The dwarf crocodile is an African species of crocodile. It is also the smallest extant crocodile

Crocodile

A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...

 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 in the world. Recent sampling has identified three genetically distinct populations. Some feel that the findings should elevate the subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 to full species status.

Physical description

Dwarf crocodiles attain a medium adult length of 1.5 meters (5 feet), though the maximum recorded length for this species is 1.9 meters (6.2 feet). Adults are a uniform black on their backs and sides with a yellowish underside with black patches. Juveniles have a lighter brown banding on body and tails and yellow patterns on the head.

As a result of its small size and heightened vulnerability to predation, this species of crocodile has a heavily armoured neck, back and tail and also has osteoderms on its belly and underside of neck.

Osteolaemus has a blunt short snout, as long as it is wide, similar in fact to that of a dwarf caiman

Cuvier's Dwarf Caiman

The Cuvier's dwarf caiman or Musky caiman, Paleosuchus palpebrosus, is a relatively small crocodilian reptile from northern and central South America. It is found in Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Surinam and Venezuela...

, probably a result of occupying a similar ecological niche

Ecological niche

In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...

. The dentition

Dentition

Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, the characteristic arrangement, kind, and number of teeth in a given species at a given age...

 consists of 4 premaxilla

Premaxilla

The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....

ry teeth, 12 to 13 on the maxilla

Maxilla

The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...

 and 14 to 15 on the dentary bone.

O. tetraspis has lighter colours, a more pointed, upturned snout and more body armour than O. osborni.

Habitat and range

Dwarf crocodiles range across tropical lowland regions of sub-Saharan West Africa

West Africa

West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...

 and West Central Africa

Central Africa

Central Africa is a core region of the African continent which includes Burundi, the Central African Republic, Chad, the Democratic Republic of the Congo, and Rwanda....

. Such a distribution greatly overlaps with that of the slender-snouted crocodile

Slender-snouted Crocodile

The African Slender-snouted Crocodile is a species of crocodile. Recent studies in DNA and morphology suggest that it may belong in its own genus, Mecistops, but at present most continue to use Crocodylus for this species.African Slender-snouted Crocodile are native to freshwater habitats in...

, encompassing countries as far West as Senegal

Senegal

Senegal , officially the Republic of Senegal , is a country in western Africa. It owes its name to the Sénégal River that borders it to the east and north...

, reaching the Central African Republic

Central African Republic

The Central African Republic , is a landlocked country in Central Africa. It borders Chad in the north, Sudan in the north east, South Sudan in the east, the Democratic Republic of the Congo and the Republic of the Congo in the south, and Cameroon in the west. The CAR covers a land area of about ,...

 in the East, and ranging as southerly as Angola

Angola

Angola, officially the Republic of Angola , is a country in south-central Africa bordered by Namibia on the south, the Democratic Republic of the Congo on the north, and Zambia on the east; its west coast is on the Atlantic Ocean with Luanda as its capital city...

. The subspecies O. t. tetraspis is found mainly in the westerly reaches of this range while O. t. osborni is restricted to the Democratic Republic of Congo's rain forest.

Osteolaemus individuals reside in permanent ponds in swamps and areas of slight current of rain forest rivers, though reports exist of dwarf crocodiles in isolated pool

Pond

A pond is a body of standing water, either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens, water features and koi ponds; all designed for aesthetic ornamentation as landscape or architectural...

s in the savannah

Savannah

Savannah or savanna is a type of grassland.It can also mean:-People:* Savannah King, a Canadian freestyle swimmer* Savannah Outen, a singer who gained popularity on You Tube...

, where burrow

Burrow

A burrow is a hole or tunnel dug into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion. Burrows provide a form of shelter against predation and exposure to the elements, so the burrowing way of life is quite popular among the...

s are dug to aestivate during the dry season

Dry season

The dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...

.

Ecology and behaviour

The dwarf crocodile is a slow, timid, and mainly nocturnal

Nocturnal animal

Nocturnality is an animal behavior characterized by activity during the night and sleeping during the day. The common adjective is "nocturnal"....

 reptile. As with all crocodilia

Crocodilia

Crocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...

ns, it is an adept predator of vertebrate

Vertebrate

Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

s, large invertebrate

Invertebrate

An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...

s such as crustaceans and, when presented with the opportunity, also eats carrion

Carrion

Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...

. Foraging is mainly done in or near the water, though in areas with substantial ground cover, they may expand their feeding pattern to land in extensive forays, specially following rains.

The Congo Basin

Congo Basin

The Congo Basin is the sedimentary basin that is the drainage of the Congo River of west equatorial Africa. The basin begins in the highlands of the East African Rift system with input from the Chambeshi River, the Uele and Ubangi Rivers in the upper reaches and the Lualaba River draining wetlands...

 subspecies demonstrates seasonality in its diet

Diet (nutrition)

In nutrition, diet is the sum of food consumed by a person or other organism. Dietary habits are the habitual decisions an individual or culture makes when choosing what foods to eat. With the word diet, it is often implied the use of specific intake of nutrition for health or weight-management...

ary regime, feeding on fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 during the wet season

Wet season

The the wet season, or rainy season, is the time of year, covering one or more months, when most of the average annual rainfall in a region occurs. The term green season is also sometimes used as a euphemism by tourist authorities. Areas with wet seasons are dispersed across portions of the...

