Orinoco crocodile

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Orinoco crocodile
Temporal range: Late Pleistocene–Present, 0.1–0  Ma [1]
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Orinoco Crocodile.jpg
Orinoco crocodile in Los Llanos, Venezuela
CITES Appendix I (CITES) [2]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauromorpha
Clade: Archosauriformes
Order: Crocodilia
Family: Crocodylidae
Genus: Crocodylus
Species:
C. intermedius
Binomial name
Crocodylus intermedius
Graves, 1819
Crocodylus intermedius Distribution.png
Range (green)

The Orinoco crocodile (Crocodylus intermedius) is a critically endangered crocodile. Its population is very small, and they can only be found in the Orinoco river basin in Venezuela and Colombia. Extensively hunted for their skins in the 19th and 20th centuries, it is one of the most endangered species of crocodiles. It is a very large species of crocodilian; males have been reported up to 6.8 m (22 ft 4 in) in the past, weighing over 900 kg (2,000 lb), [3] but such sizes do not exist today, 5.2 m (17 ft 1 in) being a more widely accepted maximum size. A large male today may attain 4.2 m (13 ft 9 in) in length and can weigh up to 450 kg (1,000 lb), while females are substantially smaller with the largest likely to weigh around 225 kg (496 lb). Sexual dimorphism is not as profound as in other crocodilian species.[ citation needed ] The coloration is light even in adults.

Contents

The ecology of the Orinoco crocodile is poorly documented in the wild, mostly due to its small population. It is thought to have a more piscivorous diet with an opportunistic nature, resulting in generalist predatory behaviour. It is an apex predator and preys on a variety of birds, mammals and reptiles, including caimans on occasion. Its prey base is mostly large predatory fish, challenging the general view by locals complaining about crocodiles hunting local fish to very low numbers. Reproduction takes place in the dry season when the water level is low. It is a hole nester and digs holes in the sand for its clutch of eggs. The females guard the nests and young for several years.[ citation needed ]

Taxonomy

The genus Crocodylus likely originated in Africa and radiated outwards towards Southeast Asia and the Americas, [4] although an Australia/Asia origin has also been considered. [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. [4]

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, [6] as revised by the 2021 Hekkala et al. paleogenomics study using DNA extracted from the extinct Voay . [4]

Crocodylinae

Voay †

Crocodylus
Asia+Australia

Crocodylus johnstoni Freshwater crocodile Freshwater crocodile white background.jpg

Crocodylus novaeguineae New Guinea crocodile

Crocodylus mindorensis Philippine crocodile

Crocodylus porosus Saltwater crocodile Crocodylus porosus white background.jpg

Crocodylus siamensis Siamese crocodile Siamese Crocodile white background.jpg

Crocodylus palustris Mugger crocodile Mugger crocodile white background.jpg

Africa+New World

Crocodylus suchus West African crocodile

Crocodylus niloticus Nile crocodile Nile crocodile white background.jpg

New World

Crocodylus moreletii Morelet's crocodile

Crocodylus rhombifer Cuban crocodile Cuban crocodile white background.jpg

Crocodylus intermediusOrinoco crocodile

Crocodylus acutus American crocodile American crocodile white background.jpg

Characteristics

Orinoco crocodile in Villavicencio, Colombia Croc inter.jpg
Orinoco crocodile in Villavicencio, Colombia

The Orinoco crocodile can be recognised by its relatively long snout, which is narrower than that of the somewhat similar-looking American crocodile. 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. The skin can change colour over long periods of time; this phenomenon has been recorded in other species that can gradually change the amount of melanin in their skin. These crocodiles have dark-brown markings, which present as more pronounced bands in younger specimens and as scattered markings on mature ones. [7] One individual measuring 3.4 m (11 ft 2 in) and weighing 182 kg (401 lb) had a bite force of 6,276  N (1,411  lbf ). [8]

Size

In spite of its somewhat narrow snout, the Orinoco crocodile is both a formidable apex predator and one of the world's largest reptiles. Orinoco crocodile Cocodrilo del Orinoco (Crocodylus intermedius).jpg
In spite of its somewhat narrow snout, the Orinoco crocodile is both a formidable apex predator and one of the world's largest reptiles.

