Acrocanthosaurus

Acrocanthosaurus was a large theropod dinosaur that lived in North America 125 million year ago in the early cretaceous period. Acrocanthosaurus means high spined reptile. It was named so for the high neural spines atop most of its vertebrae, which probably supported a ridge of muscle over the dinosaur's neck, back and hips. Acrocanthosaurus was one of the largest theropods known, only slightly smaller than it's more popular relatives like Giganotosaurus, the biggest specimen (NCSM 14345) is estimated to measure 11.5 meters (38 ft) from snout to tail tip. Its skull alone was 1.3 meters (4.3 ft) in long and weighed 6.2 to 7 tons.

Acrocanthosaurus was discovered mostly in western North America. 125 million years ago in the early cretaceous period it was wetlands and woodlands of North America and it was much hotter than today. Acro was the apex predator of it's time, and descended from dinosaurs like allosaurus. The similarities can be seen in the hands and the claws. They are like the talons of a giant hawk. This would allow the acro to jump on prey while it is running and hold on. The acro's arms were able to retract inward like hooks very strongly. As soon as acro had a good grip with it's primary weapon the mouth, it would use those powerful arms to hold the prey tightly against the body while it munches away. While all large theropod brains are similar, acrocanthosaurus' brain case was shaped more like an allosaurid. However it most resembles the brains of Carcharodontosaurus and Giganotosaurus rather than those of Allosaurus or Sinraptor. This shows that arocanthosaurus was a transition between the primitive allosaurids and the more advanced carcharodontosaurids. Teeth discovered in southern Arizona has been identified as acro teeth, and matches tooth marks found on sauropod bones from the area. Several teeth found in Arundel Formation in Maryland were also described and they're similar to the ones from Arizona. This shows that acrocanthosaurus was widespread in North America for much of the early and mid cretaceous.