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

Size has been one of the most interesting aspects of dinosaur science to the general public and to scientists. Dinosaurs show some of the most extreme variations in size of any land animal group, ranging from the tiny hummingbirds, 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).[1]

Scientists will probably never be certain of the largest and smallest dinosaurs to have ever existed. This is because only a tiny percentage of animals ever fossilize, and most of these remain buried in the earth. Few 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 art, and reconstructing the muscles and other organs of the living animal is, at best, a process of educated guesswork.[2] 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.[3]

Current evidence suggests that dinosaur average size varied through the Triassic, early Jurassic, late Jurassic and Cretaceous periods.[4] 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, whereas recent predatory carnivoran mammals peak in the 10- to 100-kilogram (22 to 220 lb) category.[5] The mode of Mesozoic dinosaur body masses is between one and ten metric tonnes.[6] 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).[7]

Record sizes [ edit ]

The sauropods were the largest and heaviest dinosaurs. For much of the dinosaur era, the smallest sauropods were larger than anything else in their habitat, and the largest were an order of magnitude more massive than anything else that has since walked the Earth. Giant prehistoric mammals such as Paraceratherium and Palaeoloxodon (the largest land mammals ever[8]) were dwarfed by the giant sauropods, and only modern whales surpass them in size.[9] There are several proposed advantages for the large size of sauropods, including protection from predation, reduction of energy use, and longevity, but it may be that the most important advantage was dietary. Large animals are more efficient at digestion than small animals, because food spends more time in their digestive systems. This also permits them to subsist on food with lower nutritive value than smaller animals. Sauropod remains are mostly found in rock formations interpreted as dry or seasonally dry, and the ability to eat large quantities of low-nutrient browse would have been advantageous in such environments.[10]

Scale diagram comparing a human and the largest-known dinosaurs of five major clades

One of the tallest and heaviest dinosaurs known from good skeletons is Giraffatitan brancai (previously classified as a species of Brachiosaurus). Its remains were discovered in Tanzania between 1907 and 1912. Bones from several similar-sized individuals were incorporated into the skeleton now mounted and on display at the Museum für Naturkunde Berlin;[11] this mount is 12–13.27 metres (39.4–43.5 ft) tall and 21.8–22.5 metres (72–74 ft) long,[12][13][14] and would have belonged to an animal that weighed between 30,000 to 60,000 kilograms (66,000 to 132,000 lb). One of the longest complete dinosaurs is the 27-metre-long (89 ft) Diplodocus, which was discovered in Wyoming in the United States and displayed in Pittsburgh's Carnegie Natural History Museum in 1907.[15]

There were larger dinosaurs, but knowledge of them is based entirely on a small number of fragmentary fossils. Most of the largest herbivorous specimens on record were discovered in the 1970s or later, and include the massive titanosaur Argentinosaurus huinculensis, which is the largest dinosaur known from uncontroversial evidence, estimated to have been 50–96.4 metric tons (55.1–106.3 short tons)[16] and 30–39.7 m (98–130 ft) long.[17][18] Some of the longest sauropods were those with exceptionally long, whip-like tails, such as the 29–33.5-metre-long (95–110 ft) Diplodocus hallorum[10][18] (formerly Seismosaurus) and the 33- to 35-metre-long (108–115 ft) Supersaurus.[19][18] The tallest was the 18-metre-tall (59 ft) Brachiosaurus.[citation needed]

In 2014, the fossilized remains of a previously unknown species of sauropod were discovered in Argentina.[20] The titanosaur, named Patagotitan mayorum, would have been around 40m long and weighed around 77 tonnes, larger than any other previously found sauropod. The specimens found were remarkably complete, significantly more so than previous titanosaurs. Research as of 2017 estimated Patagotitan to have been 37 m (121 ft) long [21] It has also been suggested that Patagotitan is not necessarily larger than Argentinosaurus and Puertasaurus.[22]

Giganotosaurus, one of the largest theropods known. Skeleton of, one of the largest theropods known.

Tyrannosaurus was for many decades the largest theropod and best-known to the general public. Since its discovery, however, a number of other giant carnivorous dinosaurs have been described, including Spinosaurus, Carcharodontosaurus, and Giganotosaurus.[23] These large theropod dinosaurs rivaled or even exceeded Tyrannosaurus in size, though more recent studies show some indication that Tyrannosaurus, although shorter, was the heavier predator.[citation needed] There is still no clear explanation for exactly why these animals grew so much larger than the land predators that came before and after them.