The Orinoco crocodile ranks among the largest living reptiles, as well as the largest predator in the Americas. It is arguably, on average, the largest crocodilian in the Americas; while American crocodiles, black caimans and the American alligator may approach similar dimensions, the Orinoco crocodile may be (or had been, when in healthy numbers) slightly longer. [9] Given its possible maximum sizes, the Orinoco crocodile may rank as the third largest extant true crocodile, after the saltwater crocodile and Nile crocodile (which is closely related to it, despite its substantially different range), and additionally rank 4th amongst all extant crocodilians behind the gharial, though there is little to suggest that Orinoco specimens in modern times can rival these species. [7] [9] Sexual maturity for Orinoco crocodiles is obtained for females at around 2.5 m (8 ft 2 in) while that of males seems to be obtained around 3 m (9 ft 10 in) length, with most adult crocodiles of the species exceeding 93 kg (205 lb). Average length of wild adult females from 1985 to 1992 was found to be 3.06 m (10 ft 0 in) while that of males is not known to have been surveyed at that time. [10] [11] If not culled by humans, mature males easily exceed 3.6 m (12 ft) and attain a length of as much as 4.1 to 4.8 m (13 to 16 ft) as they grow throughout life, perhaps weighing 500 to 700 kg (1,100 to 1,500 lb) in big specimens, while females may grow over the expected size of 3.25 m (10 ft 8 in) in length and may sometimes exceed 225 kg (496 lb). [12] [13] According to Guinness Records, the average length of adults that they were able to examine was only 3 m (9 ft 10 in) and the largest specimen found firsthand was 4.2 m (13 ft 9 in). [9] In captivity, at the Roberto Franco Tropical Biological Station (EBTRF), the largest male was recorded at 4.2 m (13 ft 9 in) and weighed 428 kg (944 lb), and maximum size recorded for females was 3.9 m (12 ft 10 in) long and 195 kg (430 lb) in weight. In Venezuela, males have been reported to reach at least 4.1 m (13 ft 5 in) in length and weigh 380 kg (840 lb), while females reach up to 3.2 m (10 ft 6 in) and weigh up to 210 kg (460 lb). [14] The largest specimen historically reported was shot in 1800, and allegedly measured at 6.78 m (22 ft 3 in), although the source is considered reliable, unfortunately, no voucher specimen is known from this. [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. [9] Merchán listed the maximum total length attainable for a male as 5.2 m (17 ft 1 in) and the maximum length of a female as 3.6 m (11 ft 10 in). [17]

Distribution and habitat

This species is restricted to the Orinoco river basin in Venezuela and Colombia. They have been occasionally reported on the island of Trinidad, but this has not been confirmed, and witnesses may have mistaken an American crocodile for the rarer species. This crocodile was once thought to have inhabited a wide range of riparian habitats, from tropical forests to the streams of the Andes foothills. Today, this species is restricted to the Llanos savanna and associated seasonal freshwater rivers. [7] [10]

Behavior and ecology

Hunting and diet

The hunting strategy of the Orinoco crocodile Crocodylus intermedius hunting technique.svg
The hunting strategy of the Orinoco crocodile

Little study has gone into the dietary biology of Orinoco crocodiles but from eye-witness accounts and partial studies from captivity and crocodile farms, the majority of the Orinoco crocodile's diet appears to consists of large fish. 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. Despite having a rather elongated skull, its base snout is wide, hinting to a generalist diet. 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. [19] It stalks both aquatic and terrestrial prey. As a large adult, terrestrial prey may include monkeys, deer, birds, other reptiles, domestic animals, and even occasionally other large predators if the opportunity arises. [7] Similar to many of the larger crocodile species, the Orinoco crocodile has also been observed catching and eating smaller species of crocodilians, such as adult common caimans and sometimes cannibalizing smaller individuals of its own kind. [20]

An Orinoco crocodile splashes into the water in the savanna near Mani, Colombia. Crocodylus intermedius 01.jpg
An Orinoco crocodile splashes into the water in the savanna near Mani, Colombia.

