What is the species of the Theropods? It's sure they are not Megapnosaurus since M. kayentakatae (the species with headcrest) is from North America...They could belong to an undiscovered crested South African Coelophysoid.
Out of curiosity, is this an "All Yesterdays" deviation or just a regular deviation? In any case, I like it. For 1, Heterodontosaurids look really cool. For another, the idea of ornithischian quills being porcupine-like is really cool. Personally, I imagine ornithischian quills being more for show/defense than for insulation like the proto-feathers of coelurosaurs. Specifically, I imagine heterodontosaurids rattling their quills like African porcupines or the "Primeval" raptors.
I think it is just assumed that it had quills because Tianyulong (a relative of it) had them. I dont think Pegomastax was found with any quills. Whether the quills were stiff and sharp like a porcupine's I don´t know but I obviously went for that idea due to rule of cool.