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

Fabio Marco Dalla Vecchia

doi:10.7717/peerj.12468

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.

Highlights

Since the beginning of this century, the Middle Triassic Torbiditi d’Aupa Formation (Aupa Turbidites, TAF) of the eastern Carnic Alps (NE Italy) has begun to yield abundant reptile remains belonging to tanystropheids, archosauriforms, sauropterygians and ichthyosaurs (Dalla Vecchia, 2006, 2008).These remains were found in a small area along the Aupa Creek near Saps village (Moggio Udinese Municipality, Friuli Venezia Giulia Autonomous Region, Trieste, Italy; Figs. 1A–1B)
MFSN 46485, partial armor made of eight columns of osteoderms and five neural arches of dorsal vertebrae (Fig. 2)
MFSN 46485 is comprised of a dorso-lateral fragment of armor with a row of neural arches of the dorsal vertebrae

Summary

Introduction

Since the beginning of this century, the Middle Triassic Torbiditi d’Aupa Formation (Aupa Turbidites, TAF) of the eastern Carnic Alps (NE Italy) has begun to yield abundant reptile remains belonging to tanystropheids, archosauriforms, sauropterygians and ichthyosaurs (Dalla Vecchia, 2006, 2008).These remains were found in a small area along the Aupa Creek near Saps village (Moggio Udinese Municipality, Friuli Venezia Giulia Autonomous Region, Trieste, Italy; Figs. 1A–1B). Since the beginning of this century, the Middle Triassic Torbiditi d’Aupa Formation (Aupa Turbidites, TAF) of the eastern Carnic Alps (NE Italy) has begun to yield abundant reptile remains belonging to tanystropheids, archosauriforms, sauropterygians and ichthyosaurs (Dalla Vecchia, 2006, 2008). These remains were found in a small area along the Aupa Creek near Saps village Close to each other, these outcrops may represent different levels within the TAF, as suggested by the different lithologies of the specimens

Results

Discussion

Conclusion