At a Glance
- Paleontologists discovered a new extinct marine mammal species, Ontocetus posti, from Lower Pleistocene deposits in the North Atlantic.
- The study highlights convergent evolution, where O. posti independently developed feeding adaptations similar to modern walruses.
- Fossils were found in Norwich, UK, and Antwerp, Belgium, and were initially mistaken for another species, Ontocetus emmonsi, before unique jawbone features identified them as a new species.
- O. posti had specific physical traits, such as a larger lower canine tooth and fused short lower jaw, indicating adaptation for suction-feeding, akin to today’s walruses.
- The species’ migration from the North Pacific to the Atlantic and its eventual extinction due to global cooling highlight significant evolutionary events that shaped the survival and adaptation of marine mammals like the modern walrus.
Paleontologists have uncovered a new species of extinct marine mammal, named Ontocetus posti, from Lower Pleistocene deposits in the North Atlantic. Led by Dr. Mathieu Boisville from the University of Tsukuba in Japan, the research team found that this ancient creature shows remarkable similarities to modern walruses in its feeding adaptations. The study, published in PeerJ, highlights an intriguing case of convergent evolution, where different species develop similar traits independently.
The fossils of O. posti were discovered in Norwich, United Kingdom, and Antwerp, Belgium. Initially thought to be another species called Ontocetus emmonsi, closer examination of the jawbones revealed unique features that distinguish it as a new species. Notable traits include four post-canine teeth, a larger lower canine tooth, and a fused, short lower jaw. These features suggest that O. posti was adapted for suction-feeding, much like today’s walruses.
Ontocetus originated in the North Pacific Ocean and spread to the Atlantic during the Mio-Pliocene transition through the Central American Seaway. This migration was a significant event in marine mammal evolution. However, global cooling during the Late Pliocene led to the extinction of O. posti in the Early Pleistocene. This environmental shift allowed the cold-adapted walrus, Odobenus rosmarus, to thrive.
The discovery of O. posti provides valuable insights into the evolutionary history of walruses. It underscores how environmental changes have influenced the adaptations and survival of marine mammals. The similarities between O. posti and modern walruses illustrate how similar ecological pressures can lead to comparable evolutionary outcomes across different periods and environments.
References
- PeerJ. (2024, August 13). New species of extinct walrus-like mammal discovered in the North Atlantic. Phys.Org; PeerJ. https://phys.org/news/2024-08-species-extinct-walrus-mammal-north.html
- Boisville, M., Chatar, N., & Kohno, N. (2024). New species of Ontocetus (Pinnipedia: Odobenidae) from the Lower Pleistocene of the North Atlantic shows similar feeding adaptation independent to the extant walrus (Odobenus rosmarus). PeerJ, 12, e17666. https://doi.org/10.7717/peerj.17666
