Clockwise from top left: an African bush elephant, the largest extant terrestrial animal; a blue whale, the largest animal of all time; and a colossal squid, the largest invertebrate

The largest animal currently alive is the blue whale. The maximum recorded weight was 190 tonnes for a specimen measuring 27.6 metres (91 ft), whereas longer ones, up to 33.6 metres (110 ft), have been recorded but not weighed.^[1][2][3] It is estimated, this individual could have a mass of 250 tonnes or more.^[4][5][6] The longest non-colonial animal is the lion's mane jellyfish (37 m, 120 ft).^[7]

In 2023, paleontologists estimated that the extinct whale Perucetus, discovered in Peru, may have outweighed the blue whale, with a mass of 85 to 340 t (94–375 short tons; 84–335 long tons).^[8] However more recent studies suggest this whale was much smaller than previous estimates putting its weight at 60 to 113 tonnes.^[9] While controversial, estimates for the weight of the sauropod Bruhathkayosaurus suggest it was around 110–170 tons, with the highest estimate being 240 tons, if scaled with Patagotitan, although actual fossil remains no longer exist, and that estimation is based on described dimensions in 1987.^[10] The upper estimates of weight for these two prehistoric animals would have easily rivaled or exceeded the blue whale.

The African bush elephant (Loxodonta africana) is the largest living land animal. A native of various open habitats in sub-Saharan Africa, males weigh about 6.0 tonnes (13,200 lb) on average.^[11] The largest elephant ever recorded was shot in Angola in 1974. It was a male measuring 10.67 metres (35.0 ft) from trunk to tail and 4.17 metres (13.7 ft) lying on its side in a projected line from the highest point of the shoulder, to the base of the forefoot, indicating a standing shoulder height of 3.96 metres (13.0 ft). This male had a computed weight of 10.4 to 12.25 tonnes.^[1]

Heaviest living animals

The heaviest living animals are all whales. Since no scale can accommodate the whole body of a large whale, most have been weighed by parts.

Heaviest terrestrial animals

The heaviest land animals are all mammals. The African elephant is now listed as two species, the African bush elephant and the African forest elephant, as they are now generally considered to be two separate species.^[26]

Vertebrates

Mammals (Mammalia)

The blue whale is the largest mammal of all time, with the largest known specimen being 33.6 m (110.2 ft) long and the largest weighted specimen being 190 tonnes.^[12][57][58] The extinct whale species Perucetus colossus was shorter than the blue whale, at 17.0–20.1 meters (55.8–65.9 ft) but it is estimated to have rivaled or surpassed it in weight, at 85–340 tonnes. At the highest estimates, this would make Perucetus the heaviest known animal in history.^[8]

The largest land mammal extant today is the African bush elephant. The largest extinct land mammal known was long considered to be Paraceratherium orgosensis, a rhinoceros relative thought to have stood up to 4.8 m (15.7 ft) tall, measured over 7.4 m (24.3 ft) long and may have weighed about 17 tonnes.^[59][60] In 2015, a study suggested that one example of the proboscidean Palaeoloxodon namadicus may have been the largest land mammal ever, based on extensive research of fragmentary leg bone fossils from one individual, with a maximum estimated size of 22 tonnes.^[61][59]

Stem-mammals (Synapsida)

The Late Triassic Lisowicia bojani, from what is now southern Poland, probably was the largest of all non-mammalian synapsids (most of which became extinct 250 million years ago), at 4.5 m (15 ft) in length, 2.6 m (8.5 ft) in height and 9 t (20,000 lb) in weight.^[62] However, one study suggested a more conservative weight of 4.87 tonnes to 7.02 tonnes for the adult taxon, with an average body mass of 5.88 tonnes.^[63] The largest carnivorous synapsid was Anteosaurus at 5–6 m (16–20 ft) and 500–600 kg (1,100–1,300 lb).^[64]

Caseasaurs (Caseasauria)

The herbivorous Alierasaurus was the largest caseid and the largest amniote to have lived at the time, with an estimated length around 6–7 m (20–23 ft).^[65] Another huge caseasaur is Cotylorhynchus hancocki, with an estimated length and weight of at least 6 m (20 ft)^[66] and more than 500 kg (1,100 lb).^[67]

Sphenacodontids (Sphenacodontidae)

The biggest carnivorous synapsid of Early Permian was Dimetrodon, which could reach 4.6 m (15 ft) and 250 kg (550 lb).^[68] The largest members of the genus Dimetrodon were also the world's first fully terrestrial apex predators.^[69]

