A non-aristonectine plesiosaur from Antarctica reveals new data on the mandibular symphysis of elasmosaurids

O´GORMAN, JP.; BONA, P.; DE LOS REYES, M.; RAFFI, ME.; REGUERO, M.

ALCHERINGA

TAYLOR & FRANCIS LTD

Lugar: Londres; Año: 2020

0311-5518

Elasmosaurids are one of the most abundant fossil marine reptile groups identified from theUpper Cretaceous strata of Antarctica. However, the documented record of intact elasmosauridskull remains is scarce. In this study, we describe the first non-aristonectine elasmosaurid skeletonfrom Antarctica that preserves an associated lower jaw. This specimen displays a unique characterstate combination including three symphyseal alveoli, the angle between the mandibular ramiexceeding 90, and the absence of a ventral symphyseal sulcus or keel. This mandibular configurationhas not been observed previously among elasmosaurids, prompting comparisons with otherdescribed examples and suggesting that mandibular morphology reached a variability peak duringthe Maastrichtian, which might be reflective of increased trophic diversity.