Rhaeticosaurus mertensi Wintrich, Hayashi, Houssaye, Nakajima & Sander, 2017

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

Rhaeticosaurus mertensi Wintrich, Hayashi, Houssaye, Nakajima & Sander, 2017

Holotype.

LWL-MFN P 64047, partial articulated skeleton comprising occiput, mandible, partial vertebral column, left scapula and coracoid, both ilia, left ischium, left pubis, left humerus and radius, carpal, left tibia and fibula, three tarsals, and some metapodials and phalanges.

Type locality.

Brick clay pit # 3 of Lücking Ziegel / Beton company, 1 km north of Warburg- Bonenburg, Höxter district, North Rhine-Westphalia.

Type horizon.

Contorta beds, Exter Formation, Upper Keuper Subgroup. Age: Late Triassic (Rhaetian).

Diagnosis.

Distinguished by two autapomorphies: V-shaped neurocentral sutures on anterior and middle cervical vertebrae with sides of ‘ V’ ventrally concave and tip of ‘ V’ close to ventral margin of centrum; ulna and radius and tibia and fibula greatly foreshortened, with humerus / radius length ratio of 3.8 and femur / tibia length ratio of 4.3 ( Wintrich et al. 2017 a).

Comments.

Rhaeticosaurus mertensi is the first Triassic plesiosaur known from extensive skeletal remains. The initial phylogenetic analysis by Wintrich et al. (2017 a) recovered it as an early-diverging member of Pliosauridae . Puértolas-Pascual et al. (2021) found Rhaeticosaurus mertensi as the basalmost plesiosaur. The phylogenetic analysis by Sachs et al. (2024) found it in both previously cited phylogenetic positions.

Reference.

Wintrich et al. (2017 a).