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The beginning of dinosaur evolution is currently known based on a handful of highly informative Gondwanan outcrops of Ischigualastian age (late Carnian–early Norian). The richest Triassic dinosaur records of the southern continents are those of South America and South Africa, with taxonomically diverse faunas, whereas faunas from India and central Africa are more poorly known. Here, the known diversity of Gondwanan Triassic dinosaurs is increased with new specimens from central India, which allow a more comprehensive characterisation of these dinosaur assemblages. Five dinosauriform specimens are reported from the probable late Norian–earliest Rhaetian Upper Maleri Formation, including two new sauropodomorph species, the non-plateosaurian Nambalia roychowdhurii and the plateosaurian Jaklapallisaurus asymmetrica, a guaibasaurid and two basal dinosauriforms. The Lower Dharmaram Formation, probably latest Norian–Rhaetian in age, includes basal sauropodomorph and neotheropod remains, providing the second record of a Triassic Gondwanan neotheropod. The currently available evidence suggests that the oldest known Gondwanan dinosaur assemblages (Ischigualastian) were not homogeneous, but more diverse in South America than in India. In addition, the Upper Maleri and Lower Dharmaram dinosaur assemblages resemble purported coeval South American and European beds in the presence of basal sauropodomorphs. Accordingly, the current available evidence of the Triassic beds of the Pranhita–Godavari Basin suggests that dinosaurs increased in diversity and abundance during the late Norian to Rhaetian in this region of Gondwana.
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... During this time of high endemism, dinosaurs began to disperse and thus offer an opportunity to test the timing and drivers of this biogeographic pattern. Increased sampling can test this prediction: if dinosaurs initially dispersed under palaeolatitudinal-driven endemism, then an assemblage similar to those of South America 4,19-21 and India 19,22 -including the earliest dinosaurs-should be present in Carnian deposits in south-central Africa. Here we report a new Carnian assemblage from Zimbabwe that includes Africa's oldest definitive dinosaurs, including a nearly complete skeleton of the sauropodomorph Mbiresaurus raathi gen. ...
... The earliest and best preserved dinosaurs are known exclusively from a few localities in central South America, within the Ischigualasto Formation of northern Argentina 4,20,21 and the Santa Maria Formation of southern Brazil 4,26 . Most other early dinosaur records are far younger (~10-15 Ma; for example, the Chinle Formation 27 ) or only represented by loosely associated or isolated bones (lower Maleri Formation, central India 22,28 ). If dinosaur dispersal followed the broader patterns of faunal endemism during the Late Triassic, a similar faunal assemblage-including early dinosaurs-can be predicted to be present in Carnian-aged sediments of south-central Africa, which fill the palaeolatitudinal gap between modern-day central South America and India (Fig. 1). ...
... Here we report a rich new fossil assemblage from the Carnian of Zimbabwe containing Africa's oldest known dinosaurs-about equivalent in age to the oldest dinosaurs known anywhere-which greatly enhances knowledge of the origin and early evolution of the group across Pangaea. In addition to a nearly complete skeleton of a new taxon of sauropodomorph, this assemblage includes the remains of herrerasaurid dinosaurs, hyperodapedontine rhynchosaurs, gomphodontosuchine cynodonts, early-diverging aetosaurs and a possible dicynodont, revealing a palaeoecological assemblage strikingly similar to those of dinosaur-bearing Carnian stratigraphic units along this same palaeolatitude in South America and India 4,[20][21][22]26,28 . ...
