor tweaking is needed to clarify some previ-ously accepted hypotheses. For example, the statement "Dinosaurs evolved from reptiles in the latter part of the Late Triassic Period and went extinct at the end of the Cretaceous Pe-riod" has been amended in the past 20 years to "Dinosaurs evolved from archosaur lineages in the earliest part of the Late Triassic and some of them are still with us today as birds." Such shifts illustrate how scientists revise or disprove hypotheses more than affirm them (and often are delighted when they do so!), and dinosaurs in particular constitute excellent subjects for revisionist thinking. Each new discovery of dinosaur remains or dinosaur trace fossils pro-vides yet more evidence for testing whether previously accepted concepts about dinosaurs and their evolution (especially their origins) are still justified.
... Hirsch 1989;Mikhailov 1997). Jurassic egg sites are known from the Late Jurassic of the USA (Hirsch 1994;Turner and Peterson 2004), the Middle Jurassic of France (Garcia et al. 2006) and the Early Jurassic of South Africa (Kitching 1979;Zelenitsky and Modesto 2002;Reisz et al. 2012) and China (Reisz et al. 2013). Older egg sites are known only from the Late Triassic of Argentina (Bonaparte and Vice 1979). ...
Two new Late Jurassic (uppermost Late Kimmeridgian) dinosaur eggshell sites are described, Casal da Rola and Porto das Barcas, both near Lourinha˜, central-west Portugal. Casal da Rola yields eggshells with an obliquiprismatic morphotype comparable to those from a nest with the associated fossil embryos from Paimogo, tentatively assigned to the theropod Lourinhanosaurus antunesi. The Porto das Barcas eggshells have a dendrospherulitic morphotype with a prolatocanaliculate pore system. This morphotype was also recognised in eggshells from a clutch with associated Torvosaurus embryos at the Porto das Barcas locality. A preliminary cladistic analysis of eggshell morphology suggests theropod affinities for the Casal
da Rola eggs, but is unable to resolve the phylogenetic position of the Porto das Barcas eggs. The eggshells at both sites are preserved in distal flood plain mudstones and siltstones. Carbonate concretions within the deposits indicate paleosol development.
... Massospondylus is recorded from the earliest Jurassic of South Africa, Zimbabwe, North America and more recently Namibia as well. Clutches of archosaur eggs from the Free State Province of South Africa, which have been ascribed to Massospondylus (Kitching, 1979), are some of the oldest dinosaur eggs preserved with embryos yet discovered (Zelenitsky and Modesto, 2002). ...
... 0.46 to 0.93 m. Pores visible on the shell surface (Fig. 3B) are round to oval in shape, very abundant, evenly distributed, and typically filled by diagenetic sparry calcite. DISCUSSION Records of Mesozoic eggs from Africa are very limited, and, prior to this report, no detailed accounts of Cretaceous African dinosaur eggshell have been published. Kitching (1979) described as dinosaurian a clutch of six eggs from the Lower Jurassic Elliot Formation of South Africa, which contain embryonic remains including a reasonably wellpreserved skull. Carpenter later (1999) suggested that these small (65 55 mm) eggs were not dinosaurian, as Kitching originally believed, but instead may have derived from cro ...
Investigations over the last several decades at Gondwanan Mesozoic localities have significantly expanded our knowledge of the diversity and distribution of Southern Hemisphere dinosaurs. These records are primarily based on skeletal remains, but included among them are in- stances of preserved eggshell, notably from Argentina (e.g., Calvo et al., 1997; Chiappe et al., 1998) and India (e.g., Khosla and Sahni, 1995). In general, however, dinosaur eggshell is relatively poorly known from Gondwana, and from Africa in particular. Newly initiated (summer 2002) field research in Cretaceous-age deposits of the Red Sandstone Group in southwestern Tanzania has resulted in the discovery of a rich terrestrial/freshwater vertebrate fauna, which includes lungfishes and teleost fishes, turtles, crocodilians, sauropod and both avian and non- avian theropod dinosaurs, and mammals. Included among the dinosaur specimens are pieces of well-preserved eggshell. This is the first dinosaur eggshell from the Cretaceous of Africa to be studied and described in detail; it is here placed in the Oofamily Megaloolithidae on the basis of its structural details and surface ornament, which closely resemble those of Cretaceous megaloolithid eggshell from a number of other, non-African localities.
