 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Natural Science Forum / Biology / Paleontology / March 2007have a most fundamental question
Hello, I am new to this group, but have loved dinosaurs all of my life. I have a most fundamental question, which I hope will receive good feedback in lieu of facetious or snide remarks. My question, which seems simple at first is as follows : What scientific proof exists which definitively proves that dinosaurs such as the Tyrannosaur, Allosaur, Spinosaur, as well as the well known velociraptor and other various theropod dinosaurs were in fact carnivores as opposed to being herbivores? Is there such definitive proof? I pose the most fundamental question of-how does the scientific community know that certain dinosaurs were carnivores? One of the first things I think of is-what about herd culling by natural predators-similar to the lions of Africa and other present day predators? Perhaps there were no natural predators at that time-perhaps all dinosaurs were herbivores instead? I know this is a fundamental question, and I am sure that it will draw flak by those who would accuse me of being ignorant, but this is a serious question, and I ask only for serious answers. > Hello, > [quoted text clipped - 18 lines] > ignorant, > but this is a serious question, and I ask only for serious answers. The short answer is they make the deduction that certain dinosaurs were carniverous or herbiverous (or omniverous) based mainly on their teeth, plus the occasional very rare find of fossilised plant or animal remains within the gut area of dinosaur fossils. It depends exactly what you mean by "definitive proof", but in the absence of a time-machine, or some kind of Jurassic (or Cretaceous) Park, the most we can hope for is "beyond reasonable doubt". It might be thought possible, since no-one has ever seen a real live one, that Tyrannosaurus was a plant-eater, but the evidence is so strongly the other way that it would be extremely difficult to argue the case. Who knows, perhaps there were some very fleshy plants around in that era that it was perfectly adapted to eat, but on the whole it seems very unlikely. Mike > Hello, > [quoted text clipped - 7 lines] > I pose the most fundamental question of-how does the scientific community > know that certain dinosaurs were carnivores? I would think that the teeth would be enough. Sharp, serrated teeth are not tools for crunching lettuce. The sickle claws of many maniraptorans are also a good clue. However, there's more than that. There are known dinosaur fossils with theropod toothmarks in them, and, if I recall, even a few with broken-off theropod teeth embedded in them. > One of the first things I think of is-what about herd culling by natural > predators-similar to the lions of Africa and other present day predators? > Perhaps there were no natural predators at that time-perhaps all dinosaurs > were herbivores instead? I know this is a fundamental question, and I am > sure that it will draw flak by those who would accuse me of being ignorant, > but this is a serious question, and I ask only for serious answers. I'm puzzled. Whatever would make you think that such obvious carnivores were herbivorous? Now there were in fact herbivorous theropods, including therizinosaurs and at least come oviraptorosaurs. But they display signs of herbivory: modified teeth, modified bodies, and in some cases gizzard stones. Lifestyle is reflected in morphology. Lions and lambs look different for a reason. > Hello, > [quoted text clipped - 14 lines] > sure that it will draw flak by those who would accuse me of being ignorant, > but this is a serious question, and I ask only for serious answers. Perhaps a good point to start is the (British) Natural History Museum,s latest temporary exhibition Dino-Jaws http://www.nhm.ac.uk/visit-us/whats-on/temporary-exhibitions/dino-jaws/index.htm l?hp-promo to those who answered this in the spirit of information sharing, I thank you. As to the question which was raised regarding my question: I'm puzzled. Whatever would make you think that such obvious carnivores were herbivorous? The reason I posed the question is as follows: Suppose for a minute that in the time of the Jurassic and Cretaceous periods that the dinosaurs were in fact herbivorous as opposed to longstanding scientific thought that some animals such as the Tyrannosaur and the Velociraptor were carnivores while others such as the Brontosaurs and Apatosaurus were known herbivores. When I grew up I was enthralled by children's books about dinosaurs which always showed the triceratops and the Tyrannosaur always as mortal enemies, always fighting each other. As I grew older I heard theories that the Tyrannosaur and the Triceratops would never have fought because they lived in two different time periods. I never really gave it any thought because I always loved both animals and always saw them together in the same period--usually, as the books shown, fighting it out to the last. Another example of theories--as I was young I always saw the T-Rex using its front limbs to hold and tear its prey animals, and now sceintific theory has tended to lean--or so I have heard, that the front limbs were really useless for this due to their short size. It would seem to me that the limbs did serve a useful purpose, probably to help balance the animal some, but more so I would think to help rend its food once it has captured it. Now, imagine for a moment--that scientific thought could be wrong on the diet of the dinosaurs, and that in fact there could be no natural predators for these animals, and that the animals were, as opposed to longstanding thought--all herbivorous animals. I