David Peters (davidrpeters@earthlink.net) wrote:
<If the epipubic bones turn out to be oversized hemal arches, with
anterior articular surfaces instead of sharp points, then that clears the
way for the posterior shifting of the cloaca -- incrementally making room
for an ever longer stiffer cervical series in the neonate. Development in
utero would not hinder development of a stiff neck, as it would within the
typical confines of spheroid.>
Even further, the bones found are never found anterior to the pelvis,
unlike epipubics, but epipubics in pterosaurs are virtually ALWAYS either
adacent to or anterior to the pelvis without extreme disarticulation. They
may NOT be haemal arches, but extraneous neomorphic dermal bones, as
Silvio implied (heterotopic ossification), without any correllate in other
fossils, such as chevrons, epipubics, or ribs. It may be, therefore, that
these elements are completely useless phylogenetically.