Sinosauropteryx
"Sinosauropteryx" was a small bipedal theropod, noted for its short arms, large first finger (thumbs), and long tail. The taxon includes some of the smallest known adult non-avian theropod specimens, with the holotype specimen measuring only in length, including the tail. However, this individual was relatively young. The longest known specimen reaches up to in length, with an estimated weight of .
Nanuqsaurus
"Nanuqsaurus" has been estimated to have been about six meters (twenty feet) long, about half the length of "Tyrannosaurus rex". This diminutive size was postulated by Fiorillo and Tykoski as being an adaptation to its high-latitude habitat.