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re: theropod phylogenetics paper



Stephan Pickering (StephanPickering@cs.com) wrote:

<Let us try once again for those who can't follow the equation: crown
dinosaurs > feathered dinosaurs > flying dinosaurs. One cannot define
"bird" apart from "dinosaur." A footnote: those would obfuscate the
question by referring to other lineages should stop; humans are primates,
highly derived from either a mutated group of chimpanzees, or from a clade
from which chimpanzees and hominids are derived.>

  And once again, we must try to clarify that the group Dinosauria cannot
be a crown group unless you define a crown group to include any extinct
ancestors you want. If so, then *Ichthyostega* can be a crown bird, too. A
crown group is defined on _extant_ membership ... and nothing else.
Neornithes is the most inclusive crown group that can be defined: it is
the most recent common ancestor of the living birds, and all descendants
(extinct or extant) of that common ancestor. This includes the ratites,
tinamous, chickens and ducks, and neoavians, and all descendants of their
recent common ancestors, respective of how those fall. That's the crown
definition, anyway. Gauthier (1984 not published, refer to 1986
publication) defined Aves by the membership of what other authors consider
to be Neornithes.

<I choose to not to define extant humans as chimpanzees or apes or lemurs,
etc., regardless of the fact that, in informal usage, humans are "apes".>

  That's good, because humans are in no way lemurs ... they are, according
to most primatological studies, an exclusive group including forms found
almost exclusively on Madagascar, and a few African forms. They lie
outside the simian node (monkeys and apes). Problematically, defined man
apart from apes reflects a non-primatological stance wherein workers on
primates (Bermudez de castro, Simons, Bown, Rasmussen, Leakey, etc.)
consider man to be an extraordinarily adapted ape. Hominoidea, a group
often associated with "ape," includes man and the "great apes" apart from
humans and hominines, like *Australopithecus*, *Orrorin*, etc.

<Again, we are talking about clarity of words; perhaps extant humans are a
form of chimpanzee, but, until the evidence is discovered, I lean toward
the hypothesis chimps and humans are from the same clade.>

  This would be true if humans were a subspecies of *Pan*, but it's clear
that modern chimps and great apes with man all group amongst themselves
via molecular analyses. No reason to support another theory except by the
theory of nested speciation, where a species simply developes from within
another, rather than a deep, distinct schism between two (sympatric).

<So: is a "bird" a "dinosaur", and a "dinosaur" a "bird"? Of course.>

  Neither. Both are colloquial useage. Dependant on a person's
_individual_ concept, not a majority application to an actual taxon.
However, for the concept, Neornithes is a subgroup of Dinosauria, but in
no way can Dinosauria be a subgroup of Neornithes, and in this way, there
can be no crown dinosaurs. Sorry.

<How quickly one can forget that it was Percy Lowe (a name quite familiar
to John Ostrom) who saw Archaeopteryx as a theropod.>

  How quickly can it be to forget Thomas Huxley, Darwin's Bulldog, who was
the first proponent of the avian relationship of *Archaeopteryx*, and
provided in a succession of papers (in the lates 1800's and early
1900's)the relationship, via Archie, between birds and dinosaurs? Even
Owen drew a line between *Archaeopteryx* and birds, but capitulated too
easily when Wagner scratched it out and renamed *Archaeopteryx* as
*Griphosaurus*, the "mystery reptile".

<Aves cannot be separated from the  crown clade of Dinosauria.>

  Actually quite easy to do this, as I show above.

<And it is my personal choice to, as much as possible, in my book and on
the List, use dinosaur and not "bird".>

  As you state, a personal choice. But does not dismiss the effective
impoirtance of the word "bird" or use of the terms "avian", "birdy", etc.
They have relative use to describe those which have feathered wings, fly,
and poop on people's cars -- to use a fellow listmember's wonderful
colloquial definition.

 ...

  And when one sees a duck, crane, pigeon, one sees a bird, too ... but
also a dinosaur. The terms are _not_ exclusive.

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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