Crocodilians

Family Crocodylidae

Crocodylus acutus, American Crocodile

C. cataphractus, Slender-Snouted Crocodile

C. intermedius, Orinoco Crocodile

C. johnstoni, Australian Freshwater Crocodile

C. mindorensis, Philippines Crocodile

C. moreletii, Morelet's Crocodile

C. niloticus, Nile Crocodile

C. novaeguinae, New Guinea Crocodile

C. palustris, Mugger Crocodile

C. porosus, Saltwater Crocodile

C. rhombifer, Cuban Crocodile

C. siamensis, Siamese Crocodile

Osteolaemus tetraspis, African Dwarf Crocodile

Subfamily Alligatorinae

Alligator mississippiensis, American Alligator

A. sinensis, Chinese Alligator

Caiman crocodilus, Spectacled Caiman

C. latirostris, Broad-Nosed Caiman

C. yacare, Yacare Caiman

Melanosuchus niger, Black Caiman

P. trigonatus, Smooth-Fronted Caiman

P. trigonatus, Smooth-Fronted Caiman

Subfamily Gavialinae

Gavialis gangeticus, Indian Gavial

Tomistoma schlegelii, False Gavial

Scientific Name

Common Name

Distribution

Size

Notes

Family Crocodylidae

Crocodylus

17 to 19 upper and 15 lower teeth on each side; fifth maxillary tooth largest; the fourth mandibular usually fitting into a notch in the upper jaw. Snout more or less elongate; nasal bones extending to the nasal aperture, which is undivided and larger than the supratemporal fossae; a very small anterior bony plate in the upper eyelid. Splenial bones not entering the mandibular symphysis, which does not extend beyond the eighth tooth. A dorsal shield formed of four or more longitudinal series of juxtaposed, keeled, bony scutes.

Crocodylus acutus

American Crocodile

S USA (S Florida only), C America, northern S America (Columbia, Peru, Venezuela), Caribbean

9-12' [21']

C. acutus is a somewhat timid species and fairly scarce throughout its range, including places where it was once abundant. It has not colonised areas populated by C. intermedius or M. niger. Apart from its usual range it may also occur as individuals on the Cayman and Tres Marias Islands and on Trinidad. It has a limited temperature tolerance, and in water of 65 deg F or less will sink into a torpor and drown. On the other hand it has a high tolerance of marine environments due to the 20-40 salt glands on its tongue. Anatomy: thin snout, especially in S. American individuals: this may help the latter in competition with caimans. Distinct median ridge extends along half the snout length. Maxillae have 13-14 pairs of teeth, lower jaw 15 pairs. Usually 4 large nuchal plates in a two by two arrangement: dorsal plates are arranged in 4-6 longitudinal rows comprising 15-16 transverse  series. 2nd & 3rd front toes are slightly webbed: outer toes on hindfoot are united by a membrane. Subcaudal whorls of scales are interrupted by irregular groups of small scales. Coloration: adult animals are dorsally blackish-olive with yellowish underparts. Hatchlings are dorsally grey-green with blackish cross-bars (often broken into spots): 4-5 on body, 8-10 on tail. Cuban individuals lack these. Reproduction: breeding season is in northern spring. Eggs are laid mid-March to mid-May (February-May in Yucatán), peaking in April. Most hatchlings appear in late July-early August (rainy season). Nests are about 12-18" high and 10-12' wide, accommodating up to 35 eggs. They are usually located above beaches in hardwood thickets, shrubs or mangrove stands. Females will guard nests, except against humans. Incubation is about 85 days (70-80 in Yucatán). The female carries the hatchlings (9½" long) to water. Juvenile distress calls are usually answered by adults but older juveniles may sometimes be predatory. In the first month the hatchlings grow to 12", thereafter an extra inch per month. By four years old they are 4-5' in length, when they begin to employ the adult roar. B I

Crocodylus cataphractus

Slender-Snouted Crocodile

W & C Africa, Lake Tanganyika

7½-9'