know that is probably an impossible to prove idea, but imagine a time when there were no unnatural deaths for these mostly massive animals, and that only old age, disease or (in lieu of natural predators), faminine that actually culled these herds. Starvation would be a terrible way for any living thing to die. Now--to answer my own question with my own personal view of this-do I really believe that all dinosaurs were herbivorous? I want to believe it...but as has been pointed out, evidence strongly suggests the contrary. The issue of teeth that was raised is a prime example. The sharp pointed teeth of the T-Rex and the Velociraptor could have been used for plants true, and perhaps were used to eat plants in times of scarce hunting, but the sharp teeth lead to only one honest conclusion, that the Tyrannosaur and the Velociraptor were by and large carnivores. But imagine a world where all of the animals got along and subsisted on plant material..no unnatural death, no natural predators..a world of true peace. Sounds silly I know.... Thanks again for all of the good, constructive comments. > to those who answered this in the spirit of information sharing, I thank > you. As to the question which was raised regarding my question: I'm [quoted text clipped - 11 lines] > Tyrannosaur and the Triceratops would never have fought because they lived > in two different time periods. I don't know where you heard that, but it isn't true. They lived at the same time, the Maastrichtian or latest part of the Cretaceous. > I never really gave it any thought because I > always loved both animals and always saw them together in the same [quoted text clipped - 24 lines] > plant material..no unnatural death, no natural predators..a world of true > peace. Sounds silly I know.... You would have to imagine all the lions, tigers, hyenas, snakes, hawks, warblers, and so on starving to death too. Many animals are constructed so as not to be able to survive as herbivores. > Thanks again for all of the good, constructive comments. If it is of any consolation, the ecological pyramid logic predicts that most of the animals will be herbivores anyway. That wouldn't mean of course that those with clear adaptations to predation or feeding on meat would be too. And for those, some could be omnivorous. I've heard for instance that the manned wolf is 60% herbivorous; wikipedia asserts that it is 50%; and I think I've read once speculations in a mail list of paleontologists that small and gracile predators such as the Velociraptor and Troodons, perhaps could have a similar diet.Some of the biggest ones, such as T. rex, in the other hand are proposed by some people to be scavengers to a great extent. ...other possible way to infer that an animal is a carnivore, I think it might not have been mentioned, is the space it has for the gut; meat provides more nourishment, so carnivores need smaller gut to extrect the nutrients. Herbivores also often have multiple stomachs, alongside with larger gut. I'm not sure of how these things stand with reptiles, but the main "rules" are likely the same, and despite of these items not being easily fossilized, the avaliable space probably can be infered in reconstructions. There's also the possibility of eventual exceptional markings of these internal organs. The dentition, however, when avaliable, is probably the strongest indicator of an animal's diet. Danniel Soares > If it is of any consolation, the ecological pyramid logic predicts > that most of the animals will be herbivores anyway. That wouldn't mean [quoted text clipped - 20 lines] > > Danniel Soares Excerpt from Adam's diary, translated by S. Clemens: "She engages herself in many foolish things; among others; to study out why the animals called lions and tigers live on grass and flowers, when, as she says, the sort of teeth they wear would indicate that they were intended to eat each other. This is foolish, because to do that would be to kill each other, and that would introduce what, as I understand, is called "death"; and death, as I have been told, has not yet entered the Park. Which is a pity, on some accounts." >> to those who answered this in the spirit of information sharing, I thank >> you. As to the question which was raised regarding my question: I'm [quoted text clipped - 63 lines] > warblers, and so on starving to death too. Many animals are constructed > so as not to be able to survive as herbivores. And denuded of most plant life by the starving herbivores. >> Thanks again for all of the good, constructive comments. > And denuded of most plant life by the starving herbivores. Maybe most of the plants were carnivorous. > One of the first things I think of is-what about herd culling by natural > predators-similar to the lions of Africa and other present day predators? > Perhaps there were no natural predators at that time-perhaps all dinosaurs > were herbivores instead? I know this is a fundamental question, and I am > sure that it will draw flak by those who would accuse me of being ignorant, > but this is a serious question, and I ask only for serious answers. This is true for a lot of prehistoric animals, including but not exclusive of dinosaurs. 1) Pointy teeth and bulky jaws are extremely suggestive. 2) Sometimes a nearly intact dinosaur skeleton is found with the bones of another animal in the gut position. 3) Sometimes one finds a dinosaur skeleton with tooth marks on the bone, marks that fit the tips of dinosaur skeletons. All circumstantial evidence. I am sure there would be a mistake in a few cases. However, I think there is enough to say that most theropods really ate other dinosaurs. |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.