|
Susan E Evans in The Early HIsotry and
relationships of the Diapsida, in Benton's Phylogeny and Clasification Blah blah
blah says
"Four derived character states...can be used to
diagnose diapsids: upper temporal fenestra; suborbital fenestra...lower temporal
fenestra; cervical vertebrae longer than mid dorsals." she then notes that
afifth character state of locked tibio-astragalar joint might be used, but
doesnt use it in her study.She also says that the two major groups within
diapsida are Araeoscelidia and neodiapsida. I will not pretend i know what
and araeoscledian is.
i hope this is helpful, and ya, i just got this book a
week or two ago so i keep refering to it. I am confused tho, how is
definition of a group different than diagnosis of a group?
----- Original Message -----
Sent: Saturday, December 01, 2001 1:58
PM
Subject: Re: Feduccia's delusion
On Sat, 1 Dec 2001 Dinogeorge@aol.com wrote:
> In
a message dated 12/1/01 0:40:27 AM EST, tmk@dinosauricon.com
writes:
>
> << Problem here is that the node of the
node-stem triplet *is* a crown group.
> (And would we really want
"Archosaurolepidosauria" anyway?) >>
>
> Wait a minute--how
can a node all by itself be a crown group?
A crown clade is a type of
node-based clade in which all the specifiers
are extant. The specifiers for
this clade are _Crocodylia_, _Neornithes_
(=_Aves sensu stricto_), and
_Lepidosauria sensu stricto_, all of which
are extant. Hence it is a crown
clade.
> My understanding of a node-stem triplet is that it is a
clade
> comprising a node and its two descendant stem groups.
I
thought it was a set of three clades (a node-based and two
internal
stem-based ones).
> Also, isn't a crown group bounded by
extant taxa (so that, for
> example, Archaeopteryx would not be included
in the crown group Aves)?
Yep. But Archie would be included in the
crown clade _Archosauria_, and
the crown clade _Sauria_.
> I
wouldn't use a combo name if there were a better, long-standing name
>
already available, of course. The combo name here would be
>
Archolepidosauria--no need to multiply the saurias.
Indeed, you can
abbreviate it to just _Sauria_.
> Would be nice to use Diapsida, but
there are other diapsids besides
> archosaurs and
lepidosaurs.
Does anyone know what the phylogenetic definition of
_Diapsida_
is?
_____________________________________________________________________________
T.
MICHAEL KEESEY
The
Dinosauricon <http://dinosauricon.com>
BloodySteak
<http://www.bloodysteak.com>
personal
<keesey@bigfoot.com> -->
<tmk@dinosauricon.com>
Dinosauricon-related <dinosaur@dinosauricon.com>
AOL Instant Messenger <Ric
Blayze>
ICQ
<77314901>
Yahoo!
Messenger <Mighty
Odinn>
|