There are a number of reasons why ostriches are a better analogy, actually (at least for me). First, they are not extinct It’s usually easier to watch living critters do things like stand up than extinct ones.
Second, they (ostriches) are the largest living flightless birds, so they are currently the biggest critter going that might have had some of the same problems T. rex did.
Third, most people are more familiar with ostriches than moas.
Really, though, any large flightless bird works. The point is, wings or no, these animals don’t need their forearms to stand up.
Omnivores…all Onmivores…are scavengers when they can be and predators when they have to be. That solves the great T-Rex quandry so Jack Horner (and this is the correct spelling) can stop worrying about it. This also applies to rats, which hunt bugs and whatever else they can catch when the peanut butter supply runs low.
What did T-Rex do with it’s forearms? Well the arms served some purpose, else they would not have been there. Delicate slicing and dicing seems logical, but the real answer is “whatever it wanted to”. The same question may be asked of the forelegs of Kangaroos.
T-Rex couldn’t run?!?!?!? Don’t even bother to start that with me. Want an example of an omnivore that can’t run? A tortoise. But a T-Rex is a big raptor. You can study raptor behavior all you want by watching Mynah birds. Or watching Roadrunners catch rattlesnakes. Or watching women/men plot to catch a rich husband/wife. Watch how I handle it if a cute, rich, intelligent, single female over 45 responds to this post.
[QUOTE]
**
Omnivores…all Onmivores…are scavengers when they can be and predators when they have to be. That solves the great T-Rex quandry so Jack Horner (and this is the correct spelling) can stop worrying about it. This also applies to rats, which hunt bugs and whatever else they can catch when the peanut butter supply runs low.
**
[QUOTE]
T. rex was not an omnivore. It was a carnivore. So, this solves nothing (and, btw, ‘Jack’ is a nickname - his real name is John Horner).
[QUOTE]
**
What did T-Rex do with it’s forearms? Well the arms served some purpose, else they would not have been there. Delicate slicing and dicing seems logical, but the real answer is “whatever it wanted to”. The same question may be asked of the forelegs of Kangaroos.
**
[QUOTE]
That is a classic Functional Morphology Purist response, but hardly an accurate one. Natural selection works to eliminate those characteristics which reduce an organism’s ability to pass on its genes to the next generation. It does not operate to eliminate ‘excess baggage’. The reality is the arms did not have a specific function, as many seem to think. They were (relatively) small and had only two fingers each, which severely limits what they could be used for. They certainly did not hang limply, since they had sufficient musculature to be as useful as they could be, considering their size.
The moral is, T. rex’s arms did not necessarily ** serve a purpose**, but rather were used for whatever was within their ability, be it grabbing something that they could reach, picking teeth if the animal’s neck was sufficiently flexible, scratching anything within reach, balance, or giving other dinosaurs a ‘two-fingered salute’.
Also, a kangaroo uses its front limbs for locomotion, and manipulating things, just like most animals. Granted, they aren’t the primary means of locomotion, but have you ever seen one graze?
Again, T. rex was not an omnivore. Nor was T. rex a big raptor. Raptor (and here I mean ‘bird of prey’, not Crichton’s bastardization of the term to mean ‘dromaeosaur’) behavior is very different - T. rex did not have much opportunity to swoop down on its prey, for example.
Geeeez, Mauve Dog, chill out. This isn’t my Doctoral thesis…I’m done with that, so grant me a little latitude. I identified T.rex as an omnivore, informally, because, like all other carnivores, it did not necessarily live on a strict flesh diet and would scavenge when it could. See, if it was a CARNIVORE, it had to hunt. Then Jack Horner (and I meant his last name…it was spelled incorrectly in a previous message) would have to regroup. I was giving him the benefit of the doubt, even though he is probably wrong on this particular subject.
Maybe we need to agree on what a carnivore is. How about a cat? The LA Museum of Natural History says:
“Cats belong to the family Felidae within the order Carnivora, a diverse group of meat-eating mammals. Like all mammals (ourselves included), cats have hair and nurse their live-born young.
All cats are hunters. They have large, forward-facing eyes, excellent hearing, sharp teeth, and strong limbs armed with sharp claws for catching prey.”
