Acrocanthosaurus

Acrocanthosaurus is a genus of large theropod dinosaur from the Early Cretaceous of North America. The name means “high-spined lizard,” referring to tall neural spines along its back. It lived about 113 to 100 million years ago, during the Aptian to Cenomanian stages, and its fossils are primarily found in what is now the central United States, especially Oklahoma and Texas.

The type species, Acrocanthosaurus atokensis, was named in 1950 from remains found in the Atokan rocks of Oklahoma. The genus has typically been placed among the allosauroids, and most analyses treat it as a member of the broader group Carcharodontosauridae or a closely related lineage within Allosauroidea; the exact relationships have fluctuated with new data.

Acrocanthosaurus was a large predator. Length estimates commonly place it around 12 meters, with body mass of several tons. It had a long, narrow skull with sharp, serrated teeth, powerful hind limbs, and a long tail. The most distinctive feature is the series of tall neural spines on the dorsal vertebrae, which formed a prominent back crest or “sail” in some individuals. The forelimbs were relatively short and bore three fingers.

In its ecosystem, Acrocanthosaurus was likely an apex predator, preying on large herbivores such as sauropods and armored ornithischians that inhabited mid-continent North America during the Early Cretaceous. Its fossils contribute to understanding North American theropod diversity during this period.