Auctionata will offer a seven foot long stegosaurus skeleton in a May 28 online sale.
The incredible specimen is over 90% complete and is the finest example of the genus ever offered at auction.
Bidding will start at $1.3m.
The dinosaur was discovered in Wyoming, which has proven a particularly rich source of dinosaur fossils.
It lived during the late Jurassic era, around 150m years ago, and bears evidence of fight marks on its bones.
In 2011, Heritage Auctions sold a stegosaurus and allosaurus "fighting pair" for $2.3m.
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