On the presence of the subnarial foramen in Prestosuchus chiniquensis (Pseudosuchia: Loricata) with remarks on its phylogenetic distribution

Abstract

Many authors have discussed the subnarial foramen in Archosauriformes. Here presence among Archosauriformes, shape, and position of this structure is reported and its phylogenetic importance is investigated. Based on distribution and the phylogenetic tree, it probably arose independently in Erythrosuchus, Herrerasaurus, and Paracrocodylomorpha. In Paracrocodylomorpha the subnarial foramen is oval-shaped, placed in the middle height of the main body of the maxilla, and does not reach the height of ascending process. In basal loricatans from South America (Prestosuchus chiniquensis and Saurosuchus galilei) the subnarial foramen is 'drop-like' shaped, the subnarial foramen is located above the middle height of the main body of the maxilla, reaching the height of ascending process, a condition also present in Herrerasaurus ischigualastensis. These results suggest that this structure might be phylogenetically important and further investigation with a large set of valid taxa is necessary to properly evaluate its importance among Archosauria.

The anatomy and phylogenetic position of the erythrosuchid archosauriformGuchengosuchus shiguaiensisfrom the earliest Middle Triassic of China

“…This non-articular margin is absent in Guchengosuchus shiguaiensis , the articular facets of the premaxilla and maxilla being adjacent to each other. If an opening was present between the premaxilla and maxilla, as originally suggested by Peng (1991), this would have been more similar in its position and relationships with the surrounding bones to the subnarial fenestra that has been described for some loricatan pseudosuchians (e.g., Decuriasuchus quartacolonia : França, Langer & Ferigolo, 2013; Prestosuchus chiniquensis : Roberto-Da-Silva et al, 2016; but see Nesbitt & Desojo (2017) for an alternative interpretation of these openings as the result of deformation during taphonomic processes) and the early dinosaur Herrerasaurus ischigualastensis (Sereno & Novas, 1993). As a result, we think it is likely that Guchengosuchus shiguaiensis did not have a secondary antorbital fenestra homologous with that present in some Middle Triassic erythrosuchids, and we cannot confirm the presence of an opening between the premaxilla and maxilla because the specimen has been damaged since its original description.…”

Revision ofErpetosuchus(Archosauria: Pseudosuchia) and new erpetosuchid material from the Late Triassic ‘Elgin Reptile’ fauna based on μCT scanning techniques

“…BGS assigned an individual register number to each sandstone block, but this nomenclature cannot be used easily herein because the μCT scans show that the skeletons of at least two individuals of distinct species are embedded within them. The first of these belongs to a pseudosuchian archosaur – the specimen that is currently referred to Ornithosuchus woodwardi (Walker 1964; Von Baczko & Ezcurra 2016) – and is partially exposed on the surfaces of the blocks; the second is a previously undocumented partial skeleton of the procolophonid Leptopleuron lacertinum (also known from the LSF fauna) (Benton & Walker 1985; Säilä 2010). For example, BGS GSM 91075 contains both cranial material of the archosaur and the L. lacertinum remains.…”

Anatomy, taxonomy and phylogenetic relationships of Prestosuchus chiniquensis (Archosauria: Pseudosuchia) from the original collection of von Huene, Middle-Late Triassic of southern Brazil

“…Furthermore, with the aggregation of new taxa and characters and the reassessment of proposed characters, it is to be expected that at least most phylogenetic analyses represent a step forward in this task. Recently, several anatomical and phylogenetic studies concerning Prestosuchus have been carried out (Mastrantonio, 2010;Mas-trantonio et al, 2013Mas-trantonio et al, , 2019Liparini and Schultz, 2013;Raugust, 2014;Lacerda et al, 2016;Roberto-da-Silva et al, 2016; however, none of these authors reassessed the original materials recovered by von Huene in detail, and no detailed justification for the referral of new materials to Prestosuchus chiniquensis, based on detailed comparisons with the type specimen, was given.…”

“…The purpose of this work is to present a detailed taxonomic revision, anatomical description, and phylogenetic relationships of the type and referred materials of Prestosuchus from the original collections of von Huene, as part of a larger project revising all of von Huene's "rauisuchian" material from the Triassic of Brazil (Desojo and Rauhut, 2009;Ezcurra et al, 2015;Lautenschlager and Rauhut, 2015;von Baczko et al, 2019). This revision is crucial to assess the taxonomy and phylogenetic position of the "rauisuchids" recently exhumed from Brazil and assigned to Prestosuchus chiniquensis (Mastrantonio et al, 2013;Raugust, 2014;Lacerda et al, 2016;Roberto-da-Silva et al, 2016, as well as to resolve the relationships among Pseudosuchia of several taxa recently discovered or redescribed, such as Mandasuchus tanyauchen Butler et al, 2018, Stagonosuchus nyassicus von Huene, 1939, Pagosvenator candelariensis Lacerda et al, 2018, and Venaticosuchus rusconi Bonaparte, 1970.…”