SKELETAL TAPHONOMY OF CONFUCIUSORNIS AND MICRORAPTOR: INSIGHTS INTO THE FORMATION OF THE JEHOL BIOTA (LOWER CRETACEOUS, NE CHINA)

The cause of death of the birds, feathered dinosaurs and other vertebrates from the early Cretaceous in age Jehol Biota of NE China remains enigmatic. Other recent investigations into the formation of the Jehol Biota rely heavily on sedimentological data, whereas we seek to address the problem through analysis of skeletal taphonomy. Semi quantitative skeletal completeness and articulation metrics are powerful tools that can be used to reliably compare skeletal taphonomy between individuals and taxa and infer the taphonomic history of an organism independent of the surrounding sediment. Our results indicate no significant difference in the articulation or completeness of skeletal elements between Microraptor and Confuciusornis. The similarities in the decay patterns of Microraptor and Confuciusornis suggest anatomical differences linked to skeletal and soft tissue adaptations for flight had little effect on disarticulation or loss of completeness. Disarticulation in different body regions in Confuciusornis specimens is consistently present, albeit limited; most carcasses experienced short floating phases before sinking and lying relatively undisturbed on the floor of the lake. This information can be used to develop further taphonomic models for vertebrate taxa in the Jehol biota. Specifically evidence of a clear separation in time between the carcasses entering the lake and being buried calls into question recent claims that Jehol animals were routinely killed, transported into a lake environment, and buried immediately by pyroclastic event deposits.