Largest prehistoric animals

Non-mammalian synapsids (Synapsida)

Caseasaurs (Caseasauria)

Edaphosaurids (Edaphosauridae)

Sphenacodontids (Sphenacodontidae)

Tappenosauridae

Therapsids (Therapsida)

Anomodonts (Anomodontia)

Biarmosuchians (Biarmosuchia)

Dinocephalians (Dinocephalia)

• Perhaps the largest known dinocephalian was the titanosuchid Jonkeria truculenta, with volumetric models suggesting it could have weighed. Tapinocaninus pamelae was slightly smaller, volumetric models suggesting it weighed.
• The largest carnivorous non-mammalian synapsids was the anteosaurid Anteosaurus, which was long, and weighed. Fully grown Titanophoneus from the same family Anteosauridae likely had a skull of long.

Gorgonopsians (Gorgonopsia)

Therocephalians (Therocephalia)

Non-mammalian cynodonts (Cynodontia)

• The largest known non-mammalian cynodont, as well as the largest member of Cynognathia, is Scalenodontoides, a traversodontid, which had a maximum skull length of approximately based on a fragmentary specimen. Paceyodon davidi was the largest of morganucodontans, cynodonts close to mammals. It is known by a right lower molariform in length, which is bigger than molariforms of all other morganucodontans.
• The largest known docodont was Castorocauda, almost in length.

Mammals (Mammalia)

Non-therian mammals

Gobiconodonts (Gobiconodonta)

Multituberculates (Multituberculata)

Monotremes (Monotremata)

• The largest known monotreme ever was the extinct long-beaked echidna species known as Murrayglossus hacketti, known from a couple of bones found in Western Australia. It was the size of a sheep, weighing probably up to.
• The largest known ornithorhynchid is Obdurodon tharalkooschild. Kollikodon ritchiei was likely the largest monotreme in the Mesozoic. Its body length could be up to a.

Metatherians (Metatheria)

• The largest non-marsupial metatherian, as well as the largest carnivorous metatherian, was Proborhyaena gigantea, which is estimated to have weighed weigh. Another large metatherian was Thylacosmilus atrox, weighing, with one estimate suggesting. Australohyaena is another large metatherian, weighing up to.
• Stagodontid mammal Didelphodon was one of the largest Mesozoic metatherians and all Cretaceous mammals. Its skull could reach over in length and a weight of complete animal was.

Marsupials (Marsupialia)

• The largest known marsupial, and the largest metatherian, is the extinct Diprotodon, about long, standing tall and weighing up to. Fellow vombatiform Palorchestes azael was similar in length being around, with body mass estimates indicating it could exceed.
• The largest known carnivorous marsupial was Thylacoleo carnifex. Measurements taken from a number of specimens show they averaged in weight. The largest known koala is the giant koala which has an estimated weight of, which is the same weight as a large contemporary male koala. The largest ever member of the Tasmanian devil genus was Sarcophilus laniarius which were around 15% larger and 50% heavier than modern devils.
• The largest known kangaroo was an as yet unnamed species of Macropus, estimated to weigh, larger than the largest known specimen of Procoptodon, which could grow up to and weigh. Some species from the genus Sthenurus were similar in size or a bit larger than the extant grey kangaroo. The largest ever tree kangaroo, Bohra, had an estimated body mass of.
• The largest potoroid ever recorded was Borungaboodie, which was nearly 30% bigger than the largest living species and weighed up to.
• The largest member of the Thylacinidae is Thylacinus megiriani, which is somewhat reasonably larger than the Tasmanian wolf, and bigger than its fellow Miocene relative Thylacinus potens, usually being 57.3 kilograms in weight.

Non-placental eutherians

Cimolestans (Cimolesta)

Leptictids (Leptictida)

Tenrecs and allies (Afroscida)

Even-toed ungulates (Artiodactyla)

• The largest known land-dwelling artiodactyl was Hippopotamus antiquus, estimated to be 14.1 ft in length and in weight. However, volumetric models suggests it was slightly smaller, weighing. While Hippopotamus gorgops estimated to have weighed over, other experts consider it to be smaller than Hippopotamus antiquus. Daeodon and Paraentelodon were the largest-known entelodonts that ever lived, at long and high at the shoulder. The huge Andrewsarchus from the Eocene of Inner Mongolia had a skull about long though the taxonomy of this genus is disputed.
• The largest bovine and bovid was possibly Bison latifrons. It reached a weight from to possibly, in length, shoulder height of, and had horns that spanned. The African giant buffalo may have rivaled Bison latifrons in size. It reached weight from to, measured in length from muzzle to the end of the tail, in height at the withers, in height at the hindquarters, and the distance between the tips of its horns was as large as. The African Pelorovis reached in weight and had bony cores of the horns about long. The North American Bison antiquus reached up to long, tall, weight of, and horn span of. Aside from local populations and subspecies of extant species, such as the gaur population in Sri Lanka, European bison in British Isles, Caucasian wisent and Carpathian wisent, the largest modern extinct bovid is aurochs with an average height at the shoulders of in bulls and in cows, while aurochs populations in Hungary had bulls reaching. The kouprey, reaching in shoulder height, has existed since the Middle Pleistocene and is also considered to be possibly extinct.
• The long-legged Megalotragus is possibly the largest known alcelaphine bovid, bigger than the extant wildebeest. The tips of horns of M. priscus were located at a distance of about from each other.
• The extinct cervid Irish elk reached over in height, in mass and could have antlers spanning up to across, about twice the maximum span for a moose's antlers. The giant moose reached high and was twice as heavy as the Irish elk but its antler span at was smaller than that of Megaloceros. North American stag-moose reached in length and a weight of.
• The largest known giraffid, aside from the extant giraffe, is Sivatherium, with a body weight of.
• The largest protoceratid was Synthetoceras, it reached long and in mass.
• The largest known wild suid to ever exist was Kubanochoerus gigas, having measured up to and stood around tall at the shoulder. Megalochoerus could be similar in size, possibly weighing or.
• The largest tayassuid extinct Platygonus species were similar in size to modern peccaries especially giant peccary, at around in body length, and had long legs, allowing them to run well. They also had a pig-like snout and long tusks which were probably used to fend off predators.
• The largest camelid was Titanotylopus from the Miocene of North America. It possibly reached and a shoulder height of over. The Syrian camel was twice as big as the modern camels. It was at the shoulder and tall. Camelops had legs 20% longer than that of the dromedary and was about tall at the shoulder, weighing about.
• The anoplotheriid Anoplotherium is thought to have been capable of reaching up to in the case of A. commune and in the case of A. latipes. A. latipes in particular could have measured more than in length and in shoulder height. Because it was probably capable of facultative bipedalism, it could have been capable of standing over tall.

