Real spinosaurs included Spinosaurus aegyptiacus and Oxalaia quilombensis. Oxalaia lived in South America, the same continent that the real Carnotaurus is known to have lived, and Spinosaurus lived in Africa, which was joined to South America until the Early Cretaceous (but see the Science & Speculation section of the Ankylosaurus article for a discussion of the difficulty of assigning a definite location to Terra Nova). Neither are known to have had spikes on their backs and necks like the one seen on Terra Nova, however (though Spinosaurus did have a sail like the Empirosaur).
All the known spinosaurs have been found in earlier parts of the Cretaceous than the time Terra Nova is set (the last known spinosaurs lived in Asia). The Empirosaur might be imagined to be a descendant of some known spinosaur like Spinosaurus, one which didn't leave fossils (in this interview executive producer Rene Echevarria makes reference to the idea that the dinosaurs we know from fossils may represent only about 10% of all that existed).
Ecological speculations: Most Spinosaurs are fish-eating dinosaurs, and this one is likely no exception, though large Spinosaurs are thought to have supplemented their diet by preying on other dinosaurs or scavenging. Little is known about the habits of the Empirosaur, but it is likely not native to the area around the colony, as it would likely drive out other creatures such as Carnotaurus and Allosaurs that do inhabit the area, unless its different diet means they don't compete for the same prey.