A massive dinosaur death bed in Alberta has helped map out the animal's life span and thrown doubt on long-held theories about how one species lived, says new research conducted in part at the University of Alberta.
"One of the surprises to me was that the overall pattern of survivorship fits closer to an attritional model rather than the catastrophic model we were expecting," said world-renowned paleontologist Dr. Phillip Currie and professor in the U of A's Department of Biological Sciences. "Hopefully this will help us to unravel the cause of death of so many carnivores at one location.
"It's also surprising that something like this study has never been done before."
For decades, scientists believed dinosaurs were bigger versions of living reptiles but this new research, published in the current issue of Science, shows that the life pattern of the Albertosaurus is closer to that of living large mammals. The pattern also shows that if the Albertosaurus lived until the age of two, he enjoyed a low death rate until the teenage years when mortality increased.
In 1910, a collecting party from the American Museum of Natural History floated down Alberta's Red Deer River. Led by Barnum Brown, they excavated skeletons of nine individuals of Albertosaurus sarcophagus from a single quarry. It is the best evidence that exists to suggest that tyrannosaurids may have been gregarious, or pack, animals. The almost complete lack of herbivore bones from the excavation suggests that this was probably not a predator trap. Recognizing the importance of the site, Currie led an expedition in 1997 to try to find Brown's original quarry and returned annually with a group from the Royal Tyrrell Museum of Palaeontology to excavate the site. The number of Albertosaurus individuals is now known to be at least 22, which range from two to almost 10 metres in total length.