Rearing Sauropods

[andrewsaurus rex]

does anyone know of a reference that lists the sauropod species that are thought to have been able to rear up on their back legs.  I know of a couple of species but would like to read a comprehensive list, if one exits. 

iirc Brachiosaurs and others like it were not able to rear, which makes sense as their center of gravity would be so far forward.  So, does that mean that all other types of sauropods would be able to rear, or is there more to it then just center of gravity issues? eg hip structure

[Newt]

It seems to be the consensus that diplodocids (and presumably other diplodocoids such as rebacchisaurids and dicraeosaurids), with their rearward center of mass, would have been particularly good at rearing. Jensen, in the description of the camarasaurid Cathetosaurus lewisi, made the case that it was built for rearing to a much greater degree than other sauropods (Cathetosaurus translates more or less to "upright lizard"). Cathetosaurus is not much different from other camarasaurids (in fact, it is usually treated as a species of Camarasaurus) so the same arguments probably apply to the family in general. Check out the paper - it has the most thorough treatment I know of of what you should be looking for in a sauropod adapted for rearing.


A fourth new sauropod dinosaur from the Upper Jurassic of the Colorado Plateau and sauropod bipedalism



I haven't seen much discussion of the rearing capabilities of, for example, titanosaurs, mamenchisaurs, or turiasaurs. They don't look to me like they'd be good at it, but that's not much of an argument. Especially since elephants don't look like they should be good at rearing either, but they go on and do it anyways.

[andrewsaurus rex]

very helpful thanks

this is a topic of much interest to me.  Not only the capability to rear, but the reasons to rear.  Aside from the obvious reaching higher vegetation, other reasons put forward are during intra specific combat and during defense against predators.  I have some reservations about the last two.

Rearing while defending yourself from a theropod (or group thereof) does not seem like a good idea to me.  The front limbs are too high to be of much use, the animal is unable to move around and must stay in place making it easy for predators to attack its rear legs and there would be no ability to use its tail in defence.  However its towering appearance alone may have been enough to frighten off predators.

For intraspecific combat, each animal would be very unstable, with a decent chance one could get knocked over.  A fall like that would undoubtedly kill or very seriously injure.  However, again, the act of rearing alone could look so intimidating that a rival gives up.

It's a possibility that rearing was possible in all sauropods briefly, even brachiosaurs,  for a few seconds, to get a quick bite or scare off a predator.  Prolonged rearing would most likely have been possible in only a few species.

It would have been a magnificent sight to see..

[stargatedalek]

Diplodocids are the main example I'm aware of, with them being specialized at eating from high growing plants despite their low slung posture implying they reared as a primary way of reaching food.

[Halichoeres]

Thanks, Newt, that's a really interesting paper that I hadn't seen before. Paul Sereno also vocally speculated about Jobaria being able to rear based on its limb proportions, but I don't think he ever published anything peer-reviewed on the subject. There was no mention of it in the description, but of course it was published in Science, which doesn't give you much room. (I know it's good for their careers and all, but I wish people wouldn't publish descriptions in Science.)

[andrewsaurus rex]

Diplodocids are the main example I'm aware of, with them being specialized at eating from high growing plants despite their low slung posture implying they reared as a primary way of reaching food.

this comment didn't fully sink in the first time I read it.  How was it determined that Diplodocids were specialized for eating high growing plants?  It does seem an odd adaptation given their low slung stature, but I guess as they were evolving, competition was fierce at lower levels, so a longer neck and the ability to rear up on hind legs became a big advantage.

Lately I've been wondering about the reasons for sauropods rearing up.  I've pretty much concluded it was useless for defense and unlikely for intraspecific combat (but not perhaps for courtship display), so that really just leaves for accessing higher up vegetation...not to sound dismissive of this as it is of course extremely valuable..

[Papi-Anon]

I'm surprised no one mentioned rearing for mating (assuming it was done in such a way that the males reared up to mount their female partner and not another posture/stance).

I'm reminded of the diplodocus mating scene from WWD, but have a difficult time imagining a male brachiosaurus doing so given their natural limb proportions and overall back posture. Unless, of course, mating was done in different bodily positioning than how most of the limbed reptiles do today.

[andrewsaurus rex]

I thought I had mentioned that earlier in this thread but maybe it was another.  I guess it is a form of rearing, at least briefly.  Once the male supports himself on the female's back (presumably) I don't know if it could still be called rearing.  But I really wonder about sauropod mating and how it was done.  It's really a topic for another thread but some sauropods were of such stupendous size, I just can't see it being possible for the male to rear up and rest on the female.

