 Dinosaur size, size has been one of the most interesting aspects of dinosaur science to the general public and to scientists. Dinosaur show some of the most extreme variations in size of any land animal group, ranging from the tiny hummingbirds, which can weight as little as 3 grams, to the extinct titanosaurus, which could weight as much as 70 tons, 69 long tons, 77 short tons. Scientists will probably never be certain of the largest and smallest dinosaurs to have ever existed, especially for the sauropods and furipods. This is because only a tiny percentage of animals ever fossilized, and most of these remain buried in the earth. View of the specimens that are recovered are complete skeletons, and impressions of skin and other soft tissues are rare. Rebuilding a complete skeleton by comparing the size and morphology of bones to those of similar, better known species is an inexact dart, and reconstructing the muscles and other organs of the living animal is, that best, a process of educated guesswork. Weight estimates for dinosaurs are much more variable than length estimates, because estimating length for extinct animals is much more easily done from a skeleton than estimating weight. Estimating weight is most easily done with the laser skin skeleton technique that puts a virtual skin over it, but even this is only an estimate. Current evidence suggests that dinosaur average size varied through the triassic, early Jurassic, late Jurassic and Cretaceous periods. Predatorifera pod dinosaurs, which occupied most tristral carnivore niches during the Mesozoic, most often fall into the 100- to 1000 kg 220- to 2200 lb category when sorted by estimated weight into categories based on order of magnitude, were as a recent predatory carnivore animals peak in the 10- to 100 kg 222 lb category. The mode of Mesozoic dinosaur body masses is between 1 and 10 metric tons. This contrasts sharply with the size of Cenozoic mammals, estimated by the National Museum of Natural History as about 225 kg 4.4211.0 lb.