WASHINGTON ¨C The dinosaur group called theropods included the largest land meat-eaters ever to roam the Earth ¡ª up to the size of a school bus. But there also were theropods the size of a tabby cat and others of various dimensions, including beaked and toothless fruit-eaters and some bizarre long-clawed species that redefine weird.
Scientists had long believed that these dinosaurs followed a uniform pattern in determining the body size of a species, whether gigantic or diminutive, with the rate of growth being the deciding factor ¡ª faster meaning bigger and slower meaning smaller. A new study adds to the evidence overturning that idea.
Researchers said on Thursday they examined rings called cortical growth marks laid down annually inside the bones as these animals grew ¡ª akin to growth rings inside tree trunks ¡ª of three dozen theropod species. Widely spaced rings indicate a speedier growth rate. Closely spaced rings indicate slower growth.
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