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The vertebrate lineages that would shape Mesozoic and Cenozoic terrestrial ecosystems originated across Triassic Pangaea1–11. By the Late Triassic (Carnian stage, ~235 million years ago), cosmopolitan ‘disaster faunas’ (refs. 12–14) had given way to highly endemic assemblages12,13 on the supercontinent. Testing the tempo and mode of the establishment of this endemism is challenging—there were few geographic barriers to dispersal across Pangaea during the Late Triassic. Instead, palaeolatitudinal climate belts, and not continental boundaries, are proposed to have controlled distribution15–18. During this time of high endemism, dinosaurs began to disperse and thus offer an opportunity to test the timing and drivers of this biogeographic pattern. Increased sampling can test this prediction: if dinosaurs initially dispersed under palaeolatitudinal-driven endemism, then an assemblage similar to those of South America4,19–21 and India19,22—including the earliest dinosaurs—should be present in Carnian deposits in south-central Africa. Here we report a new Carnian assemblage from Zimbabwe that includes Africa’s oldest definitive dinosaurs, including a nearly complete skeleton of the sauropodomorph Mbiresaurus raathi gen. et sp. nov. This assemblage resembles other dinosaur-bearing Carnian assemblages, suggesting that a similar vertebrate fauna ranged high-latitude austral Pangaea. The distribution of the first dinosaurs is correlated with palaeolatitude-linked climatic barriers, and dinosaurian dispersal to the rest of the supercontinent was delayed until these barriers relaxed, suggesting that climatic controls influenced the initial composition of the terrestrial faunas that persist to this day. A new Triassic dinosaur assemblage from Zimbabwe reveals that the earliest dinosaurs were confined to a temperate region in the far south of Pangaea.
... These suggestions were followed by some authors (e.g. Novas et al. 2011;Baron et al. 2017b;Cau2018), whereas others allied Gu. candelariensis to theropods (Yates 2017a, b;Langer et al. 2011;Marsh et al. 2019). This gave rise to the notion that at least some Carnian sauropodomorphs form a clade, either including Gu. candelariensis or not, exclusive of most younger members of the group (e.g. ...
... Another likely coeval stratigraphic unit (Langer 2005), the lower Maleri Formation of India, yielded the controversial dinosaur Alwalkeria maleriensis (Chatterjee 1987). As previously discussed (Langer 2004;Remes and Rauhut 2005;Novas et al. 2011;Ezcurra 2012a), this taxon shares several traits with early sauropodomorphs, but its fragmentary and chimeric nature hampers a proper evaluation of its affinities. Also from India, but from the younger (possibly Norian) upper Maleri Formation, Novas et al. (2011) described a fragmentary specimen (ISI R277) that may belong to Guaibasauridae. ...
... As previously discussed (Langer 2004;Remes and Rauhut 2005;Novas et al. 2011;Ezcurra 2012a), this taxon shares several traits with early sauropodomorphs, but its fragmentary and chimeric nature hampers a proper evaluation of its affinities. Also from India, but from the younger (possibly Norian) upper Maleri Formation, Novas et al. (2011) described a fragmentary specimen (ISI R277) that may belong to Guaibasauridae. Finally, the only proposed non-Gondwanan record of the group corresponds to Agnosphitys cromhallensis (Fraser et al. 2002;Ezcurra 2010). ...
Chapter
Carnian (Late Triassic) deposits of South America provide the oldest unequivocal dinosaur records worldwide, most of which has been assigned to the sauropodomorph lineage. This includes Eoraptor lunensis, Panphagia protos, and Chromogisaurus novasi, from the Ischigualasto Formation, Argentina, and Saturnalia tupiniquim, Pampadromaeus barberenai, Buriolestes schultzi, and Bagualosaurus agudoensis, from the Santa Maria Formation, Brazil. Here, we demonstrate that their holotypes anatomically differ from one another, supporting the taxonomic validity of the species. In addition, a morphological disparity analysis, with significant statistical support, clustered some of the better-known specimens of E. lunensis, Sat. tupiniquim, and Bu. schultzi, with the respective holotypes. For the latter two taxa, this was corroborated by a specimen-level phylogenetic analysis that also found Ba. agudoensis as the sister taxon to post-Carnian sauropodomorphs. Our results also suggest that Bu. schultzi and E. lunensis are the earliest branching sauropodomorphs and that Sa. tupiniquim and Pam. barberenai are closer to Bagualosauria. A species-level phylogenetic analysis further suggests that Bu. schultzi and E. lunensis form a clade, that Sa. tupiniquim is the sister taxon to Bagualosauria, and that Pan. protos and Ch. novasi are also more highly nested, forming a clade with Pam. barberenai.
