The largest living reptile, a representative of the order Crocodilia, is the saltwater crocodile (Crocodylus porosus), with adult males being typically 4.5 to 5 m (14.8 to 16.5 ft) long. The largest confirmed saltwater crocodile on record was 20.6 feet (6.3 meters) long, and weighed over 1,900 kg (4,100 lbs). Unconfirmed reports of much larger crocodiles exist, but examinations of incomplete remains have never suggested a length greater than 23 feet (7 meters).
Extinct crocodilians were sometimes much larger, such as Deinosuchus, at up to 12 m (40 ft) and 9.1 tonnes (10 tons), Sarcosuchus imperator, also at up to 12 m (40 ft) and 13.6 tonnes (15 tons), and Rhamphosuchus, possibly up to 18 m (60 ft) long.
- Lizards & snakes (Squamata). The most massive member of this reptilian superorder is the Green Anaconda (Eunectes murinus). The maximum verified size is 9.5 m (31.4 ft) and 250 kg (550 lb), although much larger anacondas have been reported. Even longer, the Reticulated Python (Python reticulatus), can be up to 10 m (33 ft), but is more slender than the anaconda. The largest of the living lizards is the Komodo Dragon (Varanus komodoensis). The largest-ever member of the order was probably one of the giant mosasaurs, such as Hainosaurus, Mosasaurus, or Tylosaurus, all of which grew to around 15 m (50 ft). Some prehistoric snakes such as Gigantophis and Madtsoia are thought to have reached sizes analogous or even superior to those of anacondas and pythons. However, the fossil remains of these snakes are too incomplete to know for sure the size they attained. The largest terrestrial squamate ever, Megalania, could have possibly weighed as much as 2.7 tonnes (3 tons) and measured up to 7 m (23 ft) long.
- Tuataras (Sphenodontia). The larger of the two extant species of tuatara is the Brothers Island Tuatara (Sphenodon guntheri). The maximum size is 1.4 kg (3.1 lb) and 76 cm (30 in).
- Turtles (Testudines). The largest living turtle is the Leatherback Sea Turtle (Dermochelys coriacea), reaching a maximum size of nearly 2.7 m (9 ft) and a weight of 932 kg (2050 lb). There are many extinct turtles that vie for the title of the largest ever. The largest seems to be Archelon ischyros, which reached a size of 4.84 m (16 ft) and a weight of 5.1 tonnes (5.7 tons).
- Pterosaurs (Pterosauria); now extinct. A dinosaur-era reptile (although not technically a dinosaur) is believed to have been the largest flying animal that ever existed: the pterosaur Quetzalcoatlus northropi. The maximum size of this soaring giant was believed to have been about 127 kg (280 lb) and 12 m (40 ft) across the wings. Some incomplete remains, however, demonstrate the existence of larger pterosaurs, with some estimates suggesting a maximum wingspan of 18 meters.
- Dinosaurs (Dinosauria); now extinct, except for Theropod descendants, the Aves.
- All of the largest dinosaurs, and the largest animals to ever live on land, were plant-eating sauropods. The tallest and heaviest sauropod known from a complete skeleton is the Brachiosaurus which was discovered in Tanzania between 1907 and 1912, and is now mounted in the Humboldt Museum of Berlin. It is 12 m (38 ft) tall, and probably weighed between 30,000 ? 60,000 kg (30 ? 65 tons). The longest is the 27 m (89 ft) long Diplodocus which was discovered in Wyoming, and mounted in Pittsburgh's Carnegie Natural History Museum in 1907.
- There may have been larger sauropods, but they are known from only a small handful of bones. The current record holders all date from the 1970s or later, and include the massive Argentinosaurus, which may have weighed 80,000 ? 100,000 kg (90 to 110 tons); the longest, the 40 m (130 ft) long Supersaurus; and the tallest, the 18 m (60 ft) Sauroposeidon, which could have reached into a 6th-floor window. Seismosaurus was once thought to have measured around 50 m (170 ft) in length, making it the longest known vertebrate, but more recent reconstructions have dropped this figure significantly ? down to 40 m (130 ft).
- Less well described finds may even exceed this. Bruhathkayosaurus may have weighed as much as a blue whale and have been considerably longer, and the almost mythical Amphicoelias fragillimus would have been longer still, but Bruhathkayosaurus is based on very poor material, and the only fossil of Amphicoelias was destroyed soon after discovery.
- Theropods (Theropoda). The longest and heaviest theropod was the Spinosaurus, at 15 to 17.4 metres (49.2 to 57.1 feet) in length and a weight of up to 9 tons. This is significantly more masive than other contenders such as the Giganotosaurus and Tyrannosaurus. Spinosaurus is notable for having been the largest terrestrial predator known to exist.
- Armored Dinosaurs (Thyreophora). The largest of the Thyreophorans was Ankylosaurus, which may have measured up to 9 meters in length.
- Cerapods (Cerapoda). The largest Cerapod was the Ceratopsian, Triceratops.
- Triceratops are estimated to have reached about 8 m (26 ft) in length and weighed 6.1 tonnes (13,400 lb).