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 .
Sauropoda
Neosauropoda is quite plausibly the largest clade of dinosaurs ever to have existed, with a few exceptions. Most exceptions are hypothesized to be caused by island dwarfism, although there is a trend in Titanosauria towards a smaller body size. The titanosaurs, however, have also been some of the largest sauropods ever. Other than titanosaurs, a clade of diplodocoids, a group of giants, called Dicraeosauridae, is diagnosed by a small body size. No sauropods were very small, however, for even "dwarf" sauropods are larger than , a size reached by only about 10% of all mammalian species.