Originally the most bizarre aspect of Atopodentatus was the anterior view of the rostrum. Unlike any other tetrapod, the premaxillae were thought to be medially split and filled with teeth that faced one another. And these pseudo-jaws were thought to be immobile, filtering sea water like the lateral needle-like teeth were thouht to have done. The second most bizarre aspect of Atopodentatus was the extreme bend in the maxilla. As the mandible closed the tip raked up the ventrally directed portion of the maxilla.

A second and third specimen showed that the jaws were exceptionally wide, not deep. Crushing caused the confusion and illusion. Now Atopodentatus is thought to have been a scraping grazer with a more typical jaw mechanism.

Cheng L, Chen XH,Shang QH and Wu XC 2014. A new marine reptile from the Triassic of China, with a highly specialized feeding adaptation. Naturwissenschaften. doi:10.1007/s00114-014-1148-4.

Chun L, Rieppel O, Cheng L and Fraser NC 2016. The earliest herbivorous marine reptile and its remarkable jaw apparatus. Science Advances 06 May 2016: 2(5), e1501659
DOI: 10.1126/sciadv.1501659

wiki/Atopodentatus