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Dwarf Caiman (Paleosuchus palpebrosus) Fact Sheet: Physical Characteristics

Physical Characteristics

Body measurements

Attribute Male Female
Weight Up to 20 kg (40 lb) Up to 12 kg (26 lb)
Length*

Up to 2.0 m (6.7 ft)

Up to 1.5 m (4.9 ft)

*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)

General Appearance

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

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

Sexual Dimorphism

Body size

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

Identification

Paleosuchus species look alike

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

Senses

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

Other Physical and Physiological Characteristics

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

Less Speedy, More Robust

Head of a dwarf caiman

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.

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