FIG 2 - uploaded by Daniel E. Barta
Content may be subject to copyright.
Source publication
Haya griva is an early-diverging neornithischian (“hypsilophodontid”) dinosaur known from several well-preserved skulls and articulated postcranial skeletons, in addition to dozens of partial or isolated finds from the Upper Cretaceous Khugenetslavkant and Zos Canyon localities (Javkhlant Formation and equivalent beds) in the Gobi Desert of Mongoli...
Contexts in source publication
Context 1
... 100/3137 ( fig. 29), articulated postcrania lacking skull. IGM 100/3178 (figs. 7, 32, 36, 39, 40, 45, 46, 48), skull (CT scanned) and partially articulated postcrania. IGM 100/3181 ( fig. 8), skull (CT scanned) and articulated dorsal series with ribs, manual phalanges, radius and ulna (Norell and Barta, 2016). IGM 100/3182 ( fig. 50), partial postcrania, ...
Context 2
... (CT scanned) and partially articulated postcrania. IGM 100/3181 ( fig. 8), skull (CT scanned) and articulated dorsal series with ribs, manual phalanges, radius and ulna (Norell and Barta, 2016). IGM 100/3182 ( fig. 50), partial postcrania, including a largely complete left leg, some dorsal vertebrae, and associated gastroliths. IGM 100/3557 ( fig. 12), crushed partial skull. IGM 100/3661 ( fig. 14), disarticulated partial skull and skeleton. IGM 100/3672 ( fig. 15), partial pelvic region and articulated legs and feet from two individuals in close proximity, centra of the axis and third cervical vertebra, a jaw fragment and other surface collected fragments, including a possible ...
Context 3
... The otic region of IGM 100/2014 contains a small, rod-shaped element with a flat plate on its dorsally facing end ( fig. 20). The flat plate is probably the footplate of the stapes. Despite its slight displacement within the crushed skull, its relative size, location, and morphology are all consistent with the stapes of Lesothosaurus and Thescelosaurus, as well as other dinosaurs and extant reptiles (Colbert and Ostrom, 1958;Sereno, 1991;Galton and Upchurch, ...
Context 4
... The basisphenoid and parasphenoid are fused, as in most dinosaurs, and together they contribute to the ventral floor of the braincase ( fig. 21). The body of the basisphenoid is anteroposteriorly concave ventrally, and narrows along its middle, flaring both at the basipterygoid processes anteriorly and at its contributions to the basal tubera along its contacts with the basioccipital posteriorly. The basisphenoid is proportionally longer in Heterodontosaurus than in Haya and ...
Context 5
... other neornithischians (Norman et al., 2011). As in Thescelosaurus, the parasphenoid is at the same level as the dorsal surface of the basisphenoid (Boyd, 2014), instead of offset ventrally from it in lateral view as in Dysalotosaurus ( Sobral et al., 2012) . The cultriform process extends from the parasphenoid anteriorly along the midline (fig . 21). The short, dorsoventrally deep keel of the cultriform process is restricted to the middle one third of the cultriform process and is separated from the body of the basisphenoid by a distinct "neck" in lateral view, unlike Thescelosaurus, in which the keel merges more gradually with the body of the basisphenoid (Boyd, 2014), and ...
Context 6
... in lateral view, unlike Thescelosaurus, in which the keel merges more gradually with the body of the basisphenoid (Boyd, 2014), and Lesothosaurus, which lacks such a keel (Sereno, 1991;Porro et al., 2015). The cultriform process contains a broad groove dorsally. A faint transverse ridge separates this groove from the pituitary fossa posteriorly ( fig. 21). The rounded, knoblike basipterygoid processes extend anteroventrally, as in Lesothosaurus, Heterodontosaurus, and Thescelosaurus (Sereno, 1991;Norman et al., 2011;Boyd, 2014;Porro et al., 2015), but in contrast to the more ventrally directed basipterygoid processes of Zephyrosaurus and Dysalotosaurus (Sues, 1980;Sobral et al., 2012). ...
Context 7
... The pterygoid is divided into a sheet-to rodlike palatine ramus, tabular mandibular ramus, and sheetlike quadrate wing (or ramus), all roughly orthogonal to one another ( fig. 22). The two pterygoids are closely appressed along part of their palatine rami anteriorly, but are separated by a narrow interpterygoid vacuity posteriorly. The pterygoid tapers to form a narrow palatine ramus that arches upward to contact the vomer anteriorly, near the level of the base of the lacrimal (Makovicky et al., 2011). The ...
Context 8
... Only portions of the vomer are externally visible in IGM 100/2017. As in Hypsilophodon (Galton, 1974a) and Thescelosaurus (Boyd, 2014), the vomers form two separate compressed sheets posteriorly that join to form a single median rod-shaped element that tapers slightly anteriorly ( fig. 25). The posterior ends of the vomers overlap the palatal rami of the pterygoids dorsally, as is typical of most dinosaurs and possibly plesiomorphic for Archosauria (Sereno, 1991). In Haya, this contact occurs ventral to the (Galton, 1974a;Thomas, 2015), but in contrast to Lesothosaurus and Thescelosaurus (Boyd, 2014;Porro et al., 2015). ...
Context 9
... scans reveal that the five erupted teeth have single replacement teeth below them in the right dentary of IGM 100/2017: at the first, fourth, seventh, ninth, and 14th alveoli (counted from anterior to posterior) ( fig. 26A). The erupted teeth at these positions are among the most heavily worn along the toothrow. Only the replacement tooth at the ninth alveolus has partially erupted, lingual to a heavily worn, erupted tooth. The left dentary contains replacement teeth at the third, sixth, ninth, and 12th alveoli; those at the third and sixth positions are ...