Cetaceans (Cetacea)

• The heaviest archeocete was Perucetus, with weight estimated at, while length is estimated at. However, Motani and Pyenson in 2024 argued that it is extremely difficult for Perucetus to rival or exceed the blue whale in weight. They discussed that since Perucetus is much shorter than the blue whale in length, it should be at least 3.375 times denser or 1.83 times fatter to weigh heavier, which is impossible for vertebrates whose whole-body density range from 0.75 to 1.2. Motani and Pyenson tested the hypotheses of Bianucci and colleagues by performing various body mass estimation methods: the regression-based and volumetric mass estimation resulted in for a length range of, though the likely body mass range would fall within. They also claimed that the previous estimation is inflated by assumed isometry, and that the effect from pachyostosis on the estimation of body mass is not negligible as it resulted in underestimation. The longest of known Eocene archeocete whales was Basilosaurus at in length.
• The largest squalodelphinid was Macrosqualodelphis at in length.
• Some Neogene rorquals were comparable in size to modern huge relatives. Parabalaenoptera was estimated to be about the size of the modern gray whale, about long. Some balaenopterids perhaps rivaled the blue whale in terms of size, though other studies disagree that any baleen whale grew that large in the Miocene.
• The largest macroraptorial sperm whale is Livyatan, with an estimated length of 44–57 ft and an estimated weight of 62.8 short tons.

Odd-toed ungulates (Perissodactyla)

• One of the largest known perissodactyls, and the second largest land mammal an unnamed species of Dzungariotherium may have been even larger than has been thought, estimated to be around. Its more famous relative, Paraceratherium, also grew to large sizes. The largest individual known from the species Paraceratherium transouralicum, was estimated at tall at the shoulders, in length from nose to rump, and in weight.
• Some prehistoric horned rhinos also grew to large sizes. The biggest Elasmotherium reached up to long, high and weighed. Such parameters make it the largest rhino of the Quaternary. Woolly rhinoceros of the same time reached or, at the shoulder height and in length.Metamynodon, an amynodontid, reached in length, comparable to Hippopotamus in measurement and shape.
• The giant tapir was the largest tapir ever, at about and tall at the shoulders. Earlier, this mammal was estimated even bigger, at tall, and assigned to the separate genus Megatapirus.
• The largest known lophiodont is Lophiodon, with L. lautricense being estimated to reach more than in weight.
• One of the biggest chalicotheres was Moropus. It stood about tall at the shoulder.
• Late Eocene perissodactyls from the family Brontotheriidae attained huge sizes. The North American Megacerops reached tall at the shoulders, in length, and in weight.Embolotherium from Asia was equal in size.
• The largest prehistoric horse was Equus giganteus of North America. It was estimated to grow to more than and at the shoulders. The largest anchitherine equid was Hypohippus at, comparable to large modern domestic horses. Megahippus is another large anchitheriine. With the body mass of it was much heavier than most of its close relatives.
• Among the largest-sized genera of palaeotheres, close relatives of horses, is Palaeotherium, with P. giganteum being estimated to reach weights of more than. Previously until the naming of P. giganteum in 1994, P. magnum was considered the largest species of Palaeotherium, potentially reaching in shoulder height and in length. Another palaeothere Cantabrotherium is estimated to have weighed about.

Phenacodontids (Phenacodontidae)

Dinoceratans (Dinocerata)

Carnivores (Carnivora)

Caniformia

• The largest terrestrial mammalian predator, as well the largest known bear and terrestrial carnivoran of all time, was Arctotherium angustidens, the giant South American short-faced bear. A humerus of A. angustidens from Buenos Aires indicates that the males of the species could have weighed and stood at least tall on their hind-limbs. Another huge bear was the giant North American short-faced bear, with the average weight of and the maximum estimated at. There is a guess that the largest individuals of this species could reached even larger mass, up to. The extinct cave bear was also heavier than many recent bears. Largest males weighed as much as. The largest males of the possibly disrupted subspecies of brown bear, steppe brown bear, is also estimated to have weighed. Another large bear was Agriotherium africanum, this species was estimated to have initially estimated to have weighed, but more recent estimates suggest it could've weighed. Ailuropoda baconi from the Pleistocene was larger than the modern giant panda.
• The biggest odobenid and one of the biggest pinnipeds to have ever existed is Pontolis magnus, with a skull length of and having a total body length of more than. Only the modern male elephant seals reach similar sizes. The second largest prehistoric pinniped is Gomphotaria pugnax with a skull length of nearly.
• One of the largest of prehistoric otariids is Thalassoleon, comparable in size to the biggest extant fur seals. An estimated weight of T. mexicanus is no less than.
• The biggest known mustelid to ever exist was likely the giant otter, Enhydriodon omoensis. It exceeded in length, and would have weighed in at around, much larger than any other known mustelid, living or extinct. There were other giant otters, like Siamogale, at around and Megalenhydris, which was larger than a modern-day giant river otter. Megalictis was the largest purely terrestrial mustelid. Similar in size to the jaguar, Megalictis ferox had even wider skull, almost as wide as of the black bear. Another large-bodied mustelid was the superficially cat-like Ekorus from the Miocene of Africa. At almost, the long-legged Ekorus was about the size of a wolf. Other huge mustelids include Perunium and hypercarnivorous Eomellivora, both from the Late Miocene.
• The heaviest procyonid was possibly the South American Chapalmalania. It reached in body length with a short tail and, comparable in size to an American black bear. Another huge procyonid was Cyonasua, which weighted about, about the same size as a medium-sized dog.
• The largest canid of all time was Epicyon haydeni, which stood tall at the shoulder, had a body length of and weighed, with the heaviest known specimen weighing up to. The extinct dire wolf reached in length and weighed between. The largest wolf subspecies ever existed in Europe is the Canis lupus maximus from the Late Pleistocene of France. Its long bones are 10% larger than those of extant European wolves and 20% longer than those of C. l. lunellensis. The Late Pleistocene Italian wolf was morphometrically close to C. l. maximus.
• The largest amphicyonid was a species of Pseudocyon weighing around, representing a very large individual.

