Marcianosuchus angustifrons Sues, Spiekman & Schoch, 2024

Sues, Hans-Dieter & Schoch, Rainer R., 2025, Synopsis of the Triassic reptiles from Germany, Fossil Record 28 (2), pp. 411-483 : 411-483

Marcianosuchus angustifrons Sues, Spiekman & Schoch, 2024

Holotype.

SMNS 91318 , mostly disarticulated but associated elements of a skeleton including a right premaxilla, right maxilla, frontals, right postorbital, right quadratojugal, right squamosal, right quadrate, articulated left articular, surangular, and angular, left prearticular, teeth, both scapulae, left coracoid, both humeri, partial right ilium, right ischium, both pubes, both femora, partial tibia, fragment of? fibula, vertebrae from various regions of the vertebral column, neural arches, ribs, gastralia, and osteoderms (Fig. 5 A ). There are additional bones that could not yet be identified due to the lack of detailed information for possibly homologous elements in other known archosauriform reptiles.

Type locality.

Former Kössig Quarry, about 100 m south of Rotfelden, Ebhausen municipality, Calw district, Baden-Württemberg.

Type horizon.

Plattensandstein Formation ( Nitsch 2024), Upper Buntsandstein Subgroup. Age: Middle Triassic (Anisian: Aegean).

Diagnosis.

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, anteroposteriorly extending grooves; squamosal with distinct lateral ridge extending for entire length of bone; teeth with proportionately small, weakly recurved crowns; humerus much shorter than femur; distal shaft of ischium rod-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 / posterior view; centra of dorsal vertebrae 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 region anteriorly and sculpturing consisting of radially arranged grooves and pits more posteriorly ( Sues et al. 2024).

Comments.

Marcianosuchus angustifrons represents the only definitive body-fossil record of a non-archosaurian archosauriform from the Buntsandstein Goup known to date. Although it resembles Euparkeria capensis Broom, 1913 from the Trirachodon-Kannemeyeria Subzone of the Cynognathus Assemblage Zone (Anisian) of South Africa, Sues et al. (2024) did not recover it as a member of Euparkeriidae in their phylogenetic analysis.

References.

Sues et al. (2024).

Figures

Figure 5. Reptiles from the Upper Buntsandstein Subgroup. A. Non-archosaurian archosauriform Marcianosuchus angustifrons, holotype (SMNS 91318), disarticulated skeleton. Scale bar: 5 cm. B. Rhynchosaurid rhynchosaur Eifelosaurus triadicus, holotype (IGPB JAEKEL- 1), partial postcranial skeleton. Scale bar: 3 cm.