The Slender-Snouted Crocodile is a shy and secretive species found mainly in West and Central Africa, reaching as far east as Lake Tanganyika. It is easily distinguished from other crocodilians in its range by its long snout, which abruptly tapers to become quite slender (being 2½ times as long as wide at the level of the eyes). The end of the snout is bulbous, with two valved nostrils at the top. The tail is about 30-40% of the total length, with two raised keels. The rear toes are slightly webbed. It lives between sea level and 3,000ft (1,000m) in lakes and rivers in forest and forest-savannah mosaic, being sometimes found in savannah rivers. It will also use dams and swamps if the pools therein are large enough. Although a CITES Appendix I species, it is still threatened by hunting for bushmeat and parts for traditional medicine. When threatened it will hide in waterside vegetation rather than diving as Niles do, but it is nevertheless a fast and agile swimmer. It may use waterside holes as shelters. Specimens in Lake Tanganyika bask in secluded spots.  Despite its size, C. cataphractus is primarily a fish eater, although it will take other fare such as reptiles, birds and amphibians. The young take tadpoles, frogs and insects. They are not known to be ambushers of creatures at the water's edge. A captive specimen lived 30 years in captivity. Scalation: pair of large occipital bumps form a transverse row on the neck, with a smaller bump on each side; 18-19 transverse rows of dorsals, of which 4^th/5^th to 15^th are composed of 6 scutes; sides with large, keeled scutes; gular and ventral scutes bony in adults; scales on limbs strongly keeled. Anatomy: mandibular symphysis long, extending to 7^th or 8^th tooth; premaxillo-maxillary suture , on the palate, directed backwards; maxillaries form median suture above, behind the nasal opening; slight web between 2^nd and 3^rd fingers; outer toes two-thirds webbed; serrated fringe on outer edge of leg. Colour: uniform grey or brown. Specimens around Lake Tanganyika, especially in forested areas, may have black blotches or spots. Ventral surfaces are cream or yellow. Juveniles are brightly marked, being grey-green with irregular black blotches and crossbars: they also have proportionately short snouts. Reproduction: in Ivory Coast mating has been observed in February. In March-April the female constructs a nest of rotting vegetable matter on the elevated bank of a forest stream and guards it. She lays a clutch of 12-30 eggs and covers it with the rotting vegetation. At temperatures of 27-34 deg C incubation time takes 90-100 days. The juveniles enter the water quickly and spend the first part of their lives in backwaters and shallow flooded areas. [SOURCES: Boulenger, Spawls et al, Steel] B I

C. c. cataphractus

18-19 ventral shields

C. c. congicus

24-27 ventral shields

Crocodylus intermedius

Orinoco Crocodile

S America (Meta & Orinoco river systems)

12' [21']

The Orinoco Crocodile derives its common name from its range which is principally the Meta and Orinoco Rivers. Although a freshwater species, some individuals have been reported from Trinidad. Its closest relation is possibly C. acutus. The Orinoco Crocodile seems to prefer still waters: in the rainy season it may wander considerable distances to find still lakes and pools, while in the dry season it favours wide and deep rivers. In some areas it allegedly aestivates in caves under steep river banks. Prey is mainly fish and capybaras. The outlook for this crocodile species is difficult as it is still hunted for its hide which is considered more valuable than those of the caimans with which it is usually in competition. In addition, it is difficult to find viable populations in the wild on which observations can be made. Anatomy: long and relatively deep snout, lacks ridges but has median elevation, concave profile and unossified nasal septum. Maxillae have 13-14 pairs of teeth, lower jaw 15-16 pairs. Mandibular symphysis extends backwards to level of 6th, 7th or 8th tooth; premaxillo-maxillary suture on the palate is produced backwards; maxillaries usually form a median suture above, behind the nasal opening. 6 large nuchal scutes, of which 4 in a square and 1 on each side, widely separated from the dorsals; dorsal scutes in 16 transverse series, widest of which contain 6 scutes in an uninterrupted series; other large keeled scutes isolated on the sides. Scales on limbs keeled; serrated fringer on outer edge of leg; short web between 2^nd and 3^rd fingers; outer toes extensively webbed. Coloration: dorsally olive-brown, ventrally yellow. Reproduction: In January-February the female excavates a nest in sandbanks well above the water level. A clutch of 15-70 eggs is laid: these are subject to predation chiefly by tegus and black vultures. [SOURCES: Boulenger, Steel] B I

