Just a few scraps of Early Jurassic dinosaurs have been found in the Huizachal Canyon, Tamaulipas, Mexico… but thanks to the work of among others David Fastovsky, René Hernández and Angel Ramírez what is clear now is that among them were Heterodontosaurs and Coelophysids... I have taken this opportunity to fiddle with the current “new look” of heterodontosaurs after Chinese and South African discoveries (Pegomastax et al)… and I must admit I was amazed by the wonderful, artful and over the top reconstruction of Tianyulong in the new exhibition at the American Museum of Natural History in NY, that has taken care to vindicate early ornithischians forever… so I started to think: what could I do to go more extreme than that? After all this was Mexico! What if a really angry heterodontosaur in full display would have a modern porcupine pale by comparison… fangs added to the threatening show?
Heterodontosaurus might have been a small animal, but Coelophysis would have to think twice to try to take a bite. Please note that based on what little we know of Early Jurassic Mexico, the reconstructions here are merely speculative, specially in regards to the detail… both animals appearances are based on what we know from others.Who says Palaeontology can’t have a sense of humour… even as deadly serious as this is?
Luis V. Rey Blog 
But, we have any evidence of the presence of spines on heterodontosaurs or this is something speculative???
Still sketchy but yes we do. Check the heterodontosaur Pegomastax…According to Paul Sereno and by inference from dinosaurs like Tianyulong See http://www.livescience.com/23655-fanged-dracula-dinosaur-fossils.html