Supercrocs

Now this is the sort of story I like: finds of five different fossil crocodile types detailed in this month's National Geographic. Paul Sereno, from the University of Chicago, found the first of the these in 2000 and has been leading a series of lengthy expeditions since to the Sahara of Morocco and Niger. The sites are famous for their rich dinosaur deposits, but these trips also turned up some fantastic croc finds.

The first find, of Sarcosuchus imperator, was nice enough. Sarchosuchus is the real monster of the bunch; one of the largest crocodilians ever to have lurked by a riverbank. Fully grown, it's reckoned to have got up to about 12 meters long and weighed over 8 tons. The heaviest saltwater croc on record - the biggest species alive - was a puny 1.3 tons. It had been known for a while, but only from a few bits and bobs. Sereno found a lot of material; enough to piece together a decent reconstruction. SuperCroc's challengers for the title are only known from skulls or less. Deinosuchus, an ancestor of the North American alligator is the best known, and may yet turn out to be the biggest. Nigel Marven visits some in this clip from CITV's Prehistoric Park.

The rest of the crocs found by Sereno's group include three new species, each with handy common names. BoarCroc, Kaprosuchus saharicus, has three pairs of protruding caniniforms, giving it a wicked bite. It would have been a similar size to today's saltwater crocs. RatCroc, Araripesuchus rattoides, is named for the Araripe Plateau, in Northeastern Brazil - home to a famous fossil locality, the Santana Formation. Which, in turn, is home to the RatCroc's closest relative, Araripesuchus gomesii. Ratcroc is a tiddler at only three feet long. The unhappily-named PancakeCroc, Laganosuchus thaumastos (and Laganosuchus maghrebensis), has a strange, flat head. You can see someone's reconstruction here. DogCroc and DuckCroc make up the numbers, though they were also previously known.

Aside from the list of new species, the amount of material collected is also remarkable. Quite a contribution to science.