Dinosaur Walk Museum modern day birds. Troodon: The Troodon, a very small bird-like dinosaur, grew to be up to in length, tall and only weighed up to 130 pounds. Living during the late Cretaceous Period, 75–66 million years ago. Originally thought to be carnivorous, modern evidence shows that it is possible that they were omnivorous or possibly an herbivore. Plesiosaurs: The Plesiosaurs were carnivorous aquatic reptiles. First appearing at the beginning of the Jurassic Period they thrived throughout the Cretaceous Period. They lived during the same time as the dinosaurs but were not dinosaurs, they are considered reptiles. Oviraptor: The Oviraptor, or "Egg
Archaeopteryx common uses of that term. A more thorough analysis was published soon after to test this hypothesis, and failed to arrive at the same result; it found "Archaeopteryx" in its traditional position at the base of Avialae, while "Xiaotingia" was recovered as a basal dromaeosaurid or troodontid. The authors of the follow-up study noted that uncertainties still exist, and that it may not be possible to state confidently whether or not "Archaeopteryx" is a member of Avialae or not, barring new and better specimens of relevant species. Phylogenetic studies conducted by Senter, "et al." (2012) and Turner, Makovicky, and Norell