Scientists have recently discovered that the small dinosaur named "Zheng's Xiaoting Dragon" is a "relative" of the Archaeopteryx and is very close to the Survival and Late Jurassic Archaeopteryx. The phylogenetic relationship of the species was reanalyzed, and it was found that the archaeopteryx was not a bird, but the primitive Deinonychus, that is, the archaeopteryx was the ancestor of the raptor, not the bird. If the following items are true, which of the following is the most important question? ['Deinonychus are a class of birds closely related to dinosaurs.', 'Deinonychus are a group of dinosaurs that are closely related to birds.', 'A theropod dinosaur evolved into a herbivorous dinosaur and evolved into a bird.', 'Archaeopteryx specimens have been considered the most primitive and oldest birds ever since they were named.']