Dinosaur growth rates varied, study finds

<body leftmargin="0" bgcolor="#000060" text="#FFFFFF" link="#FFFF00" vlink="#FF9900"> <table border="0" cellpadding="0" cellspacing="0" width="95%" height="1"> <tr> <center> <td valign="top" width="33%" height="33"> <p class="MsoNormal"><b><font face="Arial" size="5">Dinosaur growth rates varied, study finds</font></b></p> <p class="MsoNormal"><font size="1" face="Arial">March 30</font><font face="Arial"><font size="1">, 2005<br> Courtesy <br> and World Science staff<br> </font><br> </font><font face="Arial" size="2"><b>New research on 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. <br> <br> This growth pattern, say Martin Sander and Nicole Klein, is similar to growth in reptiles such as turtles and alligators and less like the pattern followed by later dinosaurs, birds and mammals. <br> <br> 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 independent from environmental conditions and end up full size at roughly the same age. <br> <br> 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. <br> <br> Plateosaurus might represent the first step in the evolution of warm-blooded dinosaurs, a development that would have allowed the animals to better regulate their own metabolism and break the tie between growth and environmental conditions, the researchers say. <br> <br> 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.</b></font></p> <p class="MsoNormal"><b><font face="Arial" size="2">* * *</font></p> <p><font face="Arial" size="2" color="#FFFFFF">Send us a <a href="mailto:editor@world-science.net">comment</a> on this story, or <a href="mailto:?Body=http://www.world-science.net/othernews/051215_plateofrm.htm">send it to a friend</a></font></p> <p></b></p> </center></td> </tr> </table> </body>