Re: Sinosauropteryx filament melanosomes challenged

[Tim Williams <tijawi@gmail.com>]

Sim Koning <simkoning@msn.com> wrote:


>  I consider Archosaurs to be a class "above" reptiles. I would also include 
> crocs since they probably evolved from warm-blooded
> ancestors and have 4 chambered hearts. The name "class" suggests something 
> analogous to a social hierarchy,


For that reason (as well as many others), the term "class" has
effectively been abandoned.  "Class" is a loaded term, and so can
actually be misleading when discussing evolutionary relationships.


For the same reason, "class" Aves is unhelpful when discussing the
origin of birds, because it suggests that birds are a "class above"
the lowly reptiles (dinosaurs included).  Instead, birds comprise a
clade *inside* Paraves, which is in turn a clade inside Maniraptora,
which is a clade inside Coelurosauria, and so on through successively
larger (more inclusive) clades: Tetanurae, Theropoda, Saurischia,
Dinosauria, Ornithodira, Archosauria, Diapsida, Amniota, Craniata,
Vertebrata, Chordata.... (OK, I've skipped quite a few clades along
the way, but you get the general idea.)  No good can come from
arbitrarily raising any one of these clades (such as Archosauria) to a
"class".  In fact, it's as pointless as maintaining Reptilia or Aves
or Mammalia at the rank of "class".  The terms "kingdom" and "phylum"
and "order" are equally pointless.  All this Linnaean rank-based
taxonomy is just rearranging deckchairs on the typological Titanic.


Oh, and "warm-blooded" (like "cold-blooded") is also misleading.  I
thought while I was being pedantic and nit-picky, I might as well jump
in with both feet.    :-)



Cheers

Tim