[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

New(ish) paper on polyphyletic Aves (Kurochkin)

I had heard that at least one Russian paleontologist still fervently believed that birds (and avian flight) evolved twice. I didn't believe it, until I saw this...

Kurochkin, E.N. (2006). Parallel evolution of theropod dinosaurs and birds. Zoologicheskii Zhurnal. 85(3): 283-297.

ABSTRACT: "In recent years, the hypothesis of an origin of birds from theropod dinosaurs has been
widely spread. Direct sisterly relations between theropods and birds are established based on such casual and formal synapomorphies, as the number of tail vertebrae, relative length of the humerus,
flatness of the dorsal edge of the pubis, etc. In essence, this hypothesis is developed on such characters (recognized as homologies), as feathers, furcula, uncinate processes, pygostyle, double-condyled cranial joint of quadrate, and inverted back pubic bone, which are discovered in various groups of Coelurosauria. Not so long ago, they were considered as apomorphies in birds. Nevertheless, all these characters are mosaically distributed among dromeosaurids, troodontids, oviraptorosaurids, therizinosaurids, and tyrannosaurids. There is no Theropoda group, where they would occur together. This fact testifies to parallelism in the evolution of theropods and birds. Theropod dinosaurs and Sauriurae (Archaeornithes with Enantiomithes) have a number of important system synapomorphies that demonstrate their close relationships. Ornithurine birds do not have such synapomorphics, but their monophyly is established according to a great number of diagnostic characters. The hypothesis of independent origin of Sauriurae and Ornithurae is substantiated. According to this hypothesis, Sauriurae originated from Theropoda in the Jurassic period and Ornithurae from basal Archosauromorpha in the Late Triassic one. Findings of small avian footprints in the upper Triassic and lower Jurassic deposits on different continents support the existence of birds in the Early Mesozoic era."

I have to say, I don't know the difference between a "formal" and "casual" synapomorphy. I guess I'll have to track down the paper and read it to find out.

BTW, it was Tracy Ford who told me about this idea ('diphyletic Aves') still being around - so sorry for doubting you, Tracy. I guess the idea is not quite dead after all. More 'undead', I'd say. It's had enough cladistic stakes driven through its heart, but on it goes...