How did apatosaurs avoid predation?

Factual Questions
1

I’ve got problems with apatosaurs (aka brontasaurs), diplodocusii, branchiosaurs and the like. Whereas plant eaters like triceratops, stegosaurs, ankylosaurs and duck-billed dinosaurs were either fast moving or had defensive weaponry, the big, fat, long-necked, long-tauled apatosaurs and their ilk had diddly. They look like they were designed by carnovores to be well-stocked (with flesh), slow-moving, defenseless, preshistoric convenience stores.

I am familiar with the notion that they defended themselves against predators with their tails. I think this might have worked against the smaller ones, but I see a tyrannosaur, spinosaur or pack of allosaurs being fast and agile enough to avoid the tail while being big enough to make short work of the apatosaurs’ exposed flank.

I can’t see these animals surviving long enough to show up in the fossil record in any quantity with large predators around, but the fossil record makes clear – they were very successful species.

I just don’t see how the hell that happened. Anybody got any ideas?

2

Well, shear size makes them difficult to attack, plus there tails could probably move much faster than your realize - some researchs calculate the tip of the tail would be moving supersonic
http://www.sciencenews.org/20000318/mathtrek.asp

3

Also, remember that they were pack animals and they could rise up on their hind legs (supposedly) for brief stretches. At least long enough to threaten crushing whatever predator was coming along.

4

Drat. Forgot to say this. Most predators don’t like to work that hard for their meal. So, an apatosaurus herd would likely have one or two elderly or sickly members that would be much easier to take down. Predators would go after the sicker, older animals just because it was easier. And they got just as much meat off of it, so it’s not like they had to kill lots of apatosaurs at a time to keep full. So why bother with the younger ones and risk death when you can just take down an easier target?

5

They lived in groups. Sure, if you’re a T. Rex you can kill one, but when you do, another one sits on you.

Predators don’t like to kill things where they’d get killed back.

6

It had been my understanding one of the defenses for such large herbivores was that they spent much of their time in the water. Similar behavior is seen today with animals such as hippopotamuses.

However, in my search for a cite for this, I’ve discovered that this idea is out of favor, as water pressure would prevent the animal from breathing.

http://216.239.53.100/search?q=cache:y8PLFLJFxRAC:www.4to40.com/earth/geography/htm/prehistoricanimalsindex.asp%3Fcounter%3D1+apatosaurus+water&hl=en&ie=UTF-8

7

Hippos are very formidable animals in or out of the water
so I doubt your analagy to be all that applicable here.

Certainly the juveniles might be taken by a predator, as many other juveniles of many species are but the adults are a differant matter.

8

Just to be clear, of the animals you mentioned there, the only one that would likely have gone after Apatosaurus would have been Allosaurus. Tyrannosaurus and Spinosaurus were both Cretaceous critters, and Spinosaurus was thought to have dined on fish anyway (don’t believe everything you’ve seen in Jurassic Park - for that matter, don’t believe anything you’ve seen in Jurassic Park…).

As others have mentioned, being big is quite enough defense. Predators have a hard job to do, in that they have to find, attack, and kill their prey, all without getting themselves killed in the process. Even without whip-like tails, many sauropods simply had their weight to throw around. Just giving a good smack to a bipedal theropod with one’s neck (or any other body part) could knock it over. Falling, as big as the predators themselves were, could present a real danger, but being trampled once down would have been even worse. Think about how you might fare against a Sumo wrestler, and you can get a good idea why messing with something much larger than yourself (assuming the OP isn’t a Sumo wrestler himrself…) probably isn’t a good idea, even if you do have the tooth-and-claw advantage.

Note that biggness wasn’t a ploy only used by dinosaurs. Mammals had some big brutes as well, after the dinosaurs shuffled off their mortal coils. See Indricotherium, for an example.

9

I’ll bet they still had pretty shitty existences. A lot of the small-to-mid sized carivores look like they had jaws good enough for a bite-and-run attack even on an apatosaur’s tough hide. In the water, there were probably creatures analogous to the fin-nipping species of piranhas.