... Material from Frick (MSF1-13) was described as part of P. 'engelhardti', and thus P. ingens was considered as a junior synonym of P. 'engelhardti' (Galton 2012). In Novas et al. (2011), all these specimens were included in P. ingens, and the composition of this OTU does not seem to have changed through the literature. Nevertheless, additional material from the same locality has also been referred to as P. trossingensis (= P. 'engelhardti' in Galton 1986) rather than P. ingens, as it has been used in the iterations of phylogenetic analyses. ...
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A literature review showed that there is not a defined consensus on what specimens belong to Plateosaurus in current phylogenetic analyses, and after the assignation of SMNS 13200 as the neotype for Plateosaurus, the specimen composition of Plateosaurus as an operational taxonomic unit (OTU) needs to be addressed in further iterations of phylogenetic analyses. At least one of the specimens used to illustrate plateosaurian anatomy contains several characters identified in more derived sauropodomorphs commonly referred to as massopodans. This partial skeleton, traditionally known as specimen ‘GPIT IV’, was found in the lower dinosaur bone bed of the Obere Mühle, a Trossingen Formation outcrop, during an excavation in 1922 near the city of Tübingen, Germany. The holotype of Plateosaurus trossingensis and several other specimens referred to as this species were found in this level, which was initially interpreted as a synchronic deposit of animals. However, the current understanding of the Trossingen Formation indicates that this bed was probably a constant accumulation of carcasses through miring and transport down a river for hundreds of years. In this work, a framework to compare phylogenetic signals with morphological and histological data is provided to help in the species delineation of Plateosaurus, and support is found to refer the historic specimen ‘GPIT IV’ as a new genus and a new species.
... Diagnostic skeletal remains of Dinosauriformes such as the silesaurid Asilisaurus are known from the Middle Triassic (e.g., Sereno and Arcucci, 1994;Irmis et al., 2007;Novas et al., 2010;Nesbitt et al., 2010;Langer et al., 2013;Benton et al., 2014;Mancuso et al., 2014;Marsicano et al., 2016). As dinosaurs originated, body size exhibited complex evolutionary patterns. ...
Article
Archosauria diversified throughout the Triassic Period before experiencing two mass extinctions near its end ∼201 Mya, leaving only the crocodile-lineage (Crocodylomorpha) and bird-lineage (Dinosauria) as survivors; along with the pterosaurian flying reptiles. About 50 years ago, the “locomotor superiority hypothesis” (LSH) proposed that dinosaurs ultimately dominated by the Early Jurassic Period because their locomotion was superior to other archosaurs’. This idea has been debated continuously since, with taxonomic and morphological analyses suggesting dinosaurs were “lucky” rather than surviving due to being biologically superior. However, the LSH has never been tested biomechanically. Here we present integration of experimental data from locomotion in extant archosaurs with inverse and predictive simulations of the same behaviours using musculoskeletal models, showing that we can reliably predict how extant archosaurs walk, run and jump. These simulations have been guiding predictive simulations of extinct archosaurs to estimate how they moved, and we show our progress in that endeavour. The musculoskeletal models used in these simulations can also be used for simpler analyses of form and function such as muscle moment arms, which inform us about more basic biomechanical similarities and differences between archosaurs. Placing all these data into an evolutionary and biomechanical context, we take a fresh look at the LSH as part of a critical review of competing hypotheses for why dinosaurs (and a few other archosaur clades) survived the Late Triassic extinctions. Early dinosaurs had some quantifiable differences in locomotor function and performance vs. some other archosaurs, but other derived dinosaurian features (e.g., metabolic or growth rates, ventilatory abilities) are not necessarily mutually exclusive from the LSH; or maybe even an opportunistic replacement hypothesis; in explaining dinosaurs’ success.
