The one, the only:
Archaeopteryx!
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Dinosaur Art: The World's Greatest Paleoart recently renewed my interest, and now Complete Dinosaur is on my to read list. Thanks for starting the thread Mumei.
My favourite growing up was Apatosaurus, not Brontosaurus. I also liked Euoplocephalus, (frequently mistaken for Ankylosaurus). Sauropods and ankylosaurs were my two go-to groups; I remember really disliking all the attention theropods got, what with the feathers and the bird connection. Hadrosaurs were dull and ceratopsians were too flashy. Stegosaurs just suck when I thought they petered out after the Jurassic. It's all pretty funny reflecting now back on it.
I have a particular soft spot for the Rourke series of dinosaur books, published in the late 1980's. They were unique in that they were first and foremost story books: A day in the life of _____. Growing up, most dinosaur books are pretty much fact books, full of measurements . C.M. Kozemen, one of the authors of All Yesterdays, just did a podcast talking about many popular works reducing dinosaurs to things without any sort of context. But they are not machines; they were living breathing creatures with ecological connections. The narratives of the Rourke books provide the creature and the world and utilized a variety of artists. They're obviously not accurate representations anymore, but I still love them. I actually tracked down a couple of the volumes for inspiration on a new book idea I have.
If anyone is interested in dino art and analysis, I heartily recommend a blog called Love in Time of Chasmosaurs. It's chock full of the latest findings as well as vintage paleoart. Pretty hilarious reads too.
Hey, I drew that Amargasaurus picture.
There is a growing consensus, from biomechanical, geochemical, and bone histological disciplines, that dinosaurs had elevated metabolisms. Whether or not they were fully in the range of mammals or their avian descendants is open to some debate, but it is highly unlikely that ecotothermy in the traditional "reptilian" sense was a viable metabolic strategy, and it's one that very few people in the field seem to be advocating these days.
The bones tell us that, physiologically, dinosaurs were doing things that living, and, as far as we can tell, extinct, reptiles simply cannot. The growth rates estimated by counting LAGs, (lines of arrested growth, which are not limited to ectotherms as once thought), in dinosaurs are elevated well above those observed in both wild and captive reptiles. It was traditionally thought that ectothermic dinosaurs could retain heat simply via their often large body sizes, and such "gigantothermy" would also show higher growth rates than the reptilian norm, but LAG-count analyses on some contemporaneous giant crocodilians, such as Deinosuchus, have shown that they grow much like their modern relatives: slowly over a long period of time. The growth profile of many dinosaurs was fundamentally different: accelerated growth early on allowed them to reach adult size, even in 30-50+ tonne sauropods, in no more than two or three decades. As far as I know, a means by which a typical ectothermic metabolism could sustain such growth rates has yet to be proposed.
Finally, (and I'm not sure how much of this was covered in The Complete Dinosaur, 2nd ed., as I haven't been able to give my copy the time it deserves), with a group as long-lived and diverse as the dinosaurs, with a range of body sizes spanning several orders of magnitude, it's not unreasonable to suppose that their metabolic rates were similarly varied, with some running "hotter" than others.
I might be missing something, but ... wouldn't having a fast digestive rate, a need for an elevated amount of food, and digestive, respiratory, and cardiovascular systems that allow for - and demand - this greatly increased intake of food imply that said creature also had a high metabolic rate? I'm not really understanding how he's demarcating between those features to this extent. And I think his argument about humans only proves that growth of endotherms is indeed limited by genes; it doesn't seem to me to be a good argument for then arguing that such growth patterns are possible for low or moderate basal metabolic rates.
What am I missing?
You have actually given a nice overview of the perspectives that the book spend three chapters and about 135 pages explaining.
I don't think that any of them mentioned anything about comparisons of contemporaneous giant crocodilians, however. In the ""Intermediate" Dinosaurs" chapter by R.E.H. Reid, he argues:
"Correspondingly, in assessing other studies I do not accept arguments or assertions based on actualistic assumptions that cannot be verified, like the notions that erect limbs and fast growth imply high metabolic rates. This puts me at odds with others who do rely on them, but I think that this is justified. For me, both these notions are flawed in depending on the uniformitarian view that the present is the key to the past, which, while of proven value in interpreting the physical world, is potentially misleading if applied to the anatomical features of modern evolutionary end forms. Fully erect limbs and fast growth to large sizes are now seen only in endotherms, but we do not know whether they are only possible for endotherms or first appeared in preendothermic ancestors that only now have endothermic descendants"
And I don't know much about anatomy and physiology but:
"Growth rates change with, but, in terms of age and final weight only, a T. rex grows 24 times as fast as Ferguson's C. porosus. Such contrasts indicate some major physiological differences between nonavian dinosaurs and reptiles; but they still do not tell us that such dinosaurs had high metabolic rates, because the only things we know to be needed for such growth are the right genetic makeup (genome), an adequate food intake, and digestive, respiratory, and cardiovascular systems able to supply growing tissues with the necessary substrates and energy at the rate that it requires. A high basal metabolic rate could be a further requirement; but there is currently no proof that it is, because actual metabolic rates can only be measured in live animals. Further, if there were a causal connection between fast growth and endothermy, all endotherms would have to grow quickly, which we humans do not, and the periodic fast growth of some turtles and crocodiles would not be possible."
