Content uploaded by Robert Reisz
Author content
All content in this area was uploaded by Robert Reisz on May 29, 2016
Content may be subject to copyright.
A preview of the PDF is not available
On the skull of Massospondylus carinatus Owen, 1854 (Dinosauria: Sauropodomorpha) from the Elliot and Clarens formations (Lower Jurassic) of South Africa
Abstract and Figures
This paper presents a comprehensive description of the cranial structure of the sauropodomorph dinosaur Massospondylus carinatus, based on four well-preserved skulls (including one of a juvenile individual) from the Lower Jurassic Elliot and Clarens formations of South Africa. Massospondylus can be distinguished from other basal sauropodomorph dinosaurs by the following combination of primitive and derived cranial character-states: The greatest transverse width of the skull exceeds its dorsoventral height by at least 10 percent. Even in adult specimens, the orbit is proportionately large and the antorbital region proportionately short. The maxilla has a tall, nearly vertical dorsal process, and its medial sheet is narrow anteroposteriorly. A long posterior process of the prefrontal extends along the dorsal margin of the orbit, but the frontal still participates significantly in the formation of the orbital margin. There is a distinct ridge on the dorsolateral aspect of the lacrimal and a knob on the lateral surface of the prefrontal. A partial skull from the Lower Jurassic Kayenta Formation of Arizona previously attributed to Massospondylus differs from the South African material in several cranial and dental features and is not referable to this taxon.
Figures - uploaded by Robert Reisz
Author content
All figure content in this area was uploaded by Robert Reisz
Content may be subject to copyright.
... On the anterolateral surface of the premaxillary body, three neurovascular foramina are present in a subvertical row, which are more visible on the left premaxilla (Fig. 3) and at least two can be identified on the right side (Fig. 2). This foramina arrangement is similar to those of Adeopapposaurus (Martínez, 2009), Jingshanosaurus (CXM-LT9401) and Massospondylus (Sues et al., 2004). ...
... The anterodorsal region of the ascending process is overlapped by the ventrolateral process of the nasal, and the posterodorsal region contacts the lacrimal. The posteroventral surface of the ascending process is excavated, forming a thin subtriangular medial lamina of the antorbital fossa, as in Adeopapposaurus (Martínez, 2009), Jingshanosaurus (CXM-LT9401), Massospondylus (Sues et al., 2004), and Mussaurus (Pol & Powell, 2007), different from the anteroposteriorly broad medial lamina of Coloradisaurus (Apaldetti et al., 2014), Lufengosaurus (IVPP V 15), Melanorosaurus (Yates, 2007), Plateosaurus (Prieto-Márquez & Norell, 2011), Riojasaurus (Bonaparte & Pumares, 1995) and Unaysaurus (Leal et al., 2004). ...
... The nasal comprises an anterior premaxillary process, a ventral maxillary process, and a posterior process (Fig. 2). In lateral view, the dorsal and lateral surfaces of the nasal are slightly convex without a depression posterior to the naris, which is present in Adeopapposaurus (Martínez, 2009), Lufengosaurus (IVPP V 15), Massospondylus (Sues et al., 2004) and Plateosaurus (Prieto-Márquez & Norell, 2011). ...
The Lower Jurassic Lufeng Formation of China has long been recognized for its diverse early-diverging sauropodomorph dinosaurs, with eight genera and ten species, representing more than half the Laurasian records. In this paper, we describe a new genus and species of non-sauropodan sauropodomorph, Lishulong wangi gen. et sp. nov., from Yunnan Province in southwestern China. This new taxon is represented by a partial skeleton including the skull and nine articulated cervical vertebrae, which differs from other Lufeng forms in both cranial and cervical characteristics. It bears several autapomorphies of the nasal process, the maxillary neurovascular foramen, and the cervical neural spine. Phylogenetic analysis reveals that Lishulong is an early-diverging member of the Sauropodiformes, and the sister-taxon of Yunnanosaurus. Elucidating the novel osteology of Lishulong, it possessed the largest sauropodomorph cranial material currently identified from the Lufeng Formation, not only enriches the diversity of the Lufeng dinosaur assemblage, but also enhances our understanding of the character evolution in early-diverging sauropodiforms. Furthermore, information about paleobiogeographic distributions indicates that Early Jurassic sauropodomorphs, especially Chinese taxa, have maintained multiple dispersions and exchanges within Pangaea.
