Nihohae matakoi’s tusk-like teeth suggest adaptive advantages for horizontally procumbent teeth in ancient dolphins.
Nihohae matakoi lived during the Late Oligocene epoch, approximately 25.2 million years ago.
This extinct dolphin had a long rostrum and symmetrical, conical, procumbent tusk-like teeth.
“The diversity of body sizes and feeding strategies in living odontocetes (toothed whales and dolphins) ranges from the giant, deep diving suction feeding sperm whales to small raptorial dolphins,” said University of Otago paleobiologist Ambre Coste and her colleagues.
“A variety of feeding apparati have been associated with this diversity since the origins of odontocetes in the Oligocene epoch.”
“Changes in polydonty, monophyodonty and heterodonty, including the presence of tusks, illustrate some extreme modifications of teeth in cetaceans.”
“In living cetaceans, true tusks are found in narwhals (Monodon monoceros),” they added.
“Their canines are highly modified with the most common presentation being the left canine erupting as an ever-growing tusk in males.”
“Narwhal tusks have been suggested to be used to disturb or pierce prey, to open breathing holes in the ice, as defense weapons against predators, or for sexual display.”
The fossilized remains of Nihohae matakoi was collected in 1998 from a block below the North-West face of Island Cliff, Awamoko Valley in North Otago, New Zealand.
The type specimen is a relatively complete skull with unusually long and procumbent teeth, including all incisors and canines.
“The tusk-like teeth are long, single rooted, procumbent, ranging in length from 8.2 cm to over 11.2 cm,” the paleontologists said.
“The upper incisors are large tusk-like teeth modified and harbored in the premaxilla, anterior to the suture with the maxilla.”
“Among the loose tusk-like teeth, the root is about twice the length of the crown.”
“The most complete root is 8.2 cm long and the longest and most…
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