It is worth mentioning that unlike the upper weight of mammals, birds or fish, mass in reptiles is frequently poorly documented, thus subject to conjecture and estimation.
[2] Larger specimens have been reported albeit not fully verified,[3] the maximum of which is purportedly 7 m (23 ft) long with an estimated mass of 2,000 kg (4,400 lb).
Until 2024, the largest ichthyosaur was believed to be the Late Triassic species Shastasaurus sikanniensis, at approximately 21 m (69 ft) long[88][89] and 81.5 t (180,000 lb) in weight,[90] from the Norian stage in what is now British Columbia.
[92][93] The specimen was referred in 2024 to Ichthyotitan severnensis, with revised estimates of 25 metres (82 ft) making it the largest known marine reptile.
Based on crown diameter, the animal was about 18 m (59 ft) long and weighed 55 t (121,000 lb), making it one of the largest marine reptiles ever.
[117] A Mesozoic reptile is believed to have been the largest flying animal that ever existed: the pterosaur Quetzalcoatlus northropi, from North America during the late Cretaceous.