You claimed that pectoral fins were required, and yet there are fish and non-fish species that swim and don’t have fins.
I made no such claim. I said T rex would be unable to (then modified to have a great deal of difficulty to, which is essentially the same to my mind) swim without having arms (AKA forelimbs). I later explained that this is because a terrestrial tetrapod, especially a large one, would need lift at the front end, both for propulusion and especially to keep its head above water. Various people then tried to make various disclaimers, such as fish being able to swim without having arms, apparently unaware that arms are homologous with pectoral fins. Meanwhile, if you wish to explain how T rex could swim using anguilliform locomotion (which is indeed practiced by limbless vertebrates), please go ahead.
“Fish do indeed have arms, or at least the homologous structures (pectoral fins). They rely on these to provide lift at the front end of the body.”–Pandora
And then later in the post:
A walking motion with the hind limbs would seem to work just fine.
Probably not, given that coelurosaurs generally have relatively inflexible tails and trunks. But I still think that extant coelurosaurs are the best modern analog for tyrannosaurs, and you are still thinking about the way quadrupeds are balanced, not bipedal theropods.
If the walking motion was made with the body horizontal, there’d still be the problem of keeping the head above water. If you’re thinking that it would have the body vertical, then thrusting with the hind legs might keep the head above water, but that wouldn’t work for actually making any forward motion.
Any swimming animal has to be very aware of the problem of drag: and the bigger the animal, the greater the issue with drag. That’s why animals swim with a horizontal body, not a vertical one. A vertical body would present the maximum surface area to the water and make the drag on the body prohibitive for forward motion, especially for an animal the size of T rex. No animal swims that way today, for good reason.
Balance in air is a different matter from thinking about motion in water. I think you’re still thinking that T rex could somehow paddle at the surface, like a duck. To do that, it would have to orientate its head at a 90 degree angle to the body, which I don’t think is possible. Also, the very large head would not make this feasable. Then, there’d be the drag caused by the large tail. Also, only relatively small birds swim this way (nothing the size of an ostrich, for example). Some birds can propel themsevles underwater using just the hind feet, but here I think a large tail would be a problem (and also the body size and the large head would be a problem for T rex).
Vaguely like a crocodile, just worse. Legs hanging along the body in this angle:
Head above water, body probably not fully horizontal, but maybe a 30 degree angle or thereabouts.
there’s a reason why this is a death pose
That’s not an argument at all.
That’s a pretty big assumption. I see no reason why it would be true.
Now that’s an interesting question. I haven’t done any detailed study of the cervical anatomy, but I can see that tyrannosaurs are frequently shown in reconstruction assuming just such a position. Here’s a photo of the tyrannosaur at AMNH:
amnh-tyrannosaurus.pdf (808.1 KB)
Not quite 90 degrees, but close enough, and they aren’t even trying hard.
I don’t find any of those arguments persuasive. What’s the problem with a large head except balance? How does drag prevent swimming? And do you even know how an ostrich would swim?
I’m talking about swimming on the suface. Pretty much all birds that swim on the surface (again except for penguins) use their feet to paddle.
Big, heavy head. Front end of body needs lift in water.
Why wouldn’t it have the necessary lift near the head? Elphants have big, huge heads and they can swim just fine.
It’s a perfectly good argument. This is a postmortem head position with the head pulled back because of the contraction of the tendons along the neck and the back, not a natural posture. Poor critter probably tried to go for a swim. Either that, or it drowned in The Flood.
2 Likes
They use their front legs, and this argument is about an animal that has tiny little useless front legs.
Elephants have arms.
I’m sorry but I just don’t see the relevance of any of that to whether it could swim in the way I describe.
Whether it ever adopted that particular death pose posture, or only did it when it died, is totally besides the point I tried to make, which only had to do with the position of the legs in relation to the body angle.
Lift can be provided by angling the body slightly upwards and generating thrust with the tail or legs. Kinda like this.
I just don’t see the problem you do.
After a glass of some good Kentucky bourbon, I can imagine our dolphin overlords in a few million years unearthing a well-preserved human specimen and chuckling at someone’s proposition that this animal might actually swim. The size and position of the head, especially the nostrils. No obvious means of locomotion in bodies of water (webbing, a long tail, flippers, or anything).
By dolphin standards, they might indeed have a chuckle. But I suspect that if they understood the versatility of these long arms, they’d say “jeez, I wouldn’t want to swim that way, but I guess it works.”
1 Like