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Early dinosaurs had
unusual growth abilities, study finds
Dec. 15,
2005
Courtesy American Association for the Advancement of Science
and World Science staff
New research suggests one of the earliest large dinosaurs shows that these primitive dinosaurs reached their
adult sizes at different ages, making for some smaller and larger versions of the same species.
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Plateosaurus. (Courtesy Martin
Sander, University of Bonn)
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This growth pattern is like that of reptiles such as turtles and alligators, and less like
that of later dinosaurs, birds and mammals, say Martin Sander and Nicole
Klein of the University of Bonn, Germany.
Reptiles can adjust their growth rates to environmental conditions—sometimes growing fast and reaching adult size at a young age, sometimes growing slowly to become full size at an older age.
Mammals and birds, on the other hand, grow mostly independently of environmental conditions and end up full size at roughly the same age.
Sander and Klein studied the microscopic structure of long bones from a large collection of
Plateosaurus engelhardti fossils in Germany and found both small and large fully grown dinosaurs within the group.
Plateosaurus might represent the first step in the evolution of warm-blooded dinosaurs, a development that would have allowed the animals to better
control their own metabolism and break the tie between growth and environmental conditions, the researchers say.
Plateosaurus is a member of the prosauropods, a group of primitive dinosaurs of the Triassic period, the time between 248 and 213 million years ago that is the first part of the age of dinosaurs. Prosauropods are thought to have been plant eaters that walked partly on their hind legs, partly on all four legs.
The study is published in the Dec. 16 issue of the research journal Science.
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