The function of the pointed plates along the Stegosaurus spine is a much-debated topic among scientists. Early paleontologists believed they were for defense, but recent research suggests they may have been to regulate heat transfer or for display purposes.
Stegosaurus was an herbivorous dinosaur from the late Jurassic period, about 200-145 million years ago. Its most distinctive features were the seventeen plates called osteoderms rising from its spine. Osteoderms are bony structures originating from beneath the skin, such as lizards’ scales.
In the late nineteenth century, paleontologist Othniel Marsh hypothesized the dinosaur’s plates were for defense. If this were the case, the sides of Stegosaurus would be left unprotected, as the plates weren’t large enough to cover the sides. This wasn’t addressed in his hypothesis, which isn’t surprising given that Marsh conducted little field work.
Like every geological puzzle, scientists examine it through the lens of uniformitarianism, the concept that the present is the key to understanding the past. The physical laws governing the universe today were in effect in the Jurassic period when Stegosaurus roamed the earth, so contemporary analogies can help us understand ancient environments. Looking at modern animals with similar structures may hold the key to understanding the function of these unique structures.
Upon dissection of fossilized dermal plates, scientists found large blood vessels running through them. In the 1970’s, paleontologists James Farlow et al speculated that air flowing around the dermal plates could have helped cool or heat the dinosaur’s blood, playing a thermoregulatory role. They compared these to modern animals such as elephants, whose ears serve a similar function.
Upon further inspection, though, this explanation didn’t hold up. The blood vessels seemed to be “dead ends”, not leading anywhere in particular. Also, not all Stegosaurus members had the plates.
Main et al believe the plates helped individual members of Stegosaurus identify each other, like antelopes’ antlers do. The evidence is that not all species of Stegosaurus had the plates, ruling out a strictly thermoregulatory function.Scientists looked to modern animals such as deer, whose antlers also have large blood vessels. In this example, those blood vessels have nothing to do with heat transfer; rather, they enable rapid growth of the antlers. Dinosaurs, too, are thought to have been fast-growing animals.
Despite recent conclusions that Stegosaurus plates were for display, paleontologists don’t rule out the possibility of their having a secondary thermoregulatory role in some species.
Main’s findings were published in the April 2005 issue of Paleobiology.
Read more at Suite101: The Function of Stegosaurus Plates: Were dermal plates for defense, thermoregulation, or display? | Suite101.com http://rachel-beavins.suite101.com/the-function-of-stegosaurus-plates-a45414#ixzz1h0TTjTG6
No comments:
Post a Comment