Gelatinous squid Posted July 29, 2014 Share Posted July 29, 2014 50 million years ago, birds were the dominant lifeform on Earth, as the proto-horses and proto-whales scurried around the toes of Gastornis. Then, 10 million years later, mammals were everywhere and birds were left to chirp in the trees. What happened? Why didn't the birds evolve to exploit the niches the mammals eventually took over? Link to comment Share on other sites More sharing options...
Auspex Posted July 29, 2014 Share Posted July 29, 2014 Well, there are about 10,000 species of birds extant; they have mastered land, sea, and sky, and every continent. Mammal species number a little over half that. "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
Gelatinous squid Posted July 29, 2014 Author Share Posted July 29, 2014 True, but no one would say this was a bird planet. Link to comment Share on other sites More sharing options...
Auspex Posted July 29, 2014 Share Posted July 29, 2014 True, but no one would say this was a bird planet. Do you think it is more of a Mammal Planet? The Cenozoic might rightly be called "The Age of Birds"! "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
Mediospirifer Posted July 29, 2014 Share Posted July 29, 2014 If not the Age of Beetles... Link to comment Share on other sites More sharing options...
Gelatinous squid Posted July 29, 2014 Author Share Posted July 29, 2014 Well, the Mesozoic and part of the Paleozoic would also be the Age of Beetles. Link to comment Share on other sites More sharing options...
Auspex Posted July 29, 2014 Share Posted July 29, 2014 ...birds were left to chirp in the trees... Chirp This! "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
Mediospirifer Posted July 29, 2014 Share Posted July 29, 2014 Heh. I've seen footage of a golden eagle attacking a caribou calf. Apparently, their claws are large and powerful enough to pierce the calf's lungs and kill. Whichever creatures are called "dominant", birds are highly evolved and very well-adapted to their niches. There are some amazing species out there! Link to comment Share on other sites More sharing options...
RyanNREMTP Posted July 30, 2014 Share Posted July 30, 2014 If you take humans out of the equation I don't think there would be a dominate group right now. Link to comment Share on other sites More sharing options...
ashcraft Posted July 30, 2014 Share Posted July 30, 2014 50 million years ago, birds were the dominant lifeform on Earth, as the proto-horses and proto-whales scurried around the toes of Gastornis. Then, 10 million years later, mammals were everywhere and birds were left to chirp in the trees. What happened? Why didn't the birds evolve to exploit the niches the mammals eventually took over? It depends on how you define dominant. Gastornis was big, and an apex predator, but there were several large mammalian apex predators also. Which is the "top dog", a 1500lb bear, or a hundred pound wolf? I suspect it is actually the wolf, it is such a good predator, it may even have pushed bears into an omnivorous life-style, except for polar bears, who do not compete with wolves. Avian physiology bests mammals where oxygen intake becomes important, such as in flight. But I suspect their hollow bones limit how quickly they can evolve into a robust predator when a niche becomes "available". It is an arms race at that point between different species. Mammals are better at it, we are nasty, mean, and vicious, and won't relenquish our "holdings". That is why it takes a mass extinction event to see large changes. My thoughts, which along with $1.50, will get you a soda in the teacher's lounge. fkaa fkaa 1 ashcraft, brent allen Link to comment Share on other sites More sharing options...
Carcharodontosaurus Posted July 30, 2014 Share Posted July 30, 2014 Do you think it is more of a Mammal Planet? The Cenozoic might rightly be called "The Age of Birds"! And that means the age of the dinosaurs hasn't ended yet. Link to comment Share on other sites More sharing options...
Paleoworld-101 Posted July 30, 2014 Share Posted July 30, 2014 (edited) Unfortunately, recent evidence has suggested that Gastornis was in fact a herbivore, not a carnivore. This was quite unsettling to me when I first read it- all my childhood memories and great interest in the first episode of 2001's 'Walking With Beasts' (New Dawn) was suddenly wrong Calcium isotope studies of its bones showed no evidence of meat in it's diet, not to mention it lacks the hooked beak of the undoubtedly carnivorous Phorusrhacids and todays modern raptors. It may have used its large powerful skull to crack nuts instead of bones. Edited July 30, 2014 by Paleoworld-101 1 "In Africa, one can't help becoming caught up in the spine-chilling excitement of the hunt. Perhaps, it has something to do with a memory of a time gone by, when we were the prey, and our nights were filled with darkness..." -Eternal Enemies: Lions And Hyenas Link to comment Share on other sites More sharing options...
painshill Posted July 30, 2014 Share Posted July 30, 2014 Bacteria are actually the dominant life form today and - in some form or another - probably always have been. Ther's also increasing evidence that they played a major role in shaping the Earth's crustal environment by assisting in mineral transformation/accumulation/concentration. Roger I keep six honest serving-men (they taught me all I knew);Their names are What and Why and When and How and Where and Who [Rudyard Kipling] Link to comment Share on other sites More sharing options...