... The bulk of the work, however, has been restricted to the study of fossil trackways (e.g., Ellenberger and Ellenberger, 1956;Haubold, 1974;Sarjeant, 1975Sarjeant, , 1990Currie, 1983;Lockley, 1986Lockley, , 1991Gillette and Lockley, 1989;Thulborn, 1989Thulborn, , 1990Schult and Farlow, 1992;Lockley et al., 1994). Of lesser familiarity are the myriad of other trace fossils of vertebrates, including gastroliths (Farlow, 1985;Gillette et al., 1990), predation marks (Haynes, 1980;Mapes et al., 1989;Fiorillo, 1991), scavenging marks (Hasiotis et al., 1999a), coprolites (Olson, 1971;Hunt et al., 1994;Chin and Gill, 1996;Smith, 1996;Wahl et al., 1998), nests (Kitching, 1979;Horner and Gormann, 1988;Coombs, 1989;Varricchio et al., 1997;Hasiotis and Martin, 1999;López-Martínez et al., 2000), and burrows (Voorhies, 1975;Martin and Bennett, 1977;Hunt et al., 1983;Smith, 1987;Groenewald, 1991;Hunt and Skolnick, 1996;Hasiotis et al., 1999b;Meyer, 1999). ...
A scratch-marked burrow complex with multiple branching tunnels and terminal chambers was excavated from the Lower Triassic Driekoppen Formation, northeastern Free State, South Africa. The burrow complex is attributed to the therapsid Trirachodon, based on disarticulated but fairly complete skulls and skeletons of at least 20 individuals recovered from a nearby less well-preserved system. The entrance shaft slopes gently downward and is characterized by a bilobate floor and vaulted roof: The bilobate floor has a central flat-topped scratch-marked ridge flanked by two smooth grooves, each approximately the width of the occupant. At deeper levels, tunnels display tighter lateral curvatures, progressively decreasing burrow diameters, variable orientations, and some right angle branches. Burrow floors at these levels are vaguely bilobate. Distally, burrows flatten dorso-ventrally, becoming wedge-shaped before they terminate. These complexes are interpreted as colonial dwelling structures. Numerous branching tunnels and terminal chambers, as well as an enlarged entrance constitute an unrealistically high expenditure of energy for a single occupant. Furthermore, the bilobate floor is atypical of a single occupant system. Absence of scratch marks in the depressions reflects the regular locomotory activity of Trirachodon. In single-occupant burrows, the center of the structure is worn. The bilobate floor with preferential wear along the flanks suggests routine travel on one side of the tunnel or the other, as multiple occupants moved past one another during daily activity. The presence of numerous fossilized Trirachodon individuals in terminal chambers at the second locality supports multiple cohabitation There, the uniform sedimentary fill and vertebrate taphonomy suggest that the occupants were drowned in a flash flood. Vertebrate remains are absent at the first locality where sediment influx was incremental, permitting the escape of burrow occupants. This constitutes the earliest record of multiple cohabitation of a burrow complex by tetrapods. The Trirachodon (Cynodontia) of the Early Triassic Cynognathus Zone probably displayed complex social behaviors previously regarded to be restricted to the mammals of the Cenozoic. This fossorial behavior may have been for thermoregulation, protection from predators, sites of reproduction, and the rearing of young.