's floods. When faced with the scarceness of food during the dry season, individuals turn to crustaceans and food intake is generally reduced.

True to its solitary, nocturnal nature, a dwarf crocodile digs out a burrow to hide in and rest during the day, which can sometimes have a submerged entrance. An individual lacking the right conditions to do so usually abides between tree roots that hang over the ponds in which it lives.

Reproduction

Interacting closely only in breeding season

Breeding season

The breeding season is the most suitable season, usually with favourable conditions and abundant food and water, for breeding among some wild animals and birds . Species with a breeding season have naturally evolved to have sexual intercourse during a certain time of year in order to achieve the...

, female dwarf crocodiles build their nest

Nest

A nest is a place of refuge to hold an animal's eggs or provide a place to live or raise offspring. They are usually made of some organic material such as twigs, grass, and leaves; or may simply be a depression in the ground, or a hole in a tree, rock or building...

 mounds at the beginning of the wet season, which spans May and June. The nest, situated near the water, is a mound of wet, decaying vegetation that incubates the egg

Egg (biology)

An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

s due to the heat generated by the decomposition of the plant material. A small number of eggs are laid, numbering about 10, though in extreme cases it can go up to 20 eggs, and they incubate in 85 to 105 days. Hatchlings measure 28 cm when emerging from the eggs. The female guards the nest during the incubation period and after the eggs hatch it watches over the young for an unknown period of time as young can be eaten, as in other of crocodiles, by a great range of predators (birds, fish, mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s and reptile

Reptile

Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...

s, including other crocodiles).

Conservation

Dwarf crocodiles are a little known species so, unlike their more studied relatives, conservationist

Conservationist

Conservationists are proponents or advocates of conservation. They advocate for the protection of all the species in an ecosystem with a strong focus on the natural environment...

s aren't as aware of how their populations are faring under the growing human pressure over the ecosystem

Ecosystem

An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

s where they abide. Where survey data is available, it shows some degree of decline, either by hunting for bush meat or habitat loss due to deforestation

Deforestation

Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....

. However, it is a widely spread, and presumably numerous, species so is not as endangered as other forest denizens.

Though some skins are used in local manufacturing of leather

Leather

Leather is a durable and flexible material created via the tanning of putrescible animal rawhide and skin, primarily cattlehide. It can be produced through different manufacturing processes, ranging from cottage industry to heavy industry.-Forms:...

 products, they are of poor quality, so there is little interest in captive breeding

Captive breeding

Captive breedingis the process of breeding animals in human controlled environments with restricted settings, such as wildlife reserves, zoos and other conservation facilities; sometimes the process is construed to include release of individual organisms to the wild, when there is sufficient...

 or a sustainable use program.

Classification

Osteolaemus tetraspis is currently the only species included in the genus Osteolaemus, with two recognized subspecies:

• Osteolaemus tetraspis tetraspis
• Osteolaemus tetraspis osborni Congo (or Osborn’s) dwarf crocodile

The second subspecies has had a somewhat convoluted taxonomical history. It was first described as Osteoblepharon osborni by Schmidt in 1919, based on a few specimen

Specimen

A specimen is a portion/quantity of material for use in testing, examination, or study.BiologyA laboratory specimen is an individual animal, part of an animal, a plant, part of a plant, or a microorganism, used as a representative to study the properties of the whole population of that species or...

s from the Upper Congo Basin in what is now the Democratic Republic of Congo. However Inger in a 1948 paper found the specimens wanting of characteristics that would justify a generic separation from Osteolaemus and referred the specimens to Osteolaemus osborni. Later, Wermuth and Mertens (1961), reduced it to the current subspecies rank.

Recent evidence from the analysis of DNA indicates that there are three distinctly different populations of Osteolaemus that may merit full species recognition. These would be O. tetrapis, O. osborni, and a third currently unnamed species.

Etymology

The generic name Osteolaemus means "bony throat", and is derived from the Ancient Greek

Ancient Greek

Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...

 οστεον (bone

Bone

Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...

) and λαιμος (throat

Throat

In vertebrate anatomy, the throat is the anterior part of the neck, in front of the vertebral column. It consists of the pharynx and larynx...

). The genus was named as such due to the osteoderms found among the scales in the neck and belly.

The specific epithet tetraspis means "four shields", and derives from the Ancient Greek τετρα (four) and ασπις (shield

Shield

A shield is a type of personal armor, meant to intercept attacks, either by stopping projectiles such as arrows or redirecting a hit from a sword, mace or battle axe to the side of the shield-bearer....

), as the back of the neck has four large shield-like scales.

Alternate names

This species is also known by various names in English

English language

English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...

:

• African broad-nosed crocodile
• African caiman
• African dwarf crocodile
• Black crocodile
• Bony crocodile
• Broad-snouted crocodile
• Rough-backed crocodile
• West African dwarf crocodile