Dino-Bird Link Confused by New Fossil
A “bizarre” new dinosaur fossil found in Spain with a hump on its back that resembles a fin also has quill knobs on its arms, interpreted as attachment points for feathers. For this reason, the BBC News announced that it “may” yield clues to the origin of birds.” It has been named Concavenator corcovatus and was described in Nature.1
The fossil, however, does not provide unequivocal evidence for a dinosaur-bird kinship; Live Science said this fossil “surprises and puzzles experts” and even National Geographic which a decade ago embarrassed itself with Archaeoraptor seemed to downplay the dino-bird link, calling it a “carnivorous camel” in its headline. Whatever attachment points the bumps on its skimpy forearms provided (assumed to be quill knobs for feathers) were certainly not anything like flight feathers of birds. NG called them “protofeathers” but the filaments in the artist’s reconstruction (not found on the fossil) may have been merely for display, since the discoverers could not think of any locomotive or thermoregulatory function for them. New Scientist alleged, “This pushes back the emergence of theropods with bird-like feathers by some 50 million years.” Live Science, however, was more cautious, stating that the idea the bumps were anchor points for feathers is “only speculation at this point….” The authors of the paper in Nature said only that “These bumps correspond topographically to, and are morphologically similar to, feather quill knobs, and we consider them homologous to those present in many birds.” The comparison photos, though, do not show them equidistant as on modern birds. At the end of the paper, they speculated on how to interpret the bumps:
Recent findings have reported the presence of filamentous tubular integumentary structures in ornithischian dinosaurs such as the heterodontosaurid Tianyulong and the ceratopsian Psittacosaurus. The debate about the homology between these structures and bird feathers is open. If ornithischian tubular filaments are a kind of feather, they are an evolutionary novelty in dinosaurs, and their presence is expected in non-maniraptoran theropods such as Concavenator. If they are not a type of feather, Concavenator marks the most primitive presence of non-scale skin appendages in the theropod lineage, placing them at the node Neotetanurae. The simplest hypothesis about the ulnar Concavenator skin appendages is that they are short, rigid filaments (Fig. 2). However, it is possible that they might have had barb ridges, because these structures appear before the formation of the follicle. In any case, Concavenator shows that the combination of scale and non-scale skin appendages exhibited in present-day poultry was already present in large theropod dinosaurs 130 million years ago.
Another surprise is that this member of the carcharodontosaurid (“shark-tooth”) family was found in Europe. “Ten or 12 years ago everybody thought that carcharodontosaurids were a group that was exclusive to South America and Africa,” NG quoted a paleontologist as saying. Now they have to surmise that the group originated in Europe then drifted or migrated across the globe.
1. Ortega, Escaso and Sanz, “A bizarre, humped Carcharodontosauria (Theropoda) from the Lower Cretaceous of Spain,” Nature 467, 203-206 (9 September 2010); doi:10.1038/nature09181.
For analysis of the confusion that reigns in the alleged evolutionary transition from dinosaurs to birds, see Casey Luskin’s entry, “Inconsistent Reasoning Governs Evolutionary Interpretations of Feathered Dinosaurs” in Evolution News and Views. If the evolutionists want to interpret the bumps on Concavenator as feather attachment points, they should apply the same reasoning to Protoavis. But they don’t want to do that, because “it would wreak havoc with standard evolutionary story” because Protoavis, in their timeline, would represent a bird living contemporaneous with the earliest dinosaurs – a conclusion that “could undermine the entire dino-to-bird evolutionary theory.”