BUT WAIT! I am sitting here right now watching several cats chow down on some avocadoes that fell out of the tree. And I have seen these cats…heck, I have seen thousands of cats, dogs, birds, lizards, bears, wasps, wallabies and turtles eat other scavenged food. Like dog biscuits, peanut butter, cat chow (pellets), cheetos, pizza, mushrooms, greens, milk, rice, (none of them exploded) popcorn, tomatoes and numerous other items that (1) they did not have to hunt and (2) was not meat. So don’t chastize me that ANY carnivore is (or ever was) a STRICT carnivore. You received an inadequate education on the subject if you believe that. Or else you don’t have a window in your cell (joke).
Oh…when I said raptor, I meant raptor. My definition allows strictly CARNIVOROUS birds to coexist on the evolutionary ladder along with OMNIVOROUS birds in a line from (something like) a Velociraptor (Dromaeosauridae).
If you want to debate this from either a strictly scientific or a less formal viewpoint, or even if you just want to play semantics some more, I will be happy to accomodate you as soon as I chase down one of these cats for dinner (another joke).
[sidetrack]
My objection to the use of ‘omnivore’ has nothing to do with scavenging. An omnivorous animal is one who eats both animal and vegetable matter. Bears, for example, are omnivores. T. rex was a carnivore (not to be confused with a Carnivore…), which means, of course, that it ate meat. It may have killed to get this meat, or it may have scavenged it. But it still ate meat, not ferns.
Mammals are not good examples of what a ‘proper’ carnivore eats. Mammalian carnivores have different teeth which allow them to eat vegetable matter if they had to (though most wouldn’t survive long on a purely vegetarian diet). Therapods did not have such differentiated teeth, thus were far more specialized in terms of diet.
[/sidetrack]
I am …aghast :eek:
Where to begin… OK, how about here: ‘carnivorae’ is not a natural group, thus has no defining characteristics. No, wait. That discussion would get too complicated.
How about this: carnivores are defined as critters who eat other critters. These critters are many and varied, and belong to many groups. ‘Carinvora’ specifically refers to a group of mammals, all of which are primarily carnivorous (or at least, descend from primarily carnivorous ancestors). What ‘defines’ carnivores is the fact that they eat meat, not how they see! Now, how they eat meat is another thing entirely. Some critters, like turtles and raptorial birds, have beaks. Others, of course, have teeth. The forms of these teeth are dependent on what the animal eats. Meat-eaters will have sharp-edged teeth, because they slice through meat better. Plant-eaters will have flat, ginding teeth or stubby, peg-like teeth. True omnivores typically will have a combination of types. T. rex has only the sharp, serrated, steak-knife-like variety. Therefore, it ate meat.
Now, the binocular vision thing is an adaptation to aid in catching prey, not in eating it. Binocular vision is common (indeed, almost necessary) in chase-and-eat predators. It is not as necessary, however, for ambush predators (crocodiles and snakes, for example). Regardless how you see your prey, though, you still need the teeth to deal with it once (if) you catch it.
One interesting thing to keep in mind is that whether birds evolved from dinos or something else, they did not evolve from pterodactyls. Moreover, they neither evolved into or from bats. Therefore, as far as we know, the ability to fly, the greatest of all abilities, has evolved not once, not twice, but at least four completely seperate times - among the pterodons, the birds, the bats, and the insects. I find that quite fascinating.
Hey there all. I know it’s been a while since I posted but I’ve been pretty busy. As have you guys. Some very good discussion going on. Anyway I read the article: http://www.washingtonpost.com/wp-dyn/articles/A44866-2000Jun22.html
on the feathered lizard that was found. Stark found a good reference here. By the way, thanks for welcoming me. For those that haven’t checked it out you should give it a read. While this fossil is being wildly dismissed in the scientific community (from the sounds of the article anyway) I think it sounds like it could open many interesting doors. But one point the article raised really intriqued me: there is a large assumption on the parts on scientist that feathers = flight. Well, we know that isn’t true, even in the bird family. And the article goes to show that this fossil doesn’t have the correct spine for flight. This leads me to two possible conclusions:
This is the anscestor of modern birds but it’s descendents developed flight somewhere down the line. Hence, birds are not descended from dinosaurs, etc.