... This sample represents nearly all the taxonomically identifiable eggs and eggshell currently available for the Mesozoic. Exceptions include dendroolithid eggs with therizinosaur embryos ( Manning et al., 1997), Lower Jurassic eggs with embryos from the Elliot Formation of South Africa (Kitching, 1979), egg material associated with an adult Deinonychus antirrhopus (Makovicky and Grellet-Tinner, 2000), and three purported avian egg types from the Cretaceous of Mongolia (Mikhailov, 1997). Eggshell and eggs associated with the therizinosaur embryos ( Manning et al., 1997) have not been described in detail nor were they available to the authors. ...
Two egg types from the Upper Cretaceous Two Medicine Formation of Montana are described and incorporated into a phylogenetic analysis of egg characters. Small (7.5 × 3.5 cm), ellipsoidal eggs with a surface ornamentation consisting of isolated round tubercles represent a new, unnamed ootaxon. The microstructure includes narrow, prismatic shell units with three structural layers. The second egg type, oospecies Prismatoolithus levis, belongs to the theropod Troodon formosus. Although previously described, the presence of a third, external layer had been overlooked. Both eggs display several features typical of avian eggs: narrowly spaced nucleation sites, barrel-shaped mammillae with blocky crystal habit, a squamatic-like texture in the prismatic layer, and a third, structural layer. In addition, the new egg type exhibits a cuticle layer and the eggs of Troodon are asymmetric.Cladistic analysis of 14 fossil and extant taxa using 15 egg and shell characters favors a phylogeny consistent with more traditional analyses based on osteologic or genetic data and supports a theropod dinosaur origin for birds. No single character unambiguously distinguishes the eggs of avians from those of non-avian theropods, and the new Two Medicine egg type is recognized simply as that of a theropod. Results also indicate that resemblances in egg characters among non-avian and avian theropods are largely homologous and imply a high-level of similarity in reproductive physiology. Egg features are phylogenetically informative; better classifications and greater utility of eggs and eggshell will be gained through their phylogenetic treatment.
The main Karoo Basin of South Africa and Lesotho preserves c. 120 myr of Earth's history. The sedimentary rocks of its Karoo Supergroup record massive environmental changes from the glacial Carboniferous to desert dunes and fiery flood basalts in the Early Jurassic. From the early Permian, the Karoo Basin was gradually filled with fluvial and lacustrine deposits, and the alluvial plains were successively colonised by a diverse suite of plants and animals. The fossils of these ancient inhabitants and their behavioural traces form an astounding Gondwanan geoheritage legacy in southern Africa, providing fossil evidence for the moving lithospheric plates and the effects of four mass extinctions and their subsequent biotic recovery. Here, we present six Karoo sites of global geoscientific importance that best display that heritage, with the caveat that these sites only touch upon the Karoo riches that are available for academic research and the emerging palaeotourism industry. It is our hope that these sites will become anchor points for a sustainable geoheritage future in southern Africa.
Massospondylus carinatus is a basal sauropodomorph dinosaur from the early Jurassic Elliot Formation of South Africa. It is one of the best-represented fossil dinosaur taxa, known from hundreds of specimens including at least 13 complete or nearly complete skulls. Surprisingly, the internal cranial anatomy of M. carinatus has never been described using computed tomography (CT) methods. Using CT scans and 3D digital representations, we digitally reconstruct the bones of the facial skeleton, braincase, and palate of a complete, undistorted cranium of M. carinatus (BP/1/5241). We describe the anatomical features of the cranial bones, and compare them to other closely related sauropodomorph taxa such as Plateosaurus erlenbergiensis , Lufengosaurus huenei , Sarahsaurus aurifontanalis and Efraasia minor . We identify a suite of character states of the skull and braincase for M. carinatus that sets it apart from other taxa, but these remain tentative due to the lack of comparative sauropodomorph braincase descriptions in the literature. Furthermore, we hypothesize 27 new cranial characters useful for determining relationships in non-sauropodan Sauropodomorpha, delete five pre-existing characters and revise the scores of several existing cranial characters to make more explicit homology statements. All the characters that we hypothesized or revised are illustrated. Using parsimony as an optimality criterion, we then test the relationships of M. carinatus (using BP/1/5241 as a specimen-level exemplar) in our revised phylogenetic data matrix.
