Prehistoric Life/Dinosaurs/Pachycephalosaurs: Difference between revisions

* Pachycephalosaurs are very rare things. Few species have been described so far, almost always from the Late Cretaceous, and they are either North American, or Asian. While the North American ones are more spectacular (''Pachycephalosaurus''), or more abundant (''Stegoceras''), the Asian ones are nonetheless very interesting; the two most classic ones were both discovered in the 1970s in Mongolia. Their names make a sort of pun if pronounced together: ''Prenocephale'' and ''Homalocephale''. ''Prenocephale'' aptly means “prominent head”; was very similar to ''Stegoceras'', size and period included, but had a shorter snout, different tubercles, and a higher dome. Like most boneheaded dinosaurs, only skull material is known, but its first skull is so well preserved that ''even osseous canals'' for the passage of blood-vessels are distinguishable! ''Homalocephale'' was also similar in size, but is known from several pieces of its skeleton as well other than the skull. Its name means ''flat head'', and with reason: it has indeed [[Exactly What It Says Onon the Tin|a flat head]], making it very unpachycephalosaur-looking. Actually its skull structure was clearly pachycephalosaurian, with slighty thickened skull-roof and bony tubercles very similar to those of ''Prenocephale''. This detail led in 2010 the hypothesis that ''Homalocephale'' [[Science Marches On|was just the juvenile form]] of ''Prenocephale'' with a not-yet developed dome. The unusual wideness of the ''Homalocephale'' pelvis led also speculation about a possible viviparity (aka giving birth to ''live'' offspring). There is no proof of this, as well as in every other non-avian dinosaur: and remember that modern dinosaurs (birds) and their closest relatives (crocs) are ''all egg-laying'' animals.