Ecological speculations: Ovosaurs might primarily scavenge or feed off small animals, since they are never seen to attack an able human. On the other hand, the Ovosaur in "What Remains" seems to jump down the hole because it's interested in Malcolm and Jim, and Jim is fearful and quickly runs into another room with Malcolm and closes the door behind them, so the Ovosaur may have been getting ready to attack (but it's also possible it was mainly interested in the unconscious soldier). Earlier the Ovosaurs had run off when Jim and Malcolm first arrived at the outpost, so they likely aren't dangerous predators of the caliber of Nykoraptor, and thus likely don't compete with them for prey.
From its appearance it is probably a type of coelurosaur, a broad group of carnivorous dinosaurs. As Carnotaurus is known only from South America, it is interesting to note that relativity few coelurosaurs have been found from the Southern Hemisphere in the Cretaceous period, as discussed in this paper (The paper refers to Laurasia and Gondwana, two supercontinents created by the breakup of Pangaea in the mid-Jurassic. Laurasia consisted of North America, Europe and Asia, while Gondwana consisted of South America, Africa, Australia and Antarctica. These supercontinents themselves underwent further breakups, with South America and Africa themselves splitting into separate continents in the Early Cretaceous). One such coelurosaur from the Southern Hemisphere in the Cretaceous period is Nqwebasaurus, from Early Cretaceous Africa, which as illustrated here has some resemblance to Ovosaurus.