Caiman gasparinae sp. nov., a huge alligatorid (Caimaninae) from the late Miocene of Paraná, Argentina

Abstract

Morphological studies of South American alligatorids are scarce, and the phylogenetic relationships within Caimaninae are poorly understood. In this context, systematic revision and detailed morphological description of the enigmatic Argentinean Miocene caimanines are highly relevant. The current record is characterized by numerous species within the genus Caiman, although morphological disparity remains unclear. Here, we describe Caiman gasparinae sp. nov., which is one of the largest known Caiman species from the late Miocene of Argentina. Similar to other Caiman species and Melanosuchus, the new taxon has orbits larger than the infratemporal fenestrae and small supratemporal fenestrae that are not lost, as in Paleosuchus. Together with the absence of conspicuous rostral crests, the shape of the snout distinguishes C. gasparinae from Melanosuchus. Caiman gasparinae can be further distinguished using other cranial characters, such as a broad and low rostrum with a narial opening oriented dorsally, a relatively long interpremaxillary suture, and the occipital surface of the braincase with a poorly developed crista tuberalis exposing the carotid foramina in lateral view.