Feliformia

• The largest barbourofelinae, as well as the largest nimravid, was Barbourofelis fricki, with the shoulder height of and could've weighed. The largest nimravinae was Quercylurus major as its fossils suggest it weighed similar in size to the modern-day lion and was scansorial. The closely related Dinailurictis bondali was slightly smaller weighing, making it as large as a lioness. Eusmilus adelos is considered the largest member of the hoplophonine subfamily, reaching a weight of, comparable to a small African lion. While it was assumed that Hoplophoneus occidentalis could've weighed, other experts suggested it was smaller, being about the size of a leopard. A 2012 study suggested this species could've weighed.
• The largest machairodont felid was Amphimachairodus kabir, with the males possibly reaching. Smilodon populator was a close contender, with males weighing. Another large member of the Amphimachairodus genus, A. horribilis, is estimated to weigh. Another contender is Nimravides catocopis with the largest specimen weighing up to. An unnamed species of Xenosmilus thought to have weighed between.
• The heaviest known pantherine felids were the extinct leonines Panthera fossilis, which has been estimated to have maximum weight of, the American lion, weighing up to, and the Natodomeri lion of eastern Africa, which was comparable in size to large members of P. atrox. The Ngangdong tiger, was estimated to have weighed up to, however this has been contested with some estimates suggesting the largest individuals weighed.
• The largest feline felid was Acinonyx pleistocaenicus, with the largest specimen weighing. Its close relative, giant cheetah, reached, approximately twice as large as the modern cheetah. The North American Pratifelis was larger than the extant cougar.
• The largest viverrid known to have existed is Viverra leakeyi, which was around the size of a wolf or small leopard at.
• The largest known extinct hyena was the percrocutid hyena, Dinocrocuta gigantea. It was originally estimated to have weighed. However, recent weight estimates may suggest it may have weighed less. An individual with a skull length of, is estimated to have weighed. One specimen is reported to have a skull length of. Pachycrocuta brevirostris was another large extinct hyena. It's estimated at at the shoulder and weight. However, other experts leaned towards representing the upper end of the species. Crocuta hyenas have also been known large sizes, even larger than the extant spotted hyena, most notably the extinct spotted hyena subspecies, the cave hyena, with average individuals weighing. Crocuta eturno was another large Crocuta species with estimates suggesting this species could've weighed.
• The extinct giant fossa had a body mass in range from to, much larger than the modern fossa weighs.

Hyaenodonts (Hyaenodonta)

• The largest hyainailourid, as well as the largest hyaenodont was Megistotherium osteothlastes at. While its close relative, Simbakubwa kutokaafrika, was estimated to reach, the same regression suggested Megistotherium was larger than Simbakubwa. Hyainailouros was another large hyainailourid. The largest species in the genus, H. bugtiensis, which could've weighed between.
• The largest hyaenodontid was Hyaenodon gigas, weighing in at around.

Oxyaenids (Oxyaenidae)

Mesonychians (Mesonychia)

Bats (Chiroptera)

Hedgehogs, gymnures, shrews, and moles (Eulipotyphla)

Rodents (Rodentia)

• Several of the extinct South American dinomyids were much bigger than modern rodents. Josephoartigasia monesi was the largest-known rodent of all time, approximately weighing an estimated. Phoberomys pattersoni weighed. Both Josephoartigasia and Phoberomys reached about tall at the shoulder. Another huge dinomyid, Telicomys gigantissimus had a minimal weight of.Amblyrhiza inundata from the family Heptaxodontidae was a massive animal, it weighed.
• The largest beaver was the giant beaver of North America. It grew over 2 m in length and weighed roughly, also making it one of the largest rodents to ever exist.
• The largest old world porcupine are the Hystrix refossa was larger than living porcupines. It was approximately 20% larger than its closest relative, the living Indian porcupine, reaching lengths of over.

Rabbits, hares, and pikas (Lagomorpha)

Pangolins (Pholidota)

Primates (Primates)

• The largest known non-hominid primate is Gigantopithecus blacki. Studies estimate heights around tall, weighing. Some suggested that it would not exceed tall with a bipedal posture. Another giant ape was Meganthropus palaeojavanicus at in body height, although it is known from very poor remains.
• During the Pleistocene, some archaic humans were close in sizes or even larger than early modern humans. Neanderthals reached and in average weight for males and females, respectively, larger than the parameters of modern humans . A tibia from Kabwe indicates an indeterminate Homo individual of possibly in height. It was one of the tallest humans of the Middle Pleistocene and noticeably large even compared to recent humans. The tallest Homo sapiens individuals from the Middle Pleistocene of Spain reached and for males and females, respectively. Some Homo erectus could be as large as tall and in weight.
• The heaviest known Old World monkey is the prehistoric baboon Theropithecus oswaldi which have weighed, some even suggested to reach. A male specimen of Dinopithecus projected to weigh an average of and up to, exceeds the maximum weight record of the chacma baboon, the largest extant baboon.
• The largest known New World monkey was Cartelles, which is studied as specimen of Protopithecus, weighing up to. Caipora bambuiorum is another large species, weighing up to.
• The largest omomyids were Macrotarsius and Ourayia from the Middle Eocene. Both reached in weight.
• Some prehistoric lemuriform primates grew to huge sizes as well. Archaeoindris was a sloth lemur that lived in Madagascar and weighed, as large as an adult male gorilla. Palaeopropithecus from the same family was also heavier than most modern lemurs, at. Megaladapis is another large extinct lemur at in length and an average body mass of around. Other estimates suggest but its still much larger than any extant lemur.

