It was probably the most fearsome battle to ever take place in the animal kingdom: The super-apex predator Tyrannosaurus versus the heavily armored Triceratops. Based on the fossil records, paleontologists have known for quite some time that the two Cretaceous-era dinosaurs often went head-to-head. But given the triceratops' extensive defenses, it has never been clear how the T-rex was able to penetrate through the thick shielding when it came time for the feast. But new research has revealed how it was done — and it wasn't pretty.

Step #1: Grab hold of the frill: According to work presented last week at the Society of Vertebrate Paleontology's annual meeting in Raleigh, North Carolina, the T-rex, upon killing the triceratops, worked to position itself such that it could take hold of the frill with its massive jaws.

Step #2: Tear the back of the neck: Once the T-rex could grab hold, it pulled the head back, thus creating tension and a subsequent tear in the flesh. The researchers, a team lead by Denver Fowler at the Museum of the Rockies in Bozeman, Montana, were able to make this determination by studying the bite marks found on the fossilized remains of 18 triceratops. Fowler believes that the T-rex's laterally thickened tooth structure made it well suited for resisting lateral stressess — a characteristic that would have substantially improve its ability to dismember carcasses.

Step #3: Rip the head off: When studying the fossils, particularly the skulls, Fowler noticed that many of the bones showed no signs of healing. This suggested that the bite marks were made after death and during the meal itself (what paleontologists refer to as postmortem carcass processing). And in addition, many of the specimens featured puncture, score, gouge, and puncture-pull marks, which in combination with tooth-spacing patterns, indicated that the marks were inflicted during the feast.

Step #4: Time to eat: The paleontologists theorize that the T-rex worked hard to get the head off so that it could get to the nutrient rich neck muscles. Fowler says this is consistent with deep parallel gouge marks found on the skull, including punctured braincases. And interestingly, the paleontologists were also able to determine that the T-rex liked to gnaw the flesh off the triceratops' face.

It's worth noting that some paleontologists dispute the predator/prey relationship between the two species. One theory is that the T-rex simply scavenged on the remains of dead triceratops, and that the elaborate armor and horns were simply ornamental/courtship displays. It's also possible that the horns were used in combat with each other and not against T-rexes. And indeed, there is evidence that the horns were used in combat (and were not just ornaments) — it's just not clear who the horns were used against. But regardless, there's little doubt that the T-rex ate the remains of triceratops.

You can check out the study at Fowler's homepage.

Top image via. All inset illustrations via Nate Carroll. H/t Nature.