Quick Bite: Clash of the Triassic Titans!

Under the canopy of an ancient fern forest near the border of Arizona and New Mexico a colossal crocodile-like reptile took a bite out of an even larger, toothy giant. The attack failed and the victim limped on to fight another day, until its carcass was finally pillaged by another scaly monster and smaller, pickier scavengers. Studying bones collected over a century ago, scientists are now able to reconstruct these scenes from the ancient Wild West using new digital tools familiar to fans of C.S.I.

Stephanie Drumheller, from the University of Tennessee, and her team first noticed the fossils, collected in 1913, in museum collections. They observed deep bite marks in two separate thigh bone specimens that would have belonged to two rauisuchians (row-ay-soo-keeans), wolf-like reptiles with the head of Tyrannosaurus rex. These 30-foot-long carnivores were supposed to be at the top of the food chain 218 million years ago in the Chinle Formation, an ancient ecosystem preserved in flame-red rock that gives the Painted Desert its name. Who took the bite out of these meat-eating giants?

Fortunately, the attacker left a weapon at the scene of the crime. Deeply embedded near the hip joint in one of the bones is a massive, curved tooth. Using the same CT-scanning technology doctors use to create 3D images of their patients, Drumheller and her team digitally extracted the tooth, identifying the powerful predator as a 25-foot long phytosaur (fight-o-sore). Scientists thought the slender-snouted, crocodile-like reptile was a fish specialist, but this new evidence shows it fought one of the largest carnivores on the planet.

CT-scanners are a new, important part of the fossil hunting toolkit, allowing scientists to digitally dissect rare and delicate fossils to expose the secrets locked inside. Around the embedded tooth, Drumheller and her team digitally extracted healed bone, evidence that the rauisuchian escaped the phyotosaur’s attack and the wound had time to heal. Near the tooth are deep, unhealed bite marks, showing another large phytosaur attacked the same rauisuchian later, but there wasn’t time for that wound to heal. Closer to the knee are shallower, smaller tooth scratches, evidence of scavengers that picked over what was left behind by the phytosaur, just as modern vultures pick at a carcass once the lions have eaten their fill.

There are a lot of gigantic reptiles in the Chinle Formation and the hypothesis was that the large rauisuchians were the top of the land-based food chain, and phytosaurs were at the top of the aquatic fo