The extinct species, named Ontocetus posti, lived almost two million years earlier than the fashionable walrus emerged.
Whereas the walrus is the one surviving member of the Odobenidae household, a number of extinct species as soon as roamed the planet. The trendy-day walrus is restricted to the northernmost areas of the world however extinct genera have been discovered as far south as Morocco.
Now, researchers have recognized a brand new species of Ontocetus, an extinct genus of the Odobenidae household, utilizing massive tooth and jaw bones. Named Ontocetus posti, the species seemingly fed by means of suction, in a fashion like the fashionable walrus.
Mathieu Boisville, a researcher on the College of Tsukuba, in Japan, and colleagues report that the species independently advanced to have the feeding conduct — an instance of convergent evolution.
“The traits of the brand new species present that Ontocetus would have specialised in suction-feeding on the finish of the Pliocene (ca. 2.6 million years in the past) following the worldwide climatic cooling of the time, filling the ecological area of interest of the fashionable walrus, absent on the time within the North Sea and North Atlantic” mentioned Boisville, in an electronic mail to Superior Science Information.
For his or her evaluation, the analysis workforce re-examined mandibles found quite a few years in the past off the coast of the UK and Belgium. The fragmented mandible present in Antwerp, Belgium, was initially categorized as belonging to Ontocetus emmonsi, a species not made for suction feeding.
On nearer inspection of the mandibles, nevertheless, the researchers discovered that some oral options matched the extinct Ontocetus emmonsi and others, the Odobenus household to which the extant walrus belongs. The brand new species had a decrease canine bigger than the cheek-teeth, a decrease incisor and 4 post-canine tooth — all options that positioned it within the Ontocetus genus. But it surely additionally had well-defined mandibular options akin to these discovered within the Odobenus genus.
“Some of the enticing options of the brand new species’ mandibles is that they’re fused, as within the trendy walrus,” added Boisville. “The truth that the mandible is fused signifies that the animal is much less topic to tensile forces contained in the oral cavity when sucking in its meals utilizing the actual strategy of suction-feeding.” As an illustration, the extant walrus sucks molluscs out of their shells utilizing this specialised mouth.
Members of the Ontocetus genus most well-liked temperate to hotter waters. Whereas the Ontocetus genus initially advanced within the North Pacific Ocean, they finally made their solution to Morocco, abandoning fossil deposits.
From the western North Atlantic, they have been welcomed by the hotter waters of the North Sea in the course of the Late Pliocene (3.6 to 2.5 million years in the past). However because the local weather cooled, mollusks within the North Sea have been affected by the sudden change in local weather as was the remoted Ontocetus, finally resulting in its extinction.
The Ontocetus and Odobenus genera didn’t share a direct widespread ancestor nor inhabit the planet throughout the identical time interval. The latter emerged almost 1,000,000 years after Ontocetus died out and thrived within the chilly waters of the north. So, whereas they seemingly favored related prey, competitors between the 2 didn’t result in the extinction of Ontocetus posti.
Boisville added that extra discoveries of specimens and reassessment of identified specimens is required to higher perceive the novel species.
Reference: Mathieu Boisville, et al., New species of Ontocetus (Pinnipedia: Odobenidae) from the Decrease Pleistocene of the North Atlantic exhibits related feeding adaptation impartial to the extant walrus (Odobenus rosmarus), PeerJ (2024). DOI: 10.7717/peerj.17666
Characteristic picture credit score: Jaime Bran