Attacks on humans have been reported, but this is highly unlikely to be a common behavior today, given the very small population of the species and its relative isolation from large human settlements. 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] A small number of better documented fatal attacks were reported in the 1900s–1930s when the species was still relatively common. [22] The only well-documented recent attack, on a fisherman in 2009, was serious but not fatal. [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. [21]

Reproduction

Orinoco crocodile's head Orinoco Crocodile (Crocodylus intermedius) (35279140461).jpg
Orinoco crocodile's head

When water recedes in the dry season, Orinoco crocodiles retreat to burrows they excavate into the riverbanks. The adult pair mates during the drier period of the year. Adult males attract the females by roaring. The females often outnumber the males two to one and appear to select the males with the deepest roars. [24] In a reintroduced population, only 6 of 14 potential adult males parented over 90% of eggs laid. [25] Usually 14 weeks after mating, the female crocodile will dig a nest and lay about 40 eggs. It is a hole-nester, as are all crocodilians, and it usually makes its nest on a sand bank. The eggs incubate under a mixture of soil and rotting vegetation for around three months. 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. Young Orinoco crocodiles are often at risk from predation by American black vultures, tegu lizards, anacondas, caimans, coatis, jaguars, and other carnivores, though these species are sometimes also caught and killed by the defending mother crocodile. Adults have no predators except for humans. Females have defended pods of juveniles for over three years, though closer to one year to independence is generally most common. [7] A study of captive Orinoco crocodiles noted the aggressive behavior of adults while nesting and noted that the normally relatively docile crocodilians could not be approached while they were actively brooding. [27] Without persecution, it is possible that Orinoco crocodiles may reach a lifespan of 70–80 years. [7]

Conservation status

A Orinoco crocodile near its wild range in Los Llanos, Venezuela in a captive breeding program intended to bolster the severely depleted population of these crocodiles. Orinoco Crocodile (Crocodylus intermedius) (35408760825).jpg
A Orinoco crocodile near its wild range in Los Llanos, Venezuela in a captive breeding program intended to bolster the severely depleted population of these crocodiles.

The Orinoco crocodile is highly endangered due to excessive hunting for its hide. During the 1940s to the 1960s, thousands of these animals were slaughtered in the Orinoco River and the Llanos wetlands, and the species came very close to extinction. The Orinoco crocodile was given protected status in the 1970s, but has yet to recover. Today, it is protected both in Colombia and Venezuela, and also included on Appendix I by CITES. 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. Another problem is the increased population of spectacled caimans, a smaller crocodilian that can outcompete the Orinoco crocodile for fish due to its much larger population and much more accelerated breeding rates. [7]

It's unclear how many individuals remain in the wild, but estimates range between 250 and 1500. [28] The largest subpopulation in Venezuela is in Cojedes and Sarare, with fewer than 500 adults remaining. A number of other smaller subpopulations exist. [29]

In November 2007, 50 individuals were held in zoos registered by Species360, [30] of which the largest population, 35 individuals, were kept in the Dallas World Aquarium. Additionally, a large number of individuals are held at captive-breeding facilities in Venezuela. 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. [32]

Related Research Articles

<span class="mw-page-title-main">Crocodile</span> Family of large reptilian carnivores

Crocodiles or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant members of the order Crocodilia, which includes the alligators and caimans, the gharial and false gharial among other extinct taxa.

<span class="mw-page-title-main">Crocodilia</span> Order of mostly large, predatory, semiaquatic reptiles

Crocodilia is an order of semiaquatic, predatory reptiles known as crocodilians. They first appeared during the Late Cretaceous and are the closest living relatives of birds. Crocodilians are a type of crocodylomorph pseudosuchian, a subset of archosaurs that appeared about 235 million years ago and were the only survivors of the Triassic–Jurassic extinction event. The order includes the true crocodiles, the alligators and caimans, and the gharial and false gharial. Although the term "crocodiles" is sometimes used to refer to all of these, it is less ambiguous to use "crocodilians".

