Tuesday , January 26 2021

A fossil named Burke Curator tells the story of evolution – GeekWire

Carlos Mauricio Peredo
Carlos Mauricio Peredo, a researcher at the National Natural History Museum, shows the 33 million years old fossil of whales, which was newly classified by the name Maiabalaena nesbittae. (Smithsonian Photography)

Kita, who lived 33 million years ago when today's Oregon was part of the ocean floor, was named after the curator at the Museum of Natural History and the Burke Culture in Seattle.

Kita Elizabeth Nesbitt is not your typical kite: the analysis of fossils, published in the November issue of the current biology, shows that Maiabalaena nesbittae bridged the gap between the types of whales that had teeth and types, a feeding mechanism known as baleen.

"For the first time we can find out the source of the original filter, which is one of the main innovations in the history of whales," said co-author Nicholas Pyenson, curator of the fossil sea mammals of the National Museum of Natural History and joined the curator at the Burke Museum, he said in a press release.

Fosil M. nesbittae was discovered in the seventies of the last century, and since then it has been widely researched. But the stone matrix and the material surrounding the fossil obscure many of its characteristics, frustrating the formal classification. Then Carlos Mauricio Peredo, researcher at the National Museum of Natural History, gave fossils thorough cleaning and studied it with the latest X-ray scanning technique.

An accurate view of the scan showed that the jaw M. nesbittae has no teeth. This is not surprising in itself: a kit, probably 15 meters long in life, lived at a time when some types of whales evolved from the use of teeth using baleen.

Baleen are types of flexible, pile-shaped plates, used by types of whales, such as hamburgers and blue whales, to filter the tiny prey from the giant ocean water gulps. Feeding technology allows white whales to consume a ton of food without biting or chewing every day.

For this reason M. nesbittae is special, that his upper jaw is thin and narrow, which seems inappropriate for supporting the Baleen structure.

"A living Chinese kit has a large, wide roof in its mouth, and it is also compact to create baleen fixing points," said Peredo, lead author of the Current Biology study. "Maiabalaena no. We can tell you nicely that the fossil line has no teeth and is more likely than not to have baleen."

This would support the hypothesis that some types of toothed whales developed in order to exploit a feeding strategy that did not require teeth or baleen.

Peredo and his colleagues say that muscle attachment to bone M. nesbittae shows that it has a strong face and a removable language. They suggest that the whale may suck large amounts of water in the mouth, while in the process it will include small fish and squid … without the necessary teeth. (A modern narwhal, which has only two sharp teeth, uses a similar strategy.)

In this scenario, tooth loss has attracted attention to the appearance of filter baline structures millions of years later. The main factor of divergence in feeding strategies was probably the dramatic cooling of ocean waters during the transition from the eocene to the oligocene period, about 34 million years ago.

The apparent status of M. nesbittae as a transitional species is reflected in the name of the genus that Peredo and his colleagues chose for their formal description of the fossil.

"The name is Maiabalaena, which brings together" Maia ", meaning mother, and" balaena ", which means kit," said Peredo. "Named after his position near the base of the family tree baleen kit."

Peredo said that the name of the species, nesbittae, the honor of Nesbit "for her lifetime contribution to the paleontology of the Pacific Northwest and her mentoring and collegiality in Burke Museum."

Elizabeth Nesbitt
Elizabeth Nesbitt is a curator of invertebrates of paleontology and micropaleontology at the Burke Museum. (University of Washington Photo)

Nesbitt studies fossils in western North America with a special focus on marine fossils. Her research also focuses on the microbiota of modern Puget Sound and how small creatures known as foraminifera serve as key indicators of Puget Sound's health. (Message Alert: Indicators do not look good.)

In addition to her research, Nesbitt has played a role as a public broker as a curator of Burke's museum of invertebrates of palaeontology and micro-palaeontology. The museum says it has prepared exhibits on topics ranging from the seismic history of the Pacific Northwest to the imaginative displays of ancient fossils as they have been seen in life.

Peredo is acquainted with the work of Nesbit, partly because his own research has made great use of fossils from Washington and Oregon – including the fossil which now carries its name.

In addition to Pered and Pyenson, the authors of the journal Current Biology, titled "Loss of teeth before the source of Baleen in whales" included Christopher Marshall and Mark Uhen.

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