title: Molecular evidence for the origin of birds.
abstract: The major groups of amniote vertebrates appeared during a relatively short time span at the end of the Paleozoic Era, a fact that has caused difficulty in estimating their relationships. The fossil record suggests that crocodilians are the closest living relatives of birds. However, morphological characters and molecular sequence data from living amniotes have repeatedly challenged this hypothesis by indicating a bird-mammal relationship. DNA sequences from four slow-evolving genes (mitochondrial 12S and 16S rRNA, tRNAVal, and nuclear alpha-enolase) now provide strong statistical support for a bird-crocodilian relationship.
authors.affiliation: Department of Biology, Pennsylvania State University, University Park 16802.
authors.forename: S B
authors.initials: SB
authors.lastname: Hedges
mesh_terms: D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D001717:Birds / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics*; D008969:Molecular Sequence Data; D012335:RNA, Ribosomal / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012366:RNA, Transfer, Val / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004272:DNA, Mitochondrial; D004275:DNA, Ribosomal; D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012366:RNA, Transfer, Val; C075526:RNA, ribosomal, 12S