Polycotylidae indet

O’Gorman, José Patricio & Otero, Rodrigo A., 2023, Revision of the short-necked Cretaceous plesiosaurians from New Zealand, Comptes Rendus Palevol 22 (6), pp. 77-90 : 79

Polycotylidae indet .

( Fig. 2 E-H)

Polycotylus tenuis – Hector 1874: 335, pl. 27. — Welles 1962: 73, nomen dubium.

Cimoliosaurus tenuis – Lydekker 1889: 188.

Polycotylidae indet. – Welles & Gregg 1971: 44.

MATERIAL. — DM R1544 , a cervical centrum .

LOCALITY AND HORIZON. — Haumuri Bluff , South Island, New Zealand. Conway Formation, Campanian ( Wilson et al. 2005; Fig. 1).

REMARKS

Welles & Gregg (1971) provided the centrum indices (HI = 145 and BI = 168), pointing out the presence of deeply excavated articular facets and a subcircular articular outline. Such morphology differs from the typical cervical centra observed among Late Cretaceous elasmosaurids, characterized by platycelous articular facets and a bilobed articular contour ( Gasparini et al. 2003). Otherwise, the elliptical and strongly concave articular facets indicate affinities with Polycotylidae ( Salgado et al. 2007) . These are non-conclusive regarding a generic determination, as previously pointed out by Welles & Gregg (1971). DM R1544 is part of the hypodigm of ‘ Polycotylus tenuis ’ Hector, 1874 (currently nomen dubium), and was designated as the paralectotype by Welles & Gregg (1971).