Crocodylus johnstoni

Australian Freshwater Crocodile

N Australia (Kimberley, NE Queensland)

10'

Unlike its larger congeneric, C. porosus, this species is strictly a freshwater dweller, being found in permanent areas of freshwater. It can be distinguished from the more dangerous "saltie" by its long and slender snout, which is smooth-scaled. Scalation: enlarged nuchal shields in a single row separated from the smooth-skinned parietal area by <8 granular scales; 6 large nuchal scutes, of which 4 in a square and 1 on each side, subcontinuous with dorsals; dorsals in 19 transverse rows, 4^th to 14^th of which are composed of 6 scutes; those of 2 middle rows wider than long; 4 oval scutes in transverse row behind occiput; scales on sides and limbs keeled. Anatomy: 19 upper teeth on each side; snout lacks distinct ridges; mandibular symphysis long, extending to 6^th tooth; maxillaries form media suture above, behind nasal opening; fingers nearly free; outer toes extensively webbed; serrated fringe on outer edge of leg. Colour: dorsally grey or olive-brown with irregular dark mottling on the flanks and whitish ventral surfaces. Reproduction: females lay 20 eggs in sandbanks towards the end of the dry season in October-November. [SOURCES: Boulenger, Cogger] B I

Crocodylus mindorensis

Philippines Crocodile

Philippines (Luzon, Mindoro, Busuango, Masabate, Samar, Negros, Mindanao, Jolo and Culion)

4½-8'

Sometimes regarded as a subspecies of the New Guinea Crocodile C. novaeguinae: Rogner points out however that the on the snout are more pronounced than in C. novaeguinae and that 80% of C. mindorensis specimens have 6 nuchal shields, as opposed to the 4 in C. novaeguinae (a characteristic admittedly shared by the other 20% of C. mindorensis individuals). Closely related to C. porosus, but differs from the latter by the presence of enlarged shields on the neck just behind the head: the ridges above the eyes are lower and more oblique. There are 16-18 very large ventral plates between the axilla and the hind limbs. Steel suggests that this is a creature of freshwater marshes, small lakes and tributaries of larger rivers, whereas Alcata does not mention marshes but cites "inland lakes and headwaters of rivers". He notes that the species, formerly abundant, was overhunted to the point of extinction. Coloration: very similar to that of C. porosus [Alcata]. Reproduction: constructs a nest in the dry season for the eggs. [SOURCES: Alcata, Boulenger] B I

Crocodylus moreletii

Morelet's Crocodile

Belize, Guatemala, Mexico

2-3½m SVL, 7½'

Relatively broad-snouted species found in freshwater lakes, rivers, ponds and aguadas (bodies of water in forested areas).Invertebrates form most of the diet into subjuvenile size, while larger individuals take larger fish, birds, turtles and mammals. Anatomy: broad snout; dorsal surface of heady and body heavily armoured with bony scales; tail laterally compressed, with numerous groups of irregular small scales intercalated between caudal whorls. Coloration: adults dorsally dark brown or nearly black, lighter bleow; juveniles have lighter, yellowish dorsum with transverse black bands on body and tail. Reproduction: in the Yucatán area, females construct nests of decaying vegetation near the water in June-July. Clutch size is 20-40, incubation takes 75-80 days. B I

Crocodylus niloticus

Nile Crocodile

Africa

9-12' [18']

