Slideshow by Mary Margaret Shamburger

This weekend, Heritage Auction Galleries is auctioning off four dinosaurs as well as other pieces of Earth’s long-ago past. Here’s a preview of what you can see:

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The stars of the auction are two dinosaurs sold together as The Fighting Pair. The skeletons of the Stegosaurus and Allosaurus are positioned as if they are about to do battle, which is probably what they were doing 155 million years ago in Wyoming.

“Actually, the Stegosaurus’ leg bone was found in the mouth of the Allosaurus,” says David Herskowitz, the Director of the Natural History department at Heritage Auctions. “This was the first time they found these two animals together, practically on top of each other in the same quarry, proving for the first time that these two dinosaurs co-existed.”

The pre-auction estimate for The Fighting Pair is $2.8 million. Which might make you ask, “Who’s spending that kind of money on dinosaur bones?”

Herskowitz says plenty of people, and not just museums. He estimates that 90 percent of his buyers are private collectors.

“The people that collect them usually take very, very good care of the specimens. And then eventually when they pass away, their estate usually ends up donating them to the museums,” he says.

Other highlights of the auction include the largest set of prehistoric shark jaws ever assembled and a 12-foot-tall Triceratops, recently on short-term loan to the Dallas Museum of Nature and Science.

“The Dallas Museum of Nature and Science really wants it back,” Herskowitz says. “So they’re hoping for a Santa Claus – someone to purchase the specimen and hopefully donate it back to the museum.”

If you want to play Santa – or even if you aren’t looking to spend – the auction is open to the public today through Sunday in the Tower Building at Fair Park.