The Smilodon skeleton is a fossilized skeleton of a Smilodon.
Battle of the Smithsonian
After the Gigantic Octopus broke loose, the Smilodon was the first of the creatures that was released underground from a crate within the Smithsonian Institution after the octopus slammed one of Kahmunrah's guards into the fossil's crate, breaking the saber-toothed cat out. It roared before it attacked the other soldiers. It was later seen in a stampede with a Pteranodon (that was released the same way the smilodon was at the same time the fossil was released), a Hippopotamus, a Giraffe, and 5 Kangaroos.