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Re: More reptile stuff
Thomas R. Holtz, Jr. wrote:
> Dwight Stewart writes:
> > Basically, we are taught that mammals are "superior" to reptiles.
> >Usually birds are placed in "2nd place", with reptiles and amphibians
> >ranked only above insects, IF that.
> I REALLY hope people aren't still being taught that, especially in schools.
> Value judgements of "superiority" and "inferiority" hearken back to the
> pre-Darwinian idea of a Scale (Ladder) of Nature.
Some places are more enlightened, but that view's still fairly
prevalent. Also prevalent is the "Step on it!" mentality for insects.
The other night, whilst waiting for dinner, I saw a woman tell her child
to step on an insect which was fairly out of the way and not bothering
anyone at all. No reason to it, just "step on it! No, it's still
alive, step on it again!" Tells you a lot about how these attitudes are
formed. It also told me that young children are cognitively indistinct
from your average dog, and even that may be doing a disservice to the
> > Correct me if I'm wrong (really asking for it here!), but aren't
> >both birds and mammals evolved from reptiles?
> You're wrong, at least under modern vertebrate systematics. To be terribly
> unfashionable and quote myself:
> "The category Reptilia is now considered a node-based taxon: the most recent
> common ancestor of turtles, lepidosaurs (lizards [including snakes] and the
> tuatara), and archosaurs (crocodiles and birds and their extinct relatives).
> Thus Aves (the birds) is part of the larger monophyletic Reptilia. Mammals,
> however, are not part of this clade, because our ancestors diverged from the
> common ancestor of all reptiles (as now defined) before the
> turtle-lepidosaur-archosaur divergence. Thus under cladistics, the
> ancestors of mammals by definition were not reptiles (i.e., were not part of
> the clade Reptilia), while birds' ancestors and birds themselves are true
> reptiles (i.e., members of the clade Reptilia)." p. 105 in Farlow &
> Brett-Surman's The Complete Dinosaur.
I guess my question here is this: isn't this rather arbitrary? I don't
think you're saying that the amniotic condition arose separately in the
lines which let to mammals and reptiles, and as such mammals and
reptiles had a common amniotic ancestor. Does that ancestor have less
in common with, say, testudines than testudines have with archosaurs?
What is it about these early amniotes that warrants placing them in a
taxonomic no man's land instead of placing them with reptilia (which
would then necessitate either ditching the term reptilia -- which gets
my vote -- or calling pretty much all of amniota reptilia as well, which
is somewhat silly)?
> >I frankly wonder if non-avian dinosaurs had not become extinct, if we would
> even be > here to discuss this? :-)
> Greg Paul, in his review of Dougal Dixon's _The New Dinosaurs_, pointed out
> that as primate ancestors were already around by the latest Cretaceous, and
> as Mesozoic dinosaurs never seemed to compete directly with these arboreal
> herbivores/omnivores, there doesn't seem to be any evidence for competative
> exclusion of Primates by Dinosauria. He suggested that human-like forms
> might well have been possible in a world dominated by dinosaurs, although
> large herd mammals, big carnivorous mammals, and the like might not have
> appeared (since dinos were already doing those things).
Is this review on-line anywhere? I'd like to read it.