Context 10
... 1974a;Jin et al., 2010). Due to slight disarticulation of the postdentary region, IGM 100/2014 reveals that the anterior prong articulates with the dentary and splenial along a tongue-in-groove joint ( fig. 9). A ridge or crease clearly defines the transition from the convex ventral face to the flat lateral face, and is especially apparent in IGM 100/2016 (fig. 10A, C). The lateral face lacks the depression present in Thescelosaurus (Boyd, ...
Context 12
... striated surfaces probably mark attachment sites for the hypaxial muscles sal series. The ventral surfaces of the transverse processes of IGM 100/3181 contain a shallow fossa, as in Changchunsaurus ( Butler et al., 2011), but in contrast to Jeholosaurus, in which this fossa is divided into anterior and posterior fossae by a ridge (Han et al., 2012). Parapophyses are likely located on the neural arch ventral to the diapophysis in the anterior dorsals, but these are obscured in articulated specimens. ...
Context 13
... visible, all sacral centra are fused or at least very tightly appressed to one another. Because not all of the sacral vertebrae are exposed in any Haya specimen, it is difficult to determine whether the sequence of fusion proceeded anteroposteriorly, as may have been the case in Parksosaurus (Brown et al., 2011), or in some other manner. The first dorsosacral centrum lacks the sharp ventral keel and laterally expanded articular facets of the successive sacral centra. ...
Context 14
... Vertebrae, Caudal Ribs, and Chevrons: A complete caudal series is not available from any Haya specimen yet collected. IGM 100/3137 preserves the most extensive portion of the tail, with 22 caudals (fig. 29). The full count was likely more than double this, based on near complete tails of Agilisaurus, Parksosaurus, Thescelosaurus, and Hypsilophodon that contain between 42 to 50 vertebrae (Gilmore, 1915;Norman et al., 2004). The first caudal vertebra is slightly dorsoventrally taller than the last sacral vertebra. It is not fused to the ...
Context 15
... becoming nearly vertical after the third caudal. This angle is steeper than on the corresponding anterior nine caudals of Albertadromeus, in which the anterior zygapophyses meet along a 45° angle ( Brown et al., 2013). The prezygapophyses of the distalmost preserved caudals of IGM 100/3137 are elongated relative to those of the anterior caudals ( fig. 29). The short, anterodorsally inclined transverse processes articulate with caudal ribs on the first 19 caudals of IGM 100/2015 (Makovicky et al., 2011). The first two of these ribs are relatively straight dorsoventrally. Subsequent ribs are gently arced dorsoventrally, until at least the eighth caudal and possibly beyond. Caudal rib ...
Context 16
... III is mediolaterally narrower overall than metacarpal II. Metacarpal IV is the shortest of the preserved metacarpals in Haya (Makovicky et al., 2011), though metacarpal V, if present, would have likely been shorter, as evidenced by the other aforementioned taxa for which metacarpals are preserved. No evidence yet exists for a fifth metacarpal in Haya, however. ...
Context 17
... Phalanges: The phalangeal formula for Haya, based on all available material is 2?-3?-4?-?-?. No complete phalangeal sequence has been preserved for any digit of either IGM 100/2015 ( fig. 37) or IGM 100/3181 (Norell and Barta, 2016: fig. 6B-E). IGM 100/3137 ( fig. 29) and IGM 100/3672 also have a few disarticulated phalanges. The proximalmost phalanges of digits I and II are about the same length, with that of digit III markedly shorter. An isolated phalanx of IGM 100/3181 (Norell and Barta 2016: fig. 6D), likely from digit III, is wider across its proximal end than it is long. All phalanges have ...
Context 18
... these differences in outline are caused by the degree of either dorsal or ventral deflection of the postacetabular process. The ilium of Haya is laterally concave, due to lateral bending of the pre-and postacetabular processes (Makovicky et al., 2011). In lateral view, the anterior end of the preacetabular process is more hooked in IGM 100/2019 ( fig. 34) than in IGM 100/2015 (fig. 38). It is also more hooked than that of most thescelosaurid taxa ( Brown et al., 2013). The overall curvature of the preacetabular process is also individually variable in Orodromeus ( Scheetz, 1999), suggesting that variation in this region in Haya is not unusual . In contrast to the description of Makovicky et al. (2011), we note that ...
Context 19
... and probably squared off. It is slightly disarticulated, and therefore its original orientation relative to the ilium cannot be determined. The pubic peduncle is dorsoventrally expanded and is also transversely compressed and probably squared off, articulating with the pubis just distal to the probable position of the obturator notch in IGM 100/2015 (fig. 38). The pubic peduncle is longer than the iliac peduncle in IGM 100/2015, as in Jeholosaurus (Han et al., 2012). The two peduncles meet at an angle of approximately 140° in lateral view. The broad, U-shaped concavity between them forms the ventral border of the acetabulum. The morphology of these peduncles differs little from other ...
Context 20
... The pubic peduncle is longer than the iliac peduncle in IGM 100/2015, as in Jeholosaurus (Han et al., 2012). The two peduncles meet at an angle of approximately 140° in lateral view. ...
Context 21
... sample of Haya contains a growth series of femora. Two isolated femora, the 64 mm long (estimated) IGM 100/2020 ( fig. 43) and the 162 mm long IGM 100/1324 ( fig. 41), bracket the size range of currently known specimens. All of the other femora are intermediate in length between these, exemplified by the 129 mm long femur of IGM 100/2015 ( fig. 42) and the 125 mm long femur of IGM 100/ 2013 (fig. 44). The histology of some of these femora is discussed in a subsequent section of this ...
Context 22
... of femora. Two isolated femora, the 64 mm long (estimated) IGM 100/2020 ( fig. 43) and the 162 mm long IGM 100/1324 ( fig. 41), bracket the size range of currently known specimens. All of the other femora are intermediate in length between these, exemplified by the 129 mm long femur of IGM 100/2015 ( fig. 42) and the 125 mm long femur of IGM 100/ 2013 (fig. 44). The histology of some of these femora is discussed in a subsequent section of this ...