... The Gondwanan continents expose extensive early Mesozoic nonmarine sedimentary sequences that contain key paleoenvironmental and biotic records for understanding global change during this time (e. g., Zavattieri and Batten, 1996;Anderson et al., 1998;de Wit et al., 2002;Artabe et al., 2007;Langer et al., 2007;Colombi and Parrish, 2008;Mancuso and Marsicano, 2008;Mancuso, 2009;Novas et al., 2011Novas et al., , 2021Retallack et al., 2011;Irmis and Whiteside, 2012;Césari and Colombi, 2013;Horn et al., 2013Horn et al., , 2018aSidor et al., 2013;Smith and Botha-Brink, 2014;Benavente et al., 2015Benavente et al., , 2019Ghosh et al., 2016;Marsicano et al., 2016;Button et al., 2017;Tabor et al., 2017;Fielding et al., 2019;Bordy et al., 2020;. These sedimentary archives include a particularly complete record of the Triassic Period, and thus are important for understanding key Earth history events such as mass extinction events, the emplacement of several large igneous provinces, and the evolution of life on land in a high-CO 2 greenhouse world (e.g., Mundil et al., 2004;Payne et al., 2004;Greene et al., 2010;Whiteside et al., 2010;Retallack et al., 2011;Dal Corso et al., 2015;Schaller et al., 2015;Burgess et al., 2017). ...
Article
Gondwanan sedimentary deposits preserve a rich archive of Triassic non-marine vertebrate evolution. This fossil record is integral to understanding early Mesozoic global change events, including the end-Permian and end-Triassic mass extinctions, Carnian Pluvial Episode, and macroevolutionary events such as the origin of dinosaurs. Until very recently, almost all of these fossil assemblages were dated by exclusively biostratigraphic means, which made robust correlation to the GSSP-defined timescale difficult. Furthermore, recent advances in radioisotopic dating and magnetostratigraphy have demonstrated that many of these biostratigraphic schemes were imprecise and that key index taxa have different first and last appearances across geographic space. Thankfully, over the past ten years, new radioisotopic and magnetostratigraphic age constraints from fossiliferous sequences in South America have allowed the revision of the absolute ages and relative correlation of key Gondwanan vertebrate assemblages. Here, we review these geochronologic age constraints from South America, describe and revise their accuracy and uncertainties, present new U–Pb zircon age data for a key section in Venezuela, infer preliminary age models for these successions, and discuss what they mean for the correlation of fossiliferous Triassic units in Gondwana. This synthesis suggests that although radioisotopic age data are often numerous, the geological uncertainties associated with U–Pb zircon dates using micro-beam techniques (LA-ICPMS and SIMS) mean that the age of most sedimentary units cannot be constrained better than a precision of ± 3–5 Ma. Although CA-TIMS U–Pb zircon ages and ⁴⁰Ar/³⁹Ar ages can be more precise and accurate, they only result in well-constrained age models when multiple ages are available throughout the section (e.g., Ischigualasto-Villa Unión Basin of northwest Argentina), and even then, issues with lateral correlation within basins remain. Nonetheless, these data demonstrate that South America has high potential for developing a precise and accurate Triassic non-marine numerical timescale for Gondwanan vertebrate evolution.
... The medial surface is gently concave. On the proximal articular surface, the medial condyle is set posterior to the lateral condyle, whereas in Jaklapallisaurus asymmetrica (ISI R274; Novas et al., 2011) andStaurikosaurus pricei (MCZ 1669;Bittencourt and Kellner, 2009) both condyles lie near the posterior margin. Distinct from Eoraptor lunensis (PVSJ 559; Sereno et al., 2013), the specimen lacks a notch between the posterior portion of the condyles, and both condyles are poorly delimited. ...
