'Gastralia' (singular 'gastralium') are
dermal bones today found in the
ventral body wall of
crocodilians and ''
Sphenodon''. They are found between the
sternum and
pelvis, and do not articulate with the
vertebrae. In modern animals, they provide support for the
abdomen and attachment sites for abdominal muscles. These bones may have been derived from the ventral scales found in animals like
rhipidistians,
labyrinthodonts, and ''
Acanthostega'', and may be related to ventral elements of
turtle plastrons.
[ Vertebrates: Comparative Anatomy, Function, Evolution, , Kenneth V., Kardong, McGraw-Hill, 2002, ] Similar but not
homologous cartilagenous elements are found in the ventral body walls of
lizards and
anurans. The terminology for these groups of structures is confused; both types, along with sternal ribs (
ossified costal cartilages), have been called abdominal ribs, a term which should be avoided.
[ Dinosaur gastralia: origin, morphology, and function, , Leon P.A.M., Claessens, Journal of Vertebrate Paleontology, 2004 ]
Gastralia are also present in a variety of
extinct animals, including
theropod and
prosauropod dinosaurs,
pterosaurs,
plesiosaurs, and
champsosaurs. In dinosaurs, the elements articulate with each other in a sort of zig-zag along the midline and may have aided in
respiration.
[ Although they were thought to be present in some basal ornithischian dinosaurs,][ Dinosaur gastralia and their function in respiration ] and sauropods (most notably ''Eobrontosaurus''), the possible occurrences have been shown to be mistaken.
References
External links
★ Dinosaur gastralia and their function in respiration