Context 23
... 1974a;Scheetz, 1999;Butler et al., 2011;Huh et al., 2011;Han et al., 2012). A broad U-shaped valley separates the head from the greater trochanter proximally. A shallow circular depression occupies the lateral surface of the greater trochanter in IGM 100/1324 ( fig. 41D), but this surface is flat in IGM 100/2013 ( fig. 44D), IGM 100/2015 ( fig. 42B), and IGM 100/2019 (fig. 34). The lateral surface of the greater trochanter is more extensively depressed in Changchunsaurus (Butler et al., 2011). In IGM 100/2013, there is a narrow, proximodistally oriented ridge on the posterior portion of the greater trochanter in lateral view that mirrors the lesser trochanter for a short distance ( fig. 44D). This ridge is ...
Context 24
... of the greater trochanter is more extensively depressed in Changchunsaurus (Butler et al., 2011). In IGM 100/2013, there is a narrow, proximodistally oriented ridge on the posterior portion of the greater trochanter in lateral view that mirrors the lesser trochanter for a short distance ( fig. 44D). This ridge is also present in Jeholosaurus (Han et al., 2012: fig. 10A, I). The lesser (or anterior) trochanter, while clearly distinct from the greater trochanter, is tightly appressed to its anterior surface, as in Heterodontosaurus, Fruitadens, and most neornithischians Butler et al., 2012;Sereno, 2012;Galton, 2014). In contrast, the lesser trochanter is separated from the greater trochanter by a wide ...
Context 25
... (Huh et al., 2011). The medial surface of its distal end contains a deep trough bounded by sharp ridges anteroventrally and posterodorsally. Another sharp ridge runs the length of the lateral surface of the fourth trochanter. The distal end of the fourth trochanter of IGM 100/2013 ( fig. 44) is more transversely expanded than in IGM 100/2015 ( fig. 42). The fourth trochanter of IGM 100/2013 is more ventrally hooked than that of IGM 100/2015 andJeholosaurus (Han et al., 2012). Scheetz (1999) also noted some intraspecific variation in fourth trochanter shape in Orodromeus . As in other ornithischians with a pendant fourth trochanter (Maidment and Bar- rett, 2011), caudofemoralis brevis ...
Context 26
... fibular condyle is separated from these by deep sulci (the anterior sulcus is the incisura tibialis) and points laterally to articulate with the fibula. The fibular condyle is smaller in Haya than in Jeholosaurus (Han et al., 2012). As in Orodromeus, Changchunsaurus, Koreanosaurus, and Hypsilophodon (Galton, 1974a;Scheetz, 1999;Huh et al., 2011), but not Hexinlusaurus, "Yandusaurus" hongheensis, Jeholosaurus, Anabi- setia, and Gasparinisaura (He and Cai, 1984;Coria and Salgado, 1996;Salgado et al., 1997;Coria et al., 2007;Han et al., 2012), there is a small anterolaterally directed accessory condyle separated posteriorly from the fibular condyle by a broad, shallow sulcus. ...
Context 27
... uncertainty as to their identities, we refer to the elements in Haya simply as the medial and lateral distal tarsals. In light of this, the distal tarsals of Orodromeus and Jeholosaurus do not seem to be as unusual as described by Han et al. (2012), as the morphologies of the medial and lateral distal tarsals are very similar to those of Haya (IMG 100/2013, fig. 47B). The lateral distal tarsal of Haya is similar to the lateralmost distal tarsal of Heterodontosaurus, which is cuboidal with a possible foramen on its posterior (plantar) surface (Santa Luca, 1980). Metatarsals: IGM 100/2013 and IGM 100/3178 have complete, articulated metatarsals and phalanges (figs. 47, 48). The overall proportions ...
Context 28
... on all the digits are the longest. Each phalanx is smooth dorsally and ventrally. All phalanges except I-1, II-1, and IV-1 have a dorsal lip that articulates with the extensor groove of the preceding phalanx. There is a short dorsal lip on phalanx III-1 in one specimen of Haya, IGM 100/3178 ( fig. 48B, C), but not in another, larger specimen, IGM 100/2013 (fig. 47). The presence of a short dorsal lip on phalanx III-1 is also variable in Jeholosaurus, but in that taxon the larger specimen (IVPP V15939) has the lip, while the smaller one (IVPP V12529) lacks it ( Han et al., 2012: fig. 12A, B, E, F). Therefore, in contrast to the observation by Makovicky et al. (2011) and the condition in ...
Context 29
... on phalanx III-1 in one specimen of Haya, IGM 100/3178 ( fig. 48B, C), but not in another, larger specimen, IGM 100/2013 (fig. 47). The presence of a short dorsal lip on phalanx III-1 is also variable in Jeholosaurus, but in that taxon the larger specimen (IVPP V15939) has the lip, while the smaller one (IVPP V12529) lacks it ( Han et al., 2012: fig. 12A, B, E, F). Therefore, in contrast to the observation by Makovicky et al. (2011) and the condition in Hypsilophodon (Galton, 1974a), Haya does not always lack dorsal lips on all proximal phalanges. All nonungual phalanges are ginglymoid and bear deep collateral ligament pits. Phalanx I-1 is relatively long, as in Changchunsaurus, ...
Context 30
... of the whole medullary cavity circumference, though less extensively from the lateral side. This erosion is likely in part a taphonomic modification. The bone is primarily woven fibered near the inner cortex and parallel fibered surrounding the growth marks in the outer 1/3 of the cortex (some woven bone is interspersed between these bands) ( fig. 52B). The section contains primarily longitudinal vascular canals, with some anastomoses stretching across two to five canals. There is some lamellar bone encircling the canals to form primary osteons. Osteocyte density is high and more regular than that of IGM 100/2020. One line of arrested growth (LAG) and two annuli are present, with ...
