More non-avian feathered Chinese dinosaurs 13 Nov 2009 “The integumentary appendages seen in non-avian dinosaurs document a series of transitional forms from typical archosaurian scales to typical avian feathers.” From here. Fig. 4 Known feather morphotypes of non-avian dinosaurs A. morphotype 1, single filament; B. morphotype 2, multiple filaments joined basally; C. morphotype 3, multiple filaments jointed basally on a central filament; D. morphotype 4, multiple filaments branching laterally from most of the length of a central filament; E. morphotype 5, multiple filaments arising from the edge of a membrane structure; F. morphotype 6, compound structure composed of a prominent rachis with symmetrical, well-organized and closed vanes on either sides; G. morphotype 7, compound structure composed of a prominent rachis with asymmetrical, well-organized and closed vanes on either side; H. morphotype 8, a prominent rachis with symmetrical, undifferentiated vanes on either side. Check out the images of dinosaur skin impressions too. Evolution
Evolution Evolution quotes 6 May 2010 But is it not possible to apply a test whereby a true species may be known from a mere variety? Is there no criterion of species? Great authorities affirm that there is—that the unions of members of the same species are always fertile, while those of distinct species are either… Read More
Book Books I am reading/reviewing 6 Feb 20148 Feb 2014 Despite marking scores of essays, after having taught a subject intensive, and preparing various papers, I get to review some books. This means reading them, familiarising myself with the technical literature, and so on. So I thought I’d do a brief summary of them for you now: The first is… Read More
Biology A not terribly good post on the species problem 18 Jul 2019 As a biological phenomenon the species problem is worthy of serious study as an end in itself, and not as a mere corollary to work in some other field. It is, to be sure, a problem so fundamentally important that it touches many such fields. Workers in any one of… Read More