Thwarting T. rex

How can an herbivore protect itself from carnivorous predators?

Strategies seen today among predators and prey of the African Serengeti apparently existed among dinosaurs in ancient ecosystems.

Paleontologists from Ohio University counted growth lines in the legbones of hadrosaurs, a group of herbivivorous duck-billed dinosaurs. By counting the number and spacing of growth rings, paleontologists can determing the animals’ age and its relative growth rate—the fast growth seen in juveniles is characterized by widely-spaced growth rings; growth slows or stops at adulthood, shown by close spacing of the growth rings.

The scientists found that hadrosaurs reached their adult size by age 13. In contrast, the carnivorous Albertosaurus reached full size at 20-30 years. Maturing quickly gave hadrosaurs an advantage over their predators, as they could produce offspring at an earlier age, and their offspring grew quickly to maturity.

Source: Drew Lee, Royal Society London B, Aug 5, 2008

How much wood would a woodchuck chuck...

The tongue-twister about woodchucks could be asked of Castoroides ohioensis, the so-called giant beaver that inhabited North America during the last ice age, about 14,000 years ago.

The ice age animal was about twice the size of modern beavers, but, surprisingly, there is no evidence that the ice age beaver ate wood.

We are what we eat, and researchers from Michigan State University and the University of Wisconsin studied the isotopic composition of a jawbone of the ice age beaver and found that the ratio of carbon 13 to carbon 12 did not match that expected for an animal that ingested wood, but was closer to that of an animals that dined on aquatic plants.

The scientists compared the giant beaver to be, ecologically, “like little hippos.”

Source: Catherine Yansa, Geological Society of America Meeting, October 19, 2010

Geological Society of America Abstracts with Programs, Vol. 41, No. 7, p. 257

Reported by Perkins, S., Science News, November 21, 2009

Illustration (inset): giant beaver compared to modern beaver. From www.nature.ca