jpc Posted July 31, 2014 Share Posted July 31, 2014 (edited) Do you think it is more of a Mammal Planet? The Cenozoic might rightly be called "The Age of Birds"! Years ago, in a Cenozoic Paleontology class, a test question we had, was very similar to this discussion; "It can be said that mammals are overrated simply because we humans are mammals, and we therefore call the Cenozoic the 'Age of Mammals'. Your assignment is to give the Cenozoic a new nickname and defend your choice" I chose an defended "The Age of Birds". I did well on that question. I think 'The Age of Mammals' is indeed homocentric. Some of the other posts here resemble other answers we had in class. Edited July 31, 2014 by jpc 1 Link to comment Share on other sites More sharing options...
RichW9090 Posted August 2, 2014 Share Posted August 2, 2014 Auspex, where and who was that class with? Just curious. The plural of "anecdote" is not "evidence". Link to comment Share on other sites More sharing options...
siteseer Posted August 2, 2014 Share Posted August 2, 2014 (edited) During the late Paleocene there were dog-sized and bear-sized mammalian predators (some oxyaenids and mesonychids) in North America but they died out by the end of the period. During the Early Eocene (50-55 million years ago), there were hyaenodonts at least collie-sized in North America and Europe and some genera reached larger size across the Eocene. Birds like Gastornis, assuming it was a predator, appears to have been quite rare. I have known people who have hunted the Early Eocene of Wyoming, Montana, and New Mexico. They have found a few teeth of the mammal predators but no Gastornis/Diatryma bones. 50 million years ago, birds were the dominant lifeform on Earth, as the proto-horses and proto-whales scurried around the toes of Gastornis. Then, 10 million years later, mammals were everywhere and birds were left to chirp in the trees. What happened? Why didn't the birds evolve to exploit the niches the mammals eventually took over? Edited August 2, 2014 by siteseer Link to comment Share on other sites More sharing options...
siteseer Posted August 2, 2014 Share Posted August 2, 2014 Yes, and even before that Andors (1992) pointed out that the hindlimb proportions are in the range of modern large-bodied ground birds that walk more than run (probably hardly ever ran). It had short, heavy toes more like a bustard than a raptor-type dinosaur, The cat-sized to dog-sized horses of its time (and which it is often shown preying on) were quite nimble in comparison especially on the swampy to spongy terrain of their subtropical forest environment. Gastornis' heavy legs were not well-suited for pursuit on such a surface. Andors also noted the lack of a hooked beak. Andors, V.A. 1992. Reappraisal of the Eocene groundbird Diatryma (Aves: Anserimorphae). Los Angeles County Museum of Natural History, Science Series 36: 109-126. Unfortunately, recent evidence has suggested that Gastornis was in fact a herbivore, not a carnivore. This was quite unsettling to me when I first read it- all my childhood memories and great interest in the first episode of 2001's 'Walking With Beasts' (New Dawn) was suddenly wrong Calcium isotope studies of its bones showed no evidence of meat in it's diet, not to mention it lacks the hooked beak of the undoubtedly carnivorous Phorusrhacids and todays modern raptors. It may have used its large powerful skull to crack nuts instead of bones. Link to comment Share on other sites More sharing options...
Auspex Posted August 2, 2014 Share Posted August 2, 2014 Gastornis was, at best, only an opportunistic predator of small critters, or even an occasional scavenger. Gastroliths frequently found in association with Gastoenis eggshell fragments strongly suggest a largely vegetable diet. "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
jpc Posted August 3, 2014 Share Posted August 3, 2014 Auspex, where and who was that class with? Just curious. That was u of Wyoming with jay lillegraven. Link to comment Share on other sites More sharing options...
jpc Posted August 3, 2014 Share Posted August 3, 2014 During the late Paleocene there were dog-sized and bear-sized mammalian predators (some oxyaenids and mesonychids) in North America but they died out by the end of the period. During the Early Eocene (50-55 million years ago), there were hyaenodonts at least collie-sized in North America and Europe and some genera reached larger size across the Eocene. Birds like Gastornis, assuming it was a predator, appears to have been quite rare. I have known people who have hunted the Early Eocene of Wyoming, Montana, and New Mexico. They have found a few teeth of the mammal predators but no Gastornis/Diatryma bones. I am one of those. I have spent a lot of time in the Eocene of Wyoming, nary a diatryma bone to show for it. The u of wy has a huge Eocene collection.... One diatryma bone it there as far as I can recall. It is a very rare beast Link to comment Share on other sites More sharing options...
Missourian Posted August 3, 2014 Share Posted August 3, 2014 After watching the geese around the lake (and crossing the busy street repeatedly), it's apparent that being as dumb as a box of rocks isn't much of a competitive advantage. Context is critical. Link to comment Share on other sites More sharing options...
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