Cryptoclididae? indet, 1925

Madzia, Daniel, Szczygielski, Tomasz & Wolniewicz, Andrzej S., 2021, The giant pliosaurid that wasn’t-revising the marine reptiles from the Kimmeridgian, Upper Jurassic, of Krzyżanowice, Poland, Acta Palaeontologica Polonica 66 (1), pp. 99-129 : 117-118

Cryptoclididae? indet .

Fig. 9 .

Material.— MZ VIII Vr-73 (“ ZPAL V-KRZ/32”) (see above with respect to the ambiguity regarding the catalogue number of the specimen), a pectoral vertebral centrum reported by Tyborowski and Błażejowski (2019a) as originating from the light yellow marl, upper Kimmeridgian of Krzyżanowice, Poland ( Dąbrowska 1957; Borsuk-Białynicka and Młynarski 1968).

Tyborowski and Błażejowski (2019a, b) reported an isolated plesiosaur pectoral centrum ( MZ VIII Vr-73 or “ ZPAL V-KRZ/32”), though their taxonomic interpretation of the element differed slightly between these two studies. While originally considered to represent an indeterminate elasmosaurid ( Tyborowski and Błażejowski 2019a: 747), in their second paper the authors referred the specimen to a plesiosauroid and noted that it resembled the vertebrae of elasmosaurids and cryptoclidids ( Tyborowski and Błażejowski 2019b: 1000).

Description.—The centrum clearly pertains to the pectoral series at the cervical-dorsal transition; the rib facet is transected by the neurocentral suture and is formed by the parapophysis on the vertebral centrum and diapophysis on the neural arch (see e.g., Sachs et al. 2013 for discussion on plesiosaur pectorals). The centrum itself is slightly kidney-shaped in anterior/posterior view, wider than high, the rib facets are circular, and the subcentral foramina are widely separated. The dorsal aspect of MZ VIII Vr-73 (“ ZPAL V-KRZ/32”) further indicates the presence of a fairly wide neural canal. Such an overall morphology corresponds well with the pectoral morphology of cryptoclidid plesiosauroids, such as Cryptoclidus eurymerus Phillips, 1871 ( Brown1981: fig. 9), Colymbosaurus megadeirus (Seeley, 1869) ( Benson and Bowdler 2014: fig. 6), and Ophthalmothule cryostea Roberts, Druckenmiller, Cordonnier, Delsett, and Hurum, 2020 ( Roberts et al. 2020: fig. 15).

Considering the morphology of the centrum and its stratigraphic provenance, the taxonomic placement among Cryptoclididae appears to be most likely. However, owing to the fact that no diagnostic features were observed that would allow us to unambiguously assign the centrum to that clade, we refer the specimen to Cryptoclididae ? indet .

Figures

Fig. 9. A plesiosauroid (Cryptoclididae? indet.) pectoral centrum, MZ VIII Vr-73 (“ZPAL V-KRZ/32”), from the Kimmeridgian of Krzyżanowice, in anterior (A1), posterior (A2), dorsal (A3), ventral (A4), left lateral (A5), and right lateral (A6) views.