Plesiosaur size

A plesiosaur.

Plesiosaurs are extinct marine reptiles.

Record sizes

Plesiosaur skeleton of Meyerasaurus in the Museum am Löwentor, Stuttgart, seen from below

In general, plesiosaurians varied in adult length from between 1.5 metres (5 ft) to about 15 metres (49 ft). The group thus contained some of the largest marine apex predators in the fossil record, roughly equalling the longest ichthyosaurs, mosasaurids, sharks and toothed whales in size. Some plesiosaurian remains, such as a 2.9 metres (10 ft) long set of highly reconstructed and fragmentary lower jaws preserved in the Oxford University Museum and referable to Pliosaurus rossicus (previously referred to Stretosaurus and Liopleurodon), indicated a length of 13 metres (43 ft). However, it was recently argued that its size cannot be currently determined due to their being poorly reconstructed. MCZ 1285, a specimen currently referable to Kronosaurus queenslandicus, from the Early Cretaceous of Australia, was estimated to have a skull length of 2.85 m (9 ft).

Plesiosaurs

The longest known plesiosauroid was Elasmosaurus at 14 metres (46 feet) long.

Longest plesiosaurs

1. Elasmosaurus platyurus: 14 m (46 ft)
2. Hydrotherosaurus alexandrae: 13 m (43 ft)

Heaviest plesiosaurs

1. Elasmosaurus platyurus: 2 t (2.0 long tons; 2.2 short tons)

Pliosaurs

Longest pliosaurs

1. The NHM symphysis: 9.1–15.1 m (30–50 ft) (hypothetical)
2. The Peterborough Vertebra: 11.6–14.2 m (38–47 ft)(hypothetical)
3. Pliosaurus rossicus/Pliosaurus macromerus: 11.4–12.7 m (37–42 ft)
4. Monster of Aramberri: 11.7–12.4 m (38–41 ft)
5. Pliosaurus funkei: 10–13 m (33–43 ft)