A team of paleontologists from Italy and Spain have compared the only well-preserved skull of Crocodylus checchiai, an extinct species of crocodile that lived in what is now Libya about 7 million years ago (Miocene epoch), to those of the four species of living crocodiles in the Americas, and discovered that the ancient African reptile is closely related to the American crocodiles. The findings suggest that the crocodiles may have migrated from Africa to America during the Miocene.
Appearance of life of Crocodylus checchiai from As Sahabi, Libya. Image credit: DA Iurino.
The skull and associated lower jaw of an adult. Crocodylus checchiai They were collected in 1938 at the As Sahabi paleontological site in northern Libya.
The specimen was described in 1947 by the Italian paleontologist Angiola Maria Maccagno and later housed in the collections of the Istituto di Paleontologia dell’Università di Roma.
To improve knowledge about Crocodylus checchiai and their possible relationships with American crocodiles, Dr. Massimo Delfino from the Università di Torino and the Universitat Autònoma de Barcelona and his colleagues tried to locate the original Crocodylus checchiai skull.
The researchers managed to find it in the collection of the Museo Universitario di Scienze della Terra at the Sapienza University of Rome.
They then used computed tomography (CT) images to re-examine the well-preserved sample.
The skull of 7 million years old Crocodylus checchiai from As Sahabi, Libya, in dorsal (a1, a2), ventral (b1, b2), right lateral (c1, c2) and left lateral (d1, d2) views. Anatomical abbreviations: bo – basioccipital, bs – phenoid base, ect – ectopterigoideo, en – external naris, f – frontal, si – incisor foramen, itf – infratemporal fenestra, j – jugal, l – lacrimal, m – maxillary, n – nasal , o – orbit, pa – parietal, pal – palatine, pf – prefrontal, pm – premaxillary, po – postorbital, pt – pterygoid, q – square, qj – quadratojugal, soc – supraoccipital, sof – suborbital fenestra, sq – squamosal, stf – supratemporal fenestra, t – tooth. Scale bar – 10 cm. Image credit: Delfino et al, doi: 10.1038 / s41598-020-68482-5.
They identified several new internal structures, including a bulge in the middle of the snout that has not been identified in any other African crocodile species.
This unique structure, called the half rostral head, is also present in all four species of live American crocodiles: Crocodylus intermedius, C. moreletiiC. acutus and C. rhombifer, and indicates a close evolutionary relationship between Crocodylus checchiai and the crocodiles of the Americas.
“Analysis of evolutionary relationships between species suggests that Crocodylus checchiai it may be part of the same lineage as the four species of American crocodiles, “the scientists said.
“The remains of Crocodylus checchiai They date back to about 7 million years ago, while the oldest remains of an American crocodile, the extinct Crocodylus falconensis, date back to about 5 million years ago. “
“Based on these findings, we propose that crocodiles reach America by migrating west from Australasia through Africa.”
The findings were published in the journal. Scientific reports.
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M. Delfino et al. 2020. Ancient African fossils provide new evidence of the origin of American crocodiles. Science representative 10, 11127; doi: 10.1038 / s41598-020-68482-5