Along with the saltwater crocodile C. porosus, the Nile crocodile is one of those species potentially fatal to man, with hundreds of humans being killed or injured by them each year (although, in fairness, more humans are killed within this range by the hippopotamus). Within their range they can be easily distinguished from other species by their size and long jaws and prominent teeth. The eyes and valved nostrils are located on the top of the head and jaws. The plates on top of the head are fused to the skull. Hind feet are webbed. The tail makes up about 40% of the total length and has two raised dorsal keels. Young Niles eat small prey, often out of the water, but subadults prefer swamps and backwaters. Full adults take not only fish but also large mammals, a favourite tactic being to ambush animals coming to drink at the edge of waterholes. In some places they are able to take advantage of the seasonal migrations of large herds of such creatures as wildebeest. Colour: the young are greenish with irregular black markings on the dorsum and flanks and ventrally a straw-yellow. Adults are darker, olive to grey, with yellow or cream ventral surfaces. Reproduction: Niles reach sexual maturity in 12-15 years when they are about 2-3m in length. The breeding season commences in May when males start to establish a dominance hierarchy. Courtships take place in July-August. The female selects a sunny sandbank for her nest, which she will use for the rest of her life. In November she digs a hole 12-18" (30-45cm) deep and lays 16-80 white hard-shelled eggs. During this time the male remains in the vicinity but is not allowed near the nest. Time to hatching is 84-90 days. While still in the eggs the hatchlings emit high peeps which alert the mother, who opens the nest and carries the young in her mouth to the water. For the first 6-8 weeks the young remain in a sort of "creche", but later they dig burrows (sometimes communally) which they use as a shelter for 4-5 years. The reproductive biology and care of Nile crocodiles is reminiscent of avian species and has been studied for possible clues to the reproduction and care of young of extinct archosaurs, especially the dinosaurs. B I

Crocodylus novaeguinae

New Guinea Crocodile

New Guinea

18'

In 1943-44 Neill observed that this species was “fairly common” 12 miles north of Port Moresby in an area of shallow lakes. Diagnosis: A crocodile with a moderately acute snout, intermediate between C. porosus and C. johnstoni. Allied to porosus by the presence of anteorbital ridges, to johnstoni by the sharper snout and the form of the palatines. Length of snout slightly more than twice its breadth. No bulbous swelling at the base of the palatines. Description of type: General form of skull acutely triangular, much depressed, and without median ridge or swelling, lightly and slenderly built throughout. Supratemporal fenestrae large. Orbits about twice the diameter of the narial aperture. Palatine fenestrae with a well-marked angulation in their posterior border. Internal narial aperture rounded, longer than wide. Premaxillaries little expanded, pierced by the anterior mandibular teeth, separated by the entry of the nasals into the external narial aperture. Maxillary-premaxillary suture produced backward to the second maxillary tooth. Premaxillary foramen arrow-head shaped. An obtuse ridge from the anteorbital border on each lacrymal. Cranial table flat. Palatines with an acute anterior angle, (as in other sharp-snouted crocodiles), nearly parallel sided, narrow. Pterygoids distinctly stalked, i. e. palato-pterygoid suture anterior to the posterior border of the palatal fenestrae. Upper teeth 18-19. [SOURCE: Neill, Schmidt]

Crocodylus palustris

Mugger/Marsh Crocodile

W Pakistan, India, Bangladesh, Sri Lanka

7½' [12']

A largeish species found in large water bodies in the plains and up to 600m above sea level across its range. Although difficult to distinguish at sight from the more dangerous C. porosus, the two species do not occur together. Daniel claims that captive breeding for the skin trade has had some success. Other individuals may live in a semi-captive state in association with a religious establishment such as a temple. In the wild the animals usually make burrows for habitation: these may have a diameter of up to 80cm and lead for up to 4½m to a roomier chamber. The burrows may be situated in the sides of waterside hills, beneath rocks or at the foot of trees. Most hunting is done in the water and the diet is largely fish, but other vertebrates may be taken: scavenging has also been reported. However, the species is rarely dangerous to man, although Daniel notes that it will feed on corpses. A captive reportedly buried meat and fish given to it. Ecologically it has been reported that the muggers may perform a useful function in keeping numbers of coarse fish in check which otherwise thrive at the expense of commercially useful species: a similar claim has been made for Nile Crocodiles. Description: the snout is broad and lacks distinct ridges in front of the eyes; there is a row of 4 distinct and sharply raised post occipitals behind the head; the back is armoured with 16-17 transverse and 6 (sometimes 4) longitudinal rows of scutes embedded in the skin: ventrally the species lacks armour. The tail has two rows of flattened vertical scales that merge and continue as a single row to the tip. The toes are webbed. Coloration: dorsally olive, speckled with black: the black speckling is more distinct in young specimens. Ventrally white or yellowish white. Reproduction: in India, breeding takes place mid-January to March, depending partly on location. A hierarchy at least among males during breeding season is observed during this time. The female lays 3-40 eggs in a clutch (depending mainly on her age and size) and guards the nest she has built, as well as sometimes moistening it with water or urine from her cloaca. Hatching takes 2-3 months. Rogner notes that the Sri Lankan population is classified as the subspecies C. palustris kimbula, but that this distinction is somewhat questionable. B I

