Therapod defined a group of carnivorous reptiles. Tiss'shar were considered to be members of this therapod group.
The term "theropod", translating to "beast foot," was created by the paleontologist Othniel Charles Marsh back in 1881. He used it to categorize a collection of dinosaurs known for walking on two legs and eating meat (however, later investigations revealed some members that were omnivores and herbivores). Theropods included well-known genera such as Tyrannosaurus, Allosaurus, and Velociraptor.
Despite the real-world spelling using an "o", the Ultimate Alien Anthology uses an "a" in the word "therapod."