First Jurassic Triconodont from South America

Rougier, Guillermo W.; Garrido, Alberto C.; Gaetano, Leandro C.; Puerta, Pablo; Corbitt, Cynthia; Novacek, Michael J.

doi:10.1206/0003-0082(2007)3580[1:fjtfsa]2.0.co;2

Cited by 43 publications

(47 citation statements)

References 37 publications

(8 reference statements)

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“…In contrast, other theropod lineages, which arose at approximately the same time, such as 'elaphrosaurs' [31], ceratosaurids [7,9,36] and basal tetanurans [19], achieved a Pangean distribution during this time (see the electronic supplementary material). Interestingly, a similar biogeographic pattern has recently been inferred for other groups of Mesozoic vertebrates, such as basal eusauropods [37], heterodontosaurid ornithischians [38] and mammals [39,40], in which some clades were restricted to southern Gondwana during the Jurassic, whereas other clades had a global distribution. The congruent pattern of restricted distribution for multiple vertebrate clades during Pangean times may be related to a common biogeographic cause.…”

Section: Discussionsupporting

confidence: 73%

A Middle Jurassic abelisaurid from Patagonia and the early diversification of theropod dinosaurs

2012

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Abelisaurids are a clade of large, bizarre predatory dinosaurs, most notable for their high, short skulls and extremely reduced forelimbs. They were common in Gondwana during the Cretaceous, but exceedingly rare in the Northern Hemisphere. The oldest definitive abelisaurids so far come from the late Early Cretaceous of South America and Africa, and the early evolutionary history of the clade is still poorly known. Here, we report a new abelisaurid from the Middle Jurassic of Patagonia, Eoabelisaurus mefi gen. et sp. nov., which predates the so far oldest known secure member of this lineage by more than 40 Myr. The almost complete skeleton reveals the earliest evolutionary stages of the distinctive features of abelisaurids, such as the modification of the forelimb, which started with a reduction of the distal elements. The find underlines the explosive radiation of theropod dinosaurs in the Middle Jurassic and indicates an unexpected diversity of ceratosaurs at that time. The apparent endemism of abelisauroids to southern Gondwana during Pangean times might be due to the presence of a large, central Gondwanan desert. This indicates that, apart from continent-scale geography, aspects such as regional geography and climate are important to reconstruct the biogeographical history of Mesozoic vertebrates.

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Section: Discussionsupporting

confidence: 73%

A Middle Jurassic abelisaurid from Patagonia and the early diversification of theropod dinosaurs

2012

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“…Kuhn (1966) is identified as the author of the taxon Heterodontosauridae, although Romer (1966) independently proposed the same taxon in the same year (synchronous publication noted by Kuhn 1967: 77, 122). In the literature, some cite Romer as the author of the taxon (e.g., Smith 1997;Sereno 1998;Sereno 2005b), some Kuhn (e.g., Norman et al 2004, 2011, and some Kuhn and Romer with one author in parentheses (e.g., Steel 1969).…”

Section: Systematic Paleontologymentioning

confidence: 99%

“…Cañadón Asfalto Formation (Stipanicic et al 1968;Rougier et al 2007); Middle Jurassic, Aalenian-Bathonian, ca. 176-165 Ma (Gradstein and Ogg 2009;Cabaleri et al 2010).…”

Section: Lycorhinus Angustidens Haughton 1924mentioning

confidence: 99%

Taxonomy, morphology, masticatory function and phylogeny of heterodontosaurid dinosaurs

Sereno

2012

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Heterodontosaurids comprise an important early radiation of small-bodied herbivores that persisted for approximately 100 My from Late Triassic to Early Cretaceous time. Review of available fossils unequivocally establishes Echinodon as a very small-bodied, late-surviving northern heterodontosaurid similar to the other northern genera Fruitadens and Tianyulong. Tianyulong from northern China has unusual skeletal proportions, including a relatively large skull, short forelimb, and long manual digit II. The southern African heterodontosaurid genus Lycorhinus is established as valid, and a new taxon from the same formation is named Pegomastax africanus gen. n., sp. n. Tooth replacement and tooth-to-tooth wear is more common than previously thought among heterodontosaurids, and in Heterodontosaurus the angle of tooth-to-tooth shear is shown to increase markedly during maturation. Long-axis rotation of the lower jaw during occlusion is identified here as the most likely functional mechanism underlying marked tooth wear in mature specimens of Heterodontosaurus. Extensive tooth wear and other evidence suggests that all heterodontosaurids were predominantly or exclusively herbivores. Basal genera such as Echinodon, Fruitadens and Tianyulong with primitive, subtriangular crowns currently are known only from northern landmasses. All other genera except the enigmatic Pisanosaurus have deeper crown proportions and currently are known only from southern landmasses.

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“…Rougier et al [2007] describe the locality as system of littoral floodplain and small lakes. Turtles are among the most common vertebrates at this locality [O. W. M. Rauhut, pers.…”

Section: Palaeoecologymentioning

confidence: 99%

Evolution and palaeoecology of early turtles: a review based on recent discoveries in the Middle Jurassic

Anquetin

2011

Bulletin De La Société Géologique De France

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POSTPRINT AbstractIn recent years, no less than five new species of stem-group turtles have been described worldwide. Among them are three new turtles from Middle Jurassic deposits that partially fill a previous temporal and morphological gap in our knowledge of the early evolution of these shelled amniotes: Heckerochelys romani, Condorchelys antiqua and Eileanchelys waldmani. For the first time, the phylogenetic position of these three new species is tested in the context of the two presently competing cladistic models of turtle evolution. The addition of these taxa to each matrix does not favour or alter any of the two opposed hypotheses. However, it is demonstrated here that, by documenting yet unknown stages in the evolution of several morphological structures, these three species give stronger support to the model of an extended phylogenetic stem for turtles. These new lines of evidence include the structure of the vomer, the position of the aditus canalis stapedio-temporalis and of the posterior opening of the canalis cavernosus, and the morphology of the processus interfenestralis of the opisthotic. These characters should be considered for future phylogenetic analyses of turtle interrelationships.Recent discoveries also reinvigorate the debate about the palaeoecology of early turtles. Whereas simple morphological characters (e.g., shell fontanelle, ligamentous bridge, flattened carapace) can be misleading, forelimb proportions and shell bone histology have led to the conclusion that most stem turtles (i.e., Proganochelys quenstedti, Palaeochersis talampayensis, Proterochersis robusta, Kayentachelys aprix and meiolaniids) were terrestrial forms. On the contrary, it is generally accepted that crown-group turtles are ancestrally aquatic. Among the five recently described stem-group turtles, Odontochelys semitestacea and Eileanchelys waldmani have been convincingly interpreted as having aquatic habits, which suggests that basal turtles were ecologically diverse. More investigation is needed, but this will undoubtedly trigger further debate on the primitive ecology of turtles and on the origin of aquatic habits in Testudines (i.e., the crown-group), respectively.This work is licensed under the Creative Commons Attribution 4.0 International License.CC-BY 4.0

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First Jurassic Triconodont from South America

Cited by 43 publications

References 37 publications

A Middle Jurassic abelisaurid from Patagonia and the early diversification of theropod dinosaurs

A Middle Jurassic abelisaurid from Patagonia and the early diversification of theropod dinosaurs

Taxonomy, morphology, masticatory function and phylogeny of heterodontosaurid dinosaurs

Evolution and palaeoecology of early turtles: a review based on recent discoveries in the Middle Jurassic

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