Crocodylus porosus

Saltwater Crocodile

Indo-Pacific, N Australia

20' [30']

The largest, most spectacular and probably most dangerous species of living crocodile, with a wide distribution and the ability to swim across sea if necessary. In recent history 30ft individuals were known, but human persecution (or in some cases defence) has reduced the normal size of a full-grown adult to 20'. That this is still a fearsome predator can be illustrated by the fact that at least a couple of decades ago, one individual in the Malaysian peninsula had taken about 40 human victims and still not been caught. Alcata also mentions that in the Philippines this animal is hated and feared. Normally, however, humans do not feature in their diet, but extreme caution must be taken in areas where C. porosus is known to live. It is found in coastal areas but also travels far inland. Anatomy: in appearance C. porosus can be distinguished by its large size and a short, blunt and granular-scaled snout. The enlarged nuchal shields are in 2 rows separated from the parietal area by >8 granular scales. 17 to 19 upper teeth on each side. Snout once and two thirds to twice and one fourth as long as broad at the base; head rough, snout with a more or less strong ridge on each side in front of the eye, slightly converging towards its fellow: mandibular symphysis extending to the fifth tooth ; premaxillo-maxillary suture, on the palate, directed backwards or W-shaped ; nasal bones separating the premaxillaries above. Four large nuchals forming a square, with one or two smaller ones on each side; postoccipital scutes usually absent, sometimes small and irregular. Dorsal shield well separated from the nuchal, the scutes forming I6 or 17 transverse and four to eight longitudinal series; scales on sides and limbs smooth or feebly keeled. Fingers webbed at the base; outer toes extensively webbed. A serrated fringe on the outer edge of the leg. Adult dark olive above; young pale olive, with larger lilac spots on the body and tail and dots on the head. Colour: grey, brown or almost black, with irregular dark mottling and whitish ventral surfaces. Reproduction: in Australia, females lay 60 eggs high up on river banks in the wet season. [SOURCE: Alcala, Boulenger, Cogger] B I

Crocodylus rhombifer

Cuban Crocodile

C Cuba, Isle of Pines

6-7' [11½']

Very rare species of which there are several hundred individuals living in an area of contiguous marshland on the island. Despite this the future of the species seems brighter as the Cuban government is working hard to conserve it. The Cuban Crocodile seems to be more adept at moving about on dry land than some other crocodiles, raising itself higher above the ground. Steel suggests that little is known of its reproduction or diet. Anatomy: 18-19 upper teeth on each side; more or less marked obtuse oblique ridge in front of each eye, forming with inner borders of the orbit a rhombus shape with anterior and posterior angles cut off; mandibular symphysis extends to level of 4^th or 5^th tooth; premaxillo-maxillary suture on palate nearly straight, transverse; nasal bones separate premaxillaries above; fingers webbed at base; outer toes half-webbed; cnemial crest feebly developed. Scalation: 6 or 8 large nuchals on 2 transverse series, and 2 pairs of smaller ones on transverse series behind occiput; dorsal shield well separated from nuchal, formed of 4 or 6 longitudinal and 16 transverse series; sides with large keeled scutes; scales on limbs strongly keeled. Coloration: olive/yellow and black, with small spots. [SOURCES: Boulenger, Steel] B I