And if you’ve ever read Brian Aldiss’ “Poor Little Warrior!” you can probably imagine what sorts of parasites were living in an apatosaur’s hard-to-reach areas. I’ll bet each one of 'em played host to a cast of thousands of smaller, highly annoying, creatures.

10

As an example, look at Bison or Water Buffalo. They may not look it, but the huge muscle and mass of these creatures makes them immune to normal predation as adults. Only and insane lion or tiger or wolf would go toe to toe with an adult specimen.

11

Would a typical carnosaur’s teeth even been able to get a purchase on something that big? I mean, try biting a wall some time. You might be able to push your teeth against it, but you can’t get the leverage to really bite down. It seems to me that an apatosaurus would present a similar obstacle to an allosaurus.

12

I’ve tried to picture these strategies and how they’d work and they just don’t make sense to me. Sure, apatosaurs were a LOT larger than carnivores of the time. But they were also a lot bulkier and slower than same. If you’ll look at their body plan, it’s a lot like an elephant’s body plan. Elephants are hardly the most agile creatures on the veldt, and you have to figure that apatosaurs, approaching the inverse square law as they do, would be even slower and less agile.

What’s more, the top carnivores of the day were a lot closer in size to the apatosaurs than the top carnivores are to our largest plant eaters, the elephants. I’ve assembled a few facts along these lines:

Apatosaur: weight, 30 tons – height, 20 feet – length, 85 feet
Tyrannosaur: weight, 7 tons – height, 23 feet – length, 50 feet
Allosaur: weight, 4 tons – height, 16 feet – length, 39 feet

Let’s compare our largest land herbivore with the top carnivore in its area, the African elephant and the African lion:

Elephant: weight, 7 tons – height, 13 feet at the shoulder – length, 11 feet or more (don’t really have an authoritative source on average length, doesn’t seem important)
Lion – weight, 550 lbs (roughly 1/4 ton), height, 4 feet, length, 8 feet

Do ya see the difference? An apatosaur weighs four times as much as a tyrannosaur and 7.5 times as much as an allosaur. Seems like a lot, but then, an elephant weighs 28 times as much as a lion does. Elephants are a LOT bigger than their top predator, apatosaurs are MUCH closer in size to their top predator.

And you have to figure elephants are a lot faster and more agile than apatosaurs, being so much smaller than they are.

So Im not sure that size is the answer. Sure, an apatosaur might roll over on an allosaure, but I bet allosaurs were plenty fast and agile enough to easily, and I mean VERY easily prevent that from happening.

I don’t think apatosaurs, much less tyrannosaurs, had to work very hard to get a meal off even a healthy adult apatosaur.

I’ve heard the supersonic tail theory, too. It might be the answer, but I’ve still got some questions. Like, if the tail delivered a bone crushing blow at supersonic speeds, what happened to the tail? Wouldn’t it get pretty mangled, too?

Herd defense sounds good, too, but I can’t see apatosaurs standing up to a pack of allosaurs when the allosaurs are such a close match to the apatosaurs in size.

I’m still not convinced.

13

Evil Captor, do lions prey on adult elephants?

14

Sauropod tails, at least in Diplodocus’ case, were too fragile to be whipped around at supersonic velocities. The ends were made of very small (for them), fragile bones. Whipping Allosaurus upside the head with it would be akin to hitting it with a thirty-foot long wet noodle.

15

You apparently missed the part where I mentioned that Tyrannosaurus would not have preyed upon Apatosaurus. Comparing the relative sizes of those two to arrive at some conclusion is pointless. The Allosaurus figure is more reasonable. In which case, you are still looking at a predator which is outmassed by over 7x!

**

Apatosaurs did not “roll over” on their attackers. All they had to do was give them a good bump. Given even a slight bump, what do you think is going to happen when a 30 ton mass hits a 4 ton mass?