I might be missing something, but ... wouldn't having a fast digestive rate, a need for an elevated amount of food, and digestive, respiratory, and cardiovascular systems that allow for - and demand - this greatly increased intake of food imply that said creature also had a high metabolic rate? I'm not really understanding how he's demarcating between those features to this extent. And I think his argument about humans only proves that growth of endotherms is indeed limited by genes; it doesn't seem to me to be a good argument for then arguing that such growth patterns are possible for low or moderate basal metabolic rates.
What am I missing?
That giant ape posted in the first page. Infinitely more fascinating than any lizard or seacreature. Would love to see reconstructions/skeletons.
I'm a dinosaur guy, so I have to post some dinosaurs:
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Acrocanthosaurus
Not exactly prehistoric, but it is extent. Haast's Eagle.
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These motherfuckers were alive as late as the 17th century AD.
They ate large birds (large by today's standards) and sometimes human children.
Edit: Not my favorite, but not mentioned in this thread yet.
my new fav is Yutyrannus
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Gigantopithecus blacki.
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How can this not capture your imagination?
I'm honestly not sure what to make of what Reid says here. Uniformitarianism has been a foundational principle of geology and paleontology, (basically any scientific discipline where direct observation is often not possible), since the 18th and 19th centuries. Without it, deep time would be an impenetrable obstacle to our understanding of, say, plate tectonics or the evolution and radiation of ancient life. There is of course a danger in reading too much from the modern world into our interpretations of the past, but no one is arguing for an absolute, strict uniformatarianism, which would dictate, among other things, that the physiologies of modern animals and the ecological niches they fill represent the full spectrum of adaptation that was present in the past as well.
Almost certainly, the thermoregulatory biology of dinosaurs was unique in certain aspects, but the presence of some combination of erect posture, rapid, sustained growth rates, avian-style air-sac respiratory systems, and feathery insulation in dinosaurs is most consistent with endothermy of some form. That these features are lacking in both living ectotherms, and those in the fossil record, does not completely preclude the possibility that dinosaurs were an exception, but nonetheless makes it rather unlikely.
I'd imagine when Dinosaurs were roaming the Earth that massive forests were prevalent...How did they quickly navigate their massive bodies around trees and stuff when they were hunting? Did the big boys just avoid forested areas all together?
Archaeopteryx
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It does contain a few unfortunate accuracies, though. For instance, it makes the claim that, "Despite the appeal of Tyrannosaurus, the ubiquity of Triceratops, or the stateliness of Stegosaurus, sauropods are the iconic dinosaurs." This is utter nonsense, of course.
There was this dinosaur who was otherwise nothing special to me, but had the longest name I've ever seen for a dinosaur - anyone care to remind me what that could be?
Micropachycephalosaurus, maybe?
Opisthocoelicaudia?
Wait, that might be just about the most opposite thing of what you're saying.
Gigantopithecus blacki.
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How can this not capture your imagination?
...I'm glad megalodons are extinct now.My Megalodon tooth:
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...I'm glad megalodons are extinct now.
My Megalodon tooth:
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Spaceman Spiff / Cow Mengde:
So, I was reading Unearthing the Dragon: The Great Feathered Dinosaur Discovery by Mark Norell (Chair and Curator, Division of Paleontology, American Museum of Natural History), and he has a chapter dedicated to BAND (Birds Are Not Dinosaurs). And there's an interesting bit:
*snip*
And the chapter in The Complete Dinosaur arguing that dinosaurs were ectothermal? It was written by John A. Ruben, Terry D. Jones, Nicholas R. Geist, Willem J. Hillennius, Amy E. Harwell, and Devon E. Quick. Jones is also mentioned in a later paragraph in the other book.
Hm