So I wonder if they mated standing, side by side, the male's (self guiding) penis finding its way to the female's cloaca, in a sort of U shaped path.  Alternatively I wonder if sauropods only mated while they were young and still somewhat small.  By the time the grew to be super sized maybe they got too big to mate any longer?  There are problems with that idea too..

At any rate, since Brachiosaurus and indeed most sauropods are not considered to be capable of rearing up, how could the majority of them have mated, as the 'doggy style' position would seem to be out of the question.

[amargasaurus cazaui]

why couldnt the female place herself on the ground level, allowing the male to only need to lower himself in the back to make the good deed work? Surely if a dinosaur can squat to lay eggs, it could squat to make them , right?

I sometimes think of how we learned to gentle horses when I was young...walk them out into a lake, and then slide up on top. The horse wouldnt be able to get decent footing to plunge or buck and the water prevented much kicking or movement.This could also have worked for the sauropods.....

There is some fossil evidence in the form of crushed tail bones to suggest the female was stepped on while breeding as one possible explanation for the damage.

[andrewsaurus rex]

I mentioned somewhere on here (maybe dinosaur mating the nuts and bolts thread) that one possibility for sauropods was the female lying down but I dismissed it because I feel that if a sauropod lay down, it wouldn't be able to get up again.  Maybe that belief is mistaken?

I think with most dinosaur mating it's likely that the female lay down, like female ostriches do, not on their side but on their belly.  Certainly I strongly believe that bipedal dinosaurs would have mated this way as anything else is unstable  eg standing pseudo doggy style.   Ceratopsisans I envision mating like rhinos, only with the male not directly behind the female but at an angle to her.  Stegosaurs and ankylosaurs I am not really sure.......stegosaurs with female lying on her side?  Ankylosaurs.....no idea. 

If a female sauropod could lie down then that is for sure the way I would imagine it was done.......I just have my doubts an animal that large could get up again.  Even bovines if they lie for too long have great difficulty getting up....I imagine it would be much more difficult for a 30, 40, 50 tonne sauropod.  The other problem with large animals lying down is that their body weight pressing against the ground can cause tissue damage, muscle damage, blood clots and even damage to internal organs.

[andrewsaurus rex]

I watched the Prehistoric Planet clip of the Dreadnoughtus fight.  Interesting but i'm skeptical.  First off, there was the obvious error of Dread not having thumb claws, but that was due to that information not being known at the time of production.  That they swung and bashed their necks together has me really wondering.   Sauropod necks are lightly built and full of air sacs......whacking them together does not seem like something either animal would be wiling to do and could well result in serious injury to both.  So that leaves the raking of the teeth on the underside of the opponent's neck.  Seems reasonable, but given the other two fighting options are not possible or not likely, just doing the teeth thing as a fight is kinda goofy. 

IF Dread reared to fight, and that is a big if in my mind, I think the most likely form of combat would simply be pushing against each other, trying to knock the other one down, sort of like a couple of Sumos.  That would almost certainly result in the loser being killed or seriously injured every time.

But I really feel rearing up for combat was unlikely.  Both animals would be very unstable and it would be an awkward way to assert dominance.  I think rearing would have been limited to food gathering and perhaps sexual display, to show yourself off to the ladies..

[Newt]

Apatosaurus and Brontosaurus seem to have adaptations for neck combat, including wider cervical vertebrae and absolutely massive and low-hanging cervical ribs which would protect the delicate soft tissues of the throat. Other sauropods lack these features, so it would be more dangerous for them to engage in such behaviors. Which doesn't mean it didn't happen - lethal combat does occur in modern animals. I don't know why they would need to rear up to smash their necks together, though; it seems to me that the combatants having their forelimbs on the ground would give them better leverage and balance.

[stargatedalek]

Diplodocids are the main example I'm aware of, with them being specialized at eating from high growing plants despite their low slung posture implying they reared as a primary way of reaching food.

this comment didn't fully sink in the first time I read it.  How was it determined that Diplodocids were specialized for eating high growing plants?  It does seem an odd adaptation given their low slung stature, but I guess as they were evolving, competition was fierce at lower levels, so a longer neck and the ability to rear up on hind legs became a big advantage.

Lately I've been wondering about the reasons for sauropods rearing up.  I've pretty much concluded it was useless for defense and unlikely for intraspecific combat (but not perhaps for courtship display), so that really just leaves for accessing higher up vegetation...not to sound dismissive of this as it is of course extremely valuable..

I would have to look it up again to be sure, but I believe tooth shape was the main reasoning, not being suited to low growing plants of the region. The hips themselves are built to allow a near vertical alignment of the body, but I don't remember if that's particularly unique to them.