A team of researchers have discovered a rare fossilized skull of a mammoth that is believed to belong to a transitional species of the extinct mammal.

According to the report from The Orange County Register, the complete mammoth skull was found in an eroding stream bank on Santa Rosa Island within Channel Islands National Park. The researchers noted that the skull is too small to be a Colombian mammoth and too large to be pygmy mammoth, suggesting that the skull may belong to a transitional species between the two.

"This mammoth find is extremely rare and of high scientific importance. It appears to have been on the Channel Islands at the nearly same time as humans," Justin Wilkins, a paleontologist at The Mammoth Site and one of the researchers who found the skull, said in a statement. "I have seen a lot of mammoth skulls and this is one of the best preserved I have ever seen."

Charcoal samples adjacent to the specimen suggest that the skull is approximately 13,000 years old, which coincides with the age of the Arlington Man, the oldest human skeletal remains found in North America.

While the size of the newly discovered mammoth skull suggests that it belongs to a species between the Columbian and pygmy mammoth, scientists speculate the downsizing process of the Columbian mammoth to pygmy mammoth only took about several thousand years.

Due to the relatively short time span between the two, USGS Geologist Dan Muhs believe it would be less likely for the newly discovered skull to belong a new transitional species. Instead, Muhs suggested that the skull increases the probability that there were at least two migration of Columbian mammoths to the island.

The first migration event would have occurred in the previous glacial period about 150,000 years ago, followed by the second migration during the most recent ice age 10,000 to 30,000 years ago.

The skull of the mammoth, alongside its teeth and other part, will be transported to the Santa Barbara Museum of Natural History, where it would be cleaned, preserved, studied and curated for future public display.

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