RS denotes the location of the radial sesamoid. The right hands (palm down view) of the giant panda (left) and Simocyon (right), as reconstructed by Mauricio Anton. Altogether the remains of the cougar-sized carnivores represented the heads, most of the spines, and much of the limbs of both animals, but what was most interesting about Simocyon was its wrists. It was not until 2006 that scientists Manuel Salesa, Mauricio Anton, Stephane Peigne, and Jorge Morales described the partially complete remains of two Simocyon individuals from a Late Miocene (~11.5-5 million years old) site Batallones-1 in Madrid Spain. The fossil carnivore Simocyon has been known to paleontologists since the 1850’s, but for about a century and a half our understanding of it primarily came from teeth and a few bits of skull. The skeleton of Simocyon as reconstructed by Mauricio Anton. Hence, given the similar wrist anatomy and diet of these two carnivorans, it might be assumed that the false thumbs are adaptations related to bamboo-eating, but a recent analysis of a fossil relative of red pandas suggests that the peculiar structures evolved for an entirely different reason. Red pandas ( Ailurus fulgens), which are much more closely related to raccoons than bears, also have modified sesamoid “thumbs” which they use to manipulate bamboo. Surprisingly, however, these highly-modified wrist bones are not unique to the black-and-white bears. They are jury-rigged bits of anatomy which cast nature as an “ excellent tinkerer, not a divine artificer.“
Their accessory “thumbs”, visible on the surface as a differentiated part of the pad on the “palm” of the hand, are modified sesamoid bones derived from the wrist. A red panda ( Ailurus fulgens, left, photographed at the Bronx Zoo) and a giant panda ( Ailuropoda melanoleuca, right, photographed at the National Zoo).Īs the paleontologist Stephen Jay Gould observed in one of his most famous essays, the thumbs of giant pandas ( Ailuropoda melanoleuca) are nothing at all like the large digits on our own hands.
0 kommentar(er)