Elephants, mammoths and mastodons (Proboscidea)

• The elephant Palaeoloxodon namadicus has been suggested to have been the largest land mammal ever, based on a particularly large partial femur which was estimated to have belonged to an individual in weight and about tall at the shoulder, though the author of the estimate said that this was speculative and should be treated with caution. In 2023, a publication by Gregory S. Paul and Larramendi estimated that another specimen identified as cf. P. namadicus, also only known from a partial femur, would have weighed 18–19 tonnes. Other authors have noted that weight estimates for proboscideans based on single bones can lead to estimates that are "highly improbable" compared to accurate estimates from complete skeletons. In 2024, Biswas, Chang and Tsai estimated a maximum shoulder height of over 4.5 metres and suggested that the body mass for 5 measured specimens ranged from 13.2 to 18.5 tonnes from specimens from Taiwan. The largest individual reported individual of the steppe mammoth of Eurasia was estimated to reach at the shoulders and in weight. Stegodon zdanskyi, the biggest species of Stegodon, was in body mass. Another enormous proboscidean is Stegotetrabelodon syrticus, over in height and in weight. The Columbian mammoth was about tall at the shoulder but didn't weigh as much as other huge proboscideans. Its average mass was with one unusually large specimen about.
• The mammutid "Mammut" borsoni is one of the largest known proboscideans and land mammals. The average fully-grown male is estimated to have been tall and weighed about, with very large males possibly rivalling the estimated size of the largest Palaeoloxodon namadicus. This species also had the longest tusks of any animals with the largest recorded specimen being long from basis to tip along the curve.Deinotherium was the largest proboscidean in Deinotheriidae family. Bones retrieved in Crete confirm the existence of specimen tall at the shoulders and more than in weight.

Sea cows (Sirenia)

Embrithopods (Embrithopoda)

Hyraxes (Hyracoidea)

Desmostylians (Desmostylia)

Glyptodonts, armadillos and pampatheres (Cingulata)

Anteaters and sloths (Pilosa)

• The largest known pilosan, as well as the largest sloth, was the megatheriid Eremotherium laurillardi, a ground sloth that was initially estimated to weigh up to and a length of up to, which is as big as a bull African bush elephant. However, many studies have gotten lower estimates, with one study suggesting that was the most accurate size estimate for an adult. The closely related ground sloth, Megatherium americanum, was slightly smaller, measuring in length, and weighed based on volumetric models.
• The largest known mylodontoid was Lestodon armatus, estimated to have measured in length, and weighed.
• The largest extinct anteater was Neotamandua borealis, which is estimated to have weighed between.

Astrapotherians (Astrapotheria)

Litopterns (Litopterna)

Notoungulates (Notoungulata)

Pyrotherians (Pyrotheria)

Reptiles (Reptilia)

Lizards and snakes (Squamata)

• Mosasaurs are the largest-known squamates. The largest-known mosasaur is likely Mosasaurus hoffmanni, estimated at more than in length, however these estimations are based on heads and total body length ratio 1:10, which is unlikely for Mosasaurus, and probably that ratio is about 1:7. Another giant mosasaur is Tylosaurus, estimated at in length. Another mosasaur, Prognathodon reached similar sizes.
• The largest known prehistoric snake is Titanoboa cerrejonensis, estimated at or even in length and. The madtsoiid Vasuki indicus may have rivaled or surpassed Titanoboa in length, however had smaller vertebral dimensions compared to it. A close rival in size to those snakes is palaeophiid marine snake Palaeophis colossaeus, which may have been around in length or even up to. Another known very large fossil snake is Gigantophis garstini, estimated at in length, although later study shows smaller estimation about. The largest fossil python is Liasis dubudingala with length roughly. The largest viper as well as the largest venomous snake ever recorded is Laophis crotaloides from the Early Pliocene of Greece. This snake reached over in length and in weight. Another huge fossil viper is indeterminate species of Vipera. With a length of around it was one of the biggest predators of Mallorca during the Early Pliocene. The largest known blind snake is Boipeba tayasuensis with estimated total length of.
• The largest known land lizard is probably megalania, with the most recent studies estimating it to have been about in length. As extant relatives, megalania could have been venomous and in that case this lizard was also the largest venomous vertebrate ever evolved. However, maximum size of this animal is subject to debate.

Turtles, tortoises and close relatives (Pantestudines)

Cryptodira

• The largest known turtle ever was Archelon ischyros at long and. Possible second-largest sea turtle was Protostega at in total body length. There is even a larger specimen of this genus from Texas estimated at in total length. Partially known Cratochelone is estimated to reach in total length. Another huge prehistoric sea turtle is the Late Cretaceous Gigantatypus, estimated at over in length. Psephophorus terrypratchetti from the Eocene attained in body length.
• The largest tortoise was Megalochelys atlas at up to in shell length and weighing. M. margae had carapace of long; an unnamed species from Java reached at least in carapace length. The Cenozoic Titanochelon were also larger than extant giant tortoises, with a shell length of up to. Other giant tortoises include Centrochelys marocana at in carapace length and Mesoamerican Hesperotestudo sp. at in carapace length.
• The largest trionychid ever recorded is indeterminate specimen GSP-UM 3019 from the Middle Eocene of Pakistan. Bony carapace of GSP-UM 3019 is long and wide indicates the total carapace diameter about. Drazinderetes tethyensis from the same formation had a bony carapace long and wide. Another huge trionychid is North American Axestemys byssinus at over in total length.

