Paleosuchus trigonatus

Geographic Range

Paleosuchus trigonatus is found in both the Amazon and Orinoco river basins, within the forested regions surrounding shallow streams. Their range covers a wide area in South America, from Peru in the west to French Guiana in the east (Ross,1989; Britton, 2001).

• Biogeographic Regions
• neotropical neotropical
  • native native

Habitat

This species is found in and around cool, fast-flowing forest streams and rivers, often near waterfalls or rapids. It seems to prefer cooler water than other crocodilians (Ross, 1989; Alderton, 1991; Britton, 2001).

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• rainforest rainforest

• Aquatic Biomes
• rivers and streams

• Other Habitat Features
• riparian riparian

Physical Description

Paleosuchus trigonatus is the second smallest species of crocodilian in the world. Males of this species will grow to a length ranging from 1.7 to 2.3m, while females generally peak at 1.4 meters.

Hatchlings emerge with a golden patch on their heads that disappears as they further develop. Because of this patch, they are often referred to as ‘crowned caimans.’

P. trigonatus and it’s relative, P. palpebrosus are born with brown eyes, as opposed to other crocodilians, which have yellow eyes. Both species also lack a ridge nestled between the eyes that is more typical in the related genera Caiman and Melanosuchus , hence the common name "smooth-fronted" caimans.

As they develop, the skin of P. trigonatus becomes more bony and ridged, and the scutes are very large and sharp, allowing for better protection suited for life on the land. The tail is short, with two rows of scutes that project laterally, giving the appearance of a wider tail. The tail’s heavy ossification and lack of flexibility, coupled with a more pointed snout that aids in reducing water resistance, may help the animal swim in fast currents.

This species has more and larger bony plates in its skin (called osteoderms) than most other crocodilians.

(Alderton, 1991; Ross, 1989; Britton, 2001; Cogger and Zweifel, 1992)

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

Development

In some crocodilian species the sex of individuals is determined by the temperature they incubated at as eggs. We don't know if this is the case for this species. We know that the eggs must be maintained at 28-32° C for proper development, and their incubation time is much longer than for most other crocodilians (Magnusson 1989).

Reproduction

Not much is known about courtship and mating in this species. Unlike many other crocodilians, they do not use loud calls to locate mates. Adults are very territorial, and males may chase off potential rivals.

Paleosuchus trigonatus males reach sexual maturity when they have grown to at least 1.4 meters, females at around 1.3 meters. This size is thought to correspond to 10-20 years of age.

Females of this species lay 10-20 eggs, during the late part of the dry season. Hatchlings thus emerge after annual rains of filled nearby streams. Females usually do not usually breed every year.

Eggs incubate in the nest for over 100 days, significantly longer than many other crocodilian species.

(Ross, 1989; Magnusson, 1989; Alderton, 1991)

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

Females build mound nests of decaying vegetation, and lay the eggs inside. They often build their nests next to termite mounds, apparently taking advantage of the heat generated by the nest. Sometimes they'll build on an old nest site, even if the termite nest is dead. Apparently the heat from the decaying vegetation in the nest is sufficient to incubate the eggs properly. This is the only species of crocodilian that nests around termites this way. The behavior may help compensate for the lack of heat from sunlight, in the shady forest habitat these animals live in (Magnusson 1989).

Mothers guard their nests until the eggs hatch, and protects her hatchlings in the water for several weeks. Adults may respond to the distress calls from young caimans that are not their own offspring (Ross 1989).

• Parental Investment
• female parental care female parental care

Lifespan/Longevity

Little is known about the lifespan of this species, but they very likely can live for more than 25 years (Britton 2001).

Behavior

Paleosuchus trigonatus is a solitary species, only congregating during the breeding season. Individually, adults will often have territories that they patrol ranging up to 1000 meters along streamsides. The range of this species also overlaps its relative, Paleosuchus palpebrosus , but it's not clear how the two interact.

P. trigonatus adults are often nocturnal, and may spend their days hiding in burrows, hollow logs or other debris near streams. At night the hunt in and around the streams (Ross, 1989; Alderton, 1991; Britton, 2001).

• Key Behaviors
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• solitary solitary
• territorial territorial

Food Habits

Paleosuchus trigonatus has several dietary stages form birth on up to adulthood. Hatchlings eat aquatic insects and other arthropods. Juveniles, while still eating insects, begin eating other vertebrates, such as small fish, birds and reptiles. Adults do not rely on fish as much as younger kin, since their rigid tails prevent more effective hunting in the open water. At this stage, hunting within the forests becomes more common. Larger mammals, such as porcupines and pacas become the staple food of P. trigonatus .

As terrestrial hunters, these dwarf caimans must cover a wide range in search of food. Because of this, the head is often raised high, while the neck is positioned more vertically, allowing them to track prey more efficiently (Ross, 1989; Alderton, 1991; Britton, 2001).

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • piscivore piscivore
  • insectivore insectivore
  • eats non-insect arthropods

• Animal Foods
• birds
• mammals
• reptiles
• fish
• insects
• terrestrial non-insect arthropods

Predation

This species avoids predation with its behavior (hunting at night, hiding in streams, guarding its young). Its bony hide also protects it from attack.

Jaguars eat juveniles, and possibly adults, while coatis and large lizards eat their eggs.

Ecosystem Roles

This species is a mid-level predator, eating other smaller animals, but in turn being eaten by other larger species. In fast flowing streams it may be the dominant predator.

Economic Importance for Humans: Positive

Unlike some other crocodilians, the skin of P. trigonatus is too bony to be used for leather, so this species has little commercial value. It is sometimes hunted locally for food, or for the tourist trade (Britton, 2001).

• Positive Impacts
• pet trade pet trade
• food food

Economic Importance for Humans: Negative

Because of its small size and retiring habits, this species is not considered particularly dangerous to people.

Conservation Status

Because of its heavily ossified skin, hunters have largely ignored P. trigonatus . The main threat, however, comes from the pollution of the environment as well as destruction of P. trigonatus habitat due to gold mining activities. International trade in the species is limited, it is listed on Appendix II of CITES (Britton, 2001; WGBH Educational Foundation, 2000).

Additional Links

Encyclopedia of Life

Contributors

Rene Villareal (author), Fresno City College, Carl Johansson (editor), Fresno City College.

References

Alderton, D. 1991. Crocodiles and Alligators of the World . New York: Facts on File Publications.

Britton, A. 2001. "Crocodilian Species List- Paleosuchus trigonatus (Schneider, 1801)" (On-line). Accessed October 8, 2001 at http://www.flmnh.ufl.edu/natsci/herpetology/brittoncrocs/csp_ptri.htm .

Cogger, D., D. Zweifel. 1992. Reptiles and Amphibians . New York: Smithmark Publishers.

Magnusson, W. 1989. Termite Mounds as Nest Sites. Pp. 122 in Crocodiles and Alligators . New York: Facts on File Publications.

Ross, C. 1989. Crocodiles and Alligators . New York: Facts on File Publications.

WGBH Educational Foundation, 2000. "NOVA Online | Crocodiles | Who's Who of Crocodilians" (On-line). Accessed October 21, 2001 at http://www.pbs.org/wgbh/nova/crocs/whos/nojs.html .