Crocodylus siamensis

Siamese Crocodile

Thailand, Indochina, Java and Borneo

10-11½'/4m

Cox et al call this species "relatively good-natured" and note that no unprovoked attacks on humans have been reported. It has largely disappeared from the wild in Thailand as a result of the leather trade and removal for farm stock: otherwise found in large lowland rivers across its range. Anatomy: 18 upper and 15 lower teeth on each side; mandibular symphysis extends to 4^th tooth; premaxillo-maxillary suture on the palate, directed backwards; premaxillaries narrowly separated above by nasals; interorbital space wide, with median longitudinal ridge; fingers slightly webbed, outer toes extensively webbed; serrated fringe on outer edge of leg; bony lachrmyal ridges form broad-based triangle; proportionately broad and heavy with age; old adults have distinct bony ridges at the back of the skull. Scalation: 4 large nuchal shields, forming a square, with smaller one on each side; 2 pairs of smaller nuchals form transverse series behind occiput; dorsal scutes well separated from nuchals, in 16 transverse and 4 or 6 longitudinal rows, equally strongly keeled; 1 or 2 longitudinal series of smaller scutes in addition on each side;scales on limbs strongly keeled; Coloration: dorsally dark olive, spotted with black. Reproduction: females lay 20-40 eggs. [SOURCES: Boulenger, Cox]

Osteolaemus

16 or 17 upper and ]4or 15 lower teeth on each side; fifth maxillary tooth longest; fourth mandibular tooth fitting into a notch in the upper jaw. Snout rather short; nasal bones forming a septum dividing the nasal aperture; supratemporal fossae very small; a bony plate occupying the greater part of the upper eyelid. Splenial bones not entering the mandibular symphysis, which extends to the fourth or fifth tooth. A dorsal shield formed of four or six longitudinal series of juxtaposed, keeled, bony scutes; gular and ventral scutes bony, not articulating together. [SOURCE: Boulenger]

Osteolaemus tetraspis

African Dwarf Crocodile

W Africa

4½-6'

Steel calls this species an “obscure, inoffensive, slow-moving little reptile”. Its habitat is swamps, ponds and sluggish streams in tropical African rainforest, the latter habitat being under threat and the survival of Osteolaemus in the wild being thus endangered. Apparently quite terrestrial; behaviour largely nocturnal. Anatomy: 16-17 upper and 16-15 lower teeth on each side; 5^th maxillary tooth longest; 4^th mandibular tooth fits into notch in upper jaw; snout rather short; interorbital space deeply concave, narrow; nasal bones form septum dividing nasal aperture; supratemporal fossae very small; bony plate occupies greater part of upper eyelid; splenial bones do not enter mandibular symphysis; latter extends to 4^th or 5^th tooth. Scalation: nuchal shield distinct from dorsal, composed of 2-3 pairs of strongly keeled scutes, of which anterior are very large; dorsal shield formed of 4 or 6 longitudinal series of juxtaposed, keeled, bony scutes; 17 transverse series of dorsal scutes, of which broadest is composed of 6 scutes; keels very feeble on two median series, stronger on others; gular and ventral scutes bony, not articulating together; scales on upper surfaces of limbs keeled; no cnemial crest. Coloration: adults uniform blackish; young yellowish-brown above, profusely dotted and spotted with black, with broad black transverse bands on body and tail; ventral shields black and yellow; eye has dark-coloured iris. Reproduction: clutches of 10-17 eggs laid; incubation time about 115 days; hatchlings may take up to a week to emerge. [SOURCES: Boulenger, Steel]

O. t. tetraspis

W Africa

The western form. Anatomy: snout markedly upturned. Scalation: 11 pairs of caudal scales along top of anterior third of tail, merging to form single crest along the remainder.

O. t. osborni

W Africa (Congo basin)

3¾'

The eastern form. One specimen found alive in Uganda. Anatomy: snout not upturned. Scalation: 12-15 pairs of caudal scales along top of tail immediately behind pelvis.

