The separation between plant-eaters and insect-eaters formed the basal split in the large reptile tree. The emergence of Limnoscelis and its kin and Lanthanosuchus and its kin from this clade bears further scrutiny. I’m sure there’s a story brewing there. Turtles also emerged from this clade of herbivores. Among charted lepidosauromorphs we don’t see any other herbivores until Iguana and even it supplments with insects when young. Let me know if I’m missing any others.
On the archosauromorph side, Edaphosaurus is the first herbivore with several therapsid clades not far behind. Thereafter we don’t see any until the Placodontia (if they were indeed herbivores and not shell crushers), the Aetosaurs and the Phytodinosauria.
As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.
Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.
Diedrich CG 2011. Fossil middle triassic “sea cows” – placodont reptiles as macroalgae feeders along the north-western tethys coastline with pangaea and in the germanic basin. Natural Science 3 (1) 9-27 (2011)