Do you know the difference between an alligator and a crocodile? There are a few differences. As a whole, alligators have shorter, broader snouts while crocodiles have snouts that range between long and skinny to short and broad. Crocodiles are tolerant of saltwater, there are even some species that are primarily found in salt or brackish water, while alligators are freshwater. The best visual difference, however, has to do with the teeth. Both alligators and crocodiles have a prominent fourth tooth in their lower jaws. In alligators, this tooth is often hidden in an enclosed socket in the upper jaw. In crocodiles, this tooth is exposed in a notch in the upper jaw.
Illustration 1: Chinese Alligator head shows the fourth tooth hidden. Photograph by Fritz Geller-Grimm, taken from https://commons.m.wikimedia.org/wiki/File:Alligator_sinensis_fg01.JPG.
Illustration 2: American Crocodile with its fourth tooth pointed out in red.
Do you know how many species of alligator there are? In total, there are eight. Two of these belong the the genus Alligator while the other six species, which belong to the genera Caiman, Melanosuchus, and Paleosuchus, are all considered caimans. While caimans are given a separate name, they are still classified in the family Alligatoridae, and are thus also considered alligators.
It is interesting to note that alligators, crocodiles, and the gavial all belong to separate families. Alligators, as just mentioned, belong to the family Alligatoridae, while crocodiles belong to Crocodylidae, and finally, the gavial belongs to its own family, Gavialidae. Since there has been no study to determine whether or not these animals belonged to the same or separate kinds, all we can do is make an educated guess based on these families. Most studies have indicated that a kind at least includes a family, thus without further information, it is safest to assume that alligators, crocodiles, and the gavial all belonged to separate families.i Right now, I would like to focus on the alligator kind.
When we hear the word “alligator,” the first thing we think of is usually the American alligator (Alligator mississippiensis). One of the largest living alligators, it typically does not grow larger than 13 feet long, though exceptionally large individuals that grew up to 18 feet long have been documented. The American alligator, while most often identified with Florida, is actually found in several states, ranging from the Carolinas, south to Florida, and west into the eastern part of Texas, though they are most frequently found in Florida, Georgia, and Louisiana. A large predator, the American alligator is a generalist, taking just about any kind of prey it can.
Illustration 3: An American Alligator.
The Chinese alligator (Alligator sinensis) is the only living alligator found outside of the Americas. It is much smaller than its American cousin, typically not exceeding sic and a half feet long. It also has a limited range, being only found in three provinces in China in the Yangtze valley. Living in a colder environment, they burrow into the ground, to depths of up to ten feet, into which they retreat for the winter. American alligators also dig, though they do not make burrows so much as they produce “wallows” called “gator holes.”
Illustration 4: A Chinese alligator.
The most common caiman is, well, the common caiman (Caiman crocodilus). It is also known as the spectacled caiman, so named for a ridge than runs between the eyes that looks a bit like the bridge on a pair of glasses. A smaller alligator, it can reach lengths of ten feet, though it is typically grows to less than eight feet. The natural range of the common caiman is from the south tip of Mexico, south through Central America, spreading through the north part of South America. Thanks in part to the pet trade restricting having American alligators as pets, imported common caimans have escaped or been released in Florida where some of them have established populations.
The Yacare caiman (Caiman yacare) used to be considered a sub-species of the common caiman. Its range lies a little south of the common caiman, ranging from southern Peru down into the norther parts of Argentina. It has a similar size to the common caiman.
The broad-snouted caiman (Caiman latirostris), as its name suggests, has a noticeably broader and shorter snout than the other caiman species. Most individuals can grow up to six and a half feet long, though exceptional specimens can reach ten feet. Otherwise, it looks a lot like the Yacare caiman, whose range it also overlaps, with the broad-snouted caiman’s range extending from Argentina up the east coast of South America into Brazil.
The black caiman (Melanosuchus niger) is the largest living caiman. It can grow up to 20 feet long, through smaller individuals are more common. In general appearance and behavior, it resembles the American alligator. Being the largest caiman, it also takes some of the largest prey, such as the capybara, which itself is the world’s largest rodent. It is primarily found in the Amazon basin in Brazil, though some are also found a little further north into Guyana.
There are two species of dwarf caiman: Cuvier’s dwarf caiman (Paleosuchus palpebrosus) and Schneider’s dwarf caiman (Paleosuchus trigonatus), the latter of which is also called the smooth-fronted caiman. A their names suggest, these are the smallest two caimans. Schneider’s dwarf caiman can reach lengths of five and a half feet long while Cuvier’s dwarf caiman only reaches up to five feet long. Like most caimans, they are generalists, taking a variety of prey, though their prey are smaller, simply because of their smaller size. Compared to other alligators, the snouts of the dwarf caimans are fairly tall. Such a shape may make the skull a little less streamlined, but the dwarf caimans are less aquatic compared to the other alligators. This is not to say that dwarf caimans are terrestrial: they are still semi-aquatic, but they are more than happy to wander far from rivers and streams. Also, the dwarf caimans are more heavily armored than other alligators. All alligators have osteoderms that run in parallel rows down the back. These osteoderms are bony plates that reinforce the scales. They give an alligator’s back its rough, knobby appearance. Dwarf caimans have more osteodeoms that cover more of their bodies. They even have osteoderms under their bellies for added protection. Both dwarf caimans have similar ranges centered in the Amazon basin in Brazil.
Illustration 5: The head of Cuvier’s dwarf caiman. Note that the fourth tooth is visible in this photograph because the animal’s teeth are bent outward.
That is a brief overview of the living alligators. Next post, I want to talk a bit about alligator fossils, and we will see all four of these genera again, because all four of them have been identified as fossil remains.
David Alderton (1991) Crocodiles & Alligators of the World, Facts On File, New York, New York
iTom Hennigan (2014) “An Initial Estimate toward Identifying and Numbering the Ark Turtle and Crocodile Kinds” Answers Research Journal 7:1-10, retrieved from https://answersingenesis.org/creation-science/baraminology/an-initial-estimate-toward-identifying-and-numbering-the-ark-turtle-and-crocodile-kinds/ on August 25, 2019