Elachistosuchus huenei Janensch, 1949

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

Elachistosuchus huenei Janensch, 1949

Holotype.

MB. R. 4520 , nearly complete but crushed skull (Fig. 14 C ) and partial postcranial skeleton including much of the shoulder girdle and a right humerus, preserved on six small blocks of matrix.

Type locality.

Baerecke-Limpricht brick-clay pit along the present-day highway B 79 between Halberstadt and Quedlinburg, near Halberstadt, Saxony-Anhalt.

Type horizon.

Arnstadt Formation, Middle Keuper Subgroup. Age: Late Triassic (Norian: Alaunian-Sevatian).

Diagnosis.

Distinguished by the following combination of features: frontal with distinct posterolateral process; maxillary tooth row extending back to posterior orbital margin; jugal with freely ending posterior process; palatine ramus of pterygoid covered with shagreen of teeth; angular exposed laterally for about one third of lateral surface of mandibular ramus; anterior margin of interclavicle notched; and posterior process of interclavicle spatulate ( Sobral et al. 2015).

Comments.

This taxon has been assigned to various diapsid clades since its original description. Janensch (1949) considered Elachistosuchus huenei a pseudosuchian based primarily on what he interpreted as an antorbital fenestra. Walker (1966) argued that it was a rhynchocephalian, incorrectly claiming that it has acrodont tooth implantation and reinterpreting the ‘ antorbital fenestra’ as the foramen for the lacrimal canal. Following a detailed anatomical description based on µCT-scans of the holotype, Sobral et al. (2015) attempted the first assessment of its relationships with phylogenetic analyses based on two character-taxon matrices available at the time. They recovered Elachistosuchus huenei as an archosauromorph, a lepidosauromorph, or a non-saurian diapsid. In a recent phylogenetic analysis using a much larger character-taxon matrix, Ezcurra and Sues (2021) found it as an early-diverging non-lepidosaurian lepidosauromorph.

References.

Janensch (1949), Walker (1966), Sobral et al. (2015), Ezcurra and Sues (2021).

Figures

Figure 14. Reptiles from the Middle Keuper Subgroup. A. Stem-turtle Proterochersis robusta (SMNS 17561), shell. Length 30 cm. B. Stem-turtle Proganochelys quenstedtii (SMNS), reconstructed skeleton including shell. C. Lepidosauromorph Elachistosuchus huenei, holotype (MB. R. 4520), incomplete skull in lateral and dorsal view. Scale bar: 1 cm. D. Sphenodontian rhynchocephalian Parvosaurus harudensis, holotype (MB. R. 4520.2), CT-based rendering of incomplete skull in dorsal view. Scale bar: 5 mm. From Freisem et al. (2024) – CC-BY 4.0.