Side-necked turtles (Pleurodira)

Macrobaenids (Macrobaenidae)

Meiolaniformes

Sauropterygians (Sauropterygia)

Placodonts and close relatives (Placodontiformes)

Nothosaurs and close relatives (Nothosauroidea)

Plesiosaurs (Plesiosauria)

• The largest known plesiosauroid was an indeterminate specimen possibly belonging to Aristonectes, with a body length of and body mass of. Another long plesiosauroid was Albertonectes at. Thalassomedon rivaled it in size, with its length at. Other large plesiosauroids are Styxosaurus and Elasmosaurus. Both reached some more than in length. Hydralmosaurus reached in total body length. In past, Mauisaurus was considered to be more than in length, but later it was determined as nomen dubium.
• There is much controversy over the largest-known of the Pliosauroidea. Pliosaurus funkei is a species of large pliosaur, known from remains discovered in Norway in 2008. This pliosaur has been estimated at in length. However, in 2002, a team of paleontologists in Mexico discovered the remains of a pliosaur nicknamed as "Monster of Aramberri", which is also estimated at in length, with shorter estimation about. This species is, however, claimed to be a juvenile and has been attacked by a larger pliosaur. Some media sources claimed that Monster of Aramberri was a Liopleurodon but its species is unconfirmed thus far. Another very large pliosaur was Pliosaurus macromerus, known from a single incomplete mandible. The Early Cretaceous Kronosaurus queenslandicus is estimated at in length and in weight. The Late Jurassic Megalneusaurus rex could reach lengths of. Close contender in size was the Late Cretaceous Megacephalosaurus eulerti with a length in range of.

Proterosuchids (Proterosuchidae)

Erythrosuchids (Erythrosuchidae)

Phytosaurs (Phytosauria)

Non-crocodylomorph pseudosuchians (Pseudosuchia)

• The largest shuvosaurid and one of the largest pseudosuchian from the Triassic period was Sillosuchus. Biggest specimens could have reached in length.
• The largest known carnivorous pseudosuchian of the Triassic is loricatan Fasolasuchus tenax, which measured an estimated of. It is both the largest "rauisuchian" known to science, and the largest non-dinosaurian terrestrial predator ever discovered. Biggest individuals of Postosuchus and Saurosuchus had a body length of around. A specimen of Prestosuchus discovered in 2010 suggest that this animal also reached lengths of nearly making it one of the largest Triassic pseudosuchians.Desmatosuchus was likely one of the largest known aetosaurs, about in length and in weight.

Crocodiles and close relatives (Crocodylomorpha)

Aegyptosuchids (Aegyptosuchidae)

Crocodylians (Crocodylia)

• The largest caiman and likely one of the largest crocodylians was Purussaurus brasiliensis estimated at. According to another information, maximum estimate measure and almost in length and in weight respectively. However, a 2022 study estimated a length of 7.6–9.2 metres and a mass of 2–6.2 metric tons using a phylogenetic approach; and a length of 9.2–10 metres and mass of 3.9–4.9 metric tons using a non-phylogenetic approach.
• Another giant caiman was Mourasuchus. Various estimates suggest the biggest specimens reached in length and in weight. but more recent estimates suggest in body length.
• The largest alligatoroid is likely Deinosuchus riograndensis and Deinosuchus hatcheri, both at long and weighing. However, the 2025 study which reclassified Deinosuchus as a eusuchian crocodylomorph stated that previous estimates may have overestimated its size as the genus has a relatively long snout, but these were based on taxa with shorter snouts. The authors estimated that D. riograndensis most likely reached total lengths of.
• The largest extinct species of the genus Alligator was the Haile alligator, which had a skull long and was similar in size to the extant American alligator.
• The largest gavialids were Asian Rhamphosuchus at and South American Gryposuchus at in length.
• The basal crocodyloidean Astorgosuchus bugtiensis from the Oligocene was large. It estimated at in length.
• The largest known true crocodile was Euthecodon which estimated to have reached or even long. The largest species of the modern Crocodylus were Kenyan Crocodylus thorbjarnarsoni at in length, Tanzanian Crocodylus anthropophagus at in length and indeterminate species from Kali Gedeh at in length.
• The largest known mekosuchian is Paludirex vincenti, which is estimated to reach up to. Partial jaw specimen from Pliocene that is attributed to Quinkana suggest an individual about in length, although other species are smaller with length around.

Paralligatorids (Paralligatoridae)

Tethysuchians (Tethysuchia)

• Some extinct pholidosaurids reached giant sizes. In the past, Sarcosuchus imperator was believed to be the largest crocodylomorph, with initial estimates proposing a length of and a weight of. However, recent estimates have now shrunk to a length of and a weight of. Related to Sarcosuchus, Chalawan thailandicus could have reached more than in length, although other estimates suggest.
• The largest dyrosaurid was Phosphatosaurus gavialoides, estimated at in length.

Stomatosuchids (Stomatosuchidae)

Notosuchians (Notosuchia)

• Some of largest terrestrial notosuchian crocodylomorphs were the Miocene sebecid Barinasuchus, with a skull of long, and Eocene sebecid Dentaneosuchus with estimated mandible length of. Various estimates suggest a possible length of these animals between. Using proportion of Stratiotosuchus which is also large to have long skull, Barinasuchus is estimated to have length at least.
• Other huge notosuchian, although only known from fragmentary material, is an early member Razanandrongobe, which skull size may exceeded that of Barinasuchus and overall length may be around.

Thalattosuchians (Thalattosuchia)

• The largest thalattosuchian as well as the largest teleosauroid was unnamed fossil remain from Paja Formation, which may belongs to animal with length of, which is as large as outdated length estimate of the Early Cretaceous Machimosaurus rex, more recently estimated at in length. Neosteneosaurus edwardsi was the biggest Middle Jurassic crocodylomorph, it reached long.Plesiosuchus was very large metriorhynchid. With the length of it exceeded even some pliosaurids of the same time and locality such as Liopleurodon. Other huge metriorhynchids include Tyrannoneustes at in length and Torvoneustes at in length.

