Dinosaur Lake IX: Dinosaurs Are Hard to Kill. Dinosaur Lake, #9

Park Ranger Henry Shore has been fighting large rogue, blood-thirsty, dinosaurs for over a decade.and now, finally, they have been eradicated. Or have they? Henry works hard to keep the secret of his amazing little dinosaur friend, Oscar, and Oscar's family, from the world; knowing the highly intelligent telepathic creatures must be protected for many reasons, especially because if the hostile aliens ever return, Oscar is the key to communicating with them.
Last time that communication saved the world. But now, suddenly, more malevolent large dinosaurs have shown up near the northern boundary of his park, and Henry, once more, is asked for his help to find, and to exterminate, them before they kill any more innocent humans. But when he finds the first large dinosaur, it is already dead. And then the second large dinosaur, also dead. How? And what is this virulent infection that is killing them? Now nine books in series.