On one of the Polacanthus cards, a golden Eoraptor is seen, seemingly indicating that Eoraptor was an altered dinosaur and in result, it's skin color changed.
While originally classified as an early theropod, it may also have been a very primitive sauropodomorph, could have existed before these two separate groups as an early saurischian, existed before the two main dinosaur branches split, or it may not be a true dinosaur (these last two are the least likely). In any case, there is no certainty.
Eoraptor and Pawpawsaurus are the only Secret Dinosaurs not to appear in the anime. However, Pawpawsaurus has appeared in the anime as a Move Card dinosaur.
As of the known half of Jurassic Clash, Eoraptor is also the only Secret Dinosaur to not appear in the TCG. It may be included in the 55 unknown cards, but this cannot be determined.
Out of the three Triassic dinosaurs in the arcade (the other 2 being Gojirasaurus and Liliensternus), Eoraptor is the only one that is not a Wind Dinosaur, though it likely would be if it weren't Secret.
In the DS Game, Eoraptor can be changed into another dinosaur by teaching it an elemental move; however it changes back after the turn.
In the arcade game, it changes at random.
Eoraptor's ability to evolve into any dinosaur might be seen as a parallel to Eevee from Pokémon, as the latter can evolve into a multitude of forms each representing a main type.
However, the fact that it becomes other dinosaurs instead of unique forms is instead similar to another Pokémon, Ditto, which has no abilities except to transform into other Pokémon.