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, paleontologists in Fullerton, California, have identified three new species of walrus that have been discovered in Orange County and one of the new species has “semi-tusks” – or longer teeth.
The other two new species do not have tusks and all predate the evolution of the iconic long tusks of modern-day walruses, which live in the frozen Arctic.
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 gives insights into the evolution of teeth and canines of marine mammals, was published today at Journal of Vertebrate Paleontology.
Geology graduate Jacob Bewer, and his research advisor James F. Parham, associate professor of geosciences, are the authors of the study, based on fossil skull samples.
Parham and Bewer worked with Jorge Velez-Socks, a marine mammal expert at the Los Angeles County Museum of Natural History, and co-author on the research. Velez-Socks is a former postdoctoral researcher at Parham Lab and has collaborated on other fossil research projects at CSUF. Parham is a research associate at the museum, which provides research opportunities for him and his students.
Researchers have collaborated to study and describe the anatomy of specimens, most of which are part of the museum’s collection.
“Orange County is the most important fossil walrus region in the world,” said Bure, the first author of the paper who conducted the research for the master’s thesis. This research demonstrates how walruses evolved with tusks.
Extinct species of walrus
Today there is only one type of walrus, whose scientific name is Odobenus.
For the new species found in Orange County, researchers called the semi-fanged walrus, Osodobenus eodon, by combining the words Oso and Odobenus. Another is named Pontolis Konoe in honor of Nauki Kono, a fossil researcher pronouncing the walrus from Japan. Each of these fossils has been discovered in the Irvine, Lake Forest, and Mission Viejo regions.
Both Osodobenus eodon and Pontolis kohnoi belong to the same stratum geologic as a 2018 study by Parham and his students of the genus and other new species of Tuskless walrus, Titanotaria orangensis, named after CSUF Titans. These fossils were found in an Oso member of the Capistrano Formation, a geological formation near Lake Forest and Mission Viejo.
A new third type of walrus, Pontolis barroni, is found at Aliso Viejo, near 73 Toll Road. Parham said it was named after John Barron, a retired U.S. Geological Survey researcher and world expert in the layer of rock where the samples were found.
Analysis of these samples shows that fossil walrus teeth are more diverse and complex than previously seen. Parham said most of the new specimens precede the development of canines.
“Osodobenus eodon is the most primitive walrus with fang-like teeth,” Parham said. “This new species demonstrates the important role of nourishing the environment on the origin and early development of canines.”
Bior explained that his work focuses on gaining a better understanding of the evolutionary history of walruses in relation to their teeth.
“The significance of dental development is that it shows variability within and across species of walrus. Scientists assumed that you could identify certain species based solely on teeth, but we showed how even individuals of the same species could have variation in preparing their teeth,” said Bure, who obtained Master’s degree in Geology in 2019.
In addition, everyone assumes that the tusks are the most important teeth in the walrus, but this research further confirms that the tusks were a later addition to the history of the walrus. The majority of walrus species were fish eaters and adapted to fishing, rather than using vacuum feeding on Slugs are like modern walruses. “
Bewer, now a paleontologist in the Modesto region, also studied whether climate changes in the Pacific Ocean had an effect on ancient walruses. His work indicates that warming water helped boost nutrients and plankton life, and played a role in the breeding of walruses about 10 million years ago, which may have contributed to their diversity.
For the walrus fossil research project, geology graduate Jacob Bior spent hours in the lab measuring and describing walrus bones.
“I sat for long hours with a practical caliper, taking notes on the lengths of the teeth and the width of the skulls, among many other measurements,” he said. “The description of the bones is more in-depth and accurate than it appears. There are characteristics that the bones of each type of walrus possess – the size, shape and number of teeth. I have recorded how the bones differ from or resemble other extinct species of the walrus.”
Bewer, a paleontologist who lives in Modesto, noticed that despite the pandemic, he and Barham had worked on the scientific paper 300 miles socially.
Completing the first issue in his journals, building on the master’s work, and undertaking the research project helped him understand the scientific methods and techniques he now uses in his career, as he watches construction sites in search of excavation resources. He is also teaching undergraduate geology courses at California State Stanislaus, where he earned his BA in Geology, and is considering a PhD.
“The experiences I gained conducting this research, especially the presentations at the National Paleontology Conferences, have greatly increased my confidence in my scientific abilities,” said Bewer. “I attribute my time working with Dr. Parham directly to the accomplishments I’ve made in my current job – from the skills he’s taken to the doors he helped open.”