Context 31
... 157 mm long. The midshaft cross section is crushed, but is broadly similar in shape to those of IGM 100/2015 and IGM 100/1324. Much of the bone microstructure and vascular pattern is obscured by possible postmortem fungal alteration, but the less altered patches show parallel-to wovenfibered bone typical of IGM 100/2015 and IGM 100/1324 ( fig. 52C). Four annuli consisting of narrow bands of parallel-fibered bone are visible through portions of the cortex ( fig. 52C). At least one annulus may contain a ...
Context 32
... IGM 100/1324. Much of the bone microstructure and vascular pattern is obscured by possible postmortem fungal alteration, but the less altered patches show parallel-to wovenfibered bone typical of IGM 100/2015 and IGM 100/1324 ( fig. 52C). Four annuli consisting of narrow bands of parallel-fibered bone are visible through portions of the cortex ( fig. 52C). At least one annulus may contain a ...
Context 33
... to the "posterolateral plug" described by Hübner (2012) as a site where muscle forces disrupt the organization of the surrounding bone. The medullary cavity is largely eroded. The bone is primarily parallel fibered with some woven-fibered bone interspersed, particularly between the bands of parallel-fibered bone that surround the growth marks ( fig. 52D), as in IGM 100/2015. Proceeding outward from the medullary cavity, the vasculature transitions from longitudinal with some anastomoses to extensively reticular. Many vascular canals are open at the external surface. Some primary osteons exhibit more extensive infilling with lamellar bone than either IGM 100/2020 or IGM 100/2015. ...
Context 34
... system (EFS), a series of closely spaced LAGs near the periosteal surface (figs. 51, 52). Growth mark spacing shows no sign of decreasing toward the outer surface in any specimen. No decrease in vascularity is apparent toward the outer cortex, and indeed the vascularity becomes extensively reticular near the periosteal surface in IGM 100/1324 ( fig. 52D), suggesting a high growth rate was maintained (Castanet et al., 1996(Castanet et al., , 2000). Based on these observations, all sampled Haya specimens appear to have been actively growing at their times of ...
Citations
... The next large-scale ornithischian analysis derived from a mainly independent pool of morphological characters is that of Boyd (2015), which sources a majority of its characters from Scheetz (1999); this pool was not sampled by Butler et al. (2008) and subsequent studies. As with the analysis of Butler et al. (2008), we primarily reference Boyd (2015) as the source of characters shared between it and studies its characters are derived from (Boyd et al., 2009;Varricchio et al., 2007), or later studies that rerun the matrix (Barta & Norell, 2021;Bell et al., 2018;Herne et al., 2018 analysis 1;Madzia et al., 2018 analysis 1;Manitkoon et al., 2023;Sues et al., 2023;Rotatori et al., 2022;Rozadilla et al., 2019;Zanno et al., 2023 analysis 1). The analyses of Brown et al. (2011) and Brown et al. (2013) are derived from the dataset of Boyd et al. (2009), so are only cited here where they present novel characters. ...
... This instability around the monophyly and relationships of Thescelosauridae reflects the instability of the origins of Ornithopoda that we are attempting to reconcile here. Barta and Norell (2021). ...
... Under EW (Figure 1) (Boyd, 2015;Madzia et al., 2018;Sues et al., 2023) is not found here. A close relationship between Albertadromeus syntarsus, Orodromeus makelai and Zephyrosaurus schaffi has also been recovered previously (Boyd, 2015;Brown et al., 2013;Madzia et al., 2018;Sues et al., 2023) Barta and Norell (2021 Changchunsaurus parvus and Jeholosaurus shangyuanensis are always recovered as sister taxa, and sister to the clade of Parksosaurus warreni and Thescelosaurus species. Haya griva is recovered as the next most derived node, either in a clade with RTMP 2008.45.2 (EW, Figure 1) or on its own (IW). ...
... The anterior end of the predentary is sharply pointed in dorsal view, and it curves anterodorsally in lateral view, as in all ceratopsians (with the exception of Psittacosaurus spp.), a number of basal neornithischians (e.g. Changchunsaurus parvus, Haya griva, Jeholosaurus shangyuanensis, Talenkauen santacrucensis, and Thescelosaurus neglectus; Barrett and Han 2009, Butler et al. 2011, Boyd 2014, Rozadilla et al. 2019, Barta and Norell 2021, and in Jakapil kaniukura (Riguetti et al. 2022). Similarly to the proposed rostral bone of the type specimen (MTM V2009.192.1) and other referred predentaries (MTM V2009.193 ...
... IVPP V12617; Tanoue et al. 2010), early-diverging neoceratopsians Archaeoceratops, Auroraceratops, Liaoceratops, euceratopsians Leptoceratops, Protoceratops, and ceratopsoids, in which the posteroventral process of the predentary bifurcates posteriorly to articulate with the posteriorly diverging dentaries (Tanoue et al. 2010). The posterior bifurcation of the predentary is also present in the majority of early-diverging neornithischians, such as Changchunsaurus, Dryosaurus, Haya, Thescelosaurus, and Zalmoxes (Weishampel et al. 2003, Jin et al. 2010, Makovicky et al. 2011, Boyd 2014, Nabavizadeh and Weishampel 2016, Barta and Norell 2021. It does not seem to be an ontogenetically dependent feature because the posterior bifurcation is present even in near-embryonic specimens of protoceratopsids (MPC-D 100/1021). ...
