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 (Native )

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)

Range length: 2.3 (high) mm.

Other Physical Features: ectothermic ; bilateral symmetry

• Terrestrial
• Freshwater

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).

Range elevation: 0 to 1300 m.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: forest ; rainforest

Aquatic Biomes: rivers and streams

Other Habitat Features: riparian

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).

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

Primary Diet: carnivore (Eats terrestrial vertebrates, Piscivore , Insectivore , Eats non-insect arthropods)

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.

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.

Known Predators:

• anacondas (Eunectes)
• jaguars (Panthera onca)
• coatis (Nasua nasua)
• large lizards (Squamata)

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).

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

Average lifespan

Status: captivity: 16.3 years.

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)

Breeding season: Breeding takes place during the final part of the dry season.

Range number of offspring: 10 to 20.

Range gestation period: 115 (high) days.

Range age at sexual or reproductive maturity (female): 10 to 20 years.

Range age at sexual or reproductive maturity (male): 10 to 20 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); 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

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).

US Migratory Bird Act: no special status

US Federal List: no special status

CITES: appendix ii

IUCN Red List of Threatened Species: lower risk - least concern

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

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 ; food