<span class="mw-page-title-main">Alligator</span> Crocodilian in the genus Alligator of the family Alligatoridae

An alligator, or colloquially gator, is a large reptile in the genus Alligator of the family Alligatoridae of the order Crocodilia. The two extant species are the American alligator and the Chinese alligator. Additionally, several extinct species of alligator are known from fossil remains. Alligators first appeared during the late Eocene epoch about 37 million years ago.

<i>Caiman</i> (genus) Genus of reptiles

Caiman is a genus of caimans within the alligatorid subfamily Caimaninae. They inhabit Central and South America. They are relatively small sized crocodilians, with all species reaching lengths of only a couple of meters and weighing 6 to 40 kg on average.

<span class="mw-page-title-main">Saltwater crocodile</span> Reptile of South Asia, Southeast Asia and Oceania

The saltwater crocodile is a crocodilian native to saltwater habitats, brackish wetlands and freshwater rivers from India's east coast across Southeast Asia and the Sundaic region to northern Australia and Micronesia. It has been listed as Least Concern on the IUCN Red List since 1996. It was hunted for its skin throughout its range up to the 1970s, and is threatened by illegal killing and habitat loss. It is regarded as dangerous to humans.

<span class="mw-page-title-main">Black caiman</span> Largest extant species of caiman

The black caiman is a crocodilian reptile endemic to South America. With a maximum length of around 5 to 6 m and a mass of over 450 kg (1,000 lb), it is the largest living species of the family Alligatoridae, and the third-largest crocodilian in the Neotropical realm. True to its common and scientific names, the black caiman has a dark greenish-black coloration as an adult. In some individuals, the pigmentation can appear almost jet-black. It has grey to brown banding on the lower jaw; juveniles have a more vibrant coloration compared to adults, with prominent white-pale yellow banding on the flanks that remains present well into adulthood. The banding on young animals helps with camouflage by breaking up their body outline, on land or in water, in an effort to avoid predation. The morphology is quite different from other caimans but the bony ridge that occurs in other caimans is present. The head is large and heavy, an advantage in catching larger prey. Like all crocodilians, caimans are long, squat creatures, with big jaws, long tails and short legs. They have thick, scaled skin, and their eyes and noses are located on the tops of their heads. This enables them to see and breathe while the rest of their bodies are underwater.

<span class="mw-page-title-main">Nile crocodile</span> Reptile of Africa

The Nile crocodile is a large crocodilian native to freshwater habitats in Africa, where it is present in 26 countries. It is widely distributed in sub-Saharan Africa, occurring mostly in the eastern, southern, and central regions of the continent, and lives in different types of aquatic environments such as lakes, rivers, swamps and marshlands. It occasionally inhabits deltas and brackish lakes and rarely also saltwater. Its range once stretched from the Nile Delta throughout the Nile River. Lake Turkana in Kenya has one of the largest undisturbed Nile crocodile populations.

<span class="mw-page-title-main">American crocodile</span> Species of crocodile endemic to the Neotropics

The American crocodile is a species of crocodilian found in the Neotropics. It is the most widespread of the four extant species of crocodiles from the Americas, with populations present from South Florida, the Caribbean islands of Cuba, Jamaica, Hispaniola, and the coasts of Mexico to as far south as Peru, Ecuador, Colombia, and Venezuela.

<span class="mw-page-title-main">Freshwater crocodile</span> Species of reptile

The freshwater crocodile, also known commonly as the Australian freshwater crocodile, Johnstone's crocodile, and the freshie, is a species of crocodile native to the northern regions of Australia. Unlike its much larger Australian relative, the saltwater crocodile, the freshwater crocodile is not known as a man-eater, although it bites in self-defence, and brief, nonfatal attacks have occurred, apparently the result of mistaken identity.

<i>Purussaurus</i> Extinct genus of reptiles

Purussaurus is an extinct genus of giant caiman that lived in South America during the Miocene epoch, from the Friasian to the Huayquerian in the SALMA classification. It is known from skull material found in the Brazilian and Peruvian Amazon, Colombian Villavieja Formation, Panamanian Culebra Formation, Urumaco and Socorro Formations of northern Venezuela.

