Keith, who lived 33 million years ago when the current Oregon was part of the ocean floor, was recently named after the curator at the Museum of Natural History and Culture of Burke in Seattle.
And Elizabeth Nesbitt's whale is not your typical cetacean: a fossil analysis published in Current Biology on November 29 suggests that the Maiabalaena nesbittae bridged the gap between species of whales with teeth and species that is known as a mustache.
“For the first time, we can now identify the origins of filtering filters, which is one of the major innovations in whale history,” said study co-author Nicolas Puenson, curator of the national museums of natural sciences about fossil marine mammals and a branch curator at Berka Museum, said in a press release .
The fossil M. nesbittae was discovered in the 1970s and has since been widely studied. But the stone matrix and material surrounding the fossil hid many of its features, disrupting the formal classification. Then Carlos Mauricio Peredro, a researcher at the National Museum of Natural History, gave the fossil a thorough cleanup and examined it using modern X-ray scanning technology.
A careful look at the scans revealed that the jawbone of M. nesbittae lacked teeth. This in itself is not surprising: the whale, which probably measured 15 feet in length, lived in an era when some species of whales made an evolutionary transition from using teeth instead of using mustaches.
Baleen are rows of flexible, hairy plates that whales, such as humpback whales and blue whales, use to filter tiny prey from giant sips of ocean water. The feeding technique allows whale animals to consume tons of food daily without biting or chewing.
What makes M. nesbittae special is that its upper jaw is thin and narrow, which apparently makes it unsuitable for supporting the structure of the manor.
“The live mustache has a large, wide roof in its mouth and is also thickened to create attachment sites for the estate,” said Peredro, who is the main author of the study Current Biology. “Mayabalaena does not do this. We can quite convincingly tell you that these fossil species do not have teeth, and most likely, they did not have catches. ”
This would confirm the hypothesis that some species of jagged whales developed to use a feeding strategy that did not require teeth or mustaches.
Before and his colleagues say that muscle attachments on the bones of M. nesbittae suggest that he had strong cheeks and a retractable tongue. They suggest that the whale be able to suck a large amount of water in the mouth, engaging in small fish and squid in the process … without any teeth. (A modern narwhal, which has only two rudimentary teeth, uses a similar strategy.)
In this case, the loss of teeth has become the basis for the emergence of filtering feed shrink structures after millions of years. The main factor underlying the divergence in nutritional strategies was, apparently, a sharp cooling of ocean waters during the transition from the Eocene to the Oligocene about 34 million years ago.
The characteristic appearance of M. nesbittae as a transitional species is reflected in the name of the genus, which Peredro and his colleagues chose for their formal description of the fossil.
“This is Mayabalaen's name, which combines“ Maya ”, that is, mother and“ balaena ”, which means“ whale ”, said Peredo. "It is named after its position at the base of the tree family of baleen whales."
Before said, the name of the species, nesbittae, honors Nesbitt "for her life's contribution to the paleontology of the Pacific Northwest and her mentorship and collegiality at the Burke Museum."
Nesbitt studies fossils throughout western North America with a special focus on marine fossils. Her research also focuses on the microbiota of modern Puget Sound and how tiny creatures known as foraminifera serve as key indicators of Puget Sound's health. (Spoiler warning: indicators do not look good).
In addition to his research, Nesbitt plays a public outreach role as curator of the Museum of Invertebrate Invertebrates and Micro-Palaeontology. The museum says that it collected exhibits on topics ranging from the seismic history of the Pacific Northwest and to the figurative representations of ancient fossils, as they looked in life.
He is well acquainted with the work of Nesbitt, because his own research made extensive use of fossils from Washington State and Oregon, including, of course, the fossil that now bears her name.
In addition to Peredo and Pyenson, the authors of this biology, entitled “Tooth Loss of Baleen in Whales”, include Christopher Marshall and Mark Wen.