Ancient African skull sheds light on the origins of the American crocodile

The extinct species of African crocodile Crocodylus checchiai may be closely related to live American crocodile species today, according to a study published in Scientific reports. The findings suggest that crocodiles may have migrated from Africa to America during the late Miocene epoch (11-5 million years ago).

Before this discovery, it was unclear whether crocodiles arrived in America from Africa, via a hypothetical transatlantic voyage, or vice versa. Massimo Delfino and his colleagues used computed tomography images to re-examine a C. checchiai skull stored in the MUST Earth Sciences museum at Sapienza University of Rome, which was discovered in 1939 in As Sahabi, Libya. The authors identified several new skull structures, including a protrusion in the middle of C. checchiai’s snout that had not been identified in any other African crocodile species, but is present in the skulls of all four living American crocodile species. Crocodylus intermedius, C. moreleti, C. acutus and C. rhombifer. This shared skeletal structure indicates a close evolutionary relationship between C. checchiai and American crocodiles.

Other analyzes of evolutionary relationships between species suggest that C. checchiai may be part of the same lineage as the four crocodile species found today in North and South America. The remains of C. checchiai date from about seven million years ago, while the oldest remains of an American crocodile, the extinct C. falconensis, date from about five million years ago. Based on these findings, the authors propose that crocodiles arrived in America by migrating west from Australasia through Africa.