<span class="mw-page-title-main">Broad-snouted caiman</span> Species of reptile

The broad-snouted caiman is a crocodilian in the family Alligatoridae found in eastern and central South America, including the Pantanal habitat of Bolivia, Southeast Brazil, and Paraguay, as well as northern Argentina and Uruguay. Behind the black caiman, it is the second-largest caiman species; it is the third-largest alligatorid behind the American alligator and the aforementioned black caiman. Primarily, the species inhabits freshwater wetlands, including floodplains, marshes, swamps, and some mangrove forests, as well as various streams, rivers, lakes or ponds, preferring bodies of rather still or slower-moving water. They will often utilize man-made cow ponds, disused stock tanks, and canals and ditches, as well.

<span class="mw-page-title-main">Philippine crocodile</span> Species of crocodile

The Philippine crocodile, also known as the Mindoro crocodile, the Philippine freshwater crocodile, the bukarot in Ilocano, and more generally as a buwaya in most Filipino lowland cultures, is one of two species of crocodiles found in the Philippines; the other is the larger saltwater crocodile (Crocodylus porosus). The Philippine crocodile, the species endemic only to the country, went from data deficient to critically endangered in 2008 from exploitation and unsustainable fishing methods, such as dynamite fishing. Conservation methods are being taken by the Dutch/Filipino Mabuwaya foundation, the Crocodile Conservation Society and the Zoological Institute of HerpaWorld in Mindoro island. It is strictly prohibited to kill a crocodile in the country, and it is punishable by law.

<span class="mw-page-title-main">Cuvier's dwarf caiman</span> Species of reptile

Cuvier's dwarf caiman is a small crocodilian in the alligator family from northern and central South America. It is found in Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname, Trinidad and Venezuela. It lives in riverine forests, flooded forests near lakes, and near fast-flowing rivers and streams. It can traverse dry land to reach temporary pools and tolerates colder water than other species of caimans. Other common names for this species include the musky caiman, the dwarf caiman, Cuvier's caiman, and the smooth-fronted caiman. It is sometimes kept in captivity as a pet and may be referred to as the wedge-head caiman by the pet trade community.

<span class="mw-page-title-main">Smooth-fronted caiman</span> Species of reptile

The smooth-fronted caiman, also known as Schneider's dwarf caiman or Schneider's smooth-fronted caiman, is a crocodilian from South America, where it is native to the Amazon and Orinoco Basins. It is the second-smallest species of the family Alligatoridae, the smallest being Cuvier's dwarf caiman, also from tropical South America and in the same genus. An adult typically grows to around 1.2 to 1.6 m in length and weighs between 9 and 20 kg. Exceptionally large males can reach as much as 2.3 m (7.5 ft) in length and 36 kg (79 lb) in weight.

<span class="mw-page-title-main">Morelet's crocodile</span> Species of reptile

Morelet's crocodile, also known as the Mexican crocodile or Belize crocodile, is a modest-sized crocodilian found only in the Atlantic regions of Mexico, Belize and Guatemala. It usually grows to about 3 metres (10 ft) in length. It is a species at least concern for extinction according to the International Union for Conservation of Nature. The species has a fossil record in Guatemala.

<i>Mecistops</i> Genus of reptiles

Mecistops is a genus of crocodiles, the slender-snouted crocodiles, native to sub-Saharan Africa.

<span class="mw-page-title-main">Spectacled caiman</span> Species of crocodilian native to the Neotropics

The spectacled caiman, also known as the white caiman, common caiman, and speckled caiman, is a crocodilian in the family Alligatoridae. It is brownish-, greenish-, or yellowish-gray colored and has a spectacle-like ridge between its eyes, which is where its common name come from. It grows to a length of 1.4–2.5 m and a weight of 7–40 kg (15–88 lb), with males being both longer and heavier than females. Its diet varies seasonally, commonly consisting of crabs, fish, small mammals, amphibians and snails. Breeding occurs from May to August and 14–40 eggs are laid in July and August. This crocodilian has a large range and population; it is native to much of Latin America, and has been introduced to the United States, Cuba, and Puerto Rico.

