Ask Experts Questions for FREE Help !
    petesauber's Avatar
    petesauber Posts: 2, Reputation: 1
    New Member

    Dec 9, 2011, 04:31 PM
    Why do we currently have no fossils of four-legged carnivorous dinosaurs?
    First of all, I am only asking this question about true dinosaurs. I am aware of, but not asking about: Pelycosaurs, which lived before the dinosaurs; or Crocodilians, which lived before, with, and after them, etc... It seems that every purely carnivorous dinosaur fossil we have found has been a two-legged Therapod. We have found bipedal herbivorous dinosaurs, but no quadrupedal carnosaurs. Is there a theory as to a reason behind this? Were Therapods simply first and "guarded their niche" successfully, or is there a good reason why a quadrupedal carnosaur wouldn't be successful. Or, is it simply that we haven't found their fossils yet?
    ebaines's Avatar
    ebaines Posts: 12,132, Reputation: 1307

    Dec 16, 2011, 10:58 AM
    This question has been languishing a bit without response, and while I am not an expert on this topic I thought I'd offer a conjecture. I find it really interesting that ALL dinosaur carnivores known to date were bipedal (theropods), and ALL dinosaur herbivores known to date walked on 4 legs. I didn't know that prior to this post, so thanks for raising the question. Much has been written about the supposed advantages for predators who can stand upright and use their forelimbs (arms?) to grab and tear at prey. But by that same reasoning why don't mammal predators like lions and wolves stand on two legs? There really aren't any mammal predators who are bipedal - except man.

    I am guessing that the difference is in the nature of the prey. Lions, cheetahs, wolves, etc typically hunt very fast animals like gazelle and deer. They have to run fast enough to catch such prey, and animals with four legs are typically much faster than those with two. But the prey for dinosaurs were much larger, and I suspect slower, so speed of the predator was less important. And to attack a large dinosaur there is advantage in being able to grab and hold on with fore limbs. So perhaps the answer is in the differences between the speed of the prey, and their size? Again, just a guess.
    petesauber's Avatar
    petesauber Posts: 2, Reputation: 1
    New Member

    Dec 16, 2011, 12:13 PM
    Not ALL herbivores found have been bipedal, that's kind of my point: We have found both quadrupedal & bipedal herbivores, but only bipedal therapod carnivores.

    Also, as we have seen from human hunters, bipedal locomotion is more energy efficient over long distances than quadrupedal. Many humans used to (and the Bushmen of the Kalahari still do) hunt by the "persistience" method: they run down (chase) a quadruped until the animal collapses from exhaustion.
    blaydelk's Avatar
    blaydelk Posts: 3, Reputation: 1
    New Member

    Jun 12, 2012, 03:30 PM
    I think I found part of your answer, I am providing a link:

    My thoughts are also conjecture.

    Look at the tree, dinosaurs diverged from mammals at a common ancestor and it appears that the bipedal dinosaurs diverged again. I think your question is interesting and it makes me ask why we really don't see bipedal mammalian carnivores, the upright posture could have diverged for mammals as well. I suspect it has something to do with protecting the uterus, imagine a pregnant female lion running on her hind legs as a buffalo rammed her gut. Lions also use leverage to pull prey down by the neck and it seems that dinosaur carnivores may have picked their prey apart using their hind legs and teeth (beak) more like a bird of prey, which would leave them far more vulnerable since they have paws rather than talons.
    weemart's Avatar
    weemart Posts: 1, Reputation: 1
    New Member

    Jun 17, 2013, 08:13 PM
    I think it's most likely to do with speed. Although elephants can move fast, they can't actually run. Since in order to run an animal must lift all it's feet off the ground simultaneously and elephants always keep 1 foot on the ground they don't actually run.

    So assuming the large 4-legged dinosaurs couldn't run, this would give 2-legged carnivores an advantage in that they would be faster than the 4-legged herbivores. A 4-legged large carnivore would therefore not have this advantage so it's unlikely they would have evolved.

    Just my thoughts.

Not your question? Ask your question View similar questions


Question Tools Search this Question
Search this Question:

Advanced Search

Add your answer here.

Check out some similar questions!

Are these fossils? [ 2 Answers ]

These forms in a polished limestone that is used in building Yfrog - fossil11 - Uploaded by ezrahi Could they be fossils or just casual paterns in the stone? To MACROIDEAL I've tried the links and the picture opens. ...

What is the difference between 10 legged and 8 legged spiders [ 5 Answers ]

Large brown spider, 2 white stripes on back , 8 legged. Sometimes they will jump at you. They have invaded my house. Are they poisionous? How can I safely get rid of them? I would like them outside, way outside.

Dinosaur fossils? [ 5 Answers ]

Are dinosaur bones discovered as fossils? If yes,could you please link me so I can read up on it. Thank you in advance for all your help.:)

Carnivorous plant terrarium [ 3 Answers ]

Hello, I want to make a carnivorous plants terrarium. Im interested in finding glass globes or hi-tech looking recipients or odd shape glass recipients to give them a dramatic futuristic there a web site or advise on where could I find these? I think that they could be turn into art pieces...

Insect Fossils [ 1 Answers ]

What is the largest insect fossil ever found?

View more questions Search