Dorsal or ventral? Homologies of the forefin of Caypullisaurus (Ichthyosauria: Ophthalmosauria)

ABSTRACT

The original description of Caypullisaurus (Ichthyosauria: Ophthalmosauria) depended on the orientation of the fins of the holotype. Later, the forefins of this taxon were reoriented contrary to the original description. The arrival of the holotype carcass at the sea floor is analyzed taphonomically such that the original interpretation is confirmed. The analysis of the homologies of the forefin elements also confirms that the topological criteria developed for the identification of the primary axis of all Ichthyosauria are also applicable for Caypullisaurus. A comparison with the forefins of other Callovian and Late Jurassic ichthyosaurs shows that Caypullisaurus belongs to the Ophthalmosauria and that the forefins of this clade are more diverse than previously supposed.