Dwarf Caiman (Paleosuchus palpebrosus) Fact Sheet: Physical Characteristics

Body measurements

*Note: Estimated by Campos et al. (2010), based on snout-vent length. In Brazil, maximum size may exceed these lengths (Campos et al. 2010).

Data sources
Weight: Male: Campos and Magnusson (2013); female: Campos and Magnusson (2013) and Campos, Sanaiotti, et al. (2015)
Length: Campos et al. (2010)

Body

• Size
  • Smallest living crocodilian (Magnusson 1989; Campos et al. 2010; Campos et al. 2019; Stevenson 2019)
• Skin
  • Rigid scales (osteoderms) on back and belly (Medem 1958; Magnusson 1989; Thorbjarnarson 1992; Stevenson 2019)
    • Protection against abrasion
  • Enlarged scales (scutes) near eyes and tail (Medem 1958)

Head and jaws

• Skull
  • High profile, compared to similar crocodilians (e.g., Medem 1958; McHenry et al. 2006)
    • Less hydrodynamic but better adapted for crushing and subduing prey (McHenry et al. 2006; Grigg and Kirshner 2015)
  • Broader and shorter than smooth-fronted caiman, P. trigonatus (Medem 1958; Neill 1971)
    • Detailed skull comparison in Medem (1958)
• Snout
  • Short and often concave (McHenry et al. 2006)
  • As juvenile, more narrow and pointed (Medem 1958)
    • Widens and becomes more rounded during development
• Teeth
  • Sharply pointed (Medem 1958)
    • More curved farther back in mouth
  • Number of teeth
    • Upper jaw: 36 to 38 teeth (Stevenson 2019)
    • Lower jaw: 72 to 76 teeth (Stevenson 2019)
• Eyes
  • Bony plates over upper eyelids (Stevenson 2019)
    • Also see Nomenclature
  • Iris brown (Magnusson 1989; Stevenson 2019)
  • Pupil has vertical slit (Stevenson 2019)
    • Aids vision in low-light conditions
    • Aids judging distance for prey strikes

Limbs and feet

• Little webbing on hind feet (Stevenson 2019)
  • May be adaptive for shallow-water habitats

Tail

• About half of body length (Stevenson 2019)
  • Suggests less dependence on water than other crocodilian species

Coloration

• Rich brown to dark brown or black (e.g., Medem 1958)
• Dark markings on lower jaw (e.g., Medem 1958)
• Hatchling coloration differences
  • Head color lighter (Magnusson 1992)
    • Becomes dark brown with age
  • Alternating dark and light bands on back (Medem 1971)
    • Provides camouflage with leaves on land and gravel in streams

Body size

• Female smaller than male (Medem 1981; Campos et al. 2010)

Paleosuchus species look alike

• Dwarf caiman and smooth-fronted caiman easily confused for each other (Magnusson et al. 2019)
  • Range overlaps

Few investigations of Paleosuchus palpebrosus senses. See Grigg and Kirshner (2015) and other general references (e.g., CSG: “The Crocodilian Body”) for overview of crocodilian sensory systems.

Vision

• Sight adapted for vision in air (above water) (Fleishman et al. 1988; Grigg and Kirshner 2015)
  • Quality of underwater vision not well known

Body temperature and thermoregulation

• Body temperature relatively low and constant, compared to other crocodilians (Medem 1958; Medem 1967, as cited by Campos and Magnusson 2013; Campos and Magnusson 2013)
  • Adaptive for cooler water habitats
  • Use cool refuges during warm periods
  • No evidence of sun basking to increase body temperature

Similar to this crocodilian, the dwarf caiman has a short, high-profile skull.

This head shape is less hydrodynamic than crocodilians with long, slender skulls—but better for crushing and subduing prey (e.g., fish, shellfish, turtles, crabs, etc.).

Image credit: © Liez / Wikimedia Commons. Some rights reserved; CC BY-SA 3.0.