“When people look of non-avian dinosaur they’re thinking of extrapolating a cow up to that size. Mammals are much much denser than birds are, because a lot of the skeletons of sauropods (the big, long-necked ones—Apatosaurus, Brachiosaurus and the like) and theropod dinosaurs are just air. Theropods don’t have solid bones like we do; they have hollow bones. Sauropods don’t, but they have tremendous air sacs that fill up a lot of their bodies. And thus they weigh way less than a mammal scaled up to that size.”

— Mark Norell

As quoted in "How Dinosaurs Loved: An Interview with Dr. Mark Norell on Dino Relations" http://motherboard.vice.com/blog/t-rexxx-how-dinosaurs-lived-loved-and-tasted-q-a-with-dr-mark-norell-american-museum-of-natural-history, Vice (March 20, 2012)

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Mark Norell7

American paleontologist 1957

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“Ever since the early '80s I have applied feathers to many of the small dinosaurs, and never did smaller theropods without them. I did so because birds evolved from small theropods, and the evidence for the latter having the high metabolic rates that would have promoted the evolution of insulation was solid. I used to receive endless grief for this. The counter-argument was that no feathers had been found on any dinosaurs, and scales had, so I was engaging in unfounded speculation. But these points were actually not scientific. Scales had been discovered only on large dinosaurs, so illustrating small ones with scales was no less speculative than putting feathers on them. It would be like illustrating little mammals with naked skin if all we had was elephants and rhinos to base mammal integument on. I knew that my thesis was logical, so I bided my time.”

Gregory Scott Paul (1954) U.S. researcher, author, paleontologist, and illustrator

Autobiography, part III http://gspauldino.com/part3.html, gspauldino.com

“The message from the tropics is unambiguous: To be a successful big land animal, you must cope with mammals, and to cope with mammals you must be a mammal yourself, or at least have metabolism as high as a mammal's. And big mammals have suppressed big reptiles in our tropics for the last sixty-five million years. So how can the dinosaurs' success over mammals' be explained? By assuming that dinosaurs had low-energy metabolic styles? Not very likely.”

Robert T. Bakker book The Dinosaur Heresies

The Dinosaur Heresies: A Revolutionary View of Dinosaurs (1986), Longman Scientific & Technical, p. 101
The Dinosaur Heresies (1986)

“Every feature that is known to exist in every bird universally accepted as such is also found on dinosaurs: four-chambered heart, fused caudal vertebrae, gastroliths, even the avian respiratory system have all been found on fossil theropods, especially dromaeosaurs and maniraptors. You can distinguish birds among dinosaurs, but it is no longer possible to distinguish birds from dinosaurs.”

Aron Ra (1962) Aron Ra is an atheist activist and the host of the Ra-Men Podcast

Youtube, Other, Geerup's Terrible Lizard Classification https://www.youtube.com/watch?v=qhZeowON8l8 (July 28, 2009)

“The classical view of dinosaurs presents a perplexing problem. The group of vertebrates which dominated the land before the rise of the dinosaurs were the synapsids, the mammal-like reptiles… Most paleontologists have believed that the locomotion and physiology of these mammal-like synapsids were more similar to those of active, warm-blooded mammals than to sluggish modern lizards or alligators. Surprisingly, though, when the first dinosaurs and their near relatives appeared in the Triassic period, the synapsids began to decline and soon became extinct. The dinosaurs then ruled the land unchallenged for over 100 million years while the early mammals, the surviving descendants of the synapsids, remained very small in size and number. Only after the dinosaurs suddenly disappeared about 70 million years ago did the mammals develop into the great variety of dominant land vertebrates we have today. The problem is this: if the later synapsids were such splendidly advanced animals with the improved physiology of mammals, and if dinosaurs were slow and sluggish, why were the mammal-like synapsids exterminated in competition with the first dinosaurs? And why didn't the mammals achieve a more significant diversification during the dinosaurs' reign?”

