Paleontologists from around the world continue to find amazing remains of extinct animal species. Recently, researchers studied fossils of ancient dolphins, whose teeth were very similar to tusks. However, scientists were surprised by the fact that these tusks were “loose”. A description of the new dolphin species was published in the journal Proceedings of the Royal Society B.
Dolphins with “loose” tusks
Fossilized fossils of unusual ancient creatures were discovered back in 1998 on Cliff Island in the Awamoko Valley, New Zealand. However, only now have scientists completed their analysis. As a result, the creature was identified as a representative of the species Nihohae matakoi. These were ancient dolphins, whose morphology was markedly different from their now living descendants.
The main feature of these sea creatures was their teeth, arranged horizontally and protruding far forward. The researchers compared them to tusks. “The tusk-like teeth are long, single-rooted, protruding, ranging in length from 8.2 to more than 11.2 centimeters,” the paleontologists report in their paper. – The upper incisors are large tusk-like teeth, modified and located in the premandibular bone. The widest diameter of the tusk-like tooth is 1 centimeter. The enamel is textured with ridges on both the lingual and vestibular surfaces of all teeth”.
Predatory dolphins
Nihohae matakoi were present during the late Oligocene, some 25.2 million years ago. Their teeth, as the researchers write, were symmetrical, conical and “protruding. However, there is nothing unusual about this finding. In the Oligocene epoch, many marine creatures were armed with tusks of some kind.
“The variety of feeding devices can be traced back to the emergence of toothed whales during the Oligocene,” says Ambre Coast, a paleobiologist at the University of Otago. – Changes in polydontia, monophyodontia and heterodontia, including the presence of tusks, illustrate some extreme tooth modifications in cetaceans. For example, in modern cetaceans, true tusks are found in the narwhal species Monodon monoceros.”
It is believed that sea creatures need tusks for several purposes. Firstly, they can be used to hunt prey and carve it. Second, a tusk can be used to punch a hole in the ice for a breath of air. Third, tusks served as weapons for defense against larger predators.
But ancient dolphins’ teeth, as the study showed, were loose and hardly suitable for the specified purposes. But even such tusks could serve for defensive purposes in a sudden attack. This is indicated, for example, by a broken tusk found on one of the fossilized dolphins.
Morphology of Nihohae matakoi skull
According to the authors of the paper, the morphology of the skull of Nihohae matakoi provides insight into the eating behavior of this species. “Our results show that Nihohae matakoi was a predator that ate its prey after a brief process of chewing,” the researchers write. – The graceful nature of Nihohae matakoi’s tusk-like teeth suggests that they were not used for intraspecific combat or defense against predators, which would have required stronger teeth. Combat or defensive use would probably have resulted in marked fractures of such teeth.”
По материалам: http://www.planet-today.com/2023/06/dolphins-with-loose-tusks-what.html