... The composition of Massospondylus refers only to Massospondylus carinatus and the different analyses have chosen different definitions for this OTU. In , this taxon is restricted to the specimens found in South Africa and Zimbabwe and uses the published descriptions of them (Cooper, 1981;Gow, 1990;Gow et al. 1990;Sues et al. 2004). A similar definition is used in Yates (2007b) but includes more information from the literature (van Hoepen, 1920;Cooper, 1981;Gow, 1990;Sues et al. 2004; Barrett and Yates, 2006) and personal observations. ...
... In , this taxon is restricted to the specimens found in South Africa and Zimbabwe and uses the published descriptions of them (Cooper, 1981;Gow, 1990;Gow et al. 1990;Sues et al. 2004). A similar definition is used in Yates (2007b) but includes more information from the literature (van Hoepen, 1920;Cooper, 1981;Gow, 1990;Sues et al. 2004; Barrett and Yates, 2006) and personal observations. As for Pol et al. (2011), this taxon is defined as the specimen BPI/1/4934 only. ...
... A99. Prefrontal, ventral process, height relative to the lacrimal height (Galton and Upchurch, 2004;Yates, 2007b;Figure 4.46 However, based on the morphologies illustrated in Gow et al., (1990), and Sues et al. (2004) and the ontogenetic sequence proposed in Neenan et al. (2018), the change in the position of the temporal bar (the structure comprised of the postorbital posterodorsal process and the squamosal anterodorsal process) may represent ontogenetic variation. ...
Non-sauropod sauropodomorphs, also known as 'basal sauropodomorphs' or 'prosauropods', have been thoroughly studied in recent years. Several hypotheses on the interrelationships within this group have been proposed, ranging from a complete paraphyly, where the group represents a grade from basal saurischians to Sauropoda, to a group on its own. The grade-like hypothesis is the most accepted; however, the relationships between the different taxa are not consistent amongst the proposed scenarios. These inconsistencies have been attributed to missing data and unstable (i.e., poorly preserved) taxa, nevertheless, an extensive comparative cladistic analysis has found that these inconsistencies instead come from the character coding and character selection, plus the strategies on merging data sets. Furthermore, a detailed character analysis using information theory and mathematical topology as an approach for character delineation is explored here to operationalise characters and reduce the potential impact of missing data. This analysis also produced the largest and most comprehensive matrix after the reassessment and operationalisation of every character applied to this group far. Additionally, partition analyses performed on this data set have found consistencies in the interrelationships within non-sauropod Sauropodomorpha and has found strong support for smaller clades such as Plateosauridae, Riojasauridae, Anchisauridae, Massospondylinae and Lufengosarinae. The results of these analyses also highlight a different scenario on how quadrupedality evolved, independently originating twice within the group, and provide a better framework to understand the palaeo-biogeography and diversification rate of the first herbivore radiation of dinosaurs.
... Historically, almost all this material has been referred to the gracile, medium-sized (up to 5 m in length and ~550 kg in body mass), bipedal taxon Massospondylus (e.g., Attridge 1963;Bond 1965;Cooper 1981;Munyikwa 1997;Rogers et al. 2004). However, to date, none of this material has been compared in detail with the more complete South African specimens on which this taxon is based (e.g., Sues et al. 2004;Chapelle and Choiniere 2018;Barrett et al. 2019). Consequently, the presence of this taxon in Zimbabwe should be regarded as tentative until more comparative work is conducted (see Barrett et al. 2019), not least as the shared presence of Massospondylus has been proposed as one of the primary biostratigraphic links between these sequences and those in the MKB (e.g., Bond 1965;Bond and Falcon 1973;Cooper 1982;Holzförster et al. 1999) (where Massospondylus is the eponymous index fossil for the latest Triassic-Early Jurassic Massospondylus Assemblage Zone [Viglietti et al. 2020a]). ...
