Largest coelacanths ever

The largest coelacanth currently known to science is a recently discovered but presently unnamed fossil marine species of mawsonid coelacanth discovered in phosphate beds at Oued Zem, in central Morocco. It is known from a single exceptionally large ossified (fossil) lung, based upon whose size the complete specimen is estimated by researchers who have studied it at the University of Portsmouth, UK, to have measured 3.65–5.52 metres (11 feet 11 inches–18 feet 1 inch) in total length, which is equivalent to the size of a great white shark (Carcharodon carcharias). The findings were published in Cretaceous Research in June 2021.

It lived during the uppermost Cretaceous period, approximately 66 million years ago, and the remainder of its body may have been eaten by a contemporary prehistoric predator.

The ossified lung is now housed in the collections of the Department of Geology at Morocco's Hassan II University in Casablanca.

The previous record holders were the fossil marine species belonging to the prehistoric genus Mawsonia and the fossil marine species Megalocoelacanthus dobiei. All of these coelacanths grew to a length of 3.5–4 m (11 feet 5 inches–13 feet 1 inch), the largest specimens being roughly the size of a rhinoceros. Mawsonia species lived over 100 million years ago during the late-Jurassic to mid-Cretaceous periods in waters around what is now North Africa and South America, and Megalocoelacanthus lived around 66 million years ago during the Upper Cretaceous in waters around what is now the USA.