Basal crocodylomorphs

Pterosaurs (Pterosauria)

• The largest known pterosaur was Quetzalcoatlus northropi, at and with a wingspan of. Another close contender is Hatzegopteryx, also with a wingspan of or more. This estimate is based on a skull long. Yet another possible contender for the title is Cryodrakon which had a wingspan. An unnamed pterodactyloid pterosaur from the Nemegt Formation could reach a wingspan of nearly. According to various assumptions, the wingspan of Arambourgiania philadelphiae reached from to more than. South American Tropeognathus reached the maximum wingspan of.
• The largest of non-pterodactyloid pterosaurs as well as the largest Jurassic pterosaur was Dearc, with an estimated wingspan between and. Only a fragmentary rhamphorhynchid specimen from Germany could be larger. Other large non-pterodactyloid pterosaurs were Sericipterus, Campylognathoides and Harpactognathus, with the wingspan of,, and, respectively.

Choristoderes (Choristodera)

Tanystropheids (Tanystropheidae)

Thalattosaurs (Thalattosauria)

Ichthyosaurs (Ichthyosauria)

• The largest known shastasaur, ichthyosaur and marine reptile was Ichthyotitan, which is estimated to have measured. In addition to the Aust specimen, which has been attributed to Ichthyotitan, could've measured over. Another large shastasaur Shastasaurus sikanniensis at in length and in weight. Shonisaurus popularis was another large Ichthyosaur, measuring in length and weighing. Thalattoarchon saurophagis is also reasonably large, being at and around.
• The largest cymbospondylidae ichthyosaur as well as the largest animal of the Middle Triassic was Cymbospondylus youngorum at in length and in weight.

Pareiasaurs (Pareiasauria)

Captorhinids (Captorhinidae)

Non-avian dinosaurs (Dinosauria)

Sauropodomorphs (Sauropodomorpha)

Sauropods (Sauropoda)

• A mega-sauropod, Maraapunisaurus fragillimus, is a contender for the largest-known dinosaur in history. It has been estimated at in maximum length and in weight. Unfortunately, the fossil remains of this dinosaur have been lost. More recently, it was estimated at in length and in weight.
• Known from the incomplete and now disintegrated remains, the Late Cretaceous Bruhathkayosaurus matleyi was an anomalously large sauropod. Informal estimations suggested as huge parameters as in length and in weight. Some estimates, however, suggest and but it's still much heavier than most other sauropods. More recent estimations by Gregory Paul in 2023 has placed its weight range around to a. If true, it would make Bruhathkayosaurus the single largest terrestrial animal to have walked the earth and would have rivalled the largest blue whale recorded.
• BYU 9024, a massive cervical vertebra found in Utah, may belong to a Barosaurus lentus or Supersaurus vivianae of a huge size, possibly in length and in body mass. Supersaurus vivianae itself may have been the longest dinosaur yet discovered as a study of 3 specimens suggested length of or over.Mamenchisaurus sinocanadorum was likely the largest mamenchisaurid, reaching nearly in length and in weight. Xinjiangtitan shanshanesis from the same family had -long neck, about 55% of its total length that could be at least.
• The Middle Jurassic Breviparopus taghbaloutensis was mentioned in The Guinness Book of Records as the longest dinosaur at although this animal is known only from fossil tracks. Originally thought to be a brachiosaurid, it was later identified as a huge diplodocoid, possibly in length and in weight.
• The tallest sauropod was Sauroposeidon proteles with estimated height at. Asiatosaurus could potentially reach in height, but this animal is known only from teeth. Giraffatitan was estimated at in height.

• The "Archbishop", a large brachiosaur that was discovered in 1930., a scientific paper on the specimen is still in progress.Brachiosaurus nougaredi is yet another large brachiosaur from Early Cretaceous North Africa. The remains have been lost, but the sacrum drawing remains. It suggests a sacrum of almost long, making it the largest dinosaur sacrum discovered so far, except those of Argentinosaurus and Apatosaurus.
• In 2010, the femur of a large sauropod was discovered in France. The femur suggests an animal that grew to immense sizes.

Non-avian theropods (Theropoda)

• The largest theropod as well as the largest terrestrial predator yet known is Tyrannosaurus rex, with the largest specimen known nicknamed Scotty, located at the Royal Saskatchewan Museum, is reported to measure 13 m in length. Using a mass estimation technique that extrapolates from the circumference of the femur, Scotty was estimated as the largest known specimen at 8.87 metric tons in body mass
• Other large theropods were Giganotosaurus carolinii, and Spinosaurus aegyptiacus, whose largest specimens known estimated at and in length, and weigh between and 14 m in length and 7.4 metric tonnes respectively. Some other notable giant theropods may also have rivaled them in size.Macroelongatoolithus, ranging from in length, is the largest known type of dinosaur egg. It is assigned to oviraptorosaurs like Beibeilong.

Armoured dinosaurs (Thyreophora)

Marginocephalians (Marginocephalia)

Pachycephalosaurs (Pachycephalosauria)

Ceratopsians (Ceratopsia)

Ornithopods (Ornithopoda)

• The very largest known ornithopods, like Shantungosaurus were as heavy as medium-sized sauropods at up to, and in length. Magnapaulia reached in length, or, according to original description, even. The Mongolian Saurolophus, S. angustirostris, reached long and possibly more. Such animal could weighed up to. The largest Edmontosaurus reached in length and around in body mass. An estimated maximum length of Brachylophosaurus is resulting in weight of. PASAC-1, informally named "Sabinosaurus", is the largest well-known North American saurolophine, around long, that is about 20% larger than other known specimens. Hypsibema missouriensis was up to long. The Late Cretaceous Charonosaurus was estimated around in length and in weight.
• The largest ornithopod outside of Hadrosauroidea was likely the Iguanodon. Biggest specimens reached in length and weighed around. Another large ornithopod is Iguanacolossus, with in length and in weight.
• The largest rhabdodontid was Matheronodon, estimated at in length. Rhabdodon reached approximately and according to 2016 estimates.

