© 2007 Society of Systematic Biologists
Fossils, Molecules, Divergence Times, and the Origin of Lissamphibians
Comparative Osteohistology, UMR CNRS 7179 Université Paris 6, 2 place Jussieu, case 7077, 75005, Paris, France E-mail: laurin{at}ccr.jussieu.fr (M.L.)
Edited by Norman MacLeod: Associate Editor
 |
Abstract |
|---|
A review of the paleontological literature shows that the early dates of appearance of Lissamphibia recently inferred from molecular data do not favor an origin of extant amphibians from temnospondyls, contrary to recent claims. A supertree is assembled using new Mesquite modules that allow extinct taxa to be incorporated into a time-calibrated phylogeny with a user-defined geological time scale. The supertree incorporates 223 extinct species of lissamphibians and has a highly significant stratigraphic fit. Some divergences can even be dated with sufficient precision to serve as calibration points in molecular divergence date analyses. Fourteen combinations of minimal branch length settings and 10 random resolutions for each polytomy give much more recent minimal origination times of lissamphibian taxa than recent studies based on a phylogenetic analyses of molecular sequences. Attempts to replicate recent molecular date estimates show that these estimates depend strongly on the choice of calibration points, on the dating method, and on the chosen model of evolution; for instance, the estimate for the date of the origin of Lissamphibia can lie between 351 and 266 Mya. This range of values is generally compatible with our time-calibrated supertree and indicates that there is no unbridgeable gap between dates obtained using the fossil record and those using molecular evidence, contrary to previous suggestions.
Keywords: Calibration point; fossil record; Lissamphibia; molecular dating; phylogenetics; stratigraphic fit; supertree
Abbreviations: Amniota, the smallest clade that includes birds and mammals (a crown-group). • Amphibia, the largest clade that includes Lissamphibia but not Amniota. • Anura, the smallest clade that includes all extant frogs (a crown-group). • Apoda, the smallest clade that includes all extant caecilians (a crown-group). • Batrachia, the smallest clade that contains Salientia and Caudata (a crown-group). • Caudata, the largest clade that includes Urodela but neither Anura nor Apoda. • Dipnomorpha, the largest clade that includes lungfish but not tetrapods. • Gymnophiona, the largest clade that includes Apoda but neither Anura nor Urodela. • Lissamphibia, the smallest clade that includes Apoda, Anura and Urodela, but not Amniota (a crown-group). • Salientia, the largest clade that includes Anura but neither Urodela nor Apoda. • Sauropsida, the largest clade that includes birds but not mammals. • Stegocephali, the smallest clade that includes all limbed vertebrates. Often called Tetrapoda in the literature. • Tetrapoda, the smallest clade that contains Lissamphibia and Amniota (a crown-group). • Tetrapodomorpha, the largest clade that includes tetrapods but not lungfish. • Theropsida, the largest clade that includes mammals but not birds. Often called Synapsida in the literature. • Urodela, the smallest clade that includes all extant salamanders (sensu lato; cryptobranchoids, sirenids, and salamandroids).
Received February 26, 2006; Revised April 12, 2006; Accepted November 27, 2006
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  Genome 10K Community of Scientists Genome 10K: A Proposal to Obtain Whole-Genome Sequence for 10 000 Vertebrate Species J. Hered., November 6, 2009; (2009) esp086v2. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Ruta, D. Pisani, G. T Lloyd, and M. J Benton A supertree of Temnospondyli: cladogenetic patterns in the most species-rich group of early tetrapods Proc R Soc B, December 22, 2007; 274(1629): 3087 - 3095. [Abstract] [Full Text] [PDF]
|
|