Gastralium

Gastralia (singular gastralium) are dermal bones found in the ventral body wall of crocodilian and "Sphenodon" species. 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.cite book |last=Kardong |first=Kenneth V. |title=Vertebrates: Comparative Anatomy, Function, Evolution |edition=3rd |year=2002 |publisher=McGraw-Hill |location=New York |isbn=0-07-290956-0 |pages=291-293 ] 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.cite journal |last=Claessens |first=Leon P.A.M. |year=2004 |month=March |title=Dinosaur gastralia: origin, morphology, and function |journal=Journal of Vertebrate Paleontology |volume=24 |issue=1 |pages=89–106 |doi= 10.1671/A1116-8 ]

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,cite web |url=http://dml.cmnh.org/1995Nov/msg00415.html |title=Dinosaur gastralia and their function in respiration |accessdate=2007-07-08 |last=Claessens |first=Leon |date= 1995-11-28 |publisher=Dinosaur Mailing List ] and sauropods (most notably "Eobrontosaurus"), the perceived occurrences have been shown to be mistaken.

References

External links

* [http://dml.cmnh.org/1995Nov/msg00415.html Dinosaur gastralia and their function in respiration]