Robert T. Bakker (1945) American paleontologist

"The Superiority of Dinosaurs", Discovery 3(2),(1968) 11–22
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“Dinosaurs seem strange, but that is just because we are mammals biased toward assuming the modern fauna is familiar and normal, and past forms are exotic and alien. Consider that elephants are bizarre creatures with their combination of big brains, massive limbs, oversized ears, teeth turned into tusks, and noses elongated into hose-like trunks. Nor were dinosaurs part of an evolutionary progression that was necessary to set the stage for mammals culminating into humans. What dinosaurs do show is a parallel world, one in which mammals were permanently subsidiary, whereas the dinosaurs show what largely diurnal land animals that evolved straight from similarly day-loving ancestors should actually look like. Modern mammals are much more peculiar, having evolved from nocturnal beasts that came into their own only after the entire elimination of nonavian dinosaurs. While dinosaurs dominated the land, small nocturnal mammals were just as abundant and diverse as they are in our modern world. If not for the accident of the later even, dinosaurs would probably still be the global norm.”

Gregory Scott Paul book The Princeton Field Guide to Dinosaurs

Gregory S. Paul (2010) The Princeton Field Guide to Dinosaurs, Princeton University Press, p. 14
The Princeton Field Guide to Dinosaurs

“Giant predator lizards can't evolve in the presence of big mammal predators. So the lesson is that mammals suppress much of the evolutionary potential of modern lizards. Is the Komodo dragon a good working model of how dinosaurs succeeded? Absolutely not. Dinosaurs suppressed the evolutionary potential of mammals, not the other way around. And dinosaurs carried out this supression everywhere, on all the continents, not merely on a few tiny tropical isles. Dinosaurs succeeded where Komodo dragons fail.”

Robert T. Bakker book The Dinosaur Heresies

The Dinosaur Heresies: A Revolutionary View of Dinosaurs (1986), Longman Scientific & Technical, p. 81
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“… if you saw a baby tyrannosaur you would probably think it was a weird looking bird. A full grown one might have had feathers too, maybe not on its whole body though, maybe more of an ornamental display sort of feathers. So traits in the theropod dinosaurs were more birdlike than say, crocodiles.”

Mark Norell (1957) American paleontologist

“Humans are proud of themselves. The guiding principle of the modern age is "Man is the measure of all things." And our bodies have excited physiologists and philosophers to a profound awe of the basic mammalian design. But the history of the dinosaurs should teach us some humility… If our fundamental mammalian mode of adaptation was superior to the dinosaurs', then history should record the meteoric rise of the mammals and the eclipse of the dinosaurs. Our own Class Mammalia did not seize the dominant position in life on land. Instead, the mammal clan was but one of many separate evolutionary families that succeeded as species only by taking refuge in small body size during the Age of Dinosaurs. As long as there were dinosaurs, a full 130 million years, remember, the warm-blooded league of furry mammals produced no species bigger than a cat.”

Robert T. Bakker book The Dinosaur Heresies

The Dinosaur Heresies: A Revolutionary View of Dinosaurs (1986), Longman Scientific & Technical, p. 17
The Dinosaur Heresies (1986)

“The more that we learn about these animals the more we find that there is basically no difference between birds and their closely related dinosaur ancestors like velociraptor. Both have wishbones, brooded their nests, possess hollow bones, and were covered in feathers. If animals like velociraptor were alive today our first impression would be that they were just very unusual looking birds.”

Mark Norell (1957) American paleontologist

As quoted in American Museum of Natural History "Velociraptor had feathers" ScienceDaily (September 20, 2007)

“A couple things that we do know about theropods—the ones that most closely related to birds—is that they brooded their nests. If you go deeper in the tree, what you see is that for sauropods, we have no direct evidence that they returned to the nest after the eggs were laid. Most of the evidence for that comes from an excavation in Argentina called Auca Mahuevo. What’s thought with sauropods is that they’d just lay a bunch of eggs and leave them alone—the turtle model. Few of those would ever reach adulthood.”

Mark Norell (1957) American paleontologist

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