Sinosauropteryx
"Sinosauropteryx" was a small theropod with an unusually long tail and short arms. The longest known specimen reaches up to in length, with an estimated weight of It was a close relative of the similar but older genus "Compsognathus", both genera belonging to the family Compsognathidae. Only one species of "Sinosauropteryx" has been named: "S. prima", meaning "first" in reference to its status as the first feathered non-avialian dinosaur species discovered. Three specimens have been described. The third specimen previously assigned to this genus represents either a second, as-yet unnamed species or a distinct, related genus.
Pachycephalosauria
Pachycephalosaurs were bipedal ornithischians characterized by their thickened skulls. They had a bulky torso with an expanded gut cavity and broad hips, short forelimbs, long legs, a short, thick neck, and a heavy tail. Large orbits and a large optic nerve point to pachycephalosaurs having good vision, and uncharacteristically large olfactory lobes indicate that they had a good sense of smell relative to other dinosaurs.They were fairly small dinosaurs, with most falling in the range of 2–3 meters (6.6-9.8 feet) in length and the largest, "Pachycephalosaurus wyomingensis," estimated to measure 4.5 meters (14.8 feet) long and weigh 450 kilograms (990 pounds). The characteristic skull of pachycephalosaurs is a result of the fusion and thickening of the frontals and parietals, accompanied by the closing of the supratemporal fenestra. In some species this takes the form of a raised dome; in others, the skull is flat or wedge-shaped. While the flat-headed pachycephalosaurs are traditionally regarded as distinct species or even families, they may represent juveniles of dome-headed adults. All display highly ornamented jugals, squamosals, and postorbitals in the form of blunt horns and nodes. Many species are only known from skull fragments, and a complete pachycephalosaur skeleton is yet to be found.