A well-preserved skull of a mammoth that possibly lived 13,000 years ago was excavated from Santa Rosa Island at Channel Islands National Park, a rare find that scientists said has high scientific importance.

The exceptionally intact fossil was first found in 2014 by National Park Service biologist Peter Larramendy. He was conducting stream studies when he noticed an ivory tusk protruding from gravel sediments in a canyon wall in the area he was working in.

Charcoal samples adjacent to the fossil that were tested by geologists at the U.S. Geological Survey (USGS) revealed the remains were about 13,000 years old, which means that it lived at about the same time as the Arlington Man, the oldest set of human skeletal remains in North America, which was also discovered in Santa Rosa Island.

The skull, however, has been puzzling scientists since its excavation. Paleontologist Justin Wilkins, from The Mammoth Site in South Dakota, who is part of the team that worked to unearth the fossil, said that the fossil does not fit the profile for a pygmy mammoth or the Columbian mammoth.

The Columbian mammoths, which could measure up to 4.3 meters or 14 feet, roamed North America a million years after the first mammoths emerged on the continent. The species later moved to the Channel Islands. The descendants of the Columbian mammoths eventually shrank in size, becoming the shorter pygmy mammoths.

Pygmy mammoths stood at about 1.8 meters, or 6 feet tall and scientists said that the skull is not small enough to belong to a pygmy mammoth. The skull is neither that big to qualify as a Columbian mammoth.

"The discovery of this mammoth skull increases the probability that there were at least two migrations of Columbian mammoths to the island," said geologist Dan Muhs from the USGS.

The migrations could have happened 10,000 to 30,000 years ago during the last ice age and the previous glacial period, which happened about 150,000 years ago.

The fossil's tusks also baffled scientists. The one on the right measures 1.4 meters (about 4.6 feet) long and coils the same way as that of an older mammoth. The left tusk though is shorter and sloped like those of a juvenile.

Scientists hope to find the answer to their questions in the teeth of the animal. The surface thickness, spacing and number of the creature's teeth would give scientists an idea of how old it was when it died. The teeth could also shed light if the mammoth is a pygmy, Columbian or a transitional mammoth species.

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