Plesiosaur size

Record sizes

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)

Longest pliosaurs

1. The NHM symphysis: 9.1–15.1 m (30–50 ft)
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)
6. Pliosaurus kevani: 10–13 m (33–43 ft)
7. Kronosaurus queenslandicus: 10.5–10.9 m (34–36 ft)

Heaviest pliosaurs

1. The NHM symphysis: 7–32 t (6.9–31.5 long tons; 7.7–35.3 short tons)
2. The Peterborough vertebra: 14.6–26.6 t (14.4–26.2 long tons; 16.1–29.3 short tons)(hypothetical)
3. Pliosaurus rossicus/Pliosaurus macromerus: 19.2 t (18.9 long tons; 21.2 short tons)
4. Monster of Aramberri: 14.9–17.8 t (14.7–17.5 long tons; 16.4–19.6 short tons)
5. Pliosaurus funkei: 10.6–17 t (10.4–16.7 long tons; 11.7–18.7 short tons)
6. Pliosaurus kevani: 10.6–17 t (10.4–16.7 long tons; 11.7–18.7 short tons)
7. Kronosaurus queenslandicus: 10.6–12.1 t (10.4–11.9 long tons; 11.7–13.3 short tons)