Abstract
Molecular and morphological phylogenies concur in indicating that the African lineages formerly referred to Crocodylus niloticus are the sister taxon the four Neotropical crocodiles (Crocodylus intermedius, C. moreleti, C. acutus and C. rhombifer), implying a transoceanic dispersal from Africa to America. So far the fossil record did not contribute to identify a possible African forerunner of the Neotropical species but, curiously, the oldest remains referred to the African C. niloticus are Quaternary in age, whereas the oldest American fossils of Crocodylus are older, being dated to the early Pliocene, suggesting that another species could be involved. We re-described, also thanks to CT imaging, the only well-preserved topotipic skull of Crocodylus checchiai Maccagno, 1947 from the late Miocene (Messinian) African site of As Sahabi in Libya. As previously suggested on the basis of late Miocene material from Tanzania, C. checchiai is a valid, diagnosable species. According to our phylogenetic analyses, C. checchiai is related to the Neotropical taxa and could be even located at the base of their radiation, therefore representing the missing link between the African and the American lineages.
Highlights
Of the American c lade[6,7,8,9], even if H ect[13] already underlined in 1987 that an African extinct species shared with the American clade a synapomorphic trait
Maccagno provided a thorough description of the skull and a lengthy series of comparisons with some of the extinct and extant crocodylian taxa known at that time, comparisons that are of little value in the context of the currently known phylogenetic relationships
On the basis of the Tanzanian remains, they included for the first time C. checchiai in a phylogenetic context and concluded that this species cannot be excluded from Crocodylus, but retrieved a broad politomy that did not support any precise relationship
Summary
Of the American c lade[6,7,8,9], even if H ect[13] already underlined in 1987 that an African extinct species shared with the American clade a synapomorphic trait. This species (Fig. 1) was originally described in Italian by Maccagno[14] on the basis of an adult, well-preserved skull and associated lower jaw collected in 1938 by Petrocchi in the area of As Sahabi in Libya and hosted in the collections of the Istituto di Paleontologia dell’Università di Roma ( apparently lost). The fourth skull, collected by Petrocchi in 1939 and brought to Rome was described by Maccagno[15] and referred to the new variety, Crocodylus checchiai var. Fragmentary new material from the same Libyan area of As Sahabi (30P24A belonging to the University of Garyounis Earth Science Museum, but currently on loan at the Department of Earth Sciences of the University of Florence, Italy) was referred to C. checchiai by Delfino[18] without any phylogenetic consideration. On the basis of the Tanzanian remains, they included for the first time C. checchiai in a phylogenetic context and concluded that this species cannot be excluded from Crocodylus, but retrieved a broad politomy that did not support any precise relationship
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