References used to compile reproductive ecology data.
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Two different kinds of rounded structures (spherical and ellipsoid ones), filled by clayey-ferruginous sediment, occur in the fine- grained sandstone of a crevasse splay origin (meandering river environment) in the Early Hettangian Zagaje Formation, in the locality called Soltykow, nearby little town of Odrowaz, central Poland. The structures are interpreted as dinosaur eggs, precisely as the 'post-egg structures'. They are strongly altered by diagenetic processes and no obvious eggshell structure is preserved. However, faint embryo remains found inside one of the ellipsoid structures and characteristic circular clutch of the spherical structures, allows conclusion that the structures represent dinosaur eggs. This conclusion is supported by other evidences, such as regular size and shape of the structures and joint occurrence with numerous dinosaur footprints. While the circular clutch laid in a shallow depression represents an in situ nest, the smaller, ellipsoid eggs were probably transported a short distance by the current associated with a flood event. The circular clutch of unhatched egg structures most probably represents a nest of earliest sauropods; their footprints and trackways have been found nearby. The smaller ellipsoid egg structures are difficult to classify, they may represent either basal ornitishian or theropod eggs. This is the first find of dinosaur egg structures in Poland and the second known Lower Jurassic dinosaur nesting ground world-wide. It may also stimulate discussion on diagenetically altered dinosaur eggs.
Dinosaur's egg-laying behaviour and incubation's physiology of the eggs belonging to the Megaloolithidae oofamily are poorly understood, mainly because the methods of observation and collecting are inadequate. Early works led to the conclusion that the dinosaurs dug a hole in the sediment in which they buried their clutches. A precise study of the outcrops previously studied led us to disagree with these conclusions. In order to understand the distribution of the eggs on the field, compare the outcrops and get a better knowledge of the ethology of dinosaurs, we have to study the structural morphotypes; so, we can range the eggs in the parataxonomy. Because of diagenesis which is responsible for the destruction of the microstructure, some species are not distinguishable and are synonyms. Shell thickness of the eggs and width of the pores, used in previous works to calculate the permeability of the shell and to demonstrate that the eggs were incubated underground, are also modified because of diagenesis. On the field, when the sediments were soft, we made precise and complete excavations using the technical principles of prehistoric archaeology; thus we were able to study the taphonomy of the clutches. We used a method to remove the eggs which permitted to study them upside up in the laboratory. We show the precise excavation of a clutch coming from hardened sediments; a silicon moulding of the outcropping surface helped us to reconstitute it. When the excavation wasn't possible, only the outcropping eggs and eggshells were studied. We cannot establish a clutch typology yet, but because of the microstructures of the eggs and the precise studies realised on the field, we can propose two kinds of incubation associated with the two oogenus belonging to the Megaloolithidae oofamily. Megaloolithus eggs, with an external surface covered with tubercles, seem to be adapted to a shallow underground incubation. Smoothed Cairanoolithus eggs, were laid on the surface of the soil and perhaps incubated under a vegetal mound.
