Re: Cladospeak (Mammalia, Crurotarsi)

["David Marjanovic" <david.marjanovic@gmx.at>]

> My clarification, using proper "cladospeak": if
> ornithosuchids are closer to birds than to crocs, then Crurotarsi probably
> becomes a junior synonym of Archosauria, but it would still need to be
> abandoned [...].

True.

> I use the traditional,
> character-based, Mammalia (sensu lato) that most mammalogists still use.
We
> [...] simply ignore (as best we can) the strictly
> cladistic equivalent (Mammaliformes, which has caused confusion ever since
> it was proposed).

This is actually a quarrel _among_ cladists, those who want the traditional
Mammalia (which includes *Morganucodon*, *Megazostrodon*, *Sinoconodon*,
*Adelobasileus*, Haramiyida and later ones) and those who want a crown group
defined like {Monotremata + Marsupialia + Placentalia} (which seems to be
agreed to contain Multituberculata, *Triconodon*, *Zhangheotherium* and
others, don't know for docodonts) and call the traditional Mammalia
Mammaliaformes. Actually, I like the former better, but I could definitely
live with either.

>       The sister group to Mammalia (sensu lato) is the eucynodont
("derived"
> therapsid) family Trithelodontidae, which had not completed the transition
> to the mammal jaw joint and associated movement of the three ear ossicles.
> [is "derived" better than "advanced"?---or are they both a cladospeak
> faux-pas, no-no, bad-bad].

"Derived" is a very useful term and even sort of defined, whereas "advanced"
is not and sort of sounds like "progress". Therefore, the former should be
used and the latter discarded like Vermes and Thecodontia :-)

>     As for Crurotarsi, I am not saying "it MUST be bad".  I am saying the
> synapomorphies supposedly supporting it as a clade do not appear
significant
> (i.e. not strong), and compared to the mammal synapomorphy, they are
> downright "weak" (comparatively insignificant).

You can't expect synapomorphies like the dentary-squamosal jaw joint for
every clade. (Of course, that's not an argument against testing the
diagnosis of Crurotarsi -- it's science.)

>      I am reluctant to say who may or may not still regard Ornithosuchids
as
> closer to birds than to crocs (as views change so rapidly sometimes), but
I
> believe Michael Benton still favors this toplology.

While I haven't asked him, in his Vertebrate Palaeontology 2nd Edition he
emphasizes that they belong into "Subdivision" Crurotarsi several times on a
few pages, he's just not sure "whether they lie above (Sereno, 1991) or
below (Parrish, 1993) the Phytosauridae in the cladogram."