[2][3][4][5] This genus itself was long considered to contain only one species, M. cataphractus, but recent genetic analysis has revealed the existence of two species: the West African slender-snouted crocodile (M. cataphractus) and the Central African slender-snouted crocodile (M. leptorhynchus).

Both species diverged during the Miocene (about 6.5–7.5 million years ago) and are separated by the Cameroon Volcanic Line.

[6][7] The cladogram below is based on two studies that combined morphological and molecular (DNA sequencing) data.

[7] Slender-snouted crocodiles are native to freshwater habitats in central and western Africa.

They prefer highly vegetated bodies of water to hide from prey and potential predators.

Nests are placed on the banks of rivers, and construction generally begins at the onset of the wet season, although breeding is asynchronous even within members of one population.

Slender-snouted crocodiles lay an average of 16 (minimum 13, maximum 27) very large eggs (relative to body size) about a week after completion of the mound nest.

Although losses from predators do occur (e.g. by soft-shelled turtles), they apparently are minimal, possibly accounting for the small number of relatively large eggs laid, and the long incubation period.

Threats include hunting (skin and bushmeat), habitat loss, overfishing (they mainly feed on fish), and general disturbance.

However, the Central African species retains a relatively robust population, especially in Gabon.

Slender-snouted crocodiles are kept and bred at a number of zoos in Europe and North America, and the Ivory Coast has started a captive-breeding program.