Eggshell structure of modern and fossil amniotic vertebrate is presented on the base of thin sections, SEM, epifluorescence, CL and EDX. In all, eggshell of 30 turtles (Testudines), 84 Lepidosauria (1 Rhynchocephalia, Sphenodon, 83 Squamata, 54 Sauria + 29 Serpentes), 8 Crocodilia and 158 Aves are studied and documented. Fossil eggshells are analyzed from the Upper Jurassic (4 localities), the Cretaceous (7 localities) and the Cenozoic (15 localities). Due to their ultrastructure they can be assigned to turtles, crocodiles, dinosaurs and palaeognathous and neognathous birds. Due to their function, most calcareous vertebrate eggshells (Testudines + Archosauria) are characterized by a regular structure of vertical columns, growing from the underlaying membrana testacea, which can be described as a threedimensional network of organic fibres. While most morphological features of the rigid shell can be explained by geochemical data, such as organic matrix and amino acid content, the arrangement of shell units seems to be controlled by the structure of the membrana testacea, especially with the architecture of prominent organic fibres. This model is supported by some case studies of modern and fossil eggshells. In general, the formation of the organic and calcareous shell must be regarded as a puzzle-like process of egg enlargement, liquid influx, nucleation, crystal growth, and pore formation. While most of the studied egg shells of Squamata (except the Gekkonidae) are soft and flexible with only few calcareous matter, a tendency of an increasing calcification can be observed in colubrid snakes, culminating in the species Spalerosophis diadema, living in arid zones, producing completely calcified and rigid egg shells. A correlation of degree of calcification in lepidosaurian eggshell and ecologic environmental conditions (especially temperatures and water content of substrates) is suggested. Due to comparisons of eggshell structure in modern taxa it can be concluded that the soft eggshell in Sauria and Serpentes (predominantly not calcified) is not homologous to the soft organic layer ('Membrana testacea') of rigid calcified eggshells in turtles, crocodiles, and birds. They mainly differ in the fine architecture of the organic fibers as well as in their amino acid composition. Additionally, the calcareous rigid shells of turtles and archosauria are not homologous, since they differ in mineralogy (aragonite versus calcite) and growth mode. Development of distinct shell units appears to be an adaption to conditions within the nest habitat and to pore formation and fragility of the shell. The high variability of avian eggshell structure can be used for classification of birds. Nearly all traditional avian orders can be defined by special morphotypes of shell structure. However, few orders exhibit very high structural variability, indicating their polyphyletic origin. Many taxa, placed far away from each other in the system of birds can have similar eggshell structure (e.g. Galliformes and Anseriformes). In contrast, others, placed very close to each other can have very different shells (e.g. Cuculiformes and Strigiformes). In general, a closer correspondence between shell structure and systematic position is more evident in the classification of birds by Sibley (e.g. his Galloanserae and Ciconiiformes). In contrast to the well-known idea published by Romer in 1957 that the egg came first while adult reptiles in the Carboniferous remained in water, it is suggested that the early evolution of the amniote egg (including the gradual formation of extraembryonic membranes) is suggested to have happened within the aquatic realm. Increasing enlargement of eggs and yolk is interpreted as an adaptation of reproduction strategies to lakes with poor nutrient contents. The first accumulation of Ca-ions in the outer organic membrane, paralleled by many modern noncalcified lepidosaurian eggs, is suggested as a process of detoxification, according to new ideas in biomineralization. The function of the shell, to protect the embryo against microbial activity and to prevent water loss, which is necessary for the preamniote egg to become a fully terrestrial egg, was the terminal step in the process of terrestrialization of eggs. Yolk-rich eggs enclosed by a more or less calcified shell can be interpreted as an essential preadaptation for tetrapods to have become fully terrestrial during the Late Paleozoic. This sequence of the suggested evolution of the amniotic egg is reflected by the ontogenetic development of embryonic membranes of living amniota: Since the allantois is the last of the fetal membranes to differentiate, Luckett (1977) concluded that the origin of the allantois was related to its function as a urinary bladder for storage of excretions after the ovum reached a size (including a stabilizing shell), when it has become impossible for toxic excretory products to diffuse out of the embryo. Concerning the presented model, the phylogenetic development of the allantois took place on dry land when diffusion of toxic excretory products has become impossible. Taphonomy and early and late diagenesis of fossil eggs and eggshells are discussed. Diagenetic phenomena of fossil avian eggshells are preservation of a calcified Membrana testacea, reprints of the Membrana testacea at the basal mammillae, mineralized color lines, primary and secondary calcified deposits on the outer surfaces, calcified pore channels and recrystallisation of the shell. Early calcification of organic material within the closed egg appears to be responsible for stabilisation of the fragile shell. Due to some few observations in modern environments, the bacterially induced decay of organic matter (sulphurication, ammonification) within vertebrate eggs is dramtically reduced when the complete egg is buried immediately into sediments. In siliciclastic sands the eggshell is dissolved while the organic content (dried yolk, embryonic remains including feathers) can be preserved unaltered for many years. Calcification of pores and mineralization of the organic Membrana testacea is, therefore, regarded as evidence for preburial diagenesis. It is concluded that fossil eggs and eggshells are mainly allochthonous, except when nest structure is preserved.
