Disputed Dino Feathers

McKellar et al. (Reports, 16 September 2011, p. 1619) analyzed Late Cretaceous amber specimens from Canada and identified some filaments as dinosaurian protofeathers. We argue that their analysis and data do not provide sufficient evidence to conclude that such filaments are feather-like structures. … Because they could not identify the fibers as any organism of an “end-member” evolutionary-developmental spectrum, and the fibers occurred concurrently with modern feather types, they inferred that the fibers were dinosaurian.

The interpretations of figure 1, B to D, in (1); figure 2, A to C, in (1); and the supporting figures in (3) convince us that adequate analysis was not conducted on these specimens and that overstated conclusions were made on subjective observations. Other figures in (1) (figure 2, D to F, and figure 3) are comparable with the feather microstructure in modern birds and cannot be regarded as anything but the ultimate stage of feather evolution. …

Additionally, comparing the amber fibers to specimens of fossil hair found in Canada (TMP 96.9.998) and France (dated Early Cretaceous) does not exclusively rule out UALVP 52821 as including hair filaments based on surface texture (cross-hatching) and diameter alone [figure S4, B to E, in (3)]. …

Although exploring amber specimens for clues to feather evolution may seem novel, this study lacks evidence and vigor to conclude that the fibers in UALVP 52821, UALVP 52822, and TMP 96.9.334 are dinosaurian. The analysis was not complete for each specimen, did not conclusively rule out hair or specialized plant parts as possible fibers, makes incorrect comparisons to modern feather microstructure, and cannot be cited as early stages of feather evolution. Because the topic of dinosaur feathers has been disputed, we feel that better analysis of the material in question, including destructive sampling of the amber specimens, is paramount.

Without concise identification of the various filaments depicted, there is no basis for assigning any of them to a particular group of organisms, to say nothing of dinosaurs. ¹