Trans-Atlantic Voyage: American Crocodiles

[Recusant]

A paper describes fossil evidence which gives further support to the idea that American crocodiles came from a particular extinct branch of African crocodiles, crossing the Atlantic in the Late Miocene (between 5 and 11 million years ago). The oldest fossil of an American crocodile is about 5 million years old.

"Miocene Fossil from Africa Provides New Evidence for Origin of American Crocodiles" | SciNews

Life appearance of Crocodylus checchiai from As Sahabi, Libya. Image credit: D.A. Iurino

A team of paleontologists from Italy and Spain has 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 living species of crocodiles from the Americas and found that the ancient African reptile is closely related to the American crocodiles. The findings suggest that crocodiles may have migrated from Africa to America during the Miocene.

The skull and associated lower jaw of an adult Crocodylus checchiai were collected in 1938 at the paleontological site of As Sahabi in northern Libya.

The specimen was described in 1947 by the Italian paleontologist Angiola Maria Maccagno and then hosted in the collections of the Istituto di Paleontologia dell'Università di Roma.

In order to improve the knowledge about Crocodylus checchiai and its possible relationships with the 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 succeeded in finding it in the collection of the Museo Universitario di Scienze della Terra of Sapienza University of Rome.

They then used computed tomography (CT) imaging to re-examine the well-preserved specimen.

They identified several new inner structures including a protrusion in the middle of the snout that has not been identified on any other African crocodile species.

This unique structure, called the mid-rostral boss, is also present in the four living American crocodile species: Crocodylus intermedius, C. moreletii, C. acutus and C. rhombifer, and indicates a close evolutionary relationship between Crocodylus checchiai and the crocodiles from the Americas.

[Continues . . .]

The paper is open access:

"Old African fossils provide new evidence for the origin of the American crocodiles" | Scientific Reports

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.

[Icarus]

We have few locations where American crocodiles can be found.  The distinction between alligators and crocs is arguable..  Or maybe semantics are involved.    We have a gazillion alligators here in Florida.  There is only one place that has the animal called crocodile.  That is at the southern tip of the Everglades where it meets Florida Bay. That location is a small bay that is called Crocodile Bay.  There are some of the more pointy nosed critters there.  I have sailed into Crocodile Bay...cautiously, I might add.

[Tank]

I was not aware there were crocodiles in Florida.

[Icarus]

Crocs are located in only one relatively small area.  They are of a variety that survive in either fresh or salt water.  Crocodile bay is located at the southern most edge of the Everglades swamp.  For whatever reason, those reptiles have not ventured far from their own little bay.   

[Magdalena]

I lived in Jacksonville, Florida for a few months and I remember seeing a lot of crocodile warning signs around.
...Or alligators, whatever they are. 


https://www.jacksonville.com/news/20190408/interactive-map-shows-where-floridas-nuisance-alligators-are

[Randy]

I lived in Jacksonville, Florida for a few months and I remember seeing a lot of crocodile warning signs around.
...Or alligators, whatever they are. 


https://www.jacksonville.com/news/20190408/interactive-map-shows-where-floridas-nuisance-alligators-are

I call them "crockigators" this way they are mutually inclusive.

[Icarus]

Alligators are in almost every lake or pond in Florida.  It is not unheard of to find one of the beasts in your swimming pool.  They are not particularly aggressive unless they are hungry or if a mother gator is protecting her young hatchlings.