The disappearance of nonavian dinosaurs is only a small part of a greater class of extinctions known as “mass extinctions.” Mass extinctions are global events characterized by unusually high rates of extinction. The five episodes of mass extinctions in Earth history are the Permo-Triassic extinction, the Late Ordovician extinction, the Late Devonian extinction, the Triassic-Jurassic extinction, and the Cretaceous-Tertiary (K/T) extinction. This chapter focuses on patterns of geologic and biotic changes that occurred during the Cretaceous-Tertiary (K/T) extinction. It also highlights the similarities and differences in interpretations of geologic and fossil records. It concludes with two scenarios explaining the differing views about dinosaur extinction.
Early Triassic coals are unknown, and Middle Triassic coals are rare and thin. The Early Triassic coal gap began with extinction of peat-forming plants at the end of the Permian (ca. 250 Ma), with no coal known anywhere until Middle Triassic (243 Ma). Permian levels of plant diversity and peat thickness were not recovered until Late Triassic (230 Ma). Tectonic and climatic explanations for the coal gap fail because deposits of fluctuating sea levels and sedimentary facies and paleosols commonly found in coal-bearing sequences are present also in Early Triassic rocks. Nor do we favor explanations involving evolutionary advances in the effectiveness of fungal decomposers, insects or tetrapod herbivores, which became cosmopolitan and much reduced in diversity across the Permian-Triassic boundary. Instead, we favor explanations involving extinction of peat-forming plants at the Permian-Triassic boundary, followed by a hiatus of some 10 m.y. until newly evolved peat-forming plants developed tolerance to the acidic dysaerobic conditions of wetlands. This view is compatible not only with the paleobotanical record of extinction of swamp plants, but also with indications of a terminal Permian productivity crash from δ13Corg and total organic carbon of both nonmarine and shallow marine shales.
Fossil discoveries from South Africa have greatly expanded knowledge of the development of life on Earth. In particular, the
enormous palaeontological wealth of the Karoo, covering a period of almost 100 million years from the Permian to the Jurassic,
has enhanced understanding of the evolution of important tetrapod lineages, including mammals and dinosaurs. These fossils
provide the best record of continental Permian to Jurassic faunal biodiversity, and have been crucial to studies of the global
Permo-Triassic mass extinction in the continental realm, as well as giving insight into other extinction events. Recent collaborative
interdisciplinary studies of stratigraphic and geographic distribution patterns of Karoo fossils have enhanced biostratigraphic
resolution and global correlation of vertebrate faunas from the Permian to the Jurassic. This in turn has led to a better
understanding of the biodiversity across Pangaea, and the places of origin and initial diversity of early tetrapod evolutionary
lineages. Many of these originated in the southern African portion of the Gondwanan super-continent. The combination of palaeontological
and sedimentological studies has led to new basin development models and solved problems which each discipline in isolation
could not have achieved.
