The Study On Oligocene Feather Fossils In Western Edge Of The Qaidam Basin

In recent years,many feather fossils have been founded and the studies on the morphology and function of these fossils have been done.It is one of research focuses to reconstruct the fossil feathers color according to the remains of melanosomes.In this thesis,by using of the scanning electron microscope(SEM)and the stereomicroscope,we have investigated feather fossils from the Oligocene Upper Ganchaigou Formation in the western edge of the Qaidam Basin,in order to discuss the feather fossils' colors,functions,carbon contents and anti-abrasion of melanosomes basing on the extant feathers.The carbon atomic percent values in fossilized feather regions are much higher than that of the corresponding values in rock regions of fossils.The result is consistent with the feather fossils preserved usually as carbonaceous residues.Combined with the clear,regular rachises and barb micro-structures of fossil feathers observed under the stereomicroscope,the feather fossils studied should be body fossils feathers,rather than print feathers.Many oblate structures were observed in dark region of light-dark feather fossil,which are similar to fossilized melanosomes.However,there are no such structures in light regions of the fossil.Furthermore,the values of carbon atomic percent in dark regions are much higher than those in light fossil regions.This result is agreement with the resistance degradation of melanosomes.It shows that the fossil feather near the proximal end should be blackish gray,and close to distal end should be white.The reliability of the deduced feather fossil colors by making use of the melanosomes is higher.And the structural colors because of the barbules micro-structures appearance should be considered.It indicates that light-dark fossil feather is not a flight feather with the prediction color.The result can be supported by symmetric structure of the fossil feather.Compared with living bird,the light-dark fossil feather should be one of primary coverts in wing,which helps to smooth airflow over the wings and also plays a role in sexual display with the black-white color.The atomic percent of carbon element has been measured on different color feathers from living birds in different positions of the feather.The distribution of atomic percent of carbon is homogeneous in different position of the same extant feather,which independent of color or melanosomes of extant feathers.However,the distribution of atomic percent of carbon is unhomogeneous in the melanosomes remain regions of fossil,which depends on the density of melanosomes.The change is consistent with the degradation of melanosomes.So the homogeneity of carbon in the fossil feathers can be used for studying the evolution on the color and flight of birds.