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How Does This Grab You? New U Of T Mississauga Study Identifies First Ancestor With A ‘Grasping Hand’

July 30, 2009

TORONTO, ON – Elongated fingers, an opposable “thumb”, and a grasping tail–a new fossil study by researchers at the University of Toronto Mississauga suggests that a small plant-eating mammal relative is the oldest known tree-climbing vertebrate.

The tree-climbing lifestyle of Suminia getmanovi, a Paleozoic animal that lived 260 million years ago, is particularly important because it gave this small herbivore the first access to new food resources high off the ground, and also provided protection from ground-dwelling predators. The evidence for this lifestyle is based on several skulls and more than a dozen complete skeletons from central Russia, as well as from coprolites (fossilized feces) that were found on the same sediments as the skeleton. The findings appear online in the Proceedings of the Royal Society B.

“Independently, this animal appears to have acquired this evolutionary innovation of a grasping hand,” says Professor Robert Reisz, chair of the Department of Biology at the University of Toronto Mississauga. “That would have allowed it to climb trees very efficiently and to grasp things. It would have allowed the animal to bring food to its mouth.” Reisz, the senior author of the paper, notes that modern animals like chameleons and flying lemurs have similar foreleg structure.

The study also provides the first evidence of “resource partitioning” — with smaller arboreal animals taking advantage of food and safety from predators in trees while larger herbivores remained on the ground. This was a change from a large numbers of terrestrial plant-eaters supporting a few top predators, and even earlier terrestrial vertebrate communities composed of various sized predators and relatively few herbivores.

The first author, Joerg Froebisch, is currently a postdoctoral fellow at the Field Museum in Chicago. Funding for the study came from the Government of Canada, the German Research Foundation, the German Academic Exchange Service, the University of Toronto, the Natural Sciences and Engineering Research Council of Canada and the National Geographic Society.

*Images available upon request.

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For more information, please contact:
Robert Reisz
Department of Biology
University of Toronto Mississauga
905-828-5364
robert.reisz@utoronto.ca

Nicolle Wahl
Communications and Marketing
University of Toronto Mississauga
905-569-4656
nicolle.wahl@utoronto.ca