Spinosaurus News ~

[tigerluver]

Informative discussion. A few questions and discussion points from me...

Would it be possible for Spinosaurus to have pneumatized cervical vertebrae but then reduction/obliteration of such more caudally? The thought came to me from this quote from Ibrahim et al. (2020):
"With much additional spinosaurid material now available for other taxa such as Baryonyx, Suchomimus and Ichthyovenator, we know that the extent of lamination and pneumaticity varies not only along the presacral column of single individuals as might be expected, but also between spinosaurid genera."

From Lakin and Longrich (2019), an indeterminate spinosaurid's thoracic vertebra lacked pneumatization.:

"FSAC-KK-18121 is a partial anterior thoracic vertebra. The neural arch is completely absent and the articular facet of the centrum is poorly defined. There is no central pneumatic foramen, nor is the parapophysis present on the centrum (Fig. 6G&6J), supporting the diagnosis of an anterior thoracic vertebra."

I am unsure what trends are in other dinosaurs. However, a pneumatized skull and cervical column would allow easy access to air and above water vision which could fit with the aquatic behavior. 

Whatever the case, the obliterated medulla of the long bones need to be reconciled with the cervical pneumatization (assuming those are correctly assigned). A floating animal (<1 density) would either mean Spinosaurus stayed at the surface or the density is wrong if Spinosaurus was a sinking animal. Reply