Osteology and phylogenetic relationships of a new archosauriform reptile from the Middle Triassic (Anisian) of Germany

ABSTRACT

Skeletal remains of archosauriform reptiles from the Lower and lower Middle Triassic Buntsandstein Group in the Central European Basin are rare. This paper reports on a partial, almost completely disarticulated skeleton of a previously unknown archosauriform reptile from the lower Middle Triassic (Anisian) Röt Formation of Rotfelden in Baden-Württemberg (Germany). Marcianosuchus angustifrons gen. et sp. nov. is distinguished by the following combination of features: posterodorsal process of premaxilla slender, slightly inclined posterodorsally, and with rounded apex; posterodorsal surface of frontal covered by slightly diverging, fine longitudinal grooves; squamosal with distinct lateral ridge extending for entire length of element; teeth with proportionately small, weakly recurved crowns; humerus considerably shorter than femur; distal shaft of ischium rod-like, not plate-like; pubis with flat distal portion forming ‘pubic apron’: neural spines of posterior cervical and anterior dorsal vertebrae with transversely greatly expanded apices that are Y-shaped in anterior or posterior view; dorsal vertebrae with centra taller dorsoventrally than long anteroposteriorly; dorsal osteoderms more or less rectangular in outline, longer anteroposteriorly than wide mediolaterally, with slightly rounded anterior and concave posterior margins and bearing dorsal ridge or eminence; and dorsal surfaces of osteoderms with unsculptured anterior region and posterior region bearing keel or eminence and covered by sculpturing of radially arranged grooves and pits. Marcianosuchus angustifrons represents the first definitive record of a non-archosaurian archosauriform from the Buntsandstein Group of Germany. Its body plan most closely resembles that of Euparkeria capensis among well-known non-archosaurian archosauriform reptiles, but the two taxa are clearly distinct.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).

ACKNOWLEDGMENTS

We thank I. Rosin for her skillful preparation of the specimen and E. Mujal for producing the three-dimensional photogrammetric model of the fossil. R. B. Sookias generously provided photographs of specimens of Dorosuchus neoetus and Euparkeria capensis and O. Damuth kindly shared 3D renderings of the pelvis of the latter taxon. We are indebted to M. D. Ezcurra, C. T. Griffin, and an anonymous reviewer as well as Editor G. Bever and Phylogenetics Editor P. Godoy for their helpful comments and suggestions. H-DS gratefully acknowledges support from the MacMillan Fund of the Department of Paleobiology. The software TNT is made freely available by the Willi Hennig Society.

DATA AVAILABILITY STATEMENT

The data that support the conclusions of this study are available in the manuscript.

AUTHOR CONTRIBUTIONS

RRS and H-DS designed the project. RRS wrote an initial draft. H-DS prepared the anatomical descriptions and he and SNFS created the figures. H-DS and RRS worked with SNFS on the phylogenetic analysis. All authors edited various drafts of the manuscript and approved the final version.

SUPPLEMENTARY FILES

Supplementary File 1.nex: Character-taxon matrix with the addition of Marcianosuchus angustifrons and Tarjadia ruthae in NEXUS format.

Supplementary File 2.tnt: Character-taxon matrix with the addition of Marcianosuchus angustifrons and Tarjadia ruthae in TNT format.

Supplementary File 3.tre: Most parsimonious trees.

Supplementary File 4.tiff: Tree from phylogenetic analysis with implied weights.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.