Early evolution of sauropodomorphs: anatomy and phylogenetic relationships of a remarkably well-preserved dinosaur from the Upper Triassic of southern Brazil

Abstract

An exceptional new specimen (CAPPA/UFSM 0035) of Buriolestes schultzi was discovered during recent fieldwork at the type locality of the taxon, which is Carnian in age (Late Triassic). This early sauropodomorph is peculiar owing to its faunivorous feeding habits, unusual amongst the members of this large omnivorous/herbivorous clade. The specimen incorporates new data on skeletal portions that have so far been unknown for B. schultzi, particularly regarding the skull and axial skeleton. As such, B. schultzi is now as complete as the best-known early dinosaurs, such as Eoraptor lunensis and Herrerasaurus ischigualastensis. A phylogenetic investigation fully supports B. schultzi as a sauropodomorph, corroborating the previous assignation. Despite the presence of traits found in Theropoda, distinct skeletal portions of B. schultzi do not share its morphospace in a morphological disparity analysis. We also propose an alternative evolutionary scenario for the first members of Sauropodomorpha: some Carnian taxa from South America form a monophyletic group instead of a series of low-diversity lineages paraphyletic with respect to Plateosauria.

Dental anatomy of the apex predator Sinraptor dongi (Theropoda: Allosauroidea) from the Late Jurassic of China

“…The distribution of apomorphic dental character states was visualized on a fully topologically constrained tree (sensu Hendrickx et al 2020) using WinClada 1.00.08 (Nixon 2002) on the basis of a Nexus file, with the data matrix and the phylogenetic tree, both created with Mesquite 3.2 (Maddison and Maddison 2017). The tree topology is congruent with the results recovered by Müller et al (2018), fifth phylogenetic analysis (which uses the data matrix of Langer et al 2017) for non-neotheropod saurischians, Ezcurra (2017) for non-averostran neotheropods, Rauhut and Carrano (2016) and Wang et al (2017) for Ceratosauria, Carrano et al (2012) and Rauhut et al (2012 for noncoelurosaurian tetanurans, Brusatte and Carr (2016) for Tyranno-sauroidea, and Cau et al (2017) on the basis of the data set of Brusatte et al (2014) for neocoelurosaurs (i.e., Compsognathidae + Maniraptoriformes; sensu Hendrickx et al 2019).…”

The distribution of dental features in non-avian theropod dinosaurs: Taxonomic potential, degree of homoplasy, and major evolutionary trends

“…We investigated dental features on teeth preserved within the upper and lower jaws as well as isolated teeth belonging to a total of 198 taxa bracketed phylogenetically between the basal saurischian Herrerasaurus ischigualastensis (Reig, 1963;Sereno and Novas, 1994) and the basal avialan Archaeopteryx lithographica (Godefroit et al, 2013a;Foth et al, 2014;Lefèvre et al, 2017; Appendix 1.1). The basal saurischians Daemonosaurus (Sues et al, 2011), Eodromaeus (Martínez et al, 2011) and Eoraptor (Sereno et al, 1993(Sereno et al, , 2013, as well as the Scansoriopterygidae (Czerkas and Yuan, 2002) and the Anchiornithinae (sensu Agnolin et al, 2019; 'Anchiornithidae' of 'Anchiorninae' of Hu et al, 2018), recently recovered as non-avialan theropods by some authors (Sues et al, 2011;Brusatte et al, 2014;Xu et al, 2015bXu et al, , 2017Cau et al, 2017;Müller et al, 2018;Hu et al, 2018), were also included in this study. Of these 200 taxa, we examined firsthand the dentition of 125 taxa deposited in 35 scientific collections from Argentina, France, Belgium, Germany, Italy, Spain, Portugal, Qatar, Switzerland, the United Kingdom, South Africa, China, Canada and the United States (Appendix 1.1).…”

“…Dentition-based synapomorphies in non-coelurosaur Saurischia. Dentition-based synapomorphies on a tree following the topology obtained by Müller et al (2018) for non-averostran Saurischia, Rauhut and Carrano (2016) and Wang et al (2017a) for Ceratosauria, and for non-coelurosaurian Tetanurae, Brusatte and Carr (2016) for Tyrannosauroidea. The list of dental synapomorphies for each clade is provided in Table 1.…”

“…In Limusaurus, however, teeth are borne by hatchling and juvenile individuals and disappear throughout ontogeny (Wang et al, 2017a). Palatal teeth have been retained by the basal sauropodomorphs Eoraptor (Sereno et al, 2013) and Buriolestes (Müller et al, 2018) as well as the putative nonneotheropod theropod Eodromaeus (Martínez et al, 2011;Müller et al, 2018, fourth phylogenetic analysis). Theropods more derived than Eodromaeus, therefore, have an edentulous pterygoid.…”

Dinossauromorfos triássicos do sul do Brasil e padrões biogeográficos da irradiação dos dinossauros

“…Similarly, the earliest definitive dinosaur body fossils are from the early Late Triassic (late Carnian) of [17][18][51][52][53][54] (Figure 3). Although the dating of many Laurasian rock sequences of putatively similar age is controversial, those in Germany (e.g.…”