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Silesauridae

Silesaurids
Temporal range: ?Middle TriassicLate Triassic, ?245–203 Ma
Silesauridae.png
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauromorpha
Family: Silesauridae
Langer et al., 2010
Subgroups

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. Some studies have instead suggested that most or all silesaurids comprised an early diverging clade or a paraphyletic grade within ornithischian dinosaurs. Silesaurids have a consistent general body plan, with a fairly long neck and legs and possibly quadrupedal habits, but most silesaurids are heavily fragmentary nonetheless. Furthermore, they occupied a variety of ecological niches, with early silesaurids (such as Lewisuchus) being carnivorous and later taxa (such as Kwanasaurus) 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.

Classification

Silesauridae is typically considered the sister group to Dinosauria. The group was named in 2010 by Max C. Langer 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. 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. 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).

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

Ornithodira 

Pterosauria

 Dinosauromorpha 
 Lagerpetidae 

Lagerpeton chanarensis

Dromomeron gregorii

Dromomeron romeri

 Dinosauriformes 

Marasuchus lilloensis

Dracohors

Dinosauria

 Silesauridae 

Lewisuchus

Asilisaurus kongwe

Sulcimentisauria

Eucoelophysis baldwini

Silesaurus opolensis

Sacisaurus agudoensis

Diodorus scytobrachion

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.


This page was last updated at 2022-10-13 00:13 UTC. Update now. View original page.

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