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Index][Thread Index][Subject Index][Author Index] Re: Spare
ribs? "My guess is [caudal ribs] are the chevrons. Transverse
processes are not chevrons are (as far as I know) homologous to
ribs in the tail." As far as I'm aware, the chevrons are
remnants of the haemal arches, bones that first developed in
fishes that provided protection for blood vessels in the tail.
As I know George is aware, chevrons are common in the tails of
many verts, and in sauropods they probably served a function in
protecting blood vessels and such. In some reptiles (snakes, for
instance), the proximal chevrons can act to anchor muscles for
sexual reproductive organs. Chevrons are not homologous to ribs,
however, because they are essentially modified haemal arches and
arise below (ventral to) the bodies (centra) of the vertebrae.
Ribs articulate with the centra and transverse processes Even
though transverse processes are not ribs, because ribs generally
have some articulation with