... Many of these taxa were supported by diagnoses based largely on features that are currently considered to be either sauropodomorph symplesiomorphies, size differences, or arguments based on provenance (e.g., Haughton, 1924). Although articulated and complete material of some Elliot Formation taxa has been recovered more recently, such as the discovery of multiple complete specimens referred to Massospondylus carinatus (Gow, 1990;Kitching & Raath, 1984;Sues et al., 2004), their taxonomy was further complicated by uncritical referrals of numerous specimens to either 'Euskelosaurus' (for large-bodied specimens from the Upper Triassic lower Elliot Formation [LEF]) or Massospondylus (for more gracile individuals recovered from the Lower Jurassic upper Elliot [UEF] and Clarens formations) (e.g., Kitching & Raath, 1984), which created poorly defined 'wastebasket' taxa that obscured the true diversity of these faunas. ...
... In case our interpretation of a common bond between DFMMh/FV 466 and DFMMh/FV 205 is misleading and they actually represent two differently matured individuals, it is still noticeable that the preserved parts of the conjoined endosseous labyrinth of DFMMh/FV 466 and DFMMh/FV 205 displays the same general features as DFMMh/FV 581.1 and DFMMh/FV 1077 and is anteroposteriorly almost as long as the latter two specimens (Figures 5 and 6; Supplementary file 1). This suggests an allometric growth between the prootic and otoccipital: during growth, the prootic reaches the 'adult' size faster than the otoccipital, producing a surprisingly small paroccipital process (or a surprisingly large prootic) in juvenile individuals of Europasaurus (seemingly, also seen in Massospondylus; Sues et al., 2004), containing a relatively large endosseous labyrinth (see also Fabbri et al., 2021, for ontogenetic transformations in the cranium of sauropodomorphs). A relatively large immature endosseous labyrinth seems also to be present in the ornithischians Dysalotosaurus (Lautenschlager and Hübner, 2013), Psitaccosaurus (Bullar et al., 2019), and Triceratops (Morhardt et al., 2018). ...
Macronaria, a group of mostly colossal sauropod dinosaurs, comprised the largest terrestrial vertebrates of Earth's history. However, some of the smallest sauropods belong to this group as well. The Late Jurassic macronarian island dwarf Europasaurus holgeri is one of the most peculiar and best-studied sauropods worldwide. So far, the braincase material of this taxon from Germany pended greater attention. With the aid of micro-computed tomography (microCT), we report on the neuroanatomy of the nearly complete braincase of an adult individual, as well as the inner ears (endosseous labyrinths) of one other adult and several juveniles (the latter also containing novel vascular cavities). The presence of large and morphologically adult inner ears in juvenile material suggests precociality. Our findings add to the diversity of neurovascular anatomy in sauropod braincases and buttress the perception of sauropods as fast-growing and autonomous giants with manifold facets of reproductive and social behaviour. This suggests that - apart from sheer size - little separated Europasaurus from its large-bodied relatives.
... 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 .
Our understanding of pre-Cretaceous dinosaur reproduction is hindered by a scarcity of evidence within the fossil record. Here we report three adult skeletons and five clutches of embryo-containing eggs of a new sauropodomorph from the Lower Jurassic of southwestern China, displaying several significant reproductive features that are either unknown or unlike other early-diverging sauropodomorphs, such as relatively large eggs with a relatively thick calcareous shell formed by prominent mammillary cones, synchronous hatching, and a transitional prehatching posture between the crocodilians and living birds. Most significantly, these Early Jurassic fossils provide strong evidence for the earliest known leathery eggs. Our comprehensive quantitative analyses demonstrate that the first dinosaur eggs were probably leathery, elliptical and relatively small, but with relatively long eggshell units, and that along the line to living birds, the most significant change in reptilian egg morphology occurred early in theropod evolution rather than near the origin of Aves.
