Final answer:
The fast dinosaur with a hollow tail is the Ornithomimus. This type of dinosaur belonged to the theropod group, which is known for hollow bones that aided in their agility and quick movements.
Step-by-step explanation:
The dinosaur that was fast and had a hollow tail is believed to be the Ornithomimus. This dinosaur belonged to the group of theropod dinosaurs, which included other fleet-footed carnivores. The hollow tail of the Ornithomimus most likely served as a counterbalance for the dinosaur's long neck and head, also aiding in fast movement and agility. It's also important to note that hollow bones, such as that in the tail, are a characteristic feature of the theropod dinosaurs that enabled them to maintain their agility.
In addition to Ornithomimus, there were also other dinosaurs with hollow bones, such as the Herrerasaurus. These dinosaurs, along with Ornithomimus, are great examples of the diversity and adaptability of dinosaurs in different environments and lifestyle needs.
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