A discovery of a rare mammoth fossil on a remote island off Ventura continues to prompt scientists to search for answers.
The fossil – the most complete skull found in the Channel Islands National Park – may be a link in the evolution of a long-extinct mammoth. It appeared bigger than other pygmy mammoths found on the islands but too small for their giant ancestors that swam over from the mainland.
“We have something in the middle,” said Jim Mead, former research director at The Mammoth Site in Hot Springs, South Dakota.
But what exactly that means is difficult to say, Mead said. He spoke about the latest on the skull earlier this month at the California Islands Symposium in Ventura and how clues may be hidden in its DNA.
For now, just where the mammoth fits into the evolutionary lineup continues to be a mystery.
For around 13,000 years, the fossil was buried deep in dirt, sand and rocks in what is now a dry stream bed on Santa Rosa Island, part of the five-island park.
A field biologist spotted part of a tusk jutting out of an eroding bank in 2014. Two years later, a team of paleontologists and archaeologists excavated the site. They believed the skull – named Larramendy after the biologist – could belong to a young Columbian mammoth. But if it belonged to an adult mammoth, then it was more likely a transitional species.
The mammoth’s teeth likely held the answers.
Scientists make a breakthrough
Researchers believe Columbian mammoths, which stood up to 14 feet tall at the shoulder and weighed 20,000 pounds, made it to the Channel Islands about 160,000 years ago.
With less space and no predators, the giants eventually shrank to their much smaller descendant, the pygmy mammoth. If the Larramendy skull was a transitional animal – something in between – it could help fill in blanks of how and when mammoths evolved on the islands. It also could show the Columbian mammoths swam out to the islands multiple times instead of just once.
After the fossil was wrapped in burlap and plaster and loaded onto a National Park Service boat to the mainland, it spent the next few years at the Santa Barbara Museum of Natural History and the South Dakota lab. Scientists methodically pried away sediment and rocks flake by flake and preserved the bone and tiny fossils of critters buried with the mammoth.
“We now have a rough age based on those teeth,” said Jonathan Hoffman, a paleontologist at the Santa Barbara museum.
The mammoth was a full-grown adult roughly between 24 and 40. Scientists had ruled out that the mammoth was a juvenile Columbian.
Still, more questions remain.
DNA may hold answers
No one has really defined exactly when a mammoth is too big to be a pygmy or when it is just a big pygmy, Mead said. To do so, they need more data.
The vast majority of the time, scientists find just one bone or one tooth or one tusk, said Hoffman, the museum’s Dibblee curator of earth science. That makes it a lot harder to find the individual’s age. Only one nearly complete pygmy mammoth skeleton was found on the islands and it was missing part of the skull.
“Larramendy was really breathtaking because it was the most complete skull that we found,” Hoffman said.
He and Mead are working with geneticists to figure out whether DNA could help them find more answers.
“It is fairly safe to say it probably represents some type of transitional or hybrid form just based on size alone,” Hoffman said. “It is so much bigger than the skulls we have found previously.”
A rare find
The right tusk curved back nearly 4 feet into the full, cream-colored skull – an early sign that the mammoth was an adult.
But the left tusk was less curvy and might have been closer in size and shape to that of a younger mammoth. The contrasting tusk shapes – or retaining a juvenile trait – also could point to a transitional or hybrid, Hoffman said.
That would make it a rare find and one that could lead scientists to reassess what is known about pygmy mammoths.
The skull is now back in Santa Barbara where it is kept in a climate-controlled collections room at the museum, Hoffman said. One of the next steps includes looking at possibilities to obtain a DNA sample to shed more light on the mammoth.
Cheri Carlson covers the environment and county government for the Ventura County Star. Reach her at [email protected] or 805-437-0260.
