A Tyrannosaurus rex skull unearthed in South Dakota is expected to sell for at least 15 million dollars (£13m) at an auction in New York next month, Sotheby’s experts have said.

The 91kg fossil, nicknamed Maximus, is being sold on December 9 by an owner who wishes to remain anonymous.

The skull was excavated in 2020 and 2021 in Harding County, South Dakota, where other T. rex skeletons have been found, according to Cassandra Hatton, Sotheby’s head of science and popular culture. She called the area “the world capital for T. rexes”.

Most of the rest of this T. rex’s remains were destroyed over time by erosion but Sotheby’s experts said the skull was a major find.

Ms Hatton said: “When you think about it, more people can fit a skull in their home than people who could fit a full dinosaur.”

The 6.6ft (2m) fossil is about 76 million years old and still has most of the external skull bones and numerous teeth.

Ms Hatton said two large puncture holes in the skull are evidence of a big fight, probably with another T. rex.

“We don’t know that this is what caused the death of this animal but we can tell that it did have a major battle during its lifetime,” she said.

Marks on the skull are interesting to study “because they give us an idea about what life was like during the Cretaceous period”, Ms Hatton added.

However, this specimen may not be heading to a research institution. “It’s the ultimate trophy to place in one’s home,” Ms Hatton said.