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Bifurcated neural spines in tetrapods beyond sauropods



From: Ben Creisler
bcreisler@gmail.com

A new paper that may be of interest:

D. Cary Woodruff  (2014)
The anatomy of the bifurcated neural spine and its occurence within Tetrapoda
Journal of Morphology (advance online publication)
DOI: 10.1002/jmor.20283
http://onlinelibrary.wiley.com/doi/10.1002/jmor.20283/abstract

Vertebral neural spine bifurcation has been historically treated as
largely restrictive to sauropodomorph dinosaurs; wherein it is
inferred to be an adaptation in response to the increasing weight from
the horizontally extended cervical column. Because no extant
terrestrial vertebrates have massive, horizontally extended necks,
extant forms with large cranial masses were examined for the presence
of neural spine bifurcation. Here, I report for the first time on the
soft tissue surrounding neural spine bifurcation in a terrestrial
quadruped through the dissection of three Ankole-Watusi cattle. With
horns weighing up to a combined 90 kg, the Ankole-Watusi is unlike any
other breed of cattle in terms of cranial weight and presence of
neural spine bifurcation. Using the Ankole-Watusi as a model, it
appears that neural spine bifurcation plays a critical role in
supporting a large mobile weight adjacent to the girdles. In addition
to neural spine bifurcation being recognized within nonavian
dinosaurs, this vertebral feature is also documented within many
members of temnospondyls, captorhinids, seymouriamorphs,
diadectomorphs, Aves, marsupials, artiodactyls, perissodactyls, and
Primates, amongst others. This phylogenetic distribution indicates
that spine bifurcation is more common than previously thought, and
that this vertebral adaptation has contributed throughout the
evolutionary history of tetrapods. Neural spine bifurcation should now
be recognized as an anatomical component adapted by some vertebrates
to deal with massive, horizontal, mobile weights adjacent the girdles.