Armor Cost and Weight for 1+ SM

[Anthony]

Originally Posted by Kenneth Latrans

I'd say that "birds are descendants of dinosaurs" is contentious.

No, that really isn't; while there's dispute about details, placing Aves under Dinosauria isn't really controversial, and the split seems to be sometime in the Jurassic; a Tyrannosaurus Rex is more closely related to birds than to, say, a Brontosaurus.

[Flyndaran]

Also reptile isn't a very biologically useful word. It's usually used as a catch all for all non-mammal, amphibian, bird tetrapods.
Dinosaurs were nearly all warm blooded, making them very different from all modern animals called reptiles. Even crocodilians may have been warm blooded in the distant past, and only the "back-falling" ones survived to today.
And at least on extinct island species of goat evolved to become "cold blooded".

[Bruno]

"Dinosaur" isn't a very useful word either, being only slightly more precise than "reptile". It encompasses two groups that diverged at a VERY ancient point and ne'er the twain shall meet again except over dinner. Modern marsupials and modern placental mammals have a closer divergence point, and my god marsupials are different from placentals.

The real failing is that we keep calling the two groups of "dinosaurs" the same thing when they aren't. Birds are clearly grouped in with one half - they've got the protein matches to go with a great fossil chain of evidence. The real point where you can get into arguments is the point where any attempt to organize species gets into arguments - where exactly to draw the line, how many lines, what to call the things on the various sides of the lines, and how many of them you get to name after Gary Larson.

[gjc8]

Originally Posted by Bruno

"Dinosaur" isn't a very useful word either, being only slightly more precise than "reptile".

So, to bring the point around, we have giant bipedal theropods, and avians are a subset of theropods. Which is consisent with giant bipeds, but not giant humanoids, and possibly requiring pneumatized bones.

[Flyndaran]

Originally Posted by gjc8

So, to bring the point around, we have giant bipedal theropods, and avians are a subset of theropods. Which is consisent with giant bipeds, but not giant humanoids, and possibly requiring pneumatized bones.

I assumed humanoid in this thread meant shape not related to modern humans and apes. You probably couldn't get much bigger than modern gorillas without enough changes to render them a new superfamily.

[malloyd]

Originally Posted by Bruno

"Dinosaur" isn't a very useful word either, being only slightly more precise than "reptile". It encompasses two groups that diverged at a VERY ancient point and ne'er the twain shall meet again except over dinner. Modern marsupials and modern placental mammals have a closer divergence point, and my god marsupials are different from placentals.

Taxonomic arguments aren't really about similarity of the things grouped in them anymore, that's just how you originally notice them. The formal definitions have to do with lines of descent. There is a species from which all mammals are descended, and all descendents are mammals, that makes them "monophyletic" and thus a valid taxon. That's true of birds too. It's not true of dinosaurs (or reptiles) if you exclude birds from them, so either birds are dinosaurs (and reptiles), or dinosaur and reptile are invalid taxa.

There's a perfectly good node in the tree you can label reptiles if you are willing to include birds - the split of Amniota, the other branch being Synapsida for mammals and a few extinct relatives, and a somewhat more recent one (splitting Archosaurs between dinosaurs (plus birds), crocodiles, pterosaurs and a couple other minor extinct groups). And yeah, that's a pretty old divergence, but not significantly older than mammals.