New river otter fossil discovered in Hagerman

Photos courtesy of the National Park Service. Pictured is a modern otter taken at Yellowstone...
Photos courtesy of the National Park Service. Pictured is a modern otter taken at Yellowstone National Park, Lontra canadaensis, and the fossil jaw of the new species Lontra weiri.(KMVT)
Published: Jun. 1, 2016 at 12:24 PM MDT
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A new fossil river otter discovered at Hagerman Fossil Beds National Monument, Hagerman Idaho

Hagerman Fossil Beds National Monument is pleased to announce the discovery of a new species of fossil river otter.

The otter was discovered and given the name of Lontra weiri by Hagerman’s park paleontologist, Dr. Kari Prassack. This otter is an ancestor of today’s North and South American otters, which are also species of the genus Lontra. The species name, weiri, distinguishes it from other otter species. It comes from the word weir, which is a type of fishing trap and reflects the otter’s diet of fish. The name is also used to honor Grateful Dead guitarist, Bob Weir.

The fossils are of a jaw and an arm bone (humerus). This was a very small otter, about half the size of the river otters that you might see playing along the Snake River today. The arm bone is curved, which tells us it swam like modern otters. The teeth tell us that it ate a diet of meat. Hagerman has a second, much larger species of fossil otter known as Satherium piscinarium. These two otters probably co-existed by eating different-sized fish and maybe other aquatic animals like crayfish, insects, and frogs.

This otter lived here over 3.8 million years ago! We know its relative age because geologists have been able to date several volcanic ash layers at the park by looking at the decay rate of chemical elements found in those ashes. Otter fossils are very uncommon in the fossil record and these new fossils provide important new information on otter evolution. For example, paleontologists thought that river otters did not enter North America from Asia until 1.8 million years ago, but this otter pushes the date back several million years. Advancements in paleontology are made with each new discovery as we piece together the ancient history of life on earth.

This find emphasizes the importance of preserving our country’s paleontological heritage and ensuring that our fossil collections are accessible to the scientific community for study and for the public to learn from and enjoy.

The Hagerman Fossil Beds National Monument visitor center is located at 221 N. State St., Hagerman 9 a.m.-5 p.m., and is open seven days a week during the summer.