|Cuvier's dwarf caiman|
Temporal range: Late Paleocene - Present
| Paleosuchus palpebrosus|
|Range in green|
Cuvier's dwarf caiman was first described by the French zoologist Georges Cuvier in 1807 and is one of only two species in the genus Paleosuchus, the other species being P. trigonatus. Their closest relatives are the other caimans in the subfamily Caimaninae. With a total length averaging 1.4 m (4.6 ft) for males and typically up to 1.2 m (3.9 ft) for females, Cuvier's dwarf caiman is not only the smallest extant species in the alligator and caiman family, but also the smallest of all crocodilians. An adult will typically weigh around 6 to 7 kg (13 to 15 lb). Its lack of size is partly made up for by its strong body armour, provided by the bony bases to its dermal scales, which provides protection against predators. Juvenile dwarf caimans mainly feed on invertebrates, but also small fish and frogs, while adults eat larger fish, amphibians and invertebrates, such as large molluscs. This caiman sometimes uses a burrow as shelter during the day and in the Pantanal may aestivate in the burrow in order to stay cool in the dry season. The female buries her eggs on a mounded nest and these take about three months to hatch. She helps the hatchlings to escape from the nest and provides some parental care for the first few weeks of their life. This caiman has a wide range and large total population and the IUCN lists its conservation status as being of "least concern".
Cuvier's dwarf caiman is the smallest living New World crocodilian. Males grow to a maximum length of about 1.6 metres (5 ft 3 in) while females do not usually exceed 1.2 metres (3 ft 11 in). The largest specimen on record measured 1.72 m (5.6 ft) in length. This may be an underestimate of the animal's maximum size as nearly all large adults have lost the tips of their tails and the largest specimen measured in the Pantanal region had a snout-to-vent length of 1.125 m (4 ft) (equivalent to a total length of 2.1 m (6.9 ft) with an intact tail). An adult will typically weigh around 6 to 7 kg (13 to 15 lb), around the same weight as a 6–12-month-old specimen of several larger species of crocodilians. The Cuvier's dwarf caiman has strong body armour on both the dorsal (upper) and ventral (lower) sides which may compensate for its small body size in reducing predation. The dermal scales that provide this protection have a bony base and are known as osteoderms.
The head has an unusual shape for a crocodilian, with a dome-shaped skull and a short smooth, concave snout with an upturned tip, the shape rather resembling the head of a dog. The upper jaw extends markedly further forward than the lower jaw. There are four pre-maxillary and fourteen to fifteen maxillary teeth on either side of the upper jaw and twenty-one or twenty-two teeth on each side of the lower jaw giving a total of about eighty teeth. The neck is relatively slender and the dorsal scutes are less prominent than in the smooth-fronted caiman (Paleosuchus trigonatus). The double row of scutes on the tail are small and project vertically. Adults are dark brownish-black with a dark brown head while juveniles are brown with black bands. The iris of the eye is chestnut brown at all ages and the pupil is a vertical slit.
The scutellation (arrangement of the scales) helps to distinguish Cuvier's dwarf caiman from Schneider's dwarf caiman (details of latter in brackets).
- Post occipitals - Usually 2 rows (usually 1 row)
- Nuchals - Usually 4 to 5 rows (usually 4 rows but sometimes 5)
- Dorsals - 18 longitudinal rows and 6 to 10 transverse rows, neatly arranged, with 4 rows between hind legs (18 longitudinal and 6 to 7 transverse rows, haphazardly arranged, with usually 2 rows between hind legs)
- Ventrals - 21 to 22 longitudinal rows and 16 transverse (19 to 21 longitudinal and 10 to 12 transverse rows)
- Tail - Single crest, usually 19 to 21 scales (17 to 19 scales)
- Tail - Double crest, usually 9 or 10 rows (usually 9 or 10 rows)
- Tail - Lateral, small scales disrupt 2 or 3 rows (5 to 8 rows)