At the climax of their evolutionary history in the latest Cretaceous, ceratopsian dinosaurs were among the most dominant components of North American and Asian land ecosystems. In other continental landmasses, however, ceratopsians were extraordinarily rare and the affinities of their proposed representatives often turned out to be inconclusive. Arguably the most significant evidence of Ceratopsia from outside North America and Asia is represented by Ajkaceratops kozmai from the Santonian (Upper Cretaceous) of Hungary. We provide a detailed osteological description of Ajkaceratops and highlight its bizarre anatomy. Ajkaceratops has been ‘traditionally’ interpreted to represent a Bagaceratops-like coronosaur, and its occurrence on the European islands was hypothesized to probably result from an early Late Cretaceous dispersal event from Asia. However, while the snout of Ajkaceratops may resemble that of some ceratopsians, closer inspection of the preserved elements indicates that these similarities are largely superficial. While it cannot be ruled out that Ajkaceratops represents a highly peculiar member of the clade, its placement is far from certain. Still, the discovery of Ajkaceratops exemplifies the importance and uniqueness of European dinosaur faunas.
... These two taxa may bear similar tooth replacement patterns which correspond to their close phylogenetic positions. Researchers conducted CT analysis on another early-diverging ornithopod, Haya griva, and found that the maxilla (IGM 100/2017) contains 14 alveoli whereas the left contains 13 [70]. The maxillae contain five replacement teeth on the left side and eight on the right, which is less than either Jeholosaurus or Changchunsaurus. ...
... The maxillae contain five replacement teeth on the left side and eight on the right, which is less than either Jeholosaurus or Changchunsaurus. In the right dentary, CT scans reveal that the five erupted teeth have single replacement teeth among 16 alveoli [70]. The degree of formation of the replacement teeth differs between the left and right sides which suggests that the timing of the replacement waves differed as is the case for the dentaries in Haya [70]. ...
... In the right dentary, CT scans reveal that the five erupted teeth have single replacement teeth among 16 alveoli [70]. The degree of formation of the replacement teeth differs between the left and right sides which suggests that the timing of the replacement waves differed as is the case for the dentaries in Haya [70]. External observations (i.e. in the absence of CT data) of the later-diverging ornithopods Parksosaurus [71] and Hypsilophodon [72] suggest that tooth replacement alternates by approximately every other tooth and the number of replacement teeth may be higher. ...
Background
Tooth replacement patterns of early-diverging ornithischians, which are important for understanding the evolution of the highly specialized dental systems in hadrosaurid and ceratopsid dinosaurs, are poorly known. The early-diverging neornithischian Jeholosaurus , a small, bipedal herbivorous dinosaur from the Early Cretaceous Jehol Biota, is an important taxon for understanding ornithischian dental evolution, but its dental morphology was only briefly described previously and its tooth replacement is poorly known.
Results
CT scanning of six specimens representing different ontogenetic stages of Jeholosaurus reveals significant new information regarding the dental system of Jeholosaurus , including one or two replacement teeth in nearly all alveoli, relatively complete tooth resorption, and an increase in the numbers of alveoli and replacement teeth during ontogeny. Reconstructions of Zahnreihen indicate that the replacement pattern of the maxillary dentition is similar to that of the dentary dentition but with a cyclical difference. The maxillary tooth replacement rate in Jeholosaurus is probably 46 days, which is faster than that of most other early-diverging ornithischians. During the ontogeny of Jeholosaurus , the premaxillary tooth replacement rate slows from 25 days to 33 days with similar daily dentine formation.
Conclusions
The tooth replacement rate exhibits a decreasing trend with ontogeny, as in Alligator . In a phylogenetic context, fast tooth replacement and multi-generation replacement teeth have evolved at least twice independently in Ornithopoda, and our analyses suggest that the early-diverging members of the major ornithischian clades exhibit different tooth replacement patterns as an adaption to herbivory.
... Galton 1977;Forster 1990;Bertozzo et al. 2017;Maidment et al. 2022), Burianosaurus augustai Madzia et al. 2018, some elasmarians such as Kangnasaurus coetzeei, Anabisetia saldiviai, Trinisaura santamartaensis, and Morrosaurus antarcticus, thescelosaurids (e.g. Barta and Norell 2021;Sues et al. 2023), and, although quite gentle, basal marginocephalians (e.g. Butler and Zhao 2009;Han et al. 2018). ...
Supposed dinosaur remains were collected between 1859 and 1906 in the Lower Cretaceous Recôncavo Basin (Northeast Brazil). Since these materials remained undescribed, and most were considered lost. Recently, some of these historical specimens were rediscovered in the Natural History Museum of London, providing an opportunity to revisit them after 160 years. The specimens come from five different sites, corresponding to the Massacará (Berriasian-Barremian) and Ilhas (Valanginian-Barremian) groups. Identified bones comprise mainly isolated vertebral centra from ornithopods, sauropods, and theropods. Appendicular remains include a theropod pedal phalanx, humerus, and distal half of a left femur with elasmarian affinities. Despite their fragmentary nature, these specimens represent the earliest dinosaur bones discovered in South America, enhancing our understanding of the Cretaceous dinosaur faunas in Northeast Brazil. The dinosaur assemblage in the Recôncavo Basin resembles coeval units in Northeast Brazil, such as the Rio do Peixe Basin, where ornithopods coexist with sauropods and theropods. This study confirms the presence of ornithischian dinosaurs in Brazil based on osteological evidence, expanding their biogeographic and temporal range before the continental rifting between South America and Africa. Additionally, these findings reinforce the fossiliferous potential of Cretaceous deposits in Bahia State, which have been underexplored since their initial discoveries.
... 22,31,41 ), with multiple analyses resolving Orodrominae as the sister-group to Thescelosaurinae, together forming a monophyletic Thescelosauridae (e.g. 27,31,[42][43][44][45][46]. Compelling trace 22,89,121 and body fossil 22,73,122 evidence for fossorial behaviours are known from the orodromine Oryctodromeus, including individuals entombed within preserved subterranean burrows 22,89,121 . ...
