Re: Spinosaurus aegyptiacus holotype

["Mickey Mortimer" <Mickey_Mortimer111@msn.com>]

Jaime Headden wrote-

>   Though it may not have been "immature," as even in some birds and
> mammals, adulthood and maturity is still known with open neurocentral
> sutures. SOME of the dorsals and the cervicals shown closed neurocentral
> sutures.

Do you have some references for this?

> <I don't see why people ignore Spinosaurus' size, or claim it's uncertain
> that it was larger than Tyrannosaurus.  Dorsal central length is one of
> the best indicators of total length, and Spinosaurus' were HUGE.>
>
>   Though the centra are fairly long, note that in *Tyrannosaurus,*
> cervical count is lower than in, say, *Dilophosaurus.* Dorsal and
> cervical, as well as caudal counts, vary among species, and the estimates
> should account for this, as well as that the vertebral counts in
> *Baryonyx,* the most complete relative of *Spinosaurus,* is unknown. But
> yes, Mickey's estimates take into account what would happen if you scaled
> up *Baryonyx* up, and expanded the ribcage, suggestive a few extra hundred
> kilos of mass beyond the scaled ratios. That's assuming there is a direct
> scaling inferrence here, and *Spinosaurus* didn't depart somehow, and that
> its femoral length, long-time the friend of allometric scalers and mass
> estimates, is unknown. I beleive it was this that has lead to skeptics
> stating the length and mass are relatively unknown and one shouldn't be
> making easy comparisons.

Regardless of how many vertebrae you count as cervicals, Dilophosaurus and
Tyrannosaurus have the same number of vertebrae through the sacrum (28 from
atlas to caudosacral).  So does every other non-maniraptoran theropod more
derived than Guaibasaurus.  So using this assumption for Spinosaurus' length
estimate is safe enough to not engender doubt.  If Spinosaurus' hypothesized
size was comparable to other large theropods (Giganotosaurus, Deltadromeus,
Tyrannosaurus, etc.), I could understand the hesitation, but it's a good
four meters longer.  Direct scaling has its inconsistancy, but that's a
_fourth_ of it's length that would need to be gotten rid of to make it
subequal to other giants.

Mickey Mortimer