[5] Phylogenetic evidence supports Crocodylus diverging from its closest recent relative, the extinct Voay of Madagascar, around 25 million years ago, near the Oligocene/Miocene boundary.

This species generally has a pale tan hide, though at least three coloration variations are known, with some almost completely yellowish, and some a dark brownish-gray.

[15][16] Because of extensive hunting for their skins in the 20th century, such giants do not exist today, and modern Orinoco crocodiles have not been reported to exceed 5.1 m (16 ft 9 in) in length.

This crocodile was once thought to have inhabited a wide range of riparian habitats, from tropical forests to the streams of the Andes foothills.

The species' relatively narrow snout is ideally suited to minimize water resistance in capturing such aquatic prey.

However, as an opportunistic apex predator, virtually any animal living within its range could be considered a potential meal, such as invertebrates,[18] reptiles, birds, and mammals.

Additionally, as they age, mature males in particular appear to manifest a broadened snout, presumably due to a shift to being able to take larger prey as is seen in several other large crocodile species.

Historically attacks were not unusual and on his trip to the region in 1800, natives told Alexander von Humboldt that two or three adult people were killed per year by Orinoco crocodiles.

[21][23] A second survivor was reported in 2011 to live in La Palmita at the Cojedes River, but any details of this attack (including when exactly it happened) are lacking.

The most common predator of buried eggs are tegu lizards although the tegus are sometimes caught and killed by the mother crocodile.

[25][26] During the night the young hatch and call to their mother; she digs them out of the nest and carries them to the water, which is considerably higher at this point.

In addition to hunting for its hide, more recent threats include the collection of juveniles for sale in the live animal trade, pollution, and the proposal of a dam in the upper Orinoco River region.

Since the early 1990s, a large number of hatchlings have been released both into private ranchlands (especially in the Llanos where nature-oriented tourism is important for the local economy) and in national parks in Venezuela.

While six Venezuelan captive-breeding programs continue today, many are plagued by lack of funds or staff, as well as conflicts between private and state-owned facilities.

[31] The Orinoco crocodile became part of Proyecto Vida Silvestre, a program launched in 2014 to protect 10 wildlife species of Colombia's Llanos.

Thanks to that program, between May 2015 and February 2016, 41 orinoco crocodiles were reintroduced at El Tuparro National Natural Park in eastern Colombia.