Two embryonic skeletons preserved inside thin-shelled eggs of a partially preserved clutch from the Upper Elliot Formation (Lower Jurassic) of South Africa have been attributed to the sauropodomorph dinosaur Massospondylus carinatus. A virtually complete skeleton is exposed in right lateral view, with the slightly telescoped skull and several cervical vertebrae extending beyond the eggshell. A second, partial skeleton has a skull preserved in dorsal view. The embryos have proportionately very large skulls, with the broad skull table formed by wide parietals and frontals. The wide posterolateral wing of the frontal separates the postorbital from contact with the parietal. The embryos have short rather than elongated cervical vertebrae, with tall rather than low neural arches. The large forelimbs are only slightly shorter than the hind limbs, which suggests an obligatory quadrupedal posture for the hatchlings. This pattern may represent an ontogenetic constraint related to the large size of the head and horizontally oriented neck. Similarities between the embryonic and post-hatchling specimens include the slenderness of the lower jaw and slight ventral curvature of the symphyseal portion of the dentary, the large supraorbital process of the prefrontal, and the tall antorbital and infratemporal fenestrae. There are 10 cervical, 14 dorsal, and three sacral vertebrae. The large distal claw-bearing phalanx of manual digit 1 is longer than any other phalangeal element of either manus or pes. The embryos of Massospondylus carinatus represent the oldest dinosaurian embryos known to date.
Embryonic dinosaur remains are extremely rare1,2 and with the exception of the specimens described here, are so fragmentary that they have yielded little or no information useful for palaeobiological interpretation. We report here the first well-documented association of dinosaur eggs containing embryos, juveniles and adults from the fossil record. The material, attributable to a new hypsilophodontid, Orodromeus makelai, n. gen., n. sp., and the hadrosaurid Maiasaura peeblesorum, comes from the Upper Cretaceous Two Medicine Formation of western Montana3. Osteo-logical and histological studies of these two animals indicate structural and morphological adaptations for their respective growth patterns and neonate behaviour.
Aus der Unterkreide (Unter-Barremium) von Galve (Provinz Teruel, SE-Spanien) werden fossile Eischalen beschrieben, die sich
verschiedenen Reptilgruppen zuordnen lassen. Nachgewiesen werden konnten a) Eischalen unbekannter, vermutlich amphibisch lebender
Schildkröten, b) großporige Eischalen, vielleicht von der Unterfamilie Batagurinae (Emydidae), die damit erstmals aus der
Unterkreide dokumentiert wäre, c) mutmaßliche Schildkröten-Eischalen, d) die bislang ältesten Krokodil-Eischalen, die ähnlich
den modernen Formen auf der Außenseite Lakunensysteme entwickelt haben und Dinosaurier-Eischalen von e) ? Ornithischiern und
f) ? Saurischiern. Entsprechend dem vermuteten fluviatilen Paläo-Environment von Galve sind die Eischalen zerbrochen und lassen
sich zum größten Teil auf Schildkröten und Krokodile zurückführen.
The Lower Cretaceous vertebrate bearing sediments of Galve (province of Teruel, SE Spain) have yielded some hundred fossil
eggshell fragments, all slightly diagenetically altered. Concerning their microstructure, an assignment of the material to
different taxa of reptiles was possible. The eggshell assemblage of Galve consists of a-c) three types of chelonian eggshells,
one of them probably representing the subfamily Batagurinae, which would extend this taxon back into the Lower Cretaceous,
d) the oldest known crocodilian eggshells, with lacunae systems on the outer surface, comparable to Recent taxa, and e-f)
two different types of dinosaurian eggshells. In correspondence to the suggested fluviatile paleoenvironment of Galve, the
fossil eggshells described herein are fragmented and represent mostly turtles and crocodiles.
Several well preserved clutches of dinosaurs have been discovered in the upper Kimmeridgian/Tithonian of Lourinhã (Estramadur Province, Portugal). Some eggs of one clutch contained embryo elements of a theropod dinosaur. The egg-shell resembles that of eggs which have been discovered in the Upper Jurassic of Colorado.