(and I think this might be closer to the truth) birds and their descendents are not the only past animals to have had feathers. Could this species have died off and dinosaurs are the actual anscestors of birds. Maybe their was a different species of “birds” all together that did not the best features for survival. But dinosaurs flourished but then had to adapt different features to survive. Anyway, I’m just hypothesizing here. It’s been a while since I read any Darwin. But this is the point that I was trying to make in my last post: the T-Rex, while finding scavenging suitable may have evolved in to an animal of a different terrain all together to scavenge more easily (please pardon the grammar but I didn’t know how else to phrase it). Anyway, this brings me to my next point. I mentioned raccoons and rats. True, as stated in another post, they don’t just scavenged. True, I have lived in the city for quite a while (used to live in the country). But doesn’t this show that raccoons and rats have adapted. They scavenge way more now because that food source is more readily available. Animals adapt and even evolve. Well, that’s all the ideas I have for now. I know some of them are going to make some people think I’m an idiot, but that’s okay. Later all.
And at least twice among the insects. Dragonflies are unique. But the ability to fly is not the greatest ability in my opinion. I can fly an airplane. And I SCUBA dive professionally, which is what flying must feel like. I would guess that ratiocination is the greatest ability. Or else the ability to get a date on short notice.
You didn’t mention fish. “Flying” fish don’t actually fly, they glide. But a case can be made that they have ‘wings’ which evolved for that purpose, and they may end up actually flying in another million years.
Micro Furry:
I reeeaaalllly hate to do this, but…
The correct name for the group you refer to is pterosaurs. Both Pterodactyl and Pteranodon are species of pterosaur.
Sorry, but I wouldn’t want tcburnett to think I was just picking on him
And I think it would be better said that flight is perhaps the greatest of locomotor abilities. As tcburnett states, “ratiocination” is a pretty handy ability
silent_rob:
Actually, it’s not so much that scientists (most, anyway) equate feathers with flight. Everyone pretty much agrees that feathers evolved for another purpose, most likely insulation, before being co-opted for flight.
What this Longisquamus specimen brings up is, as you stated, either this is the ‘most recent ancestor’ of birds (I think not), or that feathers have evolved multiple times, just like flight. Of course, these may not even be feathers, as some scientist have pointed out.
However, if these are feathers, it still means we have to re-evaluate birds. For one thing, it is a diagnostic characteristic that birds have feathers. So, if this critter has feathers, but isn’t a bird, we need a new definition of just what a bird is!
I’m not exactly sure what you mean by this. T. rex was pretty much the end of the line for its lineage. Who knows what might have happened to tyrannosaurs if Mr. Asteroid hadn’t interfered, but birds and T. rex co-existed.
Heheh, valid correction call on the pterosaur thing. But while ratiocination is a pretty nifty ability (not to mention the only word I’ve had to look up in quite a while) I still say flying is better. Of course, the ability to change one’s size would be the best… but that’s probably apparent from my appellation.
Micro, it looks to me like you have plagiarized Unca Cecil’s work from page 216 of “Triumph of the Straight Dope”, and I fell for it, having been only at page 110 when I replied to you…Naughty, Naughty! But why the moderators didn’t swoop on it is beyond me. Aren’t all of Unca Cecil’s books required reading there just as they are in my home?
Mauve Dog: “For one thing, it is a diagnostic characteristic that birds have feathers. So, if this critter has feathers, but isn’t a bird, we need a new definition of just what a bird is! I’m not exactly sure what you mean by this. T. rex was pretty much the end of the line for its lineage. Who knows what might have happened to tyrannosaurs if Mr. Asteroid hadn’t interfered, but birds and T. rex co-existed.”