The largest extant theropod is the common ostrich, up to 2.74 metres (9 ft 0 in) tall and weighs between 63.5 and 145.15 kilograms (140.0 and 320.0 lb).[24]

The smallest non-avialan theropod known from adult specimens may be Anchiornis huxleyi, at 110 grams (3.9 ounces) in weight and 34 centimetres (13 in) in length.[25] However, some studies suggest that Anchiornis was actually an avialan.[26] The smallest dinosaur known from adult specimens which is definitely not an avialan is Parvicursor remotus, at 162 grams (5.7 oz) and measuring 39 centimetres (15 in) long.[27] When modern birds are included, the bee hummingbird Mellisuga helenae is smallest at 1.9 g (0.067 oz) and 5.5 cm (2.2 in) long.[28]

Recent theories propose that theropod body size shrank continuously over the past 50 million years, from an average of 163 kilograms (359 lb) down to 0.8 kg (1.8 lb), as they eventually evolved into modern birds. This is based on evidence that theropods were the only dinosaurs to get continuously smaller, and that their skeletons changed four times faster than those of other dinosaur species.[29][30]

Sauropodomorphs [ edit ]

Size comparison of selected giant sauropod dinosaurs

Sauropodomorph size is difficult to estimate given their usually fragmentary state of preservation. Sauropods are often preserved without their tails, so the margin of error in overall length estimates is high. Mass is calculated using the cube of the length, so for species in which the length is particularly uncertain, the weight is even more so. Estimates that are particularly uncertain (due to very fragmentary or lost material) are preceded by a question mark. Each number represents the highest estimate of a given research paper. One large sauropod, Maraapunisaurus fragillimus, was based on particularly scant remains that have been lost since their description by paleontologists in 1878. Analysis of the illustrations included in the original report suggested that M. fragillimus may have been the largest land animal of all time, weighing up to 100–150 t (110–170 short tons) and measuring between 40–60 m (130–200 ft) long.[18][31] One later analysis of the surviving evidence, and the biological plausibility of such a large land animal, suggested that the enormous size of this animal was an over-estimate due partly to typographical errors in the original report.[32] This would later be challenged by a different study, which argued Cope's measurements were genuine and there's no basis for assuming typographical errors. The study, however, also reclassified the species and correspondingly gave a much lower length estimate of 30.3 metres (99 ft).[33]

Generally, the giant sauropods can be divided into two categories: the shorter but stockier and more massive forms (mainly titanosaurs and some brachiosaurids), and the longer but slenderer and more light-weight forms (mainly diplodocids).

Because different methods of estimation sometimes give conflicting results, mass estimates for sauropods can vary widely causing disagreement among scientists over the accurate number. For example, the titanosaur Dreadnoughtus was originally estimated to weigh 59.3 tonnes by the allometric scaling of limb-bone proportions, whereas more recent estimates, based on three-dimensional reconstructions, yield a much smaller figure of 22.1–38.2 tonnes.[34]

Heaviest sauropodomorphs [ edit ]

Longest sauropodomorphs [ edit ]

Shortest sauropods [ edit ]

Lightest sauropods [ edit ]

Lightest non-sauropod sauropodomorphs [ edit ]

Shortest non-sauropod sauropodomorphs [ edit ]

Eoraptor compared in size to a human. compared in size to a human.

Theropods [ edit ]

Sizes are given with a range, where possible, of estimates that have not been contradicted by more recent studies. In cases where a range of currently accepted estimates exist, sources are given for the sources with the lowest and highest estimates, respectively, and only the highest values are given if these individual sources give a range of estimates. Some other giant theropods are also known; for example, a theropod trackmaker in Morocco that was perhaps between 10 and 19 metres (33 and 62 ft) long, but the information is too scarce to make precise size estimates.[56][57]

Heaviest theropods [ edit ]

Longest theropods [ edit ]

Size comparison of selected giant theropod dinosaurs

Lightest theropods [ edit ]

Shortest theropods [ edit ]

Shortest non-avialan theropods [ edit ]

Size comparison of the smallest non-avialan theropods

Lightest non-avialan theropods [ edit ]

Ornithopods [ edit ]

Longest ornithopods [ edit ]

Size comparison of several large ornithopods

Heaviest ornithopods [ edit ]

Shortest ornithopods [ edit ]

Lightest ornithopods [ edit ]

Ceratopsians [ edit ]

Longest ceratopsians [ edit ]

Triceratops prorsus (orange) and T. horridus (green) compared to a human. Size of(orange) and(green) compared to a human.

Heaviest ceratopsians [ edit ]

Shortest ceratopsians [ edit ]

Lightest ceratopsians [ edit ]

Pachycephalosaurs [ edit ]

Longest pachycephalosaurs [ edit ]

P. wyomingensis (green), potential growth stages, and a human Size comparison of an adult(green), potential growth stages, and a human

Size by overall length, including tail, of all pachycephalosaurs measuring 3 metres (9.8 ft) or more in length.

Shortest pachycephalosaurs [ edit ]

Size by overall length, including tail, of all pachycephalosaurs measuring 2 metres (6 ft 7 in) or less in length as adults.

Thyreophorans [ edit ]

Longest thyreophorans [ edit ]

Stegosaurus ungulatus (orange) and S. stenops (green) compared to a human Size of(orange) and(green) compared to a human

Ankylosaurus compared to a human. Estimated size ofcompared to a human.

Heaviest thyreophorans [ edit ]

Shortest thyreophorans [ edit ]

Lightest thyreophorans [ edit ]

See also [ edit ]