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On rearing to mate (was RE: sauropod necks again)

Valla:

You said:
I may be compleatly insane for this, but I can't quite imagine another way
for them to do it, aside from external fertilization which doesn't seem like
it would work well amongst incredibly large land vertebrates.
Any theories? Or is that too bizarre?

Well, I'm not an "expert" by any means on reproduction (take that however you like =) ) but consider the fact that mammals really have nothing in the way of tails. Mammalian tails are not the huge, powerfully muscled tails we find in reptiles, and therefore mating by the male rearing up over on top of the female is not "problematic" in the sense that there is no huge tail in the way.

Furthermore, consider thyreophorans, the armored dinosaurs: stegosaurs with spikes and plates on their backs, ankylosaurs with large armored tails and backs. Did these animals rear to mate? No one, of course, knows the answer to a question like that (yet), but it would be very interesting indeed if they did!

I don't have a source, but I've been told that some cammels have a situation where the female lays sideways on the ground, and the male mates her from above. Maybe sauropods used a system like this? Maybe sauropods used water, and lay side by side with their underbodies facing each other? How did they get their big tails out of the way of their vents? Was there an integumentary structure that allowed sperm to travel to the female's vent from the outside (a modified form of external/internal fertilization)?

It's a fascinating subject, and I know there are paleontologists out there more knowledgeable than I on this subject, but unfortunately we are left with a lot of speculation and very little testability. Bruce Rothschild and David Berman (1991, Fusion of the caudal vertebrae in Late Jurassic sauropods. Journal of Vertebrate Paleontology, 11(1): 29-36) looked at the tail verts of various Jurassic sauropods and noted that about 50% of them had fused tail verts suggestive of sexual differences -- the reasons elude me now as I haven't read the article in quite some time. You may wish to look at that article, though, because if memory serves I think they have other references cited in it that may be of use.

In any case, rearing to mate is not the only option available for dinosaurs to procreate.

Matt Bonnan
Dept Biological Sciences
Northern Illinois University


From: Valla Bernhardt <vbernhardt@dallas.clarkbardes.com>
To: "'mbonnan@hotmail.com'" <mbonnan@hotmail.com>
Subject: RE: sauropod necks again
Date: Fri, 16 Jul 1999 11:28:04 -0500

Firstly, Matt, thanks for once again echoing my skepticism of a scientific
article.  :-)
However, I do have a question....

>> What if Barosaurus didn't rear? Is the mammalian way
> of mating (i.e., rearing up) the only way to mate? <<
>
I may be compleatly insane for this, but I can't quite imagine another way
for them to do it, aside from external fertilization which doesn't seem like
it would work well amongst incredibly large land vertebrates.
Any theories? Or is that too bizarre?

2nd technician val the skeptic
"i admit, i'm obsessed with fonts"
mailto:vbernhardt@clarkbardes.com
mailto:slackerv@flash.net



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