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Whereas sauropod dinosaurs from the Jurassic and Cretaceous Periods were the largest land animals that ever lived, some of their early relatives evolved relatively large bodies during the Triassic Period. The evolutionary pathways followed by the earliest sauropodomorphs towards the acquisition of massive bodies are poorly understood. However, new finds from South America and Africa are reshaping our knowledge of this issue. Here, we describe a new early and relatively large sauropodomorph represented by a partial postcranial skeleton excavated from Carnian-aged beds (Upper Triassic) of southern Brazil. The new specimen is recovered as a sauropodomorph more closely related to bagualosaurians than saturnaliids or other early-diverging forms in two phylogenetic analyses. The new specimen is generically indeterminate but provides important evidence of an early increase in body size in Sauropodomorpha, being significantly larger than that of coeval or older forms (except Bagualosaurus agudoensis). Furthermore, the specimen is about 3.2 times heavier than Buriolestes schultzi, the earliest-branching Sauropodomorph. The slender hind limbs and typical cursorial proportions present in the earliest sauropodomorphs are mostly maintained in the new specimen despite its larger body size.
Article
The Early Jurassic Jenkyns Event (~183 Ma) was characterized in terrestrial environments by global warming, perturbation of the carbon cycle, enhanced weathering and wildfires. Heating and acid rain on land caused a loss of forests and affected diversity and composition of land plant assemblages and the rest of the trophic web. We suggest that the Jenkyns Event, triggered by the activity of the Karoo-Ferrar Large Igneous Province, was pivotal in remodelling terrestrial ecosystems, including plants and dinosaurs. Macroplant assemblages and palynological data show reductions in diversity and richness of conifers, cycadophytes, ginkgophytes, bennetitaleans, and ferns, and continuation of seasonally dry and warm conditions. Major changes occurred to sauropodomorph dinosaurs, with extinction of diverse basal families formerly called ‘prosauropods’ as well as some basal sauropods, and diversification of the derived Eusauropoda in the Toarcian in South America, Africa, and Asia, and wider diversification of new families, including Mamenchisauridae, Cetiosauridae and Neosauropoda (Dicraeosauridae and Macronaria) in the Middle Jurassic, showing massive increase in size and diversification of feeding modes. Ornithischian dinosaurs show patchy records; some heterodontosaurids and scelidosaurids disappeared, and major new clades (Stegosauridae, Ankylosauridae, Nodosauridae) emerged soon after the Jenkyns Event, in the Bajocian and Bathonian worldwide. Among theropod dinosaurs, Coelophysidae and Dilophosauridae died out during the Jenkyns Event and a diversification of theropods (Megalosauroidea, Allosauroidea, Tyrannosauroidea) occurred after this event with substantial increases in size. We suggest then that the Jenkyns Event terrestrial crisis was marked especially by floral changes and origins of major new sauropodomorph and theropod clades, characterized by increasing body size. Comparison with the end Triassic Mass Extinction helps to understand the incidence of climatic changes driven by activity of large igneous provinces on land ecosystems and their great impacts on early dinosaur evolution.
Article
The northern-most occurrence of Sauropoda in South America was collected in the 1940s from Early–Middle Jurassic-aged continental sediments on the western flank of the Serranía del Perijá in Colombia. Relocation of the site and re-preparation of the specimen, a well-preserved dorsal vertebra, provide important information about the initial diversification of sauropods at low latitudes. The specimen possesses autapomorphies and a unique combination of character states (e.g., divided centropostzygapophyseal lamina, strongly dorsally arched postzygapophyseal facets) that diagnose it as the new genus and species Perijasaurus lapaz. A medium-sized early eusauropod, Perijasaurus inhabited tropical lowland forested areas around the Toarcian–Aalenian boundary. Our phylogenetic analysis recovers Perijasaurus near the base of Eusauropoda, in an unresolved position near Cetiosaurus, Patagosaurus and kin (Bagualia, Spinophorosaurus, Nebulasaurus), and more deeply nested eusauropods. The phylogenetic position of Perijasaurus bolsters the idea that eusauropods achieved a broad geographic distribution during the Early–Middle Jurassic, before the deeper fragmentation of Pangea and after the Toarcian faunal turnover documented at high southern latitudes. Perijasaurus and other basally diverging sauropods display an intermediate level of bone weight reduction in the axial column that represents an antecedent to the more highly developed pneumatic system characterizing Neosauropoda.
Chapter
The early evolution of Sauropodomorpha is well recorded in Carnian beds of Argentina and Brazil. During the Norian and Rhaetian, sauropodomorphs notably diversified both taxonomically and ecologically, became abundant and ultimately dominated terrestrial ecosystems, adding to the information retrieved from the records from Europe, India, and Southern Africa. Despite the fact that the last decade witnessed an increase in taxonomic abundance of Carnian sauropodomorphs, their morphological disparity is low, characterized by small, gracile, and bipedal forms, with predatory/omnivorous feeding habits. By the Early Jurassic, this group had achieved their broadest geographical distribution and morphological disparity, ranging from small to medium-sized facultative bipedal basal sauropodomorphs to giant quadrupedal sauropods. The major changes in body plan after Carnian forms include the acquisition of features related to herbivory, large body size, and quadrupedality. This chapter is focused on the post-Carnian radiation of sauropodomorphs, for which the South American record accounts for about 25% of the world record. It has provided key information in understanding certain stages of this evolutionary radiation and has therefore highlighted the understanding of the evolution of this group.
Article
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. © The Trustees of the Natural History Museum, London 2022. All rights reserved.
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Many recent studies of theropod relationships have been focused on the phylogeny of coelurosaurs and the question of the origin of birds, but the interrelationships and evolution of basal theropods are still poorly understood. Thus, this paper presents a phylogenetic analysis of all theropods, but focuses on the basal members of this clade. The result supports the inclusion of Eoraptor and herrerasaurids in the Theropoda, but differs from other recent studies in two main aspects: (1) The taxa usually grouped as ceratosaurs form two monophyletic clades that represent successively closer outgroups to tetanurans. The more basal of these clades, the Coelophysoidea, comprise the majority of Late Triassic and Early Jurassic theropods. The other clade of basal theropods that are usually included in the Ceratosauria comprises Ceratosaurus, Elaphrosaurus, and abelisaurids. (2) Two monophyletic groups of basal tetanurans are recognized: the Spinosauroidea and the Allosauroidea. In contrast to other recent phylogenetic hypotheses, both clades are united in a monophyletic Carnosauria. The branching pattern of the present cladogram is in general accordance with the stratigraphic occurrence of theropod taxa. Despite the differences in recent analyses, there is a significant level of consensus in theropod phylogeny. At least four different radiations of non-avian theropods can be recognized. These radiations show different patterns in Laurasia and Gondwana, and there are increasing differences between the theropod faunas of the two hemispheres from the Triassic to the Cretaceous.
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FIGURE 9. Photographs of dorsal vertebrae 9 – 11 in right lateral view (a) and the centrum of the 12 th dorsal vertebra (b) in cranial view. Abbreviations: d 9 – d 11, dorsal vertebrae 9 to 11. Scale bar = 2.5 cm.
Article
The Gondwana Sequence in the northern part of the Pranhita-Godavari Valley consists of four formations of the Lower Gondwana and seven formations of the Upper Gondwana. The gross lithological characters and mappability are considered as the major criteria for delineating the formations. The name Kamthi Formation which has been used by different authors in different senses, is here used in the sense of Sengupta (1970). The rocks between the Barakar and this Kamthi are divided into four lithozones for limitations of mappability. Although some of these lithozones have earlier been designated as formations, at present not sufficient information is available to justify this. Only two breaks, both within the Upper Gondwana, are found to be present: there is no recognisable break between the Lower and the Upper Gondwana. A summary of this succession is presented in tabular form taking into account the words of earlier authors. The alternative views that are radically different from the one presented here are also discussed briefly. The usefulness of plant megafossils and fossil vertebrates in understanding the stratigraphy is discussed briefly and their role in determining the possible geological ages of some of the formations is mentioned. The vertebrate fauna from a number of formations is listed. At least seven formations are fossiliferous as far as vertebrates are concerned. Of these, two belonging to the Triassic and one belonging to the Jurassic are quite well-documented. The other four are less well known, but serve as very useful time markers. All these vertebrate-bearing formations can be correlated with co-eval rocks elsewhere in the world. The difficulty of correlating continental deposits is realized and keeping this in view a tentative correlation is presented.