Largest crocodyliform ever
Sarcosuchus imperator
12 metre(s)
不适用 ()

Sarcosuchus imperator was a prehistoric species of crocodile that lived around 110 million years ago in the Mid Cretaceous. Fossilized remains found in the Sahara Desert suggest that this creature took around 50–60 years to grow to its full length of up to 11–12 metres (37–40 feet) and a maximum weight of around 8 tonnes (8.8 US tons). However, a more recent study published in 2019 suggests a more conservative maximal size of 9.5 metres (31 feet) total length and 4.5 tonnes (5 US tons). It must be said that there are several documented species of giant prehistoric crocodilian and it is currently impossible to say which was definitively the largest. Indeed, in February 2015 a research team headed by Dr Tito Aureliano published a paper containing a total length estimate of "around 12.5 metres [41 feet]" for Brazil's prehistoric giant caiman Purussaurus brasiliensis from the Late Miocene, c. 8 million years ago. However, this estimate is not based upon any single complete (or mostly complete) skeleton, and other published estimates of total length attained by this species have ranged from 10.3 to 13 metres (33–42 feet). Another contender for biggest ever croc is Deinosuchus riograndensis from the Late Cretaceous (80–73 million years ago), which has been estimated at between 10 and 12 metres (32–39 feet) based on fragmentary fossils unearthed in the USA.

Based upon the fact that it possessed upward-tilting eyes, palaeontologists studying the fossilized remains of S. imperator have theorized that this huge creature was able to conceal most of its bulk underwater while stalking prey or lying in wait for prey. It was only distantly related to modern-day crocodiles, belonging to an extinct, prehistoric family of crocodile relatives, Pholidosauridae.

Methods of determining the maximum length of living crocodile species, based on their head lengths, measured from tip of snout to the posterior margin of the supraoccipital bone at the rear of the head (known as DCL or dorsal cranial length), were established by Schmidt (1944); Wermuth (1964) and Bellairs (1964). This methodology has also been used by palaeoherpetologists to extrapolate the probable lengths of extinct crocodyliforms and crocodilians, assuming that the head to body ratios are comparable with those of extant species. In this respect it has proven very useful because lengths can be determined from excavated skulls and jaws in the absence of complete fossil skeletons.