page_title: Asperoris
section_title: Relationships
hierarchical_section_title: Asperoris / Relationships
caption_attribution_description: English: Right premaxilla of the holotype of Asperoris mnyama (NHMUK PV R36615). The premaxilla in lateral view (A) and interpretative drawing and medial view (B) and interpretative drawing. Light gray color indicates incomplete surfaces. Scale = 1 cm. Abbreviations: a., articulates with; apmx, anterior process of the premaxilla; idp, interdental plates; mx, maxilla; ppmx, posterior process of the premaxilla; to, tooth.
context_page_description: Asperoris is an extinct genus of archosauriform reptile known from the Middle Triassic Manda Beds of southwestern Tanzania. It is the first archosauriform known from the Manda Beds that is not an archosaur. However, its relationships with other non-archosaurian archosauriforms are uncertain. It was first named by Sterling J. Nesbitt, Richard J. Butler and David J. Gower in 2013 and the type species is Asperoris mnyama. Asperoris means "rough face" in Latin, referring to the distinctive rough texture of its skull bones.
context_section_description: Asperoris belongs to a clade or evolutionary grouping of reptiles called Archosauriformes, which includes Archosauria (the clade including living crocodilians and birds) and their extinct, mostly Triassic, relatives. It has several features that place it outside Archosauria with non-archosaurian archosauriforms, including the lack of an antorbital fossa and the possible presence of a postparietal bone at the back of the skull, which is not found in archosaurs. However, it also has features that place it among the closest relatives of archosaurs, including the presence of an antorbital fenestra and the lack of a hole called the parietal foramen on the skull roof. Asperoris shares with a group of archosauriforms called erythrosuchids the presence of slot in the lower part of the nasal bone that fits into a projection of the premaxilla beneath it. It also has a thecodont dentition, meaning that its teeth fit into deep sockets in the jaw. A thecodont dentition is seen in all non-archosaurian archosauriforms except proterosuchids, and is characteristic of the clade.
   
  Because of the poor preservation of NHMUK PV R36615 and the phylogenetic analysis used in the study (which focuses on relationships of Triassic archosaurs), the phylogenetic relationships of Asperoris are uncertain. Nesbitt, Butler and Gower's 2013 phylogenetic analysis resulted in a strict consensus tree with Asperoris in a polytomy or unresolved phylogenetic relationship with Erythrosuchus africanus, an erythrosuchid, Vancleavea campi, an aquatic archosauriform, the proterosuchid clade, and the clade including Euparkeria capensis, phytosaurs, and Archosauria. Other phylogenetic trees produced in the analysis placed Asperoris as the sister taxon (closest relative) of either Erythrosuchus africanus or Euparkeria capensis. A sister-taxon relationship with Erythrosuchus is more likely because it is based on a derived feature, the slot in the nasal, while the relationship with Euparkeria is less likely because it is based only on characteristics inherited from archosauriform ancestors (plesiomorphies).
  Asperoris was also featured in a phylogenetic analysis by Martin Ezcurra in 2016. Most parts of Ezcurra's analysis omitted this genus due to its incompleteness, but in versions which did feature it, it was found in a polytomy with Yarasuchus, Dongusuchus, Dorosuchus, and Euparkeria at the base of a clade which also includes proterochampsians and archosaurs. Ezcurra named this broad clade Eucrocopoda. The five-genus polytomy is resolved into a clearer system of clades when Asperoris is omitted, as the taxon's lack of postcranial features reduced the analysis's clarity. Yarasuchus and Dongusuchus are now considered to be aphanosaurs, part of a group of archosaurs at the base of the branch that leads to pterosaurs and dinosaurs (including birds) but not crocodiles.
caption: Premaxilla
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