Nobu Tamura graciously allowed us to use the picture I presented yesterday. His beautifully detailed rendition of Eoraptor is eye catching. The image captures many of simplistic basal traits of the animal as a dinosaur- the three clawed hand (which attributed it to its position as father of all theropods when initially described by Sereno, Forster, at al. but has since been reversed), gracile slender body form, perpendicular hip swivel (as opposed to the splayed 90 degree hip articulation of reptiles), long tail, small head (which possesses multiple fenestra), and an interesting mixture of carnivore and herbivore teeth, not unlike you and me.
The head of this animal does indeed possess many dinosaur traits including the fenetrae and the long shallow snout as well as two types of teeth, but these are typically found in two different types of dinosaurs. The carnivorous set of teeth near the front of the mouth are serrated and curved backwards like any other predator's teeth. The teeth in rear of the dental battery however are less suited to tearing flesh and more suited to biting into plant matter and chewing it. Omnivorous diet is nothing new to the idea of dinosaurs but initially this small dinosaur was thought to be the precursor of more advanced theropods, as such, being an omnivore is not a sin against its descendants, but to think T. Rex's greatest grandfather ate plants as well as animals seems a little unbelievable. It isn't really, everything starts out needing energy from somewhere, plants are a great source, so why not? The biggest predators in the world sitting down to a salad just seems funny.