tag:blogger.com,1999:blog-4107478525158722252.post7924023862394761116..comments2020-10-27T15:56:36.166-07:00Comments on Variety of Life: OrmoceratidaeChristopher Taylorhttp://www.blogger.com/profile/11075565866351612441noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-4107478525158722252.post-6359760877383452492011-11-27T16:35:18.978-08:002011-11-27T16:35:18.978-08:00There have been some efforts to sharpen the diagno...There have been some efforts to sharpen the diagnosis of Orthocerida, but the group still seem phylogenetically elusive because they exhibit so much convergence.<br /><br />It would be good to sort out the evolutionary details of the orthocerids, since as a grade group they include the ancestors of ammonoids and coleoids via bactritids. Moreover, several specialists have suggested that they gave rise to the Nautilida as well:<br />http://www.tiefes-leben.de/2011/08/it-is-time-for-some-news-from-the-%e2%80%9enautiloid%e2%80%9c-research/Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4107478525158722252.post-50577732370121834662011-01-23T16:22:47.428-08:002011-01-23T16:22:47.428-08:00Thanks for that, George. I get the impression that...Thanks for that, George. I get the impression that 'orthocerid' cephalopods, also discussed in the paper you pointed out to me, seem to be the most difficult group of cephalopods to pin down phylogenetically.Christopher Taylorhttps://www.blogger.com/profile/11075565866351612441noreply@blogger.comtag:blogger.com,1999:blog-4107478525158722252.post-9777988639248061962011-01-21T20:50:02.009-08:002011-01-21T20:50:02.009-08:00I like the new blog, although I'm glad the old...I like the new blog, although I'm glad the old Catalogue of Organisms is continuing.<br /><br />Regarding this post, the reference below argues that the carbactinoceratids actually evolved among the pseudorthocerids, and their resemblance to actinocerids is convergent.<br /><br />Kröger, Björn, & Mapes, Royal (2007). Actinoceratoid Nautiloidea (Cephalopoda) — A new perspective. Journal of Paleontology 81 (4): 714–724.Anonymousnoreply@blogger.com