The largest piece of Mars ever found on Earth was sold for just over US$5 million at an auction of rare geological and archaeological objects in New York on Wednesday.

But a rare young dinosaur skeleton stole the show when it fetched more than US$30 million in a bidding frenzy.

The 25-kilogramme rock named NWA 16788 was discovered in the Sahara Desert in Niger by a meteorite hunter in November 2023, after having been blown off the surface of Mars by a massive asteroid strike and travelling 225 million kilometres to Earth, according to Sotheby's.

The final bid was US$4.3 million, before fees and charges bumped the price to US$5.3 million. Bidding was slow, with the auctioneer trying to coax more offers and decreasing the minimum bid increments.

The dinosaur skeleton, on the other hand, sparked a bidding war.

Bidding for the skeleton started with a high advance offer of US$6 million, then escalated during the live round with bids US$500,000 higher than the last, and later US$1 million higher than the last before ending at US$26 million.

People applauded after the auctioneer gavelled the bidding closed.

The official sale price was US$30.5 million with fees and costs. That buyer's identity was also not immediately disclosed.

The skeleton is one of only four Ceratosaurus nasicornis to be unearthed, and the only juvenile skeleton of the species, which resembles the Tyrannosaurus rex but is smaller.

Parts of it were found in 1996 near Laramie, Wyoming, at Bone Cabin Quarry, a gold mine for dinosaur bones.

Specialists assembled nearly 140 fossil bones with some sculpted materials to recreate the skeleton and mounted it so it’s ready to exhibit, Sotheby's says.

It’s more than 2 metres tall and nearly 3 metres long, and is believed to be from the late Jurassic period, about 150 million years ago.

Ceratosaurus dinosaurs could grow up to 7.6 metres long, while the T-rex could be 12 metres long. (AP)