... ; Oryctodromeus22,89,122 ; Koreanosaurus 97 , with the holotype and paratype assumed to belong to a single individual after 97 ; Haya 45 ; Orodromeus73,173 ; and Zephyrosaurus 47 , with postcranial elements reconstructed after those of Orodromeus73,173 . Parksosaurus anatomy follows45 . Thescelosaurus is reconstructed primarily from NCSM 15728 but with additional anatomical data and maximum estimated length from 31 . ...
... Thescelosaurus is reconstructed primarily from NCSM 15728 but with additional anatomical data and maximum estimated length from 31 . Character coding follows22,39,[45][46][47][48]73,74,89,97,121,122 and discussion in the main text. Oro = Orodrominae. ...
Ornithischian dinosaurs exhibited a diversity of ecologies, locomotory modes, and social structures, making them an ideal clade in which to study the evolution of neuroanatomy and behaviour. Here, we present a 3D digital reconstruction of the endocranial spaces of the latest Cretaceous neornithischian Thescelosaurus neglectus, in order to interpret the neuroanatomy and paleobiology of one of the last surviving non-avian dinosaurs. Results demonstrate that the brain of Thescelosaurus was relatively small compared to most other neornithischians, instead suggesting cognitive capabilities within the range of extant reptiles. Other traits include a narrow hearing range, with limited ability to distinguish high frequencies, paired with unusually well-developed olfactory lobes and anterior semicircular canals, indicating acute olfaction and vestibular sensitivity. This character combination, in conjunction with features of the postcranial anatomy, is consistent with specializations for burrowing behaviours in the clade, as evidenced by trace and skeletal fossil evidence in earlier-diverging thescelosaurids, although whether they reflect ecological adaptations or phylogenetic inheritance in T. neglectus itself is unclear. Nonetheless, our results provide the first evidence of neurological specializations to burrowing identified within Ornithischia, and non-avian dinosaurs more generally, expanding the range of ecological adaptations recognized within this major clade.
... from Austria and Hungary and Zalmoxes spp. from Romania (Ősi et al. 2012;Madzia et al. 2018;Verdú et al. 2018Verdú et al. , 2020Barta and Norell 2021;Dieudonné et al. 2021). Notably, only a single phylogenetic analysis has found a closer relationship between Rhabdodon and Zalmoxes instead (Dieudonné et al. 2016), whereas the three genera have also been recovered in a polytomy by some phylogenetic analyses (e.g. ...
... Moreover, the two best-known rhabdodontid taxa, Rhabdodon and Zalmoxes, both of which have regularly been included into phylogenetic analyses (e.g. McDonald 2012; Ősi et al. 2012;Dieudonné et al. 2016Dieudonné et al. , 2021Bell et al. 2018Bell et al. , 2019Madzia et al. 2018;Verdú et al. 2018;Barta and Norell 2021;Augustin et al. 2022;Poole 2022), await taxonomic revision (see above). All of this currently hinders exploring the phylogenetic relationships of rhabdodontids in more detail, both within the group, but also with other ornithischian dinosaurs. ...
... Andrzejewski et al. 2019;Yang et al. 2020;Barta and Norell 2021;Augustin et al. 2022), it has recently also been placed within this clade(Poole 2022; Zanno et al. 2023). Muttaburrasaurus is often regarded as a basal rhabdodontomorph(Dieudonné et al. 2016(Dieudonné et al. , 2021Madzia et al. 2018;Bell et al. 2018;Barta and Norell 2021;Augustin et al. 2022), but it has also been recovered in a polytomy with the rhabdodontids Rhabdodon and Zalmoxes (McDonald et al. 2010); alternatively, it has been identified either as a more basal(Bell et al. 2019) or a more derived(Boyd 2015;Herne et al. 2019) iguanodontian compared to rhabdodontids and their close kin. ...
The Rhabdodontidae was one of the most important dinosaur groups inhabiting the Late Cretaceous European Archipelago. Currently, the clade comprises nine species within six genera, which have been found in southern France, northern Spain, eastern Austria, western Hungary and western Romania, ranging from the Santonian to the late Maastrichtian. Phylogenetic analyses consistently place the Rhabdodontidae at the very base of the iguanodontian radiation, whereas the in-group relationships of rhabdodontids are relatively poorly understood; nevertheless, the clade seems to have had a rather complicated biogeographical history. Generally, rhabdodontids were small- to medium-sized, probably habitually bipedal herbivores, characterised by a rather stocky build and a comparatively large, triangular skull. Several lines of evidence suggest that they were presumably gregarious animals, as well as selective browsers that fed on fibrous plants and occupied different ecological niches than sympatric herbivorous dinosaur clades. Moreover, the sympatry of at least two rhabdodontid taxa was rather common and can be explained, at least in some instances, by niche partitioning. While rhabdodontids disappeared prior to the K/Pg extinction event in Western Europe, they survived close to the end of the Cretaceous in Eastern Europe, where they were amongst the last non-avian dinosaurs still present before the end of the Cretaceous. In this paper, we provide an overview of the rhabdodontid taxonomic history, diversity, phylogenetic relationships and palaeobiogeographic history, as well as palaeoecology and extinction. In addition, we also highlight still open questions on each of these topics and suggest potential future research directions.
... Its lateral surface is dorsoventrally convex. The ventral margin of the angular is slightly straight to slightly convex as in Hypsilophodon [43], Jeholosaurus [61], Changchunsaurus [56], and Changmiania [45], contrary to the slightly concave margin in Haya [62,63]. ...