What you bring up about the feathers issue is exactly what I was getting at. Though I must be a little misinformed when it comes to the evolutions of dinosaurs. Though now, looking back at what I wrote, I should have said “the descendents” of the T-Rex instead of what it evolved into. I’ve read that the canary is a descendent of the the T-Rex. Though since the canary doesn’t look much like the T-Rex I just assumed that some evolving had happened. I might be totally off-base there. I’m not sure what you meant by the Mr. Asteroid comment. The T-Rex existed in the Cretaceous period. But many believe that it could have lived as long as 85 million years ago (the start of the period). That’s a full 20 million years before the asteroid or whatever it may have been. Could the T-Rex have had cousins similar to it or could off-shoots of it formed in that time? While it’s true a large amount of the world population went extinct, actually only about 60% did so. This is nothing compared to what happened later in the Mesezoic and Paleozoic Eras when the Ice-Age occurred and wiped out 90% of the Earth’s species. The dinosaurs were not really involved in that though. Anyway back to the dinosaur extinction. Mammals and many other non-dinos were not effected by the K-T extinction of the dinosaurs. Basically, what I mean is maybe the cousins of the T-Rex survived. Though the asteroid theory is still only a hypothesis. Also, scientists are not totally sure if that wiped out the dinosaurs or just weakened them. Even many of the asteroid theorists now think that the asteroid was actually several asteroids. Though I know this is somewhat long-winded, oh well. Later all.
Mauve Dog: “For one thing, it is a diagnostic characteristic that birds have feathers. So, if this critter has feathers, but isn’t a bird, we need a new definition of just what a bird is! I’m not exactly sure what you mean by this [the T-Rex evolving into bird comment]. T. rex was pretty much the end of the line for its lineage. Who knows what might have happened to tyrannosaurs if Mr. Asteroid hadn’t interfered, but birds and T. rex co-existed.”
What you bring up about the feathers issue is exactly what I was getting at. Though I must be a little misinformed when it comes to the evolutions of dinosaurs. Though now, looking back at what I wrote, I should have said “the descendents” of the T-Rex instead of what it evolved into. I’ve read that the canary is a descendent of the the T-Rex. Though since the canary doesn’t look much like the T-Rex I just assumed that some evolving had happened. I might be totally off-base there. I’m not sure what you meant by the Mr. Asteroid comment. The T-Rex existed in the Cretaceous period. But many believe that it could have lived as long as 85 million years ago (the start of the period). That’s a full 20 million years before the asteroid or whatever it may have been. Could the T-Rex have had cousins similar to it or could off-shoots of it formed in that time? While it’s true a large amount of the world population went extinct, actually only about 60% did so. This is nothing compared to what happened later in the Mesezoic and Paleozoic Eras when the Ice-Age occurred and wiped out 90% of the Earth’s species. The dinosaurs were not really involved in that though. Anyway back to the dinosaur extinction. Mammals and many other non-dinos were not effected by the K-T extinction of the dinosaurs. Basically, what I mean is maybe the cousins of the T-Rex survived. Though the asteroid theory is still only a hypothesis. Also, scientists are not totally sure if that wiped out the dinosaurs or just weakened them. Even many of the asteroid theorists now think that the asteroid was actually several asteroids. This sounds a little off topic but it all comes around to what I was saying about T-rex evolving into a scavenger. Though I know this is somewhat long-winded but oh well. Later all.
The canary is not a descendent of T. rex. Nor is any other bird, for that matter. What I meant by the ‘end of the line’ comment is that T. rex was, well, the end of its line.
Birds are believed to have evolved from dinosaurs most similar to Dromaeosaurs (Velociraptor, Deinonychus, etc.). These creatures surfaced during the Jurassic, and some believe that birds may have even evolved during the Triassic. T. rex was a Cretaceous invention. If anything, T. rex and birds are cousins.
Actually, all I meant was that if the dinosaurs hadn’t died out, who knows what T. rex’s descendents might have been…
Absolutely! Tarbosaurus, Nanotyrannus, Daspletosaurus, to name a few, are closesly related (and, in fact, are considered ‘Tyrannosaurids’).
Keep in mind that it wasn’t just dinosaurs that disappeared during the K-T ‘event’. Pterosaurs and the rest of the marine reptiles (mosasaurs and plesiosaurs) died out as well, just to name a few.
If by ‘cousins’ you mean ‘birds’, sure!
As for the asteroid theory…well, everything in science is ‘only a [theory].’
It’s usually easier to watch living critters do things like stand up than extinct ones.
Of course, the ability to change one’s size would be the best… but that’s probably apparent from my appellation. 