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A fossil named as Burke Commissioner explains a whale about a story about evolution – GeekWire


Carlos Mauricio Peredo
Carlos Mauricio Peredo, researcher of the National Natural History Museum, shows a 33 million year old whale fossil that has recently been classified under the name of Maiabalaena nesbittae. (Smithsonian photo)

A whale that lived 33 million years ago when the current Oregon was part of the ocean floor has recently been named after a curator at the Museum of Natural History and Culture of Burke in Seattle .

And Elizabeth Nesbitt's whale is not her typical cetacean: a fossil analysis, published in the November 29 edition of Current Biology, suggests that Maiabalaena nesbittae overcame a gap between whale species that they had Teeth and spices that have a different mouth, feeding mechanism known as baleen.

"For the first time, we can now analyze the source of the filter feed, which is one of the main novelties in the history of the whale," wrote co-author Nicholas Pyenson, History Commissioner Natural from fossil marine mammals and a commissioner affiliated with the Burke Museum, said in a press release.

The M. nesbittae fossil was discovered in the 1970s and has been extensively studied since then. But the rock matrix and the material that surrounded the fossil obscured many of its features, a frustrating formal classification. Next, Carlos Mauricio Peredo, a researcher at the National Natural History Museum, gave the fossil a thorough cleaning and examined it with the technology of X-ray scan of the last generation.

A look closer to the scans showed that the jaw of M. nesbittae had no teeth. This is not surprising: the whale, who probably measured 15 feet in length in life, lived during a time when some whale species were making an evolutionary transition from the use of teeth to the # 39; use of whales.

Baleen are rows of flexible and helical plates that use whale species, such as hollows and blue whales, to filter small dams from giant oceanic water droplets. Feeding technology allows whales to start eating tons of food every day without biting or chewing.

What makes M. nesbittae special is that his upper jaw is thin and narrow, which seems to be unsuitable to support the structure of the whales.

"A live whale whale has a broad and wide roof in its mouth, and it is also thickened to create attachments for whales," said Peredo, who is the main author of the Current Biology study. "Maiabalaena does not. We can conclude conclusively that this fossil species had no teeth, and it is more likely that it did not have tampons either."

This would support the hypothesis that some species of toothed whales evolved to take advantage of a dietary strategy that did not require teeth or bullets.

Peredo and his colleagues say that muscular joints on M. nesbittae's bones suggest that he had strong cheeks and a retractable tongue. They suggest that the whale can suck large amounts of water in the mouth, taking small fish and calamaries in the process … without the need for teeth. (The narwhal of today, which only has two vestigial teeth, uses a similar strategy).

In this scenario, the loss of teeth established the scenario for the appearance of structures while filtering millions of years later. The main factor of the divergence in feeding strategies was probably a dramatic cooling of ocean waters during the transition of the Eocene to the Oligocene era, it makes about 34 million years .

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

"The name is Maiabalaena, which combines" Maia ", which means mother and balaena, which means whale," said Peredo. "It is named for its position near the base of the whales genealogical tree."

Peredo said that the name of the species, nesbittae, honors Nesbitt "for his life of contribution to Pacific Northwest paleontology and his mentorship and collegiality at the Burke Museum."

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

Nesbitt studies fossils all over North America, with special emphasis on marine fossils. His research also centers on the microbiota of the modern Puget Sound, and in which small creatures known as foraminifera serve as key indicators of Puget Sound's health. (Spoiler alert: the indicators do not look good).

In addition to his research, Nesbitt plays a public outreach role as the commissioner of the paleontology and micropaleontology of Burke Museum invertebrates. The museum says that it has gathered exhibitions on topics ranging from seismic history of the Northwest Pacific to imaginative representations of ancient fossils as seen in life.

Peredo is familiar with the work of Nesbitt partly because his own investigation has made extensive use of the fossils of the state of Washington and Oregon, including, of course, the fossil that now bears his name.

In addition to Peredo and Pyenson, the authors of the document Current Biology, entitled "Losing of teeth, foresees the origin of Baleen in whales", include Christopher Marshall and Mark Uhen.

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