Morelet's crocodile

The genus Crocodylus likely originated in Africa and radiated outwards towards Southeast Asia and the Americas,[9] although an Australia/Asia origin has also been considered.[10] 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.[9]

Below is a cladogram based on a 2018 tip dating study by Lee & Yates simultaneously using morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data,[11] as revised by the 2021 Hekkala et al. paleogenomics study using DNA extracted from the extinct Voay.[9]

Morelet's crocodile is small compared to most other crocodiles. The males can become larger than the females. The average adult Morelet's crocodile is about 2.1 m (6 ft 11 in), with a typical length range of 1.5 to 2.7 m (4 ft 11 in to 8 ft 10 in) (the lower measurement representing the mean total length of a female at sexual maturity which is attained at roughly 7–8 years of age in the wild).[12][13] Almost all crocodiles in excess of 2.5 m (8 ft 2 in) are males and at this advanced stage of maturity, the male goes through a significant change in skull osteological morphology as the skull appears to increase in broadness and robustness.[14] Large adult males can attain a length of 3 m (10 ft), anything in excess of this is considered exceptionally rare for this species however the species has a maximum reported length of 4.5 m (15 ft), with two other outsized specimens reportedly measuring 4.1 and 4.3 m (13 and 14 ft), respectively.[13][15][16] One mature adult specimen measuring 2.84 m (9 ft 4 in) and weighing 110 kg (240 lb) had a bite force of 4,399 N (989 lb_f).[17] The weight of a large 3 m (10 ft) wild male crocodile is estimated to average around 150 kg (330+3⁄4 lb), although mass is likely much more in outsized individuals.[13][18] One large male with a presumed total length of around 3.5 m (11 ft 6 in) weighed about 250 kg (550 lb).[19] Another large individual measuring 3.3 m (10 ft 10 in) in length weighed 180 kg (400 lb).[20] Overall, this species is similar in appearance and morphology to the Cuban and the larger American crocodiles.

Like most crocodilians, Morelet's crocodiles are highly opportunistic and will prey on practically anything that they can overpower that comes in their territories.[40] Juvenile crocodiles feed largely on fish and insects until they become bigger and more capable of bringing down larger prey.[23] Adults largely prey on small mammals, birds, other reptiles and fish, as well as gastropods, crustaceans and other invertebrates.[16][40][41] These small mammals can include domesticated animals like cats and dogs. Large specimens have been shown to be able to overtake large prey. Dogs and goats have been taken by this species, including a record of a 2.9 m (9 ft 6 in) adult killing an English sheepdog which weighed at least 35 kg (77 lb).[42] Adults have also been recorded eating even larger animals, including adult and nearly-grown cattle and an adult tapir, although these have been cases of scavenging on caracasses, with the tapir having been killed by a jaguar (it is possible that the jaguar was present when the crocodile fed).[43] Crocodiles have been known to be cannibalistic towards smaller specimens. Although previously thought to be inoffensive, there have been recent reports that the species has attacked humans on multiple occasions and at least 12 documented human fatalities have occurred.[44] Despite the relatively small size of the species, large adult Morelet's are aggressive and easily capable of overpowering an unaware human near the water. Due to partial consumption, recorded fatal attacks are likely predatory rather than defensive in nature.[45][46][47]

Six-month-old, at Tiergarten Schönbrunn

Baby Morelet's crocodiles at the Cotswold Wildlife Park, England

Breeding usually takes place between April and June[24] and the eggs are laid before the start of the rainy season. Morelet's crocodiles are unique among North American crocodiles in that they build mound nests only, and not mound and hole nests. These mound nests are about 3 m (10 ft) wide and 1 m (3 ft 3 in) high and can be found near the water or on floating vegetation. A female crocodile can lay between 20 and 45 eggs and nests have been found containing eggs from more than one female. The eggs are buried and the nests are guarded by females. The eggs usually hatch after 80 days of incubation[24] and hatchlings are normally about 17 cm (6+1⁄2 in) long.[5] After the eggs have hatched the female crocodile will carry her young to the water where they are protected by both parents and will later leave them to fend for themselves. Females are highly protective of their young and have reportedly been observed to aggressively displace intruders and humans if distress calls of the baby crocodiles are heard and even father crocodiles have been observed to spring to the defense of young crocodiles.[48][49] In captivity, juvenile crocodiles are treated aggressively by adult crocodiles but never hatchlings.[50]