The scientists were crossing the species whose cells contained tarpan's genes. As a result of the experiment, they created the creature, whose appearance was exactly the same as that of their ancestor. The tarpans were released: several herds of them are grassing in Germany and Poland. Interestingly enough, the appearance of those animals has not changed much in several generations. The "resurrection" process was a success, which means that the animals hold the majority of the genes of the wild ancestor of the horse indeed. It is impossible to determine that, because the genetic bank of the tarpan has not been preserved.
This approach can not be applied to the resurrection of dinosaurs, though: there are no domestic species of the reptiles. There are descendants of this group, though - birds and the reptiles that are very close to the ancestral form of "terrible lizards" - crocodiles. Needless to say that nothing will come out of the crossing between these two categories of taxons, not to mention the fact that it is technically impossible.