The extensive Early Jurassic continental strata of southern Africa have yielded an exceptional record of dinosaurs that includes scores of partial to complete skeletons of the sauropodomorph Massospondylus, ranging from embryos to large adults. In 1976 an incomplete egg clutch including in ovo embryos of this dinosaur, the oldest known example in the fossil record, was collected from a road-cut talus, but its exact provenance was uncertain. An excavation program at the site started in 2006 has yielded multiple in situ egg clutches, documenting the oldest known dinosaurian nesting site, predating other similar sites by more than 100 million years. The presence of numerous clutches of eggs, some of which contain embryonic remains, in at least four distinct horizons within a small area, provides the earliest known evidence of complex reproductive behavior including site fidelity and colonial nesting in a terrestrial vertebrate. Thus, fossil and sedimentological evidence from this nesting site provides empirical data on reproductive strategies in early dinosaurs. A temporally calibrated optimization of dinosaurian reproductive biology not only demonstrates the primary significance of the Massospondylus nesting site, but also provides additional insights into the initial stages of the evolutionary history of dinosaurs, including evidence that deposition of eggs in a tightly organized single layer in a nest evolved independently from brooding.
The St. Mary River Formation (Maastrichtian) consists of anastomosed fluvial deposits containing several hundred track-bearing beds. Paleontologic and sedimentologic analyses of these beds indicate that large herbivores, ornithopods, inhabited a seasonal wetland dominated by marshes and lakes. Shallow tracks in fine-grained sediments, formed as the sediments dewatered to the point of stiffness, display the highest resolution of detail. The preservation potential of tracks in anastomosed fluvial deposits is large because of the abundance of soft substrates to record the tracks and the occurrence of annual flooding to rapidly bury the footprints. Comparison of the St. Mary River Formation to other anastomosed fluvial deposits as old as the Early Jurassic confirms that tracks are common in this type of deposit. The variation in preservation of track types and depth of penetration raises the possibility that ornithopods employed a survival strategy involving seasonal wetlands. The wetlands provided an abundant food source and at the same time the combination of a soft substrate and flooded conditions would have effectively countered the superior speed and agility of large carnivores. The relatively common occurrence of ornithopod eggshells from anastomosed fluvial deposits suggests that the abundant food supply accompanying the wet season also made the wetlands an ideal location to rear young. These data can be used to refine the interpretations of depositional environment derived from the sediments by allowing estimates to be made regarding the early post-depositional conditions of the sediments. 95 refs., 7 figs., 1 tab.
Non-avian dinosaur reproductive and parenting behaviors were mostly similar to those of extant archosaurs. Non-avian dinosaurs were probably sexually dimorphic and some may have engaged in hierarchical rituals. Non-avian coelurosaurs (e.g. Troodontidae, Oviraptorosauria) had two active oviducts, each of which produced single eggs on a daily or greater time scale. The eggs of non-coelurosaurian dinosaurs (e.g. Ornithischia, Sauropoda) were incubated in soils, whereas the eggs of non-avian coelurosaurs (e.g. Troodon, Oviraptor) were incubated with a combination of soil and direct parental contact. Parental attention to the young was variable, ranging from protection from predators to possible parental feeding of nest-bound hatchlings. Semi-altricial hadrosaur hatchlings exited their respective nests near the time of their first linear doubling. Some reproductive behaviors, once thought exclusive to Aves, arose first in non-avian dinosaurs. The success of the Dinosauria may be related to reproductive strategies.
Articulated embryos from the Lower Jurassic Elliot Formation of South Africa are referable to the prosauropod Massospondylus carinatus and, together with other material, provide substantial insights into the ontogenetic development in this early dinosaur. The large forelimbs and head and the horizontally held neck indicate that the hatchlings were obligate quadrupeds. In contrast, adult Massospondylus were at least facultatively bipedal. This suggests that the quadrupedal gait of giant sauropods may have evolved by retardation of postnatal negative allometry of the forelimbs. Embryonic body proportions and an absence of well-developed teeth suggest that hatchlings of this dinosaur may have required parental care.
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