Subfamily Alligatorinae

Alligator

Boulenger gives the characteristics of the genus as follows: 17 to 20 upper and 18 to 20 lower teeth on each side; fourth maxillary tooth longest ; fourth mandibular tooth fitting into a pit in the upper jaw. Snout rather short: nasal bones forming a septum dividing the nasal aperture; supratemporal fossa, small. Splenial bones not entering the mandibular symphysis, which extends to the fourth tooth. A dorsal shield formed of six or eight longitudinal series of juxtaposed, keeled, bony scutes; gular and ventral scutes without or with thin ossifications. [SOURCE: Boulenger]

Alligator mississippiensis

American Alligator

SE USA, Mexico, Guatemala, Honduras, El Salvador

10-12' [18']

Anatomy: 19 or 20 upper and as many lower teeth on each side. Head nearly twice as long as broad; snout much depressed, broadly rounded at the end, with the lateral outline nearly straight; a very short ridge in front of the orbit ; upper eyelid bony anteriorly. Two pairs of large nuchal scutes, forming a square, separated on the median line, with a pair of small ones in front and another pair behind. 17 or 18 transverse series of dorsal scutes, the broadest composed of 8 scutes. Fingers hardly half-webbed, outer toes about two-thirds webbed. Tail strongly compressed and crested posteriorly. Coloration: dark green or blackish above, young with yellowish crossbands; lower parts yellowish. [SOURCES: Boulenger]

Alligator sinensis

Chinese Alligator

China

4-7'

A very endangered species: some sources claim that only 130-150 individuals are still left in the wild. 17 or 18 upper and 18 or 19 lower teeth on each side. Anatomy: head nearly once and a half as long as broad; lateral outlines of snout converging towards the end, which is obtusely rounded; upper eyelid entirely bony. Three pairs of large nuchal scutes, in contact on the median line ; two small, round, isolated scutes in front of the large nuchals, and between them and the skull a semicircular row of sis conical shields. 17 transverse series of dorsal scutes, the broadest of which are composed of six scutes. Ventrals with a thin ossification. Fingers free, toes half-webbed. Tail strongly compressed and crested posteriorly. Coloration: greenish black above, speckled and vermiculate with yellow; underparts greyish. [SOURCES: Boulenger] B I

Caiman

18 to 20 upper and 17 to 22 lower teeth on each side; fourth maxillary tooth longest; fourth mandibular tooth fitting into a pit in the upper jaw. Snout moderately long, or short: no bony nasal septum; nasal bones extending to the nasal aperture: supratemporal fossae very small or absent. Splenial bones not entering the mandibular symphysis, which extends to the fourth or fifth tooth. A dorsal shield formed of six or more longitudinal series of articulated, keeled, bony scutes; a ventral armour of overlapping bony scutes, each scute formed of two distinct portions united by suture. [SOURCE: Boulenger]

Caiman crocodilus

Spectacled Caiman

S America

?'

Name derives from the bony ridges around the eye sockets, giving the appearance of a pair of glasses. B I

Caiman latirostris

Broad-nosed Caiman

S America

6-7½' [9']

Anatomy: 18 or 19 upper and 17 or 18 lower teeth on each side; fourth maxillary tooth much longer than third. Head not more than once and a half as long as broad; snout very broad and rounded, its basal width nearly equalling its length; a strong ridge from one anterior border of the orbit to the other, more or less produced anteriorly towards the fourth maxillary tooth; orbit not produced anteriorly: interorbital space concave; upper eyelid rugose or tubercular, more or less produced into a small horn, with a small bony plate anteriorly; supratemporal fossae present. Two more or less regular transverse series of small postoccipital scutes; three or four transverse series of large nuchals, the anterior composed of four scutes, the others of two, the transverse series separated from each other by an interspace. Dorsal shield composed of 18 transverse series of scutes, the broadest of which contain 8 or rarely 10 scutes; those of the median series very obtusely keeled in the adult. Bony ventral shield much less developed than in the other species, only the scutes on the sternal region imbricating ; the posterior abdominal region without any ossifications. Fingers free, outer toes webbed at the base. Coloration: adult uniform blackish; young olive and black, the latter colour usually predominating. [SOURCE: Boulenger]

