An illustration of a battle between Dimetrodon and Xenacanthus.
CREDIT: Bob Bakker
Since the 1970's, paleontologists have argued about what Dimetrodon ate. It seems that there just wasn't enough meat for all the terrestrial predators. Now, after 11 years of research Robert Bakker, of the Houston Museum of Natural History, thinks he knows what Dimetrodon ate. They got their fill by eating freshwater sharks. Check out the story over at livescience.
During the early Permian, carnivores greatly outnumbered herbivores on land, so Dimetrodon filled its belly by hunting in shallow water. In the bone beds, Bakker and his collaborators uncovered 30 Dimetrodons and only two herbivores. But the fossil hunters also found masses of freshwater shark fossils intermingled with Dimetrodon teeth. Dimetrodon shed teeth throughout its life, and the lost crowns are like bullets at a crime scene, Bakker said. "This is CSI," Bakker told Live Science. "Sharks were eaten by Dimetrodon in great numbers."
Dimetrodon resembled a sail-backed Komodo dragon on steroids, and probably hunted with ease in the water. But the shark, a Xenacanth, while nowhere near as large as aDimetrodon, fought to the death. Hundreds of shark coprolites (fossil poop) in the bone beds hold Dimetrodon bone fragments. Distinctive crescent-shaped shark bites were also discovered on intact Dimetrodon bones, although the marks suggest Xenacanthus sharks were too delicate to wrench off their foes' limbs.
In total, more than 60 Xenacanth shark fossils were intermingled with Dimetrodon teeth. (Cartilage is rarely fossilized, but the sharks left behind their protective head spines.) Three Dimetrodon teeth were imbedded in large pieces of shark cartilage. "Shark was the other red meat," Bakker said. Reptile and aquatic amphibian bones round out the chewed shark cartilage and mangled Dimetrodon bones. "We find Dimetrodon tooth marks on everything. They even ate each other," Bakker said.
