Acrophoca longirostris, also known as the swan-necked seal, is an extinct genus of Late Miocene pinniped. It was thought to have been the ancestor of the modern leopard seal; however, it is now thought to be a species of monk seal.
Taxonomy
The fossils of
A. longirostris have been discovered in the
Pisco Formation of
Peru and the BahÃa Inglesa Formation of
Chile.
When it was first described in 1981, it was thought to have been closely related to the lobodontine seals which includes the modern-day
leopard seal (
Hydrurga leptonyx), the
crabeater seal (
Lobodon carcinophaga), the
Weddell seal (
Leptonychotes weddelli) and the
Ross seal (
Ommatophoca rossii). However, it is now thought to be a basal species of
monk seal of the subfamily
Monachinae, closely related to the extinct seal
Piscophoca.
Description
Acrophoca was around long, and was not as well adapted to swimming as its descendants, possessing less developed flippers and a less streamlined neck. This may indicate that it spent a lot of time near the coast. Its teeth were built for piercing, implying a diet consisted primarily of fish. However, it also had interdigitated tooth cusps causing the teeth on the upper jaw to fit with the teeth of the lower jaw, which is consistent with
. Unlike other
,
Acrophoca had a long and flexible neck, with an elongated body. The orientation of the pelvis, which in comparison to modern earless seals is everted, as well as adaptations to the hind limbs suggest that swimming was mainly powered by the back flippers. It was less adapted for the sea than the lobodontine seals, suggesting it inhabited
littoral zone waters.
Paleoecology
Its fossils have been found alongside those of the marine sloth Thalassocnus and tusked cetacean Odobenocetops, as well as modern animals such as bottlenose dolphins, and .
Further reading
-
World Encyclopedia of Dinosaurs & Prehistoric Creatures: The Ultimate Visual Reference To 1000 Dinosaurs And Prehistoric Creatures Of Land, Air And Sea ... And Cretaceous Eras (World Encyclopedia) by Dougal Dixon
External links
