[ad_1]
Millions of years ago, in the warm Pacific Ocean off the coast of Southern California, tuskless walrus species lived in abundance.
But in a new study, Cal State Fullerton paleontologists have identified three new walrus species discovered in Orange County, and one of the new species has “half-tusks” – or longer teeth.
The other two new species have no tusks and all predate the evolution of the long and iconic ivory tusks of the modern walrus, which lives in the freezing Arctic.
The researchers describe a total of 12 fossil walrus specimens from Orange, Los Angeles and Santa Cruz counties, all estimated to be between 5 and 10 million years old. The fossils represent five species, with two of the three new species represented by male, female and juvenile specimens.
Their research, which provides insights into the evolution of marine mammal teeth and tusks, was published today in Journal of Vertebrate Paleontology.
Geology graduate Jacob Biewer and his research advisor James F. Parham, associate professor of geological sciences, are the authors of the study, which is based on specimens of fossil skulls.
Parham and Biewer worked with Jorge Velez-Juarbe, a marine mammal expert at the Los Angeles County Museum of Natural History, who is a co-author on the article. Velez-Juarbe is a former postdoctoral scholar in Parham’s lab and has collaborated on other CSUF fossil research projects. Parham is a research associate at the museum, which offers research opportunities to him and his students.
The researchers collaborated to study and describe the anatomy of the specimens, most of which are part of the museum’s collection.
“Orange County is the most important area for fossil walruses in the world,” said Biewer, first author of the paper who conducted the research for his master’s thesis. “This research shows how walruses evolved with tusks.”
Extinct species of walruses get their names
Today there is only one species of walrus and its scientific name is Odobenus.
For the new species found in Orange County, the researchers named the half-tusked walrus, Osodobenus eodon, combining the words Oso and Odobenus. Another is called Pontolis kohnoi in honor of Naoki Kohno, a Japanese researcher of fossil walruses. Both of these fossils have been discovered in the Irvine, Lake Forest, and Mission Viejo areas.
Osodobenus eodon and Pontolis kohnoi both come from the same geological bedrock of Parham and his students’ 2018 study of another new genus and species of tuskless walrus, Titanotaria orangensis, named CSUF Titans. These fossils were found in the Oso Member of the Capistrano Formation, a geological formation near Lake Forest and Mission Viejo.
The third new walrus species, Pontolis barroni, was found in Aliso Viejo near toll road 73. It is named after John Barron, a retired US Geological Survey researcher and world expert on the bedrock in which they were found. specimens found, Parham said.
Analysis of these samples shows that fossil walrus teeth are more variable and complex than previously considered. Most of the new specimens predate the evolution of the tusks, Parham said.
“Osodobenus eodon is the most primitive walrus with fang-like teeth,” Parham said. “This new species demonstrates the important role of ecological feeding on the origin and early evolution of tusks.”
Biewer explained that his work has focused on gaining a better understanding of the walrus’s evolutionary history with regards to its teeth.
“The importance of dental evolution is that it shows variability within and between walrus species. Scientists assumed that some species could only be identified on the basis of teeth, but we show how individuals of the same species could also have variability. in their dental configuration, “said Biewer, who earned a master’s degree in geology in 2019.
“Also, everyone assumes that tusks are the most important teeth in a walrus, but this research further underscores that tusks were a later addition to the walrus story. Most walrus species were fish eaters and adapted to the walrus. catching fish, rather than using suction by feeding on mollusks such as modern walruses. “
Biewer, now a paleontologist in the Modesto area, also examined whether climate change in the Pacific Ocean had an impact on ancient walruses. His work suggests that an increase in water temperature helped stimulate nutrients and planktonic life and played a role in walrus proliferation around 10 million years ago, which may have contributed to their diversity.
background
For the fossil walrus research project, geology graduate Jacob Biewer spent hours in the lab measuring and describing walrus bones.
“I sat for hours with a handy caliper taking notes on the length of the teeth and the width of the skulls, among many other measurements,” he said. “Describing bones is much more thorough and meticulous than it seems. There are traits that the bones of each walrus species have: the size, shape and number of teeth. I have recorded how the bones are different or similar to other species. extinct walrus. “
Biewer, a paleontologist living in Modesto, noted that despite the pandemic, he and Parham worked on the science paper with 300 miles of social distance.
Completing his first journal publication, based on his master’s work, and conducting the research project helped him understand the scientific methods and techniques he now uses in his career, where he monitors construction sites for paleontological resources. He also teaches undergraduate geology courses at Cal State Stanislaus, where he earned a degree in geology, and is considering pursuing a doctorate.
“The experiences I have had in conducting this research, particularly the presentations at national paleontology conferences, have led to a great increase in my confidence in my scientific abilities,” said Biewer. “I attribute my time working with Dr. Parham directly to the results of my current employment, from the skills he imparted to the doors he helped open.”
.
[ad_2]
Source link
