A caiman (also cayman as a variant spelling)[1] is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family, the other being alligators. Caimans inhabit Mexico, Central and South America from marshes and swamps to mangrove rivers and lakes. They have scaly skin and live a fairly nocturnal existence. They are relatively small-sized crocodilians with an average maximum weight of 6 to 40 kg (13 to 88 lb) depending on species, with the exception of the black caiman (Melanosuchus niger), which can grow more than 4 m (13 ft) in length and weigh in excess of 1,000 kg (2,200 Ib). The black caiman is the largest caiman species in the world and is found in the slow-moving rivers and lakes that surround the Amazon basin. The smallest species is the Cuvier's dwarf caiman (Paleosuchus palpebrosus), which grows to 1.2 to 1.5 m (3.9 to 4.9 ft) long. There are six different species of caiman found throughout the watery jungle habitats of Central and Southern America. The average length for most of the other caiman species is about 2 to 2.5 m (6.6 to 8.2 ft) long.

Caimans
Temporal range:
PaleocenePresent, 66–0 Ma
Caiman yacare.jpg
Yacare caiman, Caiman yacare
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Crocodilia
Family: Alligatoridae
Subfamily: Caimaninae
Brochu, 1999
Type genus
Caiman
Spix, 1825
Genera and species

See below

Caimans are distinguished from alligators, their closest relatives, by a few defining features: a lack of a bony septum between the nostrils, ventral armor composed of overlapping bony scutes formed from two parts united by a suture, and longer and sharper teeth than alligators, plus caimans tend to be more agile and crocodile-like in their movements.[2] The calcium rivets on caiman scales make their hides stiffer and thus less valuable than those of alligators and crocodiles, both of which have a similar appearance, but are more pliable.[3]

Several extinct forms are known, including Purussaurus, a giant Miocene genus that grew to 12 m (39 ft) and the equally large Mourasuchus, which had a wide duck-like snout.[4]

Spectacled caiman (Caiman crocodilus)
Yacare caiman (Caiman yacare)
Black caiman (Melanosuchus niger)
Cuvier's dwarf caiman (Paleosuchus palpebrosus)
Smooth-fronted caiman (Paleosuchus trigonatus)

BehaviorEdit

Caimans are predators and, like alligators and crocodiles, their diet largely consists of fish. Caimans also hunt insects, birds, and small mammals and reptiles.

Due to the large size and ferocious nature of caimans, they have few natural predators within their environments. Humans are the main predators of caimans, as they have been hunted for their meat and skin. Jaguars, anacondas and crocodiles are the only other predators of caimans, but they usually prey on the smaller specimens. During summer or droughts, caimans may dig a burrow and go into a form of summer hibernation called aestivation.

Female caimans build a large nest in which to lay their eggs. These nests can be more than 1.5 m (4.9 ft) wide. Female caimans lay between 10 and 50 eggs, which hatch within about six weeks. Once they have hatched, the mother caiman takes her young to a shallow pool of water, where they can learn how to hunt and swim.

 
Broad-snouted caiman (Caiman latirostris)

PhylogenyEdit

Caimaninae is cladistically defined as Caiman crocodylus (the spectacled caiman) and all species closer to it than to Alligator mississippiensis (the American alligator).[5][6] This is a stem-based definition for caimaninae, and means that it includes more basal extinct caimanine ancestors that are more closely related to living caimans than to alligators.

Below is a cladogram showing the phylogeny of Caimaninae, modified from Hastings et al. (2013).[7]

Stangerochampsa mccabei

Brachychampsa montana

Brachychampsa sealeyi

 Alligatoridae 

Alligatorinae

 Caimaninae 

Culebrasuchus mesoamericanus

Eocaiman cavernensis

Tsoabichi greenriverensis

crown group caimans

Paleosuchus palpebrosus Cuvier's dwarf caiman

Paleosuchus trigonatus Smooth-fronted caiman

Centenariosuchus gilmorei

Purussaurus neivensis

Mourasuchus spp.

Orthogenysuchus olseni

Caiman crocodilus Spectacled caiman

Caiman yacare Yacare caiman

Caiman latirostris Broad-snouted caiman

Caiman lutescens

Melanosuchus fisheri

Melanosuchus niger Black caiman

TaxonomyEdit

ReferencesEdit

  1. ^ Dictionary.com, retrieved February 16, 2021
  2. ^ Guggisberg, C.A.W. (1972). Crocodiles: Their Natural History, Folklore, and Conservation. p. 195. ISBN 978-0-7153-5272-4.
  3. ^ Mendal, Abram. "Comparing Exotic Leathers: American Alligator vs. Caiman Skins". Archived from the original on 2017-07-31. Retrieved 2016-12-04.
  4. ^ Brochu, C. A. (1999). "Phylogenetics, Taxonomy, and Historical Biogeography of Alligatoroidea". Society of Vertebrate Paleontology Memoir. 6: 9–100. doi:10.2307/3889340. JSTOR 3889340.
  5. ^ Brochu, C. A. (2003). "Phylogenetic approaches toward crocodylian history" (PDF). Annual Review of Earth and Planetary Sciences. 31 (31): 357–97. Bibcode:2003AREPS..31..357B. doi:10.1146/annurev.earth.31.100901.141308.
  6. ^ Brochu, C. A. (2011). "Phylogenetic relationships of Necrosuchus ionensis Simpson, 1937 and the early history of caimanines". Zoological Journal of the Linnean Society. 163: S228–S256. doi:10.1111/j.1096-3642.2011.00716.x.
  7. ^ Hastings, A. K.; Bloch, J. I.; Jaramillo, C. A.; Rincon, A. F.; MacFadden, B. J. (2013). "Systematics and biogeography of crocodylians from the Miocene of Panama". Journal of Vertebrate Paleontology. 33 (2): 239. doi:10.1080/02724634.2012.713814. S2CID 83972694.
  8. ^ Rio, Jonathan P.; Mannion, Philip D. (2021-09-06). "Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem". PeerJ. 9: e12094. doi:10.7717/peerj.12094. ISSN 2167-8359. PMC 8428266. PMID 34567843.
  9. ^ Adam P. Cossette (2020). "A new species of Bottosaurus (Alligatoroidea: Caimaninae) from the Black Peaks Formation (Palaeocene) of Texas indicates an early radiation of North American caimanines". Zoological Journal of the Linnean Society. 191: 276–301. doi:10.1093/zoolinnean/zlz178.