Heteropelta boboi n. gen., n. sp. an armored archosauriform (Reptilia: Archosauromorpha) from the Middle Triassic of Italy

Abstract

Heteropelta boboi is a new archosauriform reptile from the upper Anisian of northeastern Italy represented by a fragment of dorsal armor with a row of neural arches of the dorsal vertebrae. The dorsal armor of the new taxon is composed of two columns of paramedian osteoderms and at least six columns of lateral osteoderms. Unlike other armored archosaurs, the osteoderms are imbricated with the posterior osteoderm overlapping the anterior one. The low neural arches bear small neural spines and long postzygapophyses. The osteoderms of the lateral columns increase in size and change in shape from the most medial to the most lateral columns. Among the Archosauriformes, only the non-archosaur proterochampsians Vancleavea campi, Litorosuchus somnii, and the doswelliids have dorsal armor comprised of more than two columns of osteoderms per side, but the morphology and arrangement of their osteoderms is unlike those of the new Italian taxon. A cladistic analysis of Archosauromorpha positions Heteropelta boboi as either a basal phytosaur or a basal suchian. However, a second cladistic analysis focused on armored archosaurs alternatively positions the new taxon as a basal archosauriform, basal suchian, basal loricatan or crocodylomorph. Better resolution of the phylogenetic relationships of Heteropelta boboi will likely be obtained only with the discovery of cranial and postcranial remains associated with its diagnostic armor elements.

Palaeobiological inferences of “rauisuchians” Fasolasuchus tenax (Los Colorados Fm., Argentina) and Prestosuchus chiniquensis (Santa Maria Super sequence, Brazil) from the Middle–Upper Triassic of South America based on microstructural analyses

“…Although the “rauisuchians” (sensu lato , Butler et al, 2022) studied to date present particular differences in terms of growth modes, a more or less common pattern could be detected for these taxa (except for P. chiniquensis ), marked mainly by the presence of abundant woven bone matrix and an extensive laminar to plexiform vascularisation. This characteristic seems to exhibit a phylogenetic signal since the six species are closely related to each other (Butler et al, 2022; Dalla Vecchia, 2021; Desojo et al, 2020; Nesbitt et al, 2020; Nesbitt & Desojo, 2017; Rezende et al, 2022; Roberto‐Da‐Silva et al, 2018; Soares Damke et al, 2022; Tolchard et al, 2021). Similar to the majority of Triassic archosauromorphs, most of the “rauisuchians” studied to date show a relatively fast growth rate, which is consistent with the proposition that the histology of appendicular bones exhibits a recognisable phylogenetical signal (Benton, 2021; Legendre et al, 2012, 2016).…”

“…Although historically, the “rauisuchians” were not easily placed into discrete, well‐diagnosed clades, recent phylogenetic analyses place them as pseudosuchian paracrocodylopmorphs (Butler et al, 2022; Dalla Vecchia, 2021; Desojo et al, 2020; Nesbitt et al, 2020; Nesbitt & Desojo, 2017; Rezende et al, 2022; Roberto‐Da‐Silva et al, 2018; Soares Damke et al, 2022; Tolchard et al, 2021). Excluding some basal species, the Paracrocodylomorpha is divided into two major monophyletic lineages: Poposauroidea and Loricata, the latter group includes the Crocodylomorpha (Figure 1; Butler et al, 2022; Dalla Vecchia, 2021; Desojo et al, 2020; Nesbitt et al, 2020; Nesbitt & Desojo, 2017; Rezende et al, 2022; Roberto‐Da‐Silva et al, 2018; Soares Damke et al, 2022; Tolchard et al, 2021).…”

“…Although historically, the "rauisuchians" were not easily placed into discrete, well-diagnosed clades, recent phylogenetic analyses place them as pseudosuchian paracrocodylopmorphs (Butler et al, 2022;Dalla Vecchia, 2021;Desojo et al, 2020;Nesbitt et al, 2020;Nesbitt & Desojo, 2017;Rezende et al, 2022;Roberto-Da-Silva et al, 2018;Soares Damke et al, 2022;Tolchard et al, 2021).…”

“…Excluding some basal species, the Paracrocodylomorpha is divided into two major monophyletic lineages: Poposauroidea and Loricata, the latter group includes the Crocodylomorpha (Figure 1; Butler et al, 2022;Dalla Vecchia, 2021;Desojo et al, 2020;Nesbitt et al, 2020;Nesbitt & Desojo, 2017;Rezende et al, 2022;Roberto-Da-Silva et al, 2018;Soares Damke et al, 2022;Tolchard et al, 2021).…”

A new nominal genus for “Prestosuchus” chiniquensis Huene, 1938 (Triassic of southern Brazil): Huenesuchus, genus novus et combinatio nova

“…5.1;2016:110, tab. 1), which was also later iterated by several authors (Ezcurra et al, 2017(Ezcurra et al, , 2019(Ezcurra et al, , 2020b(Ezcurra et al, , 2021a(Ezcurra et al, , b, c, d, 2022Nesbitt et al, 2017Nesbitt et al, , 2018bSengupta et al, 2017Sengupta et al, , 2022Stoker et al, 2017;Ezcurra & Butler, 2018;Oliveira et al, 2018;Spiekman, 2018;Butler et al, 2019;Peecook et al, 2019;Baczko et al, 2020;Barrett et al, 2020;Bennett, 2020;Foffa et al, 2020Foffa et al, , 2022Maidment et al, 2020;Scheyer et al, 2020;Sues et al, , 2021Troteyn & Ezcurra, 2020;Wynd et al, 2020;DallaVecchia, 2021;Parker et al, 2021;Ezcurra & Sues, 2022;Kellner et al, 2022;Martínez et al, 2022;Pretto et al, 2022;Sengupta & Bandyopadhyay, 2022;Simão-Oliveira et al, 2022;Chen & Liu, 2023). Therefore, these scorings don't reflect, nor include the typematerial and, as consequence, they are not representative of H. chiniquensis.…”