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Pack-Hunting Dinosaurs Found As Large As T-Rex
1369IC writes "The Washington Post is reporting that the recently unearthed Mapusaurus roseae was as large as a T-Rex and may have hunted in packs. The fossils were found in Patagonia, in Argentina, though not enough were found to reconstruct an entire specimen. The meat-eaters probably lived in the same time and place as the 125-foot-long Argentinosaurus, the largest known dinosaur." From the article: "T. rex was equipped to attack and destroy animals its own size, Currie said, but Mapusaurs perhaps could 'go in, strike, pull and see what to do next,' a strategy that could work against larger animals, especially if the predators attacked together -- the prehistoric equivalent of a pack of wolves cornering a bison."
This is commonly mentioned on the Science Channel.
The world will not get better through technology. We must seek to be better people.
Yeah, and every woman is equipped to be a hooker. The facts on T-Rex show the animal very unlikely to have been a predator. The general concensus of the predation deissenters is that the T-Rex eyes were small and likely couldn't have seen and tracked prey; the arms were too small to hold prey, and its oversized legs would slow the beast too much to be a decent predator. This last point may not be as important considering some of the larger species couldn't move very fast themselves, but getting big is what species do to avoid predation and we have living examples in elephants, girraffes, rhinoceri, hippopotami and whales.
Furthermore no bones which display healed T-Rex tooth marks have ever been found, and T-Rex was around right up until the little rock slapped this big rock we live on now some 65M years ago.
Given that, I'm loathe to accept some conjecture about some other animal that supposedly lived and hunted in packs based on the spurious evidence of a group of bones comprising many species members and none of which comprise more than 80% of a single animal.
Many elephants go to "elephant graveyards" to die; will scientists in 60 million years stumble across one of these graveyards, see the tusks and the size of the animals and conclude the elephant was a vicious carnivore which hunted in packs? And will that era's Slashdot splash such spurious findings on the front page?
woof.
For more lighthearted biological names that you ever dreamed were possible, check out Curiousities of Biological Nemenclature
My personal favourite (relevent, too!) is "Tyrannasorus rex Ratcliffe and Ocampo, 2001 (Miocene hybosorid scarab from Dominican amber) The dinosaur is spelled Tyrannosaurus." Tyrant King beetle?
of course, biting monkeys is not to everyone's taste - Konrad Lorenz
With a name like that (tyrant king lizard), it wouldn't have been much of a complement.
:-) Such attempts are usually frowned upon -- if they are noticed.
No, it was named by Osborn to be descriptive. There's no requirement that names be descriptive. Naming things after people or places is common, and usually a bit of an honor, although it could be a biological joke to name something after somebody who looks a bit like the creature in question, or name something ugly after someone you don't like
Sometimes fictional names are used, like the fossil snake Monty pythonoides .
Anyway, I prefer, the wooly lemur avahi cleesei, named for John Cleese, and having an ironically funny walk.
One of the clues on fossil skeletons to look for that paleontologists use is healed injuries. If, for instance, you find a smilodon fossil showing that an individual suffered a crippling leg break that had partially healed up (but never fully recovered), you have a strong indication that this animal was probably kept alive by getting food from others as it was most likely incapable of hunting for itself or adequately defending itself. Therefore, it seems more likely that this was not a solo hunter and likely lived in a pack/herd/pride/whatever.
Bones from several specimens were found together, apparently contemporaneous; and no other animals. The supposition is they were together and killed suddenly, perhaps a flood. They wouldn't be socialising unless they had a good reason -- if they were lone hunters or scavengers they would keep well apart and guard theie territories, except in mating. So if they were together, it's at least possible it was because they needed a pack to take down their mega-prey.
[W]hy would T-Rex need such a formidable jaw if it was only scavenging and not killing?
Others have mentioned modern lions, and that could be a partial answer to this question.
Field researchers studying lions have reported that, in many areas, they rarely find instances of lions killing their own prey. Rather, lions mostly steal the prey of smaller predators like hyenas and wild dogs. If you're as big as a lion, that can be an easier way of making a living than hunting and bringing down your own prey. This seems to be especially true of lions in a "pride", typically a group of females plus one male. Individuals (mostly males) need to do more hunting because one lion can't intimidate a pack of canines as easily.
The main problem with such a bandit lifestyle is that you have to be bigger and tougher than your victims. T. rex certainly fits this description.
But we really don't seem to have enough evidence to resolve this question. And, like lions, T. rex may well have used both stategies. If you detect a kill by a smaller predator, you move in and steal a meal. If not, you try to kill your own meal.
But this could be why T. rex had such huge jaws, not for killing prey, but for fighting other smaller predators.
Those who do study history are doomed to stand helplessly by while everyone else repeats it.
[Whoever] proposed that some larger macropredators would have needed to revert from predation to scavenging in adulthood is guilty of dumbassery of the highest order. A very simple counter-example exists. Watch a documentary about a large, muscle-bound, lumbering grizzly bear snatching a leaping fish out of thin air.
Obviously you know very little about predators. First and foremost, grizzlies are not "muscle-bound and lumbering", they are surprisingly quick and agile, and I'm willing to bet your life that you can't outrun one. I've seen film of a grizzly outrunning and catching a young elk. They have excellent reflexes, as evidenced by your fish-snatching example, but what do they catch when the salmon stop running, when the caribou have moved on for the winter, there are no berries or small game available? That's right, like almost all known large terrestrial predators, they revert to scavenging for carrion. Lions do it, wolves do it, eagles do it, they all do it. If it came down to the difference between pungent roadkill and starvation, you'd do it too. Nature isn't some Cordon Bleu restaurant where predators can send back something they don't like; they take what they can when they can get it.
There are schools of thought that believe that very large theropods (T. Rex, Giganotosaurus etc) simply grew too large as adults to be active predators, and subsisted on the colossal carcasses of dead herbivores. Others believe that like many modern predators, their lifestyles were a mixture of active hunting (probably from ambush because an animal that size couldn't sneak up on prey) and scavenging for carrion. They weren't likely to pass up a free meal, particularly when they didn't have to risk life and limb to get it.
The discovery of Mapusaurus roseae is indeed very exciting, because it offers the tantilizing possibility that these very large theropod dinosaurs were pack hunters. Which, if you think about, makes a lot of sense. It doesn't matter how large the predator is, if its prey is that much larger it would make sense that they would cooperate to bring it down. Lions are an excellent example. Young males who have been forced out of their prides are much more likely to survive if two or three of them cooperate and hunt, than if they try to go it alone. The reason is that three lions (there is a lot of evidence that three will do much better than two) have a much better chance of bringing down prey large enough to feed all three well, than a single lion has of catching enough prey to even survive.