Birds (Aves)

Enantiornitheans (Enantiornithes)

Avisauridae

Pengornithidae

Gargantuaviidae

Dromornithiformes

Gastornid (Gastornithiformes)

Waterfowl (Anseriformes)

Swans (Cygnini)

Anatinae

Pelicans, ibises and allies (Pelecaniformes)

• The Early Pliocene Pelecanus schreiberi was larger than most extant pelicans. Pelecanus odessanus from the Late Miocene was probably the same size as P. schreiberi, its tarsometatarsus is long.
• The largest heron was the Bennu heron. Based on remains discovered, it was approximately tall and had a wingspan up to, thus surpassing the size of the largest living species in the heron family, the goliath heron.
• The Jamaican ibis was a large ibis, weighing about 2 kg.

Storks and allies (Ciconiiformes)

Cranes (Gruiformes)

Shorebirds (Charadriiformes)

Hesperornithines (Hesperornithes)

New World vultures (Cathartiformes)

Seriemas and allies (Cariamiformes)

Accipitriforms (Accipitriformes)

Moa (Dinornithiformes)

Tinamous (Tinamiformes)

Elephant birds (Aepyornithiformes)

Ostriches (Struthioniformes)

Pigeons and doves (Columbiformes)

Pheasants, turkeys, gamebirds and allies (Galliformes)

Songbirds (Passeriformes)

Cormorants and allies (Suliformes)

• The largest known cormorant was the spectacled cormorant of the North Pacific, which became extinct around 1850 and averaged around and.
• The largest known darter was Giganhinga with estimated weight about, earlier study even claims.
• The largest known plotopterid, penguin-like flightless bird was Copepteryx titan that is known from long femur, almost twice as long as that of emperor penguin.

Grebes (Podicipediformes)

Bony-toothed birds (Odontopterygiformes)

Woodpeckers and allies (Piciformes)

Parrots (Psittaciformes)

Penguins (Sphenisciformes)

Owls (Strigiformes)

Amphibians (Amphibia)

Lissamphibians (Lissamphibia)

Frogs and toads (Anura)

Salamanders, newts and allies (Urodela)

Diadectomorphs (Diadectomorpha)

Anthracosauria

Embolomeri

Temnospondyls (Temnospondyli)

Fishes (Pisces)

Jawless fish (Agnatha)

Conodonts (Conodonta)

Heterostracans (Heterostraci)

Thelodonts (Thelodonti)

Cephalaspidomorphs (Cephalaspidomorphi)

Spiny sharks (Acanthodii)

Placoderms (Placodermi)

Cartilaginous fish (Chondrichthyes)

Mackerel sharks (Lamniformes)

• Species in the extinct genus Otodus were huge. A giant shark, Otodus megalodon is by far the biggest mackerel shark as well as non-tetropod fish ever known. Most estimates of megalodon's size extrapolate from teeth, with maximum length estimates up to with a 2025 study estimating a maximum length estimate of and modal length estimates based on individuals from all ontogenetic stages of. Due to fragmentary remains, there have been many contradictory size estimates for megalodon, as they can only be drawn from fossil teeth and vertebrae. With the 2025 study suggesting that the animal had a more elongated slender appearance. Mature male megalodon may have had a body mass of, and mature females may have been, assuming that males could range in length from and females. Related to megalodon, Otodus angustidens and O. chubutensis reached the large sizes too. Each was estimated at and, respectively.
• Other giant mackerel sharks were Pseudoscapanorhynchidae from the Cretaceous period. Cretodus had a size range of, Leptostyrax reached lengths of.
• The Cenozoic Parotodus reached up to in length.
• The heaviest thresher shark was likely Alopias grandis. It was similar in size or even larger than the extant great white shark and probably did not have an elongated dorsal tail, characteristic of modern relatives.

Ground sharks (Carcharhiniformes)

Hybodonts (Hybodontiformes)

Ctenacanthiformes

Skates and allies (Rajiformes)

Eugeneodonts (Eugeneodontida)

Lobe-finned fish (Sarcopterygii)

Coelacanths (Actinistia)

Lungfish (Dipnoi)

Stem-tetrapods (Tetrapodomorpha)

• Not only the largest known rhizodont, but also the largest lobe-finned fish was the long Rhizodus. Another large rhizodonts were Strepsodus with estimated length around and Barameda estimated at in length.
• Tristichopterid Hyneria reached length up to.

Ray-finned fish (Actinopterygii)

Acipenseriformes

• The largest known fossil sturgeon is "Acipenser" gigantissimus known from fragmentary remains, which is estimated to reach up to.
• The largest known fossil paddlefish is unnamed remain from Judith River Formation, it may exceeded, known remains exceeded size of recently extinct Chinese paddlefish, which scientifically reported to exceed.

Pachycormiformes

Ichthyodectiformes

Pycnodontiformes

Bichirs (Polypteriformes)

Opahes, ribbonfishes, oarfishes and allies (Lampriformes)

Salmon and trout (Salmoniformes)

Pufferfishes, boxfishes, triggerfishes, ocean sunfishes and allies (Tetraodontiformes)

• Some extinct species of Balistes like B. vegai and B. crassidens are estimated to have total length up to.

Lizardfishes (Aulopiformes)

Echinoderms (Echinodermata)

Crinozoa

Sea lilies (Crinoidea)

Asterozoa

Starfish (Asteroidea)

Graptolites (Graptolithina)

Kinorhynchs (Kinorhyncha)

Arthropods (Arthropoda)

Dinocaridida

Gilled lobopodians

Radiodont (Radiodonta)

Chelicerata

Sea spiders (Pycnogonida)

Horseshoe crabs and allies (Xiphosura)

• Horseshoe crab trackway icnofossil Kouphichnium lithographicum from Cerin in Ain indicates length of animal.

Chasmataspidids (Chasmataspidida)

Eurypterids (Eurypterida)

• The largest known eurypterid was Jaekelopterus rhenaniae at in length, which is also the largest arthropod known to exist. Erettopterus grandis possibly reached this same length but this is based on an incomplete telson only. A close contender was Acutiramus bohemicus at in length. The largest megalograptid as well as the largest Ordovician eurypterid was Pentecopterus. It reached up to in length. All these were eurypterine eurypterids.
• The largest stylonurine eurypterid was Hibbertopterus, with in length.