**

The numbers aren’t comparable. Even if allosaurs did hunt in packs (for which we have no real evidence, by the way), they still would not hunt in numbers that come close to any typical herbivore herd (and we do have evidence that many sauropods congregated in herds). So, we might have but a few - let’s just say 5, heck, Allosaurus going up against easily 10 or more apatosaurs - the adults of which, I remind you, outweighed the adult allosaurs by over 7 times. Even many of the younger mebers of the herd would probably have weighed as much or more than an adult allosaur. Even with the numbers of allosaurs being on the high end in this example, I cannot fathom what part of attacking such a herd you think would be easy for them.

There’s a reason why the weak and the sick are the most likely to fall to predation, you know. Most animals don’t want to mess with a healthy adult, even if the they are of comparable size. Even the big cats of Africa tend to favor smaller animals, like the Thompson’s Gazelle. Yeah, they might go after weak or sick zebra or wildebeest, but an adult predator doesn’t take on a healthy adult prey animal unless the former is quite desperate.

16

OK, first of all, keep Tyrannosaurus out of this. The two have nothing to do with each other and never co-existed. Keep it to Allosaurus.

Now then, the reason that a healthy Apatosaurus never had to worry about being attacked by an Allosaurus was because of it’s size. While a healthy adult Allosaurus could probably take a healthy adult Apatosaur, it would likely never do so. Remember that predators don’t like to hunt if they can scavenge as it’s much safer. With it’s size, an adult Allosaur probably got most of it’s meals from animals already killed after chasing off the beasties that actually did the killing.

The second reason is that Apatosaurs were herd animals, while Allosaurs were not, so your comment about a pack of Allosaurs has no relevence. So they had both a size and numerical advantage. An Allosaur may have considered taking on an adult Apatosaur one on one, but never one on five or six or ten.

Moreover, within that herd there is probably a sick or elderly Apatosaur. This would be the target for the Allosaur, not the healthy adults. Again, predators are lazy when they can get away with it - so the healthier and more full grown the Apatosaur, the less likely it is that they would be attacked by an Allosaur. Even more so since it was probably mostly juvenile Allosaurs doing the hunting, which makes the size disaparity even greater.

Plus, if the Allosaurs did bring down an Apatosaur, it would suffice not only for that animal, but most of the predators in the area given the size of the dead Apatosaurs.

So the main point is that head to head matchups between a healthy, adult Apatosaurus and a healthy, adult Allosaurus probably almost never happened.

17

Just thought I’d quit lurking and chime in on this one…

These stats are a bit off. Because of their horizontal posture tyrannosaurs would only have been about 15ft high tops, allosaurs around 10 or less. Also the longest known tyrannosaur is only about 43ft long, and the average was in the mid 30ft range.

Also, as has been pointed out tyrannosaurs lived long after apatosaurs were extinct. There were other species of sauropods around in the late Cretaceous (some titanosaur species survived), however these are known to have been at least lightly armored along the back.

Unless they were reinforced by modified scales. Maybe even frayed to deliver more punishment. There’s no evidence for either way for this one. Also some sauropod species (although not diplodocids, which include Apatosaurus) had small bony clubs on their tails, possibly for this purpose.

Again, this is akin to a pack of lions taking on a herd of buffalo or wildebeest. It’s much safer to attack the very young (footprints show juveniles were kept in the center of the herd), the old, or the sick, which would tend to lag behind the main herd. Even a small injury could prove fatal to a predator (severely impairing its hunting ability). Better to play it safe.

18

So people keep saying T. Rex and Apatasaurus. Is it really important? Call it a Titanosaurus, then, against a T. Rex. The Titanosaurus was 40 or so feet long, and in all other respects a run of the mill vegetarian sauropod, and survived alongside T. Rex.

19

[nitpick ]

Not Titanosaurus per se, which lived in India, but the ~70ft titanosaur Alamosaurus would have coexisted with T.rex.

[/nitpick]

20

Well, yeah. Otherwise, you might as well be asking how kangaroos defend themselves from jaguars.