That tripod stance

[MetalAlimon]

Up until a few years ago (not sure how long exactly), I was familiar with the tripod stance (tail dragging on the ground, uprightish posture) and the back parallel to ground one (with the tail held high). I didn't know that the tail dragging posture was wrong.

The reason why is because the bones are not structured to be in that position. If the animal tried to stand that way, they'd break their hips, and that would either kill them instantly or slowly (either throw starvation or predation).

Why did people think dinos dragged their tails? All because of association. At the time, dinosaurs were thought of as big lizards. The name dinosaur means terrible lizard. So people studying them simply assumed they dragged their tails because modern day reptiles do.

However, the lack of drag tail fossilization pointed in a different direction. We ultimately ended up with the position we have now for dinos based on new discoveries and new understanding of their anatomy.

[kor]

I guess part of it may have come from when they first started to find dino fossils and assumed they were large reptiles and hense cold blooded. And some species were put together wrong, and discovered later, or so I read.

[MetalAlimon]

Yeah. One example I can think of is stegosaurus. It used to be portrayed as a large, small headed lizard with plates coating its back like an armory covering and with multiple spikes sticking out evenly across its back. We now know that this portrayal was inaccurate.

[kor]

Another one, forgot which one, the one with a spike for a thumb. I read at first they thought the spike was on the tip of it's muzzle/nose. But later found a near complete skeleton with the spike in the right place.

[MetalAlimon]

I believe that was iguanodon.

[kor]

That's the one. Couldn't quite remember the name of it.

[MetalAlimon]

upload.wikimedia.org/wikipedia/commons/6/6a/Stegosaur.jpg Here's what stegosaurus was originally thought to look like.

[kor]

Thanks for the link. It is interesting to see that & how they thought dinos looked back then.

[MetalAlimon]

This post comes from another board, from an old friend of mine, EbonyPatriot. Since he isn't sure if he'll be able to join or not, I'll add what he had to say about this subject. He's another dinosaur enthusiast.

(If you you don't mind, history of dinosaur exploration is a favorite of mine, so I'd like to comment on one area. :/ The tripod stance actually wasn't from dinosaurs=reptiles, ergo reptiles=guess tail dragged; it was that for I want to say T. rex, they studied the only extant bipedial, long tailed animal, the kangaroo/wallaby which has large hind legs, short forelegs and does use its tail to support its body when resting or in the kangaroo, anything but moving at full speed (hence paws facing down; I know that the paw finding has been scarce and at the time, I don't know if the wrist was preserved; to this day if I recall correctly, even Sue wasn't 100% complete) (see Dinosaurs: A to Z. Some of the first people to study dinosaur tracks, if I recall Bakker correctly, had studied their toe structure and thought the tracks were that of a primitive bird based on how the bones would have to be placed in the foot. Bakker was one of the first to suggest dinosaurs=birds, and it took a while for palentologists to accept that; I think that was roughly late eighties early nineties. One of the leaders of the Natural History Museum, Andrews, helped popularize the dinosaurs as having dragging tails, perhaps based on the trex. Horner talks about this in the preface to In The Presence of Dinosaurs, while a book I have have from I think the late eighties talks about how the focus was on more dinosaurs=bird, although ironically the illustrations weren't very bird like; in addition, that dinosaur book I obsess over, Dinosaurs A to Z, while it's out of date and gets on my nerves from time to time, gives a good overview of the history of dinosaur discovery; in fact, it has pictures of the original model of the dinosaur side by side with skeleton of the wallaby and emu. Even the recent documentary Trex walks again said how difficult it was to try and figure out the movement of an animal with the legs of an emu but pull of a muscular tail like a crocodile. I so want to see that model, it's cool;. D:) The stegosaurus was thought to have its plates horizontal to give it better protection; it was an artist who first suggested that the plates would stand vertical; I don't know the fossil history well enough to know if the later fossils of stegosaurus supported the artist or not. :/ Iguanadon was that only a few of its bones were found and based on how the bones were similar to an iguana, it was thought to have a similar structure. Later many iguanadon fossils were found in a coal mine that were more intact so that the thumb spike was placed on the right spot. Still later it was argued that the iguanadon was a quadreped)

For a time, it wasn't even known if dinosaurs laid eggs or gave birth until eggs were found; coelphysis in fact, was at first thought to be that dinosaurs gave birth. I think maiasaurus was the first that had suggestions that dinosaur cared for their young.

[kor]

That is interesting.

[jansenov]

People suspected the tripod stance is wrong for some time.
But years passed until the tripod stance has finally been abandoned, thanks to computer simulations which showed the parallel-with-ground posture is the one where the dinosaur body can exercise the greatest power, where the muscles will be best used. It's just like the two-legged upright stance for humans.
Sure we can walk on all fours, but that way we exhaust the weak arm muscles, and the strong leg muscles remain underused.

A tripod stance for dinosaurs would mean the huge muscles of the tail would be used for nothing most of the time. A huge waste.