Crocodylus acutus. By Ken Mayer.



  Meet the Alligator's Distant (but Local) Relative



Introduction  |  Taxonomy, Phylogeny & Etymology  |   Distribution & Population  |  Ecology

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American crocodile basking.AMERICAN


Crocodylus acutus


Kingdom: Animalia

Phylum: Chordata

Class: Reptilia

Superorder: Crocodylomorpha

Order: Crocodilia

Family: Crocodylidae



(Image: Georgiana Wingard, U.S. Geological Survey. Public domain.)



Taxonomy, Phylogeny & Etymology


The American crocodile whose scientific name is Crocodylus acutus (pronounced krok-o-DIL-luss ah-KOO tuss) is a reptile among the class of snakes, lizards, turtles, tortoises and the lizard-like Tuatara. It is one of about 26 crocodilians in the world, an order which includes two temperate-zone alligators, one from southeastern North America and a smaller one from China, about 14 other tropical crocodiles scattered about the globe, six alligator-like caimans from the South and Central Americas and the tropical slender-snouted gharial and Tomistoma crocodiles. You may review a complete list, and learn the basics of taxonomy and its Latin word use, here.


Austrian naturalist and zoologist Josephus Nicolaus Laurenti (1735-1805) named the genus Crocodylus in 1768,  a designation which today applies to about 12 of the known "true" crocodiles. Crocodylus is from Latin, meaning "crocodile" (which in turn means "pebble worm"). The species name, acutus, Latin for "acute" or "sharp" (describing the crocodile's snout shape) is credited to Georges Cuvier (1769-1832), a French naturalist and zoologist who applied the word in 1807.


Crocodylus intermedius, the Orinoco crocodile.The crocodile shown at left is Crocodylus intermedius, an endangered crocodile from Venezuela. A close relative of acutus, it bears a striking resemblance to it.  (Image: Creative Commons license.)



The species has been identified in the past with different names, which are now considered junior synonyms; they include: Crocodylus americanus (Laurenti, 1768),, Lacerta alligatorr(Blumenbach, 1779),, Crocodylus caudiverberaa (Bonnaterre, 1789), andd Crocodylus floridanuss (Hornaday, 1875), the last being considered by some a junior synonym..


It's origins in the evolutionary timeline began, like the alligator's, with the Archosaurs --"ruling reptiles" -- about 200 milion years ago. From these, the ancient and modern Crocodyloformes, through a clade called Pseudosuchia (and modern birds from the other branch, Ornithosuchia), derive. The Eusuchia sprang from the ancient stock about 100 million years later, the modern crocodilians of today.


The Crocodylus genus also includes the living species intermedius, johnsoni, mindorensis, moreletii, suchus, novaeguineae, palustris, porosus, rhombifer, and siamensis (and formerly cataphractus). Additonally are six established extinct species (others are suspected, but not confirmed): anthropophagus, bugtiensis, checchaiai, falconensis, palaeindicus, and thorbjarnarsoni.


The artistic restoration shown below is of the extinct - and massive- Crocodylus thorbjarnarsoni, an ancient close relative of the American crocodile, the skull fossils of which were discovered in Kenya. Note how broadA recreation of the extinct Crocodlyus thorbjarnarsoni. its snout is (resembling that of an alligator) compared to the American croc. Note the notches near the tip, through which each fourth bottom tooth protrudes, distinctive features of a true crocodile. (Image: smokeybjb. Creative Commons licensee.))


This living crocodile and its alligator relative with which it shares habitat, are quite distant genetically in the timeline described above, having diverged in evolution from a common ancestor 66 to 100 million years ago with the clade Brevirostres, named by German palaeontologist Karl Alfred von Zittel (1839-1904) in 1890. Brevirostres ((loosely translated from Latin as "brief" or "short" "snout") is placed in Late Cretaceous (epoch year 100.5-66), and is believed to be the last common point of the alligatoroids and crocodyloids, ancestors of the crocodilian descendant neighbors inhabiting Florida today.


The acutus species is hybridizing in other parts of the tropical Americas with two others of its genus, moreletii in Belize and the Yucatan of Mexico and with the endangered rhombifer in Cuba, situations which complicate taxonomical identification (and conservation) efforts for all three crocodiles.


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