Silesauridae

Silesaurids Temporal range: ?Middle Triassic—Late Triassic, ?245–203 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dracohors
Family:	†Silesauridae Langer et al., 2010
Subgroups
†Agnosphitys? †Asilisaurus †Ignotosaurus †Lewisuchus †Pisanosaurus? †Soumyasaurus †Sulcimentisauria

Silesauridae is an extinct family of Triassic dinosauriforms. It is most commonly considered to be a clade of non-dinosaur dinosauriforms, and the sister group of dinosaurs.^{[1][2][3][4][5]} Some studies have instead suggested that most or all silesaurids comprised an early diverging clade or a paraphyletic grade within ornithischian dinosaurs.^[6][7][8][9] Silesaurids have a consistent general body plan, with a fairly long neck and legs and possibly quadrupedal habits, but it is important to note that most silesaurids are heavily fragmentary nonetheless. Furthermore, they occupied a variety of ecological niches, with early silesaurids (such as Lewisuchus)^[10] being carnivorous and later taxa (such as Kwanasaurus)^[11] having adaptations for specialized herbivory. As indicated by the contents of referred coprolites, Silesaurus may have been insectivorous, feeding selectively on small beetles and other arthropods.^[12]

Classification[]

Silesauridae is typically considered the sister group to Dinosauria. The group was named in 2010 by et al. They defined it as a branch-based clade of all archosaurs closer to Silesaurus opolensis than to either Heterodontosaurus tucki or Marasuchus lilloensis.^[13] At around the same time, Sterling J. Nesbitt et al. (2010) independently named Silesauridae as a node-based clade consisting of Lewisuchus, Silesaurus, their last common ancestor and all their descendants.^[1] Currently, both definitions encompass the same group of animals. Nesbitt et al. noted that the earlier definition by Langer et al. did not include a diagnosis, and so was not sufficient to create a ranked family-level name according to the ICZN. Therefore, the family Silesauridae is attributed to Nesbitt et al. (2010) while the clade Silesauridae is attributed to Langer et al. (2010).^[3]

The fossils range in age from the Anisian to the Norian stages of the Triassic, about 245 to 203 million years ago.^[1][13] The cladogram below follows the phylogenetic analysis of basal ornithodirans conducted by , Sterling Nesbitt and Neil Shubin (2012) with clade terminology from Cau (2018) and Martz and Small (2019).^[3][5][14]

A large phylogenetic analysis of early dinosaurs and dinosauromorphs carried out by Matthew Baron, David Norman and Paul Barrett (2017) and published in the journal Nature recovered Silesauridae as a monophyletic sister group to Dinosauria. The study also recovered the taxon Agnosphitys within the clade Silesauridae, close to Lewisuchus and its synonymous taxon Pseudolagosuchus.^[4]

References[]

External links[]

• Silesauridae in the Paleobiology Database

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