Caiman yacare

Yacare Caiman

S Brazil, S Bolivia, Paraguay, N Argentina

C. y. yacare

C. y. medemi

Melanosuchus niger

Black Caiman

S America (Amazonia and central S America)

9-13½ [18']'

Anatomy: 18 (or 19) upper and 17 or 18 lower teeth on each side; fourth maxillary tooth much longer than the third. Head once and three fifths to once and two thirds as long as broad; snout moderate, obtuse, a little longer than broad ; a feeble transverse ridge in front of the concave interorbital region, bordering two deep concavities; two oblique ridges on each side of the snout, one from the orbit to the fourth maxillary tooth, the other from the frontal pits to the fifth premaxillary tooth; orbit produced anteriorly to the vortical of the ninth or tenth maxillary tooth; upper eyelid flat, finely striated above, with a small bony plate anteriorly; supratemporal fossae present ; vomer visible on the palate as a small rhomboidal plate. Four or five transverse series of small postoccipital scutes; four transverse series of large nuchals, the first two composed of four scutes, all articulated together. Dorsal shield composed of 19 transverse series of scutes, the broadest of which contain ten scutes ; all strongly and sharply keeled. Ventral scutes bony and imbricate, except on the posterior abdominal region, where the ossifications are absent or reduced to a small nucleus. Fingers free, outer toes half-webbed. Coloration: black above, yellow interiorly. [SOURCE: Boulenger]

Paleosuchus palpebrosus

Dwarf Caiman

NE S America as far east as Sao Paolo and as far south as Paraguay: range includes Columbia, British Guyana, Surinam and the mouth of the Amazon.

5'

Anatomy: 19 or 20 upper and 20 lower teeth on each side; third and fourth maxillary teeth largest. Head once and three fifths to once and two thirds as long as broad ; snout subacuminate, its basal width contained about once and a half in its length: no cross-ridge in front of the interorbital region, which is but slightly concave; upper eyelid flat and smooth, entirely bony, the bony plate consisting of four distinct pieces; lores very steep and high ; canthus rostralis angular; supratemporal fossae obliterated. Two transverse series of postoccipital scutes, followed by four or five transverse series of large, very highly and sharply keeled nuchals, the second and third usually composed of three or four scutes, the others of two. Dorsal scutes in 18 or 19 transverse series, the broadest of which are composed of six or eight scutes, which are less highly keeled than in the preceding species; those between the hind limbs constantly in four longitudinal series. The caudal crest becomes single on the twelfth or thirteenth verticil. Dorsal and ventral bony armour much developed; sides of body soft, with scattered small bony tubercles; gular and outer ventral scutes keeled. Fingers free, toes webbed at the base. Coloration: yellowish-brown above, spotted and crossbarred with black. [SOURCE: Boulenger]

Paleosuchus trigonatus

Smooth-fronted Caiman

Columbia, Venezuela, the Guyanas, Ecuador, Peru, Bolivia, the Amazon and Orinoco Rivers as far south as 10 deg lat. [Rogner]

4½-5' [7']

Anatomy: 10 or 20 upper and 20 to 22 lower teeth on each side ; third and fourth maxillary teeth largest. Head once and three fourths to twice as long as broad ; snout subacuminate, its basal width contained once and a half to twice in its length ; no cross-ridge in front of the interorbital region, which is but slightly concave; upper eyelid flat and smooth, entirely bony, the bony plate consisting of four distinct pieces; supratemporal fossae obliterated. A single series of postoccipital scutes, followed by four or five transverse series of large, very highly and sharply keeled nuchals, each composed of two or sometimes of three or four scutes. Dorsal scutes in 18 or 19 transverse series, the broadest of which are composed of six scutes; some or all of the posterior (between the hind limbs) composed of two or three scutes only: the dorsal scutes, except the two median series, very strongly and highly keeled. The caudal crest becomes single on the tenth or eleventh verticil. Dorsal and ventral bony armour much developed; sides of body soft, with scattered small bony tubercles: gular and outer ventral scutes keeled. Fingers free, toes webbed at the base. Coloration: yellowish brown above, spotted and cross-barred with black. [SOURCE: Boulenger]

Subