Pelycosaur To Therapsid Transition

[Cam28]

Know the general consensus is that Therapsids evolved from the family Sphenacodontidae, but there doesnt seem to be much proof besides one characteristic (believe it was the reflected lamina).Meanwhile I find this article arguing they evolved from family Ophiacodontidae.http://pterosaurheresies.wordpress.com/2011/09/23/ophiacodon-and-the-origin-of-the-therapsida/. As liberal as it sounds, the evidence he presents seems to bear some weight.
But maybe Ophiacodonts & Therapsids just display convergent evolution? But overall Im wondering which family most likely did Therapsida evolve from and why? I would prefer an expert opinion but anyone who has any clue can pitch in on this ancient pre-mammal lineage topic.

edit: Carcharodontosaurus is right, I did not initially realize how conceited he was/is (Mr. Peters of pterosaur heresies/ reptile evolution.com). Apparently a lot of ridiculous claims including pterosaurs being more related to lizards than dinosaurs. He should've just continued with his talent as an artist.

Edited July 22, 2014 by Cam28

[Carcharodontosaurus]

The Pterosaur Heresies guy is not a scientist. His claims are nothing more than bad pseudoscience, and the blog is a bad source of info in general.

Edited July 22, 2014 by Carcharodontosaurus

[siteseer]

I can't offer you an expert opinion nor even one up on the latest research but I can give you a little background at least some of which you already know.

The short version of the answer to your question is that the direct ancestry of the therapsids remains undetermined but it was most likely rooted among the sphenacodontids. The fossil record of sphenacodontids is good across the Early Permian of the central US (Oklahoma and Texas) but then it stops in the late part of the early Permian. Therapsids are already rather diverse when they appear in the early part of the late Permian of South Africa and western Russia. There isn't much known in between.

The "reflected lamina" refers to an extra flange on the angular, a bone of the lower jaw, and is a character sphenacodontids and therapsids have in common. The skull of one of those early Russian therapsids, Biarmosuchus shares many features of sphenacodontids. The rest of the skeleton retains features of sphenacodontids, though it lacks the elongated neural spines of advanced forms like Dimetrodon (a possible clue to its lineage having diverged from a more primitive form) while also bearing others of more advanced therapsids.

World climates became drier across the Permian - apparently past the point of tolerance of the more specialized pelycosaurs which had ruled the Early Permian of the central US and western Europe. The gap between successful pelycosaurs and early therapsids seems more spatial than temporal as rock dating techniques have become more refined. It appears the earliest therapsids lived in a different land environment than the pelycosaurs during the Early Permian or radiated in the late early Permian in an area where rocks of that time have not been sampled or no longer exist. Keep in mind that all the major landmasses were almost all connected by that time so the fossils of ancestral therapsids could show up in Early-Middle Permian terrestrial deposits almost anywhere.

Know the general consensus is that Therapsids evolved from the family Sphenacodontidae, but there doesnt seem to be much proof besides one characteristic (believe it was the reflected lamina).Meanwhile I find this article arguing they evolved from family Ophiacodontidae.http://pterosaurheresies.wordpress.com/2011/09/23/ophiacodon-and-the-origin-of-the-therapsida/. As liberal as it sounds, the evidence he presents seems to bear some weight.
But maybe Ophiacodonts & Therapsids just display convergent evolution? But overall Im wondering which family most likely did Therapsida evolve from and why? I would prefer an expert opinion but anyone who has any clue can pitch in on this ancient pre-mammal lineage topic.

edit: Carcharodontosaurus is right, I did not initially realize how conceited he was/is (Mr. Peters of pterosaur heresies/ reptile evolution.com). Apparently a lot of ridiculous claims including pterosaurs being more related to lizards than dinosaurs. He should've just continued with his talent as an artist.