The Abdominal Ribs and Hyoid Arch


(Abdominal Ribs)


                                                    (1)  Inter-clavicle

                                                    (2)  Abdominal Splint Ribs

                                                    (3) Sternum

     The abdominal ribs are actually membrane bones of the abdomen and are not homologous with any other ribs.  The most posterior set of splint ribs are the largest which extend around the pubis or epipubis to create a very strong membrane.  The abdominal ribs connect superficially to the recti-muscles in the ventral wall of the alligator.


(Hyoid arch)

     The Hyoid arch of the alligator is comprised of a broad cartilaginous plate (basilingual plate) with a pair of partly ossified cornua (seen here).  The lower ends have cartilage attached which allows for expansion.  The pair of cornua are homologus with the first branchial arches of Selachians (Reese 1915).


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