... A distinct suture line separating the neural arch from the centrum is clearly seen in dv12-dv15 (Figure 8), showing that these two elements were not fused; this indicates that the holotype was a skeletally immature individual. The dorsals have striated rims around their anterolateral and posterolateral borders, as in some neornithischians including Hexinlusaurus, Jeholosaurus, Yueosaurus, Orodromeus, Haya, Changchunsaurus, Parksosaurus, Thescelosaurus, and Hypsilophodon [10,43,46,49,59,63,69,70] The diapophyses are horizontally extended, and slightly inclined dorsally. Parapophyses are possibly still covered by sediment. ...
... The scapula of Minimocursor gen. nov. is distinctly different from the narrow and strap-like scapular blade of Heterodontosaurus [54], but similar to other basal neornithischians such as Agilisaurus [12], Hexinlusaurus [10], Changmiania [45], Hypsilophodon [43], Changchunsaurus [49], Haya [62,63], Jeholosaurus [46], and Yueosaurus [69]. The acromion process is well developed as that of Orodromeus [59] and Oryctodromeus [73] and is absent in Parksosaurus [39]. ...
An exceptional articulated skeleton of a new basal neornithischian dinosaur, Minimocursor phunoiensis gen. et sp. nov., was discovered in the Late Jurassic Phu Kradung Formation at the Phu Noi locality, Kalasin Province, Thailand, a highly productive non-marine fossil vertebrate locality of the Khorat Plateau. It is one of the best-preserved dinosaurs ever found in Southeast Asia. Minimocursor phunoiensis gen. et sp. nov. shows a combination of both plesiomorphic and apomorphic characters resembling those of Late Jurassic to Early Cretaceous small-bodied ornithischians from China: a low subtriangular boss is projected laterally on the surface of the jugal, the brevis shelf of the ilium is visible in lateral view along its entire length, a distinct supraacetabular flange is present on the pubic peduncle of the ilium, the prepubis tip extends beyond the distal end of the preacetabular process of the ilium, and the manus digit formula is ?-3-4-3-2. The phylogenetic analysis shows that this
dinosaur is among the most basal neornithischians. This study provides a better understanding of the early evolution and taxonomic diversity of ornithischians in Southeast Asia.
... We treated one character (char. 112) as additive following [31]. We used the composite Haya OTU. ...
... Following [33], we treated characters 110,150,159, and 203, as additive and used Herrerasaurus as the outgroup. We added the scores for Transylvanosaurus from [36] with the same modifications described for Barta and Norell [31] above. ...
... We omitted character 111 because of problematic homologies. We followed Poole [32] in considering the following characters additive: 22,31,48,69,70,72,81,91,96,103,105,109,120,123,124,127,129,130,136,137,150,151,153,162,172,186,200,204,205,216,218,228,248,262,263,271,278,301, 321 and using Eocursor as the outgroup. ...
Intensifying macrovertebrate reconnaissance together with refined age-dating of mid-Cretaceous assemblages in recent decades is producing a more nuanced understanding of the impact of the Cretaceous Thermal Maximum on terrestrial ecosystems. Here we report discovery of a new early-diverging ornithopod, Iani smithi gen. et sp. nov., from the Cenomanian-age lower Mussentuchit Member, Cedar Mountain Formation of Utah, USA. The single known specimen of this species (NCSM 29373) includes a well-preserved, disarticulated skull, partial axial column, and portions of the appendicular skeleton. Apomorphic traits are concentrated on the frontal, squamosal, braincase, and premaxilla, including the presence of three premaxillary teeth. Phylogenetic analyses using parsimony and Bayesian inference posit Iani as a North American rhabdodontomorph based on the presence of enlarged, spatulate teeth bearing up to 12 secondary ridges, maxillary teeth lacking a primary ridge, a laterally depressed maxillary process of the jugal, and a posttemporal foramen restricted to the squamosal, among other features. Prior to this discovery, neornithischian paleobiodiversity in the Mussentuchit Member was based primarily on isolated teeth, with only the hadrosauroid Eolambia caroljonesa named from macrovertebrate remains. Documentation of a possible rhabdodontomorph in this assemblage, along with published reports of an as-of-yet undescribed thescelosaurid, and fragmentary remains of ankylosaurians and ceratopsians confirms a minimum of five, cohabiting neornithischian clades in earliest Late Cretaceous terrestrial ecosystems of North America. Due to poor preservation and exploration of Turonian-Santonian assemblages, the timing of rhabdodontomorph extirpation in the Western Interior Basin is, as of yet, unclear. However, Iani documents survival of all three major clades of Early Cretaceous neornithischians (Thescelosauridae, Rhabdodontomorpha, and Ankylopollexia) into the dawn of the Late Cretaceous of North America.
... This passage is evident in MPEF-PV 3809, but not recognized in MPEF-PV 3211-10. This anteriorly placed opening is interpreted as a subnarial foramen, a feature repeatedly identified in specimens of Jeholosaurus shangyuanensis (Barrett & Han, 2009), and possibly present in Haya griva (maxillary fenestra: Makovicky et al., 2011;Barta & Norell, 2021), Kulindadromeus (Godefroit et al., 2014), and widely present in ceratopsians, theropods, and sauropodomorphs (e.g., Dodson et al., 2004;Langer & Benton, 2006). ...
... They mark an abrupt change between the roof and the lateral wall of the snout, and limit a medial depression dorsally, a feature named the medial or internasal sulcus by Norman et al. (2011) in Heterodontosaurus, but apparently absent in other heterodontosaurids. This internasal sulcus is similar to the nasal fossa present in Yinlong (Han et al., 2015), Liaoceratops (Xu et al., 2002), Agilisaurus (Peng, 1992), Jeholosaurus (Xu et al., 2000;Barrett & Han, 2009), Haya (Barta & Norell, 2021), and Changchunsaurus (Jin et al., 2010); however, the raised lateral rims of the snout in the skull of heterodontosaurids enhance this feature, by delimiting an even deeper and narrower internasal sulcus. The thickening of the dorsal crests and the depth of the internasal sulcus in Manidens are developed to a lesser extent than in Heterodontosaurus, and it is bounded posteriorly by an anteriorly facing concave crest entirely formed by the nasals at the nasal-frontal contact. ...