Tappenosaurids (Tappenosauridae)

The Middle Permian Tappenosaurus was estimated at 5.5 m (18 ft) in length which is comparable in size with the largest dinocephalians.^[70]

Therapsids (Therapsida)

The plant-eating dicynodont Lisowicia bojani is the largest-known of all non-mammalian synapsids, at 4.5 m (15 ft) and 9,000 kg (20,000 lb).^[62][71][72] The largest carnivorous therapsid was the aforementioned Anteosaurus from what is now South Africa during Middle Permian epoch. It reached 5–6 m (16–20 ft) long, and about 500–600 kg (1,100–1,300 lb) in weight.^[64]

Reptiles (Reptilia)

The largest living reptile, a representative of the order Crocodilia, is the saltwater crocodile (Crocodylus porosus) of Southern Asia and Australia, with adult males being typically 3.9–5.5 m (13–18 ft) long. The largest confirmed saltwater crocodile on record was 6.32 m (20.7 ft) long, and weighed about 1,360 kg (3,000 lb).^[1] Unconfirmed reports of much larger crocodiles exist, but examinations of incomplete remains have never suggested a length greater than 7 m (23 ft).^[73] Also, a living specimen estimated at 7 m (23 ft) and 2,000 kg (4,400 lb) has been accepted by the Guinness Book of World Records.^[74] However, due to the difficulty of trapping and measuring a very large living crocodile, the accuracy of these dimensions has yet to be verified. A specimen named Lolong caught alive in the Philippines in 2011 (died February 2013) was found to have measured 6.17 m (20.2 ft) in length.^{[75][76][77][78][79]}

The Komodo dragon (Varanus komodoensis), also known as the "Komodo monitor", is a large species of lizard found in the Indonesian islands of Komodo, Rinca, Flores, Gili Motang, Nusa kode and Padar. A member of the monitor lizard family (Varanidae), it is the largest living species of lizard, growing to a maximum length of more than 3 metres (9.8 feet) in rare cases and weighing up to approximately 166 kilograms (366 pounds).^[80]

Largest living reptiles

The following is a list of the largest living reptile species ranked by average weight, which is dominated by the crocodilians. Unlike mammals, birds, or fish, the mass of large reptiles is frequently poorly documented and many are subject to conjecture and estimation.^[1]

Dinosaurs (Dinosauria)

Dinosaurs are now extinct, except for birds, which are theropods.

Sauropods (Sauropoda)

The largest dinosaurs, and the largest animals to ever live on land, were the plant-eating, long-necked Sauropoda. The tallest and heaviest sauropod known from a complete skeleton is a specimen of an immature Giraffatitan discovered in Tanzania between 1907 and 1912, now mounted in the Museum für Naturkunde of Berlin. It is 12–13.27 m (39.4–43.5 ft) tall and weighed 23.3–39.5 tonnes.^{[114][115][116][117][118][119]} The longest is a 25 m (82 ft) long specimen of Diplodocus discovered in Wyoming, and mounted in Pittsburgh's Carnegie Natural History Museum in 1907. A Patagotitan specimen found in Argentina in 2014 is estimated to have been 37–40 m (121–131 ft) long and 20 m (66 ft) tall, with a weight of 69–77 tonnes.^[120][121]

There were larger sauropods, but they are known only from a few bones. The current record-holders include Argentinosaurus, which may have weighed 100 tonnes; Supersaurus which might have reached 34 m (112 ft) in length and Sauroposeidon which might have been 18 m (59 ft) tall. Some abnormal specimens such as specimen BYU 9024 of the Barosaurus genus could reach an astounding 45-48 meters long, with mass varying from the 'modest' 60-66 tons to the more immense 92-120 tons.^{[122][123][124]} Two other such sauropods include Bruhathkayosaurus and Maraapunisaurus. Both are known only from fragments that no longer exist. Bruhathkayosaurus might have been between 40–44 m (131–144 ft) in length and 175–220 tonnes in weight according to some estimates, with recent estimates being place between 110-170 tons.^[125][10] Maraapunisaurus might have been approximately 35–40 m long and 80–120 tonnes or more.^[126] Each of these two 'super-sauropods' would have easily rivalled the largest blue whale in size.^[10][12]

Theropods (Theropoda)

The largest theropod known from a nearly complete skeleton is the most complete Tyrannosaurus rex specimen, nicknamed "Sue", which was discovered in South Dakota in 1990 and now mounted in the Field Museum of Chicago at a total length of 12.3 m (40 ft). Body mass estimates have reached over 9,500 kg,^[144] though other figures, such as Hartman's 2013 estimate of 8,400 kg,^[145] have been lower.

