Menosaurus by S J House

The Mantoid lord's evil forces have depleted oxygen levels, and Zero gravity has taken effect, plunging New York City into total Jurassic chaos as dinosaurs ravage the streets. Marines hunt in camouflaged spacesuits, and every human fights to survive.               

Lieutenant RainHorn has gone AWOL, missing in action, feared dead, and a new commander has been assigned to find him and bring him home.        

Rex and Rion transcend past space-time dimensions to stay one step ahead of the enemy and defeat the Mantoid lord. But they might just have to die first before they can save themselves and Earth.