... The ventrolateral process of the nasal is assumed to articulate posteriorly with the anterior margin of the anterodorsal process of the maxilla before reaching the lacrimal, a feature evidenced by a vertically oriented depression at the anterior region of the maxilla, and shared with Heterodontosaurus and Tianyulong (Norman et al., 2011;Sereno, 2012). The ventrolateral process of the nasal prevents the premaxilla from contacting the lacrimal, as is the case in Lesothosaurus (Porro et al., 2015), Agilisaurus (Peng, 1992), Hypsilophodon (Galton, 1974), Yinlong downsi (Xu et al., 2006;Han et al., 2015;contra Dieudonné et al., 2021), Archaeoceratops oshimai (You & Dodson, 2003), the jeholosaurid Haya griva, and pachycephalosaurids, such as Dracorex, Prenocephale, and Stegoceras (Bakker et al., 2006;Makovicky et al., 2011;Barta & Norell, 2021). A premaxilla-lacrimal contact is present in J. shangyuanensis, basally branching iguanodontians (e.g., Tenontosaurus, Dryosaurus, Iguanodon, Ouranosaurus: Galton, 1983;Norman, 2004;Barrett & Han, 2009), Auroraceratops, Liaoceratops, and psittacosaurids (Xu et al., 2002;You et al., 2005;Sereno, 2010). ...
Heterodontosauridae is a clade that appears early in the ornithischian fossil record, and includes small-bodied, highly specialized species characterized by an unusual heterodont dentition. Although known from relatively few taxa, the early representation of the clade and unsolved phylogenetic relationships within heterodontosaurids and among early ornithischians implies that novel information has a marked effect on broader phylogenetic hypotheses and our understanding of early diversification patterns within Ornithischia. This paper describes the cranial osteology of the heterodontosaurid Manidens condorensis based on computed micro-tomographic scans of MPEF-PV 3211 and MPEF-PV 3809. This enabled more detailed descriptions of previously recognized bones, corrections to the literature, and the identification of undescribed elements. We present a new skull reconstruction and propose an emended diagnosis in light of novel anatomical information. Areas of jaw muscle attachment were identified and compared with Heterodontosaurus and Lesothosaurus, and mandibular function among heterodontosaurids is discussed. Our results indicate that diverse skull morphologies and functions existed among Early Jurassic ornithischians, with Manidens being intermediate between the plesiomorphic cranial shape and function associated with a generalist diet in ornithischians such as Tianyulong and Lesothosaurus, and the more derived cranial construction specialized for herbivory identified in heterodontosaurids from South Africa such as Heterodontosaurus.
... The left antorbital fenestra is small (greatest diameter 12 mm) and teardrop-shaped rather than round as in Orodromeus makelai (Scheetz, 1999). Its long axis extends anterodorsally, as in Haya griva (Barta and Norell, 2021) and Jeholosaurus shangyuanensis (Barrett and Han, 2009), rather than anteroposteriorly as in Thescelosaurus neglectus (Boyd, 2014) or dorsoventrally as in Hypsilophodon foxii (Galton, 1974a). The left infratemporal fenestra is dorsoventrally tall, and its anteroventral margin extends below the level of the ventral margin of the orbit. ...
... Its posterolateral process is dorsoventrally deep and forms an overlapping suture with the lateral surface of the maxilla. By contrast, the posterolateral process in Haya griva (Barta and Norell, 2021) extends vertically. It does not separate the maxilla and nasal on the side of the snout and is deeper than in Thescelosaurus neglectus (Boyd, 2014). ...
... An impression in the matrix establishes the presence of an anterior process of the maxilla, which would have fitted into a medial recess formed by the premaxilla, as in Hypsilophodon foxii (Galton, 1974a). The lateral surface of the maxilla bears a shallow, elliptical depression immediately posterior and slightly ventral to the posterior end of the premaxilla, which may correspond to a similar fossa in Haya griva (Barta and Norell, 2021) and Hypsilophodon foxii (Galton, 1974a). The maxilla is overlapped dorsally by the nasal and prefrontal. ...
The fossil record of Late Cretaceous non-hadrosaurid neornithischians from the Western Interior of North America is sparse. Parksosaurus warreni is an early Maastrichtian taxon currently known only from a skull and much of the associated postcranial skeleton and a referred isolated tooth from the Horseshoe Canyon Formation of Alberta, Canada. This article presents a detailed anatomical account of the holotype of this dinosaur following extensive additional preparation of the holotype and provides photographs of the postcranial elements for the first time. The premaxilla has a dorsoventrally deep posterolateral process, which overlaps the maxilla. The antorbital fenestra is small and teardrop-shaped. The lingual surfaces of dentary teeth bear nine or 10 vertically extending ridges that terminate in apical denticles. The suprascapula is mineralized or ossified. The dorsal margin of the ischium is posterodorsally concave at mid-length. The greater and lesser trochanters of the femur are not separated by a distinct cleft. The pendent fourth trochanter is placed on the proximal half of the femur. The more distal caudal vertebrae have greatly elongated prezygapophyses, which, together with a basket of ossified tendons ensheathing the caudal vertebrae, indicate that the tail may have functioned as a dynamic stabilizer during locomotion. The substantial new anatomical information from the holotype and only known skeleton of Parksosaurus warreni will allow more detailed comparisons to other closely related taxa and facilitate further discussions of unresolved aspects of the interrelationships of neornithischian dinosaurs.