Arachnids (Arachnida)

• There are three contenders for largest-known arachnid as well as the largest scorpions of all time: Pulmonoscorpius kirktonensis, Brontoscorpio anglicus and Praearcturus gigas. Each was estimated to have been, and up to, respectively.Mongolarachne jurassica is the largest described fossil spider, with the total body length of female is approximately while the front legs reach about in length. Dinodiplura ambulacra had larger body length, combined length of carapace and opisthosoma reaches.
• The largest of prehistoric whipscorpions and possibly the largest-known whipscorpion ever discovered was Mesoproctus rayoli. The type specimen has body length reaching with a carapace of in length, while another specimen has a carapace of in length and in width, comparable or even larger than the extant Mastigoproctus.
• The largest Ricinulei to ever exist was Curculioides bohemondi with a body length of.
• The largest fossil acariform mite and also the largest erythraeoid mite ever recorded was Immensmaris chewbaccei with idiosoma of more than in length.
• The largest known trigonotarbid was Kreischeria with a minimal length of. The second largest was Pleophrynus at in length.

Artiopods (Artiopoda)

Trilobites (Trilobita)

Myriapods (Myriapoda)

Non-hexapod crustaceans (Crustacea)

Cycloids (Cyclida)

Remipedes (Remipedia)

Insects (Insecta)

Sawflies, wasps, bees, ants and allies (Hymenoptera)

• The largest known of this group was the giant ant Titanomyrma giganteum with queens growing to. It had a wingspan of.Apis lithohermaea is one of the largest honey bees ever found, comparable in size to the modern Apis dorsata.
• The giant horntail Ypresiosirex orthosemos reached in length including the incomplete ovipositor. Another example of a giant sawfly is Hoplitolyda duolunica, with wingspan over.

Fleas (Siphonaptera)

Earwigs (Dermaptera)

Chresmodidae

Beetles (Coleoptera)

Titanopterans (Titanoptera)

Antlions and related net-winged insects (Neuroptera)

Cockroaches, termites, mantises and allies (Dictyoptera)

• The largest known roachoid, cockroach-like stem dictyopteran, is Opsiomylacris sp., with wing length of, which is comparable to a modern Megaloblatta longipennis.
• Cretaceous cockroach Ptiloteuthis foliatus had a long wing.
• Found in the Miocene of Austria, the giant termite Gyatermes styriensis reached in body length and had a wingspan of.

Dragonflies, damselflies and griffinflies (Odonatoptera)

• The largest known odonatopteran insect was Meganeuropsis permiana with a single wing of. Meganeura had a long wing.
• Triadotypid odonatan Reisia gelasii from Triassic had long wing, and wingspan can be.

Mayflies (Ephemeroptera)

• The largest known mayfly is Permian Ponalex maximus, with long hindwing. Cretaceous Epicharmeropsis quadrivenulosus had long forewing.
• Although Bojophlebia prokopi from the Upper Carboniferous of Moravia with a wingspan of is described as the largest mayfly, later study shows that this insect is not related to mayflies.

Palaeodictyoptera

Archaeognatha (jumping bristletails) and other wingless primitive insects

• The largest known machilid is Triassic Gigamachilis, with body length not counting the length of the filament, and estimated total length about.
• The largest specimens of the extinct suborder Monura reached or more, not counting the length of the filament.
• Although Ramsdelepidion was once considered as a -long silverfish, it was later considered that classification is uncertain and just treated as stem group insect.
• The wingless early insect Carbotriplura had body length about without tail filaments.

Arrow worms (Chaetognatha)

Ringed worms (Annelida)

Molluscs (Mollusca)

Snails and slugs (Gastropoda)

• The largest known gastropods were in the genus Campanile, with the extinct Campanile giganteum having shell lengths up to or even more than.
• The largest known cowrie is Vicetia bizzottoi, with shell length of.Pebasiconcha immanis is the largest land snail ever known, shell height is with a partial specimen that may exceed in height.

Bivalves (Bivalvia)

• The largest known bivalve ever as well as the largest inoceramid was Platyceramus platinus, a giant that usually had an axial length of, but some individuals could reach an axial length of up to. Another large prehistoric bivalve was Inoceramus. In 1952, -long specimen of Inoceramus steenstrupi was found in the Late Cretaceous deposits of Greenland.
• Some Permian alatoconchid genus like Shikamaia had shell length about. Previous estimation reconstructed length of Shikamaia around.
• The longest ostreid is Konbostrea, with shell height reaching up to.
• Rudist Titanosarcolites had overall size around.

Tusk shells (Scaphopoda)

• Complete shell length of tusk shell Prodentalium onoi is estimated to be over.

Cephalopods (Cephalopoda)

Nautiloids (Nautiloidea)

Ammonites (Ammonoidea)

Belemnites (Belemnoidea)

Squids, octopuses, cuttlefishes and allies (Neocoleoidea)

• A specimen of Octopod, a member of family Muensterellidae and Enchoteuthinae, Enchoteuthis melanae which was previously attributed to Tusoteuthis longa, had a mantle length of up to, comparable to the modern-day giant squid. Previously, this taxon was considered similar to the giant squid, with total length including arms over. However, considering other fossil relatives, the total length including arms is estimated to be less than, to be realistic and reasonable.
• Both non-octopod Yezoteuthis and teuthid Haboroteuthis are estimated to be similar in size to the modern-day giant squid. Incomplete jaw specimen from Yezo Group is twice as large as those of Yezotuethis.

Brachiopods (Brachiopoda)

Hyoliths (Hyolitha)

Cnidarians (Cnidaria)

Jellyfishes and allies (Medusozoa)

Vendobionts (Vendobionta)

Petalonamids (Petalonamae)

Proarticulata

Sponges (Porifera)