Aureia rerehua had unique teeth which might have formed a cage around small fish; these teeth, along with a weak vertex, flexible neck, and the smallest size among its relatives would make it a capable hunter in shallow waters, according to a team of paleontologists from the University of Otago.
The skull of Aureia rerehua; note the splay of the teeth and facial topography. Image credit: Meekin et al., doi: 10.1080/03036758.2024.2314505.
The newly-described species of dolphin lived in the Oligocene-period seas, approximately 22 million years ago.
Dubbed Aureia rerehua, the species was around 2 m (6.6 feet) in length and very likely echolocated.
It had a weak skull, flexible neck and unique lateral tooth orientation, suggesting it scanned shallow waters to capture small prey in a basket of teeth.
“It had widely splayed teeth which are thought to have clasped around fish, like a wide basket, which is unusual because other ancient dolphins in the area usually used their teeth to strike prey,” said University of Otago paleontologist Shane Meekin.
“When looking at the teeth of dolphins, it’s natural to think the large teeth at the front and center of the mouth would be the main tools for catching prey, stabbing or slashing unfortunate fish.”
“This is how related dolphins did appear to hunt, but Aureia rerehua looks to have taken a totally different approach, using these teeth in a more delicate manner.”
The fossils of Aureia rerehua — skull, teeth, ear bones, mandibles, vertebrae, and ribs — were found in a quarry in the Hakataramea Valley, New Zealand.
“From 22 to 27 million years ago, New Zealand sank, leaving between 1% exposure above sea-level and total submergence, during which marine life thrived,” the paleontologists said.
“The deposits from that time represent many of the cetaceans present in the collections of the University of Otago Geology Museum.”
“One such is Aureia rerehua which was collected from a Limestone Quarry in Hakataramea Valley, South Canterbury, known as ‘Haugh’s Quarry’.”
The discovery of Aureia rerehua shows there were many fossil dolphins in one small area, which varied greatly in form.
“This shows that seemingly similar animals can coexist if they explore different ecological niches,” Meekin said.
“It also further indicates that early prehistoric dolphins used many different feeding strategies to explore different niches, which is why so many different types of extinct dolphins have been retrieved from fossil localities such as Hakataramea valley.”
The findings were published on February 21, 2024 in the Journal of the Royal Society of New Zealand.
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Shane Meekin et al. Aureia rerehua, a new platanistoid dolphin from the Oligocene of New Zealand with a unique feeding method. Journal of the Royal Society of New Zealand, published online February 21, 2024; doi: 10.1080/03036758.2024.2314505
Source : Breaking Science News