Another giant theropod is Spinosaurus aegyptiacus from the mid-Cretaceous of North Africa. Size estimates have been fluctuating far more over the years, with length estimates ranging from 12.6 to 18 m and mass estimates from 7 to 20.9 t.^[146][147] Recent findings favor a length exceeding 15 m ^[148] and a body mass of 7.5 tons.^[149]

Other contenders known from partial skeletons include Giganotosaurus carolinii (est. 12.2–13.2 m and 6-13.8 tonnes) and Carcharodontosaurus saharicus (est. 12-13.3 m and 6.2-15.1 tonnes).^{[147][150][151][152][153][122]}

The largest extant theropod is the common ostrich (see birds, below).

Armored dinosaurs (Thyreophora)

The largest thyreophorans were Ankylosaurus and Stegosaurus, from the Late Cretaceous and Late Jurassic periods (respectively) of what is now North America, both measuring up to 9 m (30 ft) in length and estimated to weigh up to 6 tonnes.^[154][155]

Ornithopods (Ornithopoda)

The largest ornithopods were the hadrosaurids Shantungosaurus, a late Cretaceous dinosaur found in the Shandong Peninsula of China, and Magnapaulia from the late Cretaceous of North America. Both species are known from fragmentary remains but are estimated to have reached over 15 m (49 ft) in length^[156][157] and were likely the heaviest non-sauropod dinosaurs, estimated at over 23 tonnes.^[157]

Ceratopsians (Ceratopsia)

The largest ceratopsians were Triceratops and its ancestor Eotriceratops from the late Cretaceous of North America. Both estimated to have reached about 9 m (30 ft) in length^[158] and weighed 12 tonnes.^[159][160]

Birds (Aves)

The largest living bird, a member of the Struthioniformes, is the common ostrich (Struthio camelus), from the plains of Africa. A large male ostrich can reach a height of 2.8 m (9.2 ft) and weigh over 156 kg (344 lb).^[161] A mass of 200 kg (440 lb) has been cited for the common ostrich but no wild ostriches of this weight have been verified.^[162] Eggs laid by the ostrich can weigh 1.4 kg (3.1 lb) and are the largest eggs in the world today.^{[citation needed]}

The largest bird in the fossil record may be the extinct elephant birds (Aepyornithidae) of Madagascar, which were related to the kiwis. Aepyornis exceeded 3 m (9.8 ft) in height and 500 kg (1,100 lb), while Vorombe could reach a similar height and a mass of 732 kg (1,614 lb).^[163] The last of the elephant birds became extinct about 300 years ago. Of almost exactly the same upper proportions as the largest elephant birds was Dromornis stirtoni of Australia, part of a 26,000-year-old group called mihirungs of the family Dromornithidae.^[164] The largest carnivorous bird was Brontornis, an extinct flightless bird from South America which reached a weight of 350 to 400 kg (770 to 880 lb) and a height of about 2.8 m (9 ft 2 in).^[165] The tallest carnivorous bird was Kelenken, which could reach 3 to 3.2 meters in height and 220 to 250 kilograms. The tallest bird ever was the giant moa (Dinornis maximus), part of the moa family of New Zealand that went extinct around 1500 AD. This particular species of moa stood up to 3.7 m (12 ft) tall,^[161] but weighed about half as much as a large elephant bird or mihirung due to its comparatively slender frame.^[1]

The heaviest bird ever capable of flight was Argentavis magnificens, the largest member of the now extinct family Teratornithidae, found in Miocene-aged fossil beds of Argentina, with a wingspan up to 5.5 m (18 ft), a length of up to 1.25 m (4.1 ft), a height on the ground of up to 1.75 m (5.7 ft) and a body weight of at least 71 kg (157 lb).^{[1][166][167]} Pelagornis sandersi is thought to have had an even larger wingspan of about 6.1–7.4 m (20–24 ft), but is only about 22–40 kg (49–88 lb), half the mass of the former.^[168][167]

Heaviest living bird species

The following is a list of the heaviest living bird species based on maximum reported or reliable mass, but average weight is also given for comparison. These species are almost all flightless, which allows for these particular birds to have denser bones and heavier bodies. Flightless birds comprise less than 2% of all living bird species.^{[citation needed]}