Mammals once shared the earth with dinosaurs, but a catastrophe 66 million years ago wiped out about 75% of all life on Earth. Still, some species were able to survive. Among them were small mammals that resembled rodents. Simolodon. These animals were part of the Polytuberculata, a long-lived group that first appeared during the Jurassic period and persisted for more than 100 million years before finally becoming extinct. By studying these, scientists can better understand how early mammals withstood mass extinctions and subsequently evolved into the diverse forms we see today.
A team led by researchers at the University of Washington has identified a new species of the genus based on fossils discovered at an archaeological site in Baja California. This fossil is estimated to be about 75 million years old. The newly named species is Simolodon de SosaiIt was about the size of a golden hamster. The animals likely moved on both land and trees and ate fruits and insects, researchers said.
The results of this survey were announced on April 22nd. Journal of Vertebrate Paleontology.
“Genus Simolodon They were fairly common mammals during the Late Cretaceous period, the last period of the dinosaur era. Simolodon “The fossils have been found throughout western North America, from western Canada to Mexico,” said lead author Gregory Wilson Mantilla, professor of biology at the University of California and curator of vertebrate paleontology at the Burke Museum. Simolodon de Sosaiwas the ancestor of the species that survived the extinction event. It and its descendants were relatively small and omnivorous, two characteristics that gave them an advantage for survival. ”
Fossil discovery reveals details of rare skeleton
This fossil was first discovered in 2009 by Wilson Mantilla and his team. Unlike similar finds, which often consist only of teeth, this specimen contained a broader range of remains. The research team recovered parts of the skeleton, including teeth, skull, jaw, femur and ulna.
“It’s very difficult to find fossils here compared to other areas,” Wilson-Mantilla said. “At first my field assistant saw just a little tooth sticking out. If he had found it, I would have been overjoyed. But then I looked through the cracks in the rock and saw there were more bones.”
Having more than just teeth allowed researchers to estimate the animal’s size, body structure, and likely movements. These details will also help scientists better reconstruct their habitat and expand our knowledge of polytuberculates as a whole.
Advanced imaging helps identify new species
To analyze the fossils, the team used digital image processing and micro-computed tomography (micro-CT), which produces highly detailed images. Then they compared the teeth C.Desosai with related species Simolodon I checked the genus and confirmed that it was a different species.
“A long time ago, everything was named based on the characteristics of its teeth,” Wilson-Mantilla said. “If you find a skeleton with missing teeth, it can be difficult to name it.”
Praise the discoverer of fossils
The species is named after Michael de Sosa VI, the field assistant who first discovered this fossil. De Sosa died while the research team was still studying the specimen.
“He was a great field assistant and was like a little brother to me,” Wilson Mantilla said. “It’s a great specimen to relate to.”
Other co-authors are Isaiah Newbins, a Wisconsin biology doctoral student, and David Fastowski of the University of Rhode Island. Yue Zhang completed this research as a UW postdoctoral fellow in biology. Meng Chen completed this research as a University of California biology doctoral student. Marisol Montellano-Ballesteros and Daria García Alcantara from the National Autonomous University of Mexico;
This research was funded by UC MEXUS-CONACYT, Dirección General de Asuntos del Personal Académico PAPIIT IN111209-2, UW College of Arts and Sciences, UW Department of Biology, and the American Philosophical Society.
