Subject:
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Re: Evidence of Warm Blooded Dinosaurs
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Newsgroups:
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lugnet.off-topic.fun
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Date:
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Tue, 25 Apr 2000 21:33:41 GMT
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Viewed:
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301 times
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In lugnet.off-topic.fun, Lindsay Frederick Braun writes:
> Jeff Stembel wrote:
> > This prompted me to pull out one of my dinosaur books, and examine the
> > dinosaur family tree. :) Anyway, if this chart is correct (it's ten years
> > old, but I doubt its changed much), then I'd guess Dinosaurs and mammals
> > both evolved warm-bloodedness separetly.
>
> Darn sacci-frasso-rassin' kids, stealin' my thunder...;) But yeah, that's the
> story. Why do crocodiles not have a high, warm-blooded metabolism? They
> don't need it, and have never needed it. They're archosaurs like monotremes
> are mammals--they have *some* of the features, but not all. Dr Gregory Paul
> has written (and illustrated--he's quite talented) an excellent book called
> "Predatory Dinosaurs of the World", in which he argues quite reasonably two
> things:
I've never heard of it, so I'll have to check this book out. :)
>
> 1. Dromaeosaurs and Cretaceous coelurosaurs (an outdated term, as it
> conflates several distinct lineages) in fact are *back-evolved* from the first
> birds, based upon structural information, metabolic clues, and evidence of
> later (post K-T) bird back-evolution into large ground predators; and
I find this hard to swallow. What happened to their skulls and the wishbone?
It is true that some birds later evolved into Dinosaur-like creatures(1), but I
wouldn't use that to say some Dinosaurs evolved from birds.
> 2. Amateur and professional fossil-hunters both are guilty of mucking up the
> Archosaurian family tree by vainly trying to name "their own" dinosaur, and
> thus giving specimens we can today quite readily tell are male, female, or
> juvenile, three different genera names. Paul clears a lot of this up, and
> apparently he made some people not-too-happy by suggesting that "their"
> dinosaur be collapsed into another category.
I'm not sure why this is so terrible, other than making it seem like there are
more Dinosaurs than there actually are...
> There's a corollary to this, and that's that birds should not be in a separate
> taxonomic class (Aves). Rather, they should be a subclass under Archosauria
> (which should be a class, not a subclass of Reptilia as it's accepted
> now--Archosauromorpha). To call birds non-archosaurs is like calling bats
> non-mammals, just because they can fly.
I don't think many people could stomach putting two such different creatures as
Crocodiles and Hummingbirds in the same class. :) Also, there is more than
just flight to differentiate Birds and reptiles. The Wishbone, for example.
:) I'm sure I could come up with more if I knew more about birds. :)
> I'm not sure you can call late therapsids truly "reptiles," though. They were
> furry, after all. If you're talking finbacks (pelycosaurs/edaphosaurs), well,
> yes.
I'll have to hold off on this one 'til I get home to my book that covers these
guys... :)
>
> > I'd like to hear other's opinions on this, especially if you have evidence
> > to contradict or confirm my idea (since I just made it up :) ). I'll also
> > try to find some of my more recent books on the subject. :)
>
> I'm in basic agreement--although the relation of dinosaurian groups is kind of
> weird right now, because I've been seeing a lot of material lately that
> suggests the "traditional view" separating dinosaurs by hip type is just plain
> silly, and that separating them by size is also just plain silly.
Can you present some of this material? I seem to've missed it. :) I do think
the hip classification can be misleading, considering birds evolved from the
"lizard hipped" Saurichians. ;)
> At least we know where our 'gators stand; their ancestor arose in the
> mid-Triassic, about the same time as the earliest known "dinosaur" (is that
> still considered to be Euparkeria, or do they have a new "earliest and
> greatest" candidate?).
Again, I'll have to wait 'til home to respond to this. :)
Jeff
1 - Axebeak/Terror Bird being the prime example. Are these two the same, or
separate species? What other examples are there?
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Message has 1 Reply:
 | | Re: Evidence of Warm Blooded Dinosaurs
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| (...) That's just it--the distinction is unclear. The thought is that some late dromaeosaurs have archaeoptergyian skeletal features that really shouldn't have evolved independently unless the former were secondarily flightless. For example, what (...) (24 years ago, 26-Apr-00, to lugnet.off-topic.fun)
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Message is in Reply To:
| | Re: Evidence of Warm Blooded Dinosaurs
|
| (...) Darn sacci-frasso-rassin' kids, stealin' my thunder...;) But yeah, that's the story. Why do crocodiles not have a high, warm-blooded metabolism? They don't need it, and have never needed it. They're archosaurs like monotremes are (...) (24 years ago, 25-Apr-00, to lugnet.off-topic.fun)
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