Titanosaurian sauropod dinosaurs were diverse and abundant throughout the Cretaceous, with a global distribution. However, few titanosaurian taxa are represented by multiple skeletons, let alone skulls. Diamantinasaurus matildae, from the lower Upper Cretaceous Winton Formation of Queensland, Australia, was heretofore represented by three specimens, including one that preserves a braincase and several other cranial elements. Herein, we describe a fourth specimen of Diamantinasaurus matildae that preserves a more complete skull—including numerous cranial elements not previously known for this taxon—as well as a partial postcranial skeleton. The skull of Diamantinasaurus matildae shows many similarities to that of the coeval Sarmientosaurus musacchioi from Argentina (e.g. quadratojugal with posterior tongue-like process; braincase with more than one ossified exit for cranial nerve V; compressed-cone–chisel-like teeth), providing further support for the inclusion of both taxa within the clade Diamantinasauria. The replacement teeth within the premaxilla of the new specimen are morphologically congruent with teeth previously attributed to Diamantinasaurus matildae, and Diamantinasauria more broadly, corroborating those referrals. Plesiomorphic characters of the new specimen include a sacrum comprising five vertebrae (also newly demonstrated in the holotype of Diamantinasaurus matildae), rather than the six or more that typify other titanosaurs. However, we demonstrate that there have been a number of independent acquisitions of a six-vertebrae sacrum among Somphospondyli and/or that there have been numerous reversals to a five-vertebrae sacrum, suggesting that sacral count is relatively plastic. Other newly identified plesiomorphic features include: the overall skull shape, which is more similar to brachiosaurids than ‘derived' titanosaurs; anterior caudal centra that are amphicoelous, rather than procoelous; and a pedal phalangeal formula estimated as 2-2-3-2-0. These features are consistent with either an early-branching position within Titanosauria, or a position just outside the titanosaurian radiation, for Diamantinasauria, as indicated by alternative character weighting approaches applied in our phylogenetic analyses, and help to shed light on the early assembly of titanosaurian anatomy that has until now been obscured by a poor fossil record.
Early sauropodomorphs were diverse in Gondwana, being particularly well represented in South America. Mussaurus patagonicus is one of the best-known non-sauropod sauropodomorphs that inhabited the Southern Hemisphere. Its importance relies on its phylogenetic position close to Sauropoda and also because it is known from a well-represented ontogenetic series, including embryos, neonate and late immature skeletons, which are particularly scarce among sauropodomorphs. In this regard, Mussaurus represents an excellent opportunity to explore anatomical and palaeobiological constraints during the ontogeny of early stages of the evolution of the group. We present the osteology of the postcranial skeleton of immature specimens of Mussaurus, highlighting the main anatomical changes that occurred during its ontogeny. The phylogenetic position of this taxon based on mature specimens is evaluated through a parsimony analysis, corroborating its position as closer to Sauropoda than most other early sauropodomorphs. Immature stages of this taxon were also evaluated phylogenetically, showing an overall phylogenetic signal that positioned them closer to the root of Sauropodomorpha than the mature specimens. However, the cranial and some postcranial anatomical partitions of neonates and late immature specimens have different phylogenetic signals, showing derived traits present in Sauropoda and related taxa (and supporting the hypothesis of paedomorphic evolution in certain regions of the skeleton). Our analysis shows that most of the appendicular apomorphies in Mussaurus appear late in ontogeny, whereas axial characters (in particular for OS 1), including those of the skull and the presacral vertebrae, show derived character states early in ontogeny that are congruent with the phylogenetic position of mature specimens. Ontogenetic series of other sauropodomorph species, however, are required to test if this pattern applies to the entire group.
Re-examination of the surviving specimens of Thecodontosaurus antiquus indicates that this plesiomorphic sauropodomorph can be diagnosed on the basis of elongate basipterygoid processes, a relatively short dentary, and a squared posterior process of the ilium. Although much of the original topotype material found in the 1830s in
Bristol, England, has now been lost, some 245 specimens remain. These indicate a small, gracile prosauropod, up to 2.5 m in length, distinguished primarily on the absence of derived characters seen in other prosauropods. Although attempts were formerly made to subdivide the Bristol specimens into several dinosaurian, and other, taxa, most appear to pertain to the prosauropod Thecodontosaurus antiquus. The specimens do indicate a clear separation into two morphs, a gracile and a robust form, presumably evidence of sexual dimorphism. A juvenile Thecodontosaurus sp. from South Wales may belong to the same species. A cladistic analysis indicates that Prosauropoda is probably a clade, rather than a series of outgroups to Sauropoda, but support for this conclusion is weak. Echoing other recent cladistic analyses, stronger support is found for the existence of a clade Sauropodomorpha, made up from Prosauropoda 1 Sauropoda, for the clade Sauropoda itself, and for the clade Eusauropoda within Sauropoda.
This book, comprehensible to the informed layman, gives an account of the dinosaurs of North America. Their evolution, biogeography, feeding habits, behaviour, reproduction and methods of locomotion are described and how these deductions were made from the fossil record is discussed. The book works in chronological order from the Pre-Mesozoic origins of life and reptiles, through 8 chapters describing their Mesozoic evolution, to the penultimate chapter describing their final demise and reasons for their extinction at the end Cretaceous. The final chapter discusses the wider implications of research into the dinosaurs. A bibliography, classification of dinosaurs and an index are provided. -A.W.Hall
The species taxonomy of the sauropodomorph dinosaurs from the Löwenstein Formation of Germany is examined. Previous work has classified these into two taxa: Sellosaurus gracilis from a number of localities and the widespread Plateosaurus engelhardti from a single monospecific accumulation in the Löwenstein Formation, near the town of Trossingen. The current hypodigm of Sellosaurus gracilis is found to contain a substantial amount of variation. This includes differences in the dentition, structure of the skull, composition of the sacrum and the structure of the caudal vertebrae and pelvis. This variation was analysed using a specimen–based parsimony analysis of the sauropodomorphs from the Löwenstein Formation. It was found that two discrete taxa comprise the current hypodigm of Sellosaurus. The more common of these two is a plesiomorphic form for which the correct name is Efraasia minor comb. nov. The less common form (which includes the holotype of Sellosaurus gracilis) is found to share a number of synapomorphies with Plateosaurus engelhardti and is placed in this genus as Plateosaurus gracilis
Three newly discovered skeletons from the Carnian red beds of the Santa Maria Formation, south Brazil, represent one of the oldest dinosaurs ever found. The new taxon Saturnalia tupiniquim, is equivalent in age to the earliest dinosaurs from northwestern Argentina, being the oldest sauropodomorph dinosaur known from plentiful skeletal material. The record of Saturnalia, a 1.5-m-long gracile plant-eating animal, indicates that, like other major dinosaur lineages, the first representatives of the mainly heavy-built sauropodomorphs were gracile animals.RésuméTrois squelettes, récemment découverts dans les red-beds carniens de la formation Santa Maria (Sud du Brésil), représentent un des plus vieux dinosaures jamais découverts. Le nouveau taxon, Saturnalia tupiniquin, a un âge équivalent de celui des premiers dinosaures trouvés dans le Nord-Ouest de l'Argentine, et constitue le plus vieux dinosaure sauropodomorphe connu par un abondant matériel. Saturnalia était un animal herbivore, gracile et d'une longueur de 1,5 m. Sa présence indique, à l'instar de nombreuses lignées dinosauriennes, que les premiers représentants des sauropodomorphes massifs étaient des animaux graciles.
Juvenile sauropodomorph specimens from a Late Triassic/Early Jurassic fissure fill in Pant‐y‐ffynnon Quarry, South Wales are redescribed and named as a new species, Thecodontosaurus caducus. T. caducus can be diagnosed by the presence of pleurocoel‐like pits on the neurocentral sutures of the sixth, seventh and eighth cervical vertebrae. It is further distinguished from the type species of the genus, T. antiquus, by the primitive shape of its proximal humerus and ilium. Data from this specimen are incorporated into a cladistic analysis of basal sauropodomorph relationships. It is found that Thecodontosaurus is basal to all other sauropodomorphs, with the exception of Saturnalia from the late Carnian of Brazil. As such Thecodontosaurus is a key taxon, with a novel combination of characters that has important implications for early dinosaur phylogenetics. Thecodontosaurus provides evidence that ‘prosauropods’ are paraphyletic with respect to Sauropoda and that Herrera‐sauridae lies outside the clade containing Sauropodomorpha + Theropoda.