54.2 Thursday, Jan. 5 Back in black: new evidence on the color, ultrastructure, and nature of the isolated Archaeopteryx fossil feather CARNEY, Ryan M*; VINTHER, Jakob; SHAWKEY, Matthew D; D'ALBA, Liliana; ACKERMANN, Jörg; Brown University; University of Texas, Austin; University of Akron; University of Akron; Carl Zeiss NTS GmbH firstname.lastname@example.org
Archaeopteryx has been regarded as an icon of evolution ever since its discovery 150 years ago from the Late Jurassic limestone deposits of Solnhofen, Germany. The mosaic of plesiomorphic and derived anatomical traits in these fossils has inspired a rich scientific literature on Archaeopteryx and the origin of birds, yet the animal’s color, a diverse and multifunctional trait in modern birds, has remained only speculative. Here we report the first evidence of color from Archaeopteryx, based on scanning electron microscopy and energy-dispersive x-ray analyses that reveal the presence of fossilized color-imparting melanosomes in the isolated feather (MB.Av.100). Using a phylogenetically diverse database of 115 extant bird feathers (representing 87 taxa from 27 orders), quadratic discriminant analysis of five properties of melanosome morphology predicts that the original color of the Archaeopteryx feather was black, with 95% probability. Furthermore, reexamination of the feather’s morphology leads us to interpret it as an upper primary covert, contrary to previous interpretations. Additional findings reveal that the specimen is preserved as an organosulfur residue, and that barbule ultrastructure identical to that of modern bird feathers had evolved as early as the Jurassic. As in extant birds, the extensive melanization observed likely provided mechanical advantages to the Archaeopteryx wing feather during this early evolutionary stage of dinosaur flight. Our results demonstrate how modern microscopy techniques and statistical analysis can be coupled to reconstruct and further the understanding of plumage color and function in extinct dinosaurs.