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Reconstructed skeleton of the titanosaur Argentinosaurus huinculensis, often considered the largest-known dinosaur.

Dinosaur size has long been of interest to scientists and the public. Dinosaurs show some of the most extreme variations in size of any land animal group, ranging from the tiny hummingbirds,[1] which can weigh as little as three grams, to the extinct titanosaurs, which could weigh as much as 70 tonnes (69 long tons; 77 short tons).[2]

We will never be certain of the largest and smallest dinosaurs to have existed. This is because only a tiny percentage of animals ever fossilize, and most of these remain buried in the earth. Few specimens 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 art, and reconstructing the muscles and other organs of the living animal is, at best, a process of educated guesswork.[3] 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 scan skeleton technique that puts a "virtual" skin over it, but even this is only an estimate.[4]

Current evidence suggests that dinosaur average size varied through the Triassic, early Jurassic, late Jurassic and Cretaceous periods.[5] Predatory theropod dinosaurs, which occupied most terrestrial carnivore niches during the Mesozoic, most often fall into the 100- to 1,000-kilogram (220 to 2,200 lb) category when sorted by estimated weight into categories based on order of magnitude. In comparison, recent predatory carnivore mammals peak in the 10- to 100-kilogram (22 to 220 lb) category.[6] The mode of Mesozoic dinosaur body masses is between one and ten metric tonnes.[7] This contrasts sharply with the size of Cenozoic mammals, estimated by the National Museum of Natural History as about 2 to 5 kg (4.4 to 11.0 lb).[8]

ReferencesEdit

  1. Remembering, of course, that birds are dinosaurs
  2. Rensberger J.M. & Martínez R.N. (2015). "Bone cells in birds show exceptional surface area, a characteristic tracing back to Saurischian dinosaurs of the late Triassic". PLoS ONE 10 (4): e0119083. doi:10.1371/journal.pone.0119083. PMC 4382344. PMID 25830561. 
  3. Paul, Gregory S. (2010). Princeton Field Guide to Dinosaurs. Princeton University Press. ISBN 978-0-691-13720-9.
  4. Strauss, Bob. Why were dinosaurs so big? The facts and theories behind dinosaur gigantism. About Education. http://dinosaurs.about.com/od/dinosaurevolution/a/bigdinos.htm
  5. Sereno PC (1999). "The evolution of dinosaurs". Science 284 (5423): 2137–2147. doi:10.1126/science.284.5423.2137. PMID 10381873. 
  6. Farlow JA (1993). "On the rareness of big, fierce animals: speculations about the body sizes, population densities, and geographic ranges of predatory mammals and large carnivorous dinosaurs". In Dodson, Peter; and Gingerich, Philip (eds.). Functional morphology and evolution. American Journal of Science, Special Volume 293-A. pp. 167–199.CS1 maint: uses editors parameter (link)
  7. Peczkis, J. (1994). "Implications of body-mass estimates for dinosaurs". Journal of Vertebrate Paleontology 14 (4): 520–33. doi:10.1080/02724634.1995.10011575. 
  8. "Anatomy and evolution". National Museum of Natural History. Retrieved 2007-11-21.