Live Science on Spinosaurus

Adam Khor

The parts that caught my eye are these:

The dinosaur's upper spine was fairly flexible and its vertebrae had ball-and-socket joints, so it was likely able to arch its back to a point and may have been able to spread the sail when threatened or looking to attract a mate.

the dinosaur appeared to be twice its size when the sail was fully extended

Makes it sound as if it could extend its sail like a sailfish or something. Did I misunderstand it? Anyone knows anything about this? I've honestly imagined the sail as being foldable but I didn´t think there was any evidence of it, I thought it was just flight of fancy of mine...

Galvasean

First I've heard of it being able to fold its sail.
Got a link to the article Adam? I was just on their 'Dinosaurs' page and saw nothing about Spinosaurus.

Adam Khor

...:eek:

Ok, this is scary and I think it may have something to do with lack of sleep XD

Sorry, it was not Discovery News, it was Live Science, and here's the link I somehow forgot how to post.

http://www.livescience.com/24120-spinosaurus.html

Mea culpa mea culpa!

Also, doing some more reading it appears that this idea comes from a paleontologist named George Olshevsky. He claims to have written a paper on this but it hasn´t been published yet, to my knowledge at least.

Galvasean

Ball and socket joints they say? Now that's interesting. You'd think something like that would have been quite obvious and noticed before.

Owryan

Given that only very partial sets of remains have been found (so i am led to believe) and one set is of the jaw then there would be very little real evidence for how "spiny" looked and most of what we believe is purely conjecture ?

The linked article also refers to the detailed notes made about the german speciman , so surely ball and socket joints would ve been worth a mention .

Adam Khor

According to Wikipedia, there are remains of at least six individuals known, but most of them seem to be jaw and skull material all right... There's rumors of the hind legs having been found recently and they are supossedly much shorter than expected, but not much has been said about it. (Damn paleontologists keeping all the juicy bits for themselves!).

Apparently, the ball-and-socket vertebrae are also found in some other theropods, but this doesn´t necessarily mean Olshevsky's idea is wrong.

It also appears that Spinosaurus' spines were quite a bit different from those of Acrocanthosaurus, Altispinax/Becklespinax and other "sailed" dinos which probably had more of a ridge or hump rather than a true sail.

Ziphius

I think the ball and socket joints are between the vertebrae rather than between the spines and the vertebrae. This is the case in neck vertebrae in giraffes today.

The spines in Spinosaurus are, as far as I know, extensions of vertebrae.
See this picture from wikipeida.
http://upload.wikimedia.org/wikipedia/en/b/bd/Spinosaurus_vertebrae.png

Ball and socket joints would provide some extra flexibility in the spine and if the animal arched its back, I guess, the spines and sail would fan out a bit. I don't see how the entire structure could be folded down though.

Adam Khor

Ziphius wrote: »

I think the ball and socket joints are between the vertebrae rather than between the spines and the vertebrae. This is the case in neck vertebrae in giraffes today.

The spines in Spinosaurus are, as far as I know, extensions of vertebrae.
See this picture from wikipeida.
http://upload.wikimedia.org/wikipedia/en/b/bd/Spinosaurus_vertebrae.png

Ball and socket joints would provide some extra flexibility in the spine and if the animal arched its back, I guess, the spines and sail would fan out a bit. I don't see how the entire structure could be folded down though.

Yeah, it is between the vertebrae. It seems the spines were fixed...

I wonder if it was the same with Dimetrodon or Platyhystrix: