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

RE: Non-amniote sarcopterygians



I like this guy.  Far more eloquety argues my point.

-Dan

>===== Original Message From tholtz@geol.umd.edu =====
>Greetings,
>
>Seeing the current spate of gradistic vs. cladistic nomenclature on the DML,
>I'm reminded of the saying "the more things change, the more they stay the
>same"...  (Go to the list archives if you wonder why.  I'm not going to
>bother to post any messages in the current go round, since I've said it all
>before again and again...).
>
>However, for those interested in new analyses and studies, I believe the
>following has not yet been posted to the list:
>
>RUTA, M., M.I. COATES and D.L.J. QUICKE. 2003. Early tetrapod relationships
>revisited. Biological Reviews 78: 251-345.
>
>A 94 page long study of amphibian-grade sarcopterygian relationships.  Very
>detailed work, with 90 OTUs and 319 characters.  In their results, the
>classic -stegas (Venta-, Acantho-, Ichthyo-) as well as Tulerpeton, the
>colosteids, Crassigyrinus, Whatcheria, and the baphetids are the outgroups
>of crown-group Tetrapoda; Eucritta is the sistertaxon to temnospondyls
>(which contain Lissamphibia); embolomeres, gephryostegids, semouryiamorphs,
>and a few others are outgroups to a lepospondyl+(diadectomorph + amniote)
>clade (so that Diplocaulus is closer to us than it is to frogs...).
>
>Incidentally, the authors here follow the traditions of some of the
>paleoicthyological community (and some others): nearly all "traditional"
>names are stem-based, with their anchor taxa being living forms.
>Consequently, they use "Lissamphibia" and "Tetrapoda" more broadly than a
>lot of other folks would (i.e., Eusthenopteron and Panderichthys are
>stem-tetrapods; Eryops is a stem-lissamphibian).  They recognize that this
>results in Triceratops being a stem-bird and Dimetrodon being a stem-mammal,
>but so be it.
>
>Needless to say (based on my published work and notes on the list), I'm
>perfectly happy with restricting traditional taxon names to subclades within
>the larger total clade denoted by all taxa closer to clade A than to its
>closest living relatives.  (That is, I'm happy for Aves to be an arbitrarily
>defined node within Maniraptora, Theropoda, Dinosauria, and so forth).  But
>I give these folks credit: they are honest in respecting their taxonomic
>philosophy even if it results in Desmatosuchus as a crocodile, Stegosaurus
>as a bird, or Phacops as a chelicerate...
>
>               Thomas R. Holtz, Jr.
>               Vertebrate Paleontologist
>Department of Geology          Director, Earth, Life & Time Program
>University of Maryland         College Park Scholars
>               College Park, MD  20742
>http://www.geol.umd.edu/~tholtz/tholtz.htm
>http://www.geol.umd.edu/~jmerck/eltsite
>Phone: 301-405-4084    Email:  tholtz@geol.umd.edu
>Fax (Geol):  301-314-9661      Fax (CPS-ELT): 301-405-0796