Cannibal dinosaurs revealed by tooth marks

new scientist.com ^ | april-3-2003 | Jeff Hecht

[green team 1999]

Cannibal dinosaurs revealed by tooth marks

19:00 02 April 03 Jeff Hecht

The marks on the bones match the serrations on Majungatholus teeth (Image: Raymond Rogers, Macalester College) When the going got tough, some hungry meat-eating dinosaurs turned cannibal, suggest tooth marks found on fossil bones from Madagascar.

These indicate that a nine-metre long predator called Majungatholus sometimes ate its own kind. "If you gotta eat, you gotta eat," Ray Rogers of Macalester College in St Paul, Minnesota, told New Scientist. The evidence, discovered by Rogers and colleagues, is the best yet of cannibalism among dinosaurs.

Dinosaur teeth were better adapted for ripping meat than for crunching bone, and in most areas tooth marks on bones are rare. But not at the three sites Rogers investigated in Madagascar.

These date from between 65 and 70 million years ago, near the end of the dinosaur age. Each contains hundreds of bones from a variety of animals that lived, including turtles, birds, and crocodiles as well as dinosaurs.

The cannibal dinosaurs left evidence on more than 20 bones (Image: Demetrios Vital, University of Minnesota) The sites were shallow pools that remained after a river dried up during the dry season. As in modern Africa, local animals congregated and died at the water holes during arid years. Initially, Majungatholus feasted on its usual plant-eating prey. But eventually few plant-eaters remained and the hungry beasts turned to scavenging the corpses of other Majungatholus.

Evenly spaced

The plentiful tooth scratches suggest that food was scarce and that Majungatholus worked hard to get the meat off the bones. Gnawed bones of sub-adult Majungatholus were found at two of the sites.

The evenly spaced tooth marks match the spacing of teeth in the jaws of Majungatholus. The only other predatory dinosaur known to be in the region at the time was the much smaller Masiakasaurus knopfleri, which had unusual protruding front teeth.

At least 14 modern mammals are cannibals, including lions, hyenas, and black bears. However, cannibalism has been hard to demonstrate in dinosaur fossils.

Skeletons of an older, smaller predator called Coeleophysis have been found that look like they contained the bones of juveniles in their guts, but a recent study showed that the juvenile bones may lie below rather than inside the adult skeletons.

Journal reference: Nature (vol 422, p 515)

for information and discusion only,not for profit tc,etc.

[4mycountry]

>>"If you gotta eat, you gotta eat,"

Sounds like quote-of-the-day to me!

[green team 1999]

UPDATE,got the image from BBCnews.com