Pachystropheus rhaeticus E. Huene, 1935

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

Pachystropheus rhaeticus E. Huene, 1935

Holotype.

NMHUK R 747 , associated vertebrae from all regions of the vertebral column, ribs, both ilia, left femur, and probably a fibula. According to Quinn et al. (2024), these bones probably represent more than one individual.

Type locality.

Blue Anchor Bay, Somerset, England.

Type horizon.

Westbury Formation, Penarth Group. Age: Late Triassic (Rhaetian).

Referred material (from Germany).

Numerous isolated vertebrae, ribs, appendicular bones and cranial elements from the Rhaetian bonebed 2 in the Contorta beds of the Exter Formation exposed in a claypit at Warburg-Bonenburg, North Rhine-Westphalia ( Sander et al. 2016).

Diagnosis.

Distinguished by the following combination of features: dorsal neural spines nearly square-shaped in lateral view with crenulations extending dorsoventrally from transversely expanded tips; caudal vertebrae with elongate, slender, and vertically oriented neural spines; posterior process of interclavicle thin and elongate; humerus with relatively little torsion of articular ends; radius roughly dumbbell-shaped; and medial and lateral surfaces of the mid- and upper parts of the ilium strongly striated ( Quinn et al. 2024).

Comments.

E. Huene (1935) originally interpreted Pachystropheus rhaeticus as an early choristoderan. Storrs et al. (1996) referred additional material from British Rhaetian bonebeds to P. rhaeticus and considered it a probable choristoderan (see also Storrs and Gower 1993). Most recently, Quinn et al. (2024) published a reassessment of the skeletal structure of this taxon including data from CT-scans of the holotype. Their phylogenetic analysis recovered Pachystropheus rhaeticus as a thalattosaurian rather than a choristoderan.

References.

E. Huene (1935), Storrs and Gower (1993), Storrs et al. (1996), Quinn et al. (2024).