<span class="mw-page-title-main">Caiman</span> Subfamily of reptiles

A caiman is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family, the other being alligators. Caimans are native to Central and South America and inhabit marshes, swamps, lakes, and mangrove rivers. They have scaly skin and live a fairly nocturnal existence. They are relatively small-sized crocodilians with an average maximum weight of 6 to 40 kg depending on species, with the exception of the black caiman, which can grow more than 4 m (13 ft) in length and weigh in excess of 450 kg. The black caiman is the largest caiman species in the world and is found in the slow-moving rivers and lakes that surround the Amazon basin. The smallest species is the Cuvier's dwarf caiman, which grows to 1.2 to 1.5 m long. There are six different species of caiman found throughout the watery jungle habitats of Central and Southern America. The average length for most of the other caiman species is about 2 to 2.5 m long.

<span class="mw-page-title-main">Cuban crocodile</span> Species of crocodile endemic to Cuba

The Cuban crocodile is a small-medium species of crocodile endemic to Cuba. Typical length is 2.1–2.3 m (6.9–7.5 ft) and typical weight 70–80 kg (150–180 lb). Large males can reach as much as 3.5 m (11 ft) in length and weigh more than 215 kg (474 lb). Despite its smaller size, it is a highly aggressive animal, and potentially dangerous to humans.

