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A team of paleontologists, led by Dr. Mathieu Boisville from the University of Tsukuba, Japan, has discovered a new species of extinct walrus-like mammal.
The new species is of the extinct genus Ontocetus from the Lower Pleistocene deposits in the North Atlantic.
Named Ontocetus posti, this species exhibits remarkable similarities in feeding adaptations to the modern walrus (Odobenus rosmarus), showcasing an intriguing example of convergent evolution.
The research findings have been published in the open-access journal PeerJ Life & Environment.
The fossils of Ontocetus posti were unearthed in Norwich, United Kingdom, and Antwerp, Belgium. Initially, these remains were believed to belong to another species, Ontocetus emmonsi.
However, a detailed analysis of the mandibles revealed distinct features that set it apart as a new species. These features include the presence of four post-canine teeth, a larger lower canine, and a fused, short mandibular symphysis.
Such anatomical traits suggest that Ontocetus posti was well adapted to suction-feeding, akin to its modern relative, the walrus.
The Ontocetus genus is believed to have originated in the North Pacific Ocean, spreading to the Atlantic during the Mio-Pliocene transition.
This migration was likely facilitated by the Central American Seaway, a crucial oceanic passage before the Isthmus of Panama closed.
The global cooling that began during the Late Pliocene significantly impacted marine life, contributing to the extinction of Ontocetus posti during the Early Pleistocene. This environmental shift allowed the cold-adapted Odobenus rosmarus to emerge and eventually dominate.
This discovery provides valuable insights into the evolutionary history of walruses, highlighting how environmental changes have shaped the adaptations and survival of marine mammals.
The convergence of feeding adaptations between Ontocetus posti and the modern walrus underscores the dynamic evolutionary processes that occur across different eras and environments.
Dr. Boisville's team emphasises the importance of this finding in understanding the complex evolutionary pathways that have led to the development of current marine mammal species.
It also illustrates the significant role that environmental factors play in driving evolutionary changes, offering a deeper understanding of the history and adaptability of marine life.
