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Re: Great blue heron - Pterosaurs



Richar Travsky wrote:

Not sure I follow this. The crest is a vertical feature. Lift?

>>>A sailboat sail has lift. Perhaps this was applied similarly in
pterosaurs. Jim, hopefully will have more to say on this...

don ohmes wrote:

>  Is the fossil material good enough to determine if sexual dimorphism
> exists in ptero's/ptero crests?


When evolving a large crest a small crest would intuitively precede it
as a transitional step from a no-crest situation. In fact, if you line
up all of the Pteranodons and look at all of the characters elsewhere in
the skull (and postcranially if you've got'em), you'll find a cladogram
going in two, then three directions as one of the branches branches off
again. And the size increases as the crest increases.

Bennett's wide open pelvis, purportedly a female, may not belong to
Pteranodon but to Nyctosaurus. It was found disassociated from cranial
material, from what I gather. One of the most complete Pteranodons, the
Triebold specimen, has a short crest and a small pelvic opening.

We're stymied by a lack of complete material in Pteranodon. Hard to
detect any dimorphism.

On the tapejarid side of the fence, the same story can be told, with
smaller taxa, closer to Germanodactylus, having smaller crests. No clear
dimorphism is apparent here either.

David Peters
St. Louis