References

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  5. ↑ Oaks, Jamie R. (2011). "A time-calibrated species tree of Crocodylia reveals a recent radiation of the true crocodiles". Evolution. 65 (11): 3285–3297. doi: 10.1111/j.1558-5646.2011.01373.x . PMID   22023592. S2CID   7254442.
  6. ↑ Michael S. Y. Lee; Adam M. Yates (27 June 2018). "Tip-dating and homoplasy: reconciling the shallow molecular divergences of modern gharials with their long fossil". Proceedings of the Royal Society B . 285 (1881). doi: 10.1098/rspb.2018.1071 . PMC   6030529 . PMID   30051855.
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  8. ↑ Erickson, G. M.; Gignac, P. M.; Steppan, S. J.; Lappin, A. K.; Vliet, K. A.; Brueggen, J. A.; Inouye, B. D.; Kledzik, D. & Webb, G. J. W. (2012). "Insights into the ecology and evolutionary success of crocodilians revealed through bite-force and tooth-pressure experimentation". PLOS ONE. 7 (3): e31781. Bibcode:2012PLoSO...731781E. doi: 10.1371/journal.pone.0031781 . PMC   3303775 . PMID   22431965.
  9. 1 2 3 4 Wood, G. L. (1983). The Guinness Book of Animal Facts and Feats . Sterling Pub Co Inc. ISBN   978-0-85112-235-9.
  10. 1 2 Thorbjarnarson, J. B.; Hernández, G. (1993). "Reproductive ecology of the Orinoco crocodile (Crocodylus intermedius) in Venezuela. I. Nesting ecology and egg and clutch relationships". Journal of Herpetology. 27 (4): 363–370. doi:10.2307/1564821. JSTOR   1564821.
  11. ↑ Cohen, M. M.; Gans, C. (1970). "The chromosomes of the order Crocodilia". Cytogenetics. 9 (2): 81–105. doi:10.1159/000130080. PMID   5461083.
  12. ↑ Gladys Porter Zoo (2011). "Critically Endangered Orinoco Crocodiles Coming to Gladys Porter Zoo". prnewswire.com.
  13. ↑ Alvaro Velasco, B. (2023). "Journey of 7 Orinoco Crocodiles from Venezuela to Denmark" (PDF). Crocodile Specialist Group Newsletter. 42 (2). IUCN - Species Survival Commission: 8.
  14. ↑ Carlos A. Lasso. (2013). Biología y conservación de los Crocodylia de Colombia (PDF). [Bogotá]. p. 113. ISBN   978-958-8343-87-7.{{cite book}}: CS1 maint: location missing publisher (link)
  15. ↑ Greer, A. E. (1974). "On the Maximum Total Length of the Salt-Water Crocodile (Crocodylus porosus)". Journal of Herpetology. 8 (4): 381–384. doi:10.2307/1562913. JSTOR   1562913.
  16. ↑ Whitaker, R.; Whitaker, N. (2008). "Who's got the biggest?" (PDF). Crocodile Specialist Group Newsletter. 27 (4): 26−30.
  17. ↑ Merchán, M. (2011). Natural history and conservation of the Orinoco crocodile (Crocodylus intermedius Graves, 1819) in Colombia. Madrid: Asociación Chelonia.
  18. ↑ "Crocodilian Species - Orinoco Crocodile (Crocodylus intermedius)".
  19. ↑ Clarac, F., Souter, T., Cubo, J., De Buffrénil, V., Brochu, C., & Cornette, R. (2016). Does skull morphology constrain bone ornamentation? A morphometric analysis in the Crocodylia. Journal of Anatomy, 229(2), 292-301.
  20. ↑ Gorzula, S., & Seijas, A. E. (1986). "The Common Caiman", p. 44 in Crocodiles: Proceedings of the 7th Working Meeting of the Crocodile Specialist Group of the Species Survival Commission of the International Union for Conservation of Nature and Natural Resources, Caracas, Venezuela, 21 to 28 October 1984. IUCN.
  21. 1 2 3 Barrio-Amoros, C.L. (February 2011). "Orinoco Croc Encounters". Reptiles Magazine: 48–53.
  22. ↑ CrocBITE, Worldwide Crocodilian Attack Database: Orinoco crocodile. Charles Darwin University, Northern Territory, Australia.
  23. ↑ CrocBITE, Worldwide Crocodilian Attack Database: Orinoco crocodile, 15 June 2009. Charles Darwin University, Northern Territory, Australia.
  24. ↑ Thorbjarnarson, J. B., & Hernández, G. (1993). "Reproductive ecology of the Orinoco crocodile (Crocodylus intermedius) in Venezuela. II. Reproductive and social behavior". Journal of Herpetology. 27 (4): 371–379. doi:10.2307/1564822. JSTOR   1564822.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  25. 1 2 Lafferriere, N. A. R.; Antelo, R.; Alda, F.; Mårtensson, D.; Hailer, F.; Castroviejo-Fisher, S.; Doadrio, I.; Vilá, C. & Amato, G. (2016). "Multiple paternity in a reintroduced population of the Orinoco crocodile (Crocodylus intermedius) at the El Frío Biological Station, Venezuela". PLOS ONE. 11 (3): e0150245. Bibcode:2016PLoSO..1150245R. doi: 10.1371/journal.pone.0150245 . PMC   4794145 . PMID   26982578.
  26. ↑ Ramo, C.; Busto, B. & Utrera, A. (1992). "Breeding and rearing the Orinoco crocodile Crocodylus intermedius in Venezuela". Biological Conservation. 60 (2): 101–108. Bibcode:1992BCons..60..101R. doi:10.1016/0006-3207(92)91160-T.
  27. ↑ Blohm, T. (1982). "Husbandry of Orinoco crocodiles (Crocodylus intermedius) in Venezuela", pp. 267–285 in Crocodiles: Proceedings of the 5th Working Meeting of the Crocodile Specialist Group, IUCN–The World Conservation Union, Gland, Switzerland.
  28. ↑ Information on Crocodylus intermedius. Archived 1 May 2006 at the Wayback Machine ARKIVE.
  29. ↑ IUCN/SSC Crocodylus intermedius. Crocodile Specialist Group – Status Survey and Conservation Action Plan, 2nd edition.
  30. ↑ "Captives held in zoos registered by ISIS". Archived from the original on 9 February 2008. Retrieved 9 November 2007.
  31. ↑ "Venezuela's Fitful Effort to Save a Scaly Predator", The New York Times , 25 December 2013
  32. ↑ Endangered Colombian crocodiles get a helping hand. Fox News (15 February 2016). Retrieved on 2019-01-25.
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