A platypterygiid ichthyosaur from the Cenomanian of central New Zealand

Abstract

ABSTRACT Understanding of Cretaceous ichthyosaur diversity has substantially increased in recent years; however, Eastern Gondwana’s ichthyosaur fauna is still poorly understood, particularly in New Zealand where only scarce fragmentary material is known. A Cenomanian-aged partial ichthyosaur skeleton has been recovered from the northeastern South Island of New Zealand and is described here. Whilst the specimen is too fragmentary to formally name, this taxon shows an extreme reduction of the basioccipital extracondylar area, a scapula with a prominent acromion process and a strap-like scapula shaft, as well as a complete left pelvic girdle with an elongated depression on the anteroproximal face of the ischiopubis. We suggest that it is a late branching member of the platypterygiid ichthyosaurs, closely related to the Eastern Gondwanan ichthyosaur Platypterygius australis and to many European Cretaceous taxa. However, it appears to be unrelated to the Cretaceous ichthyosaurs of Western Gondwana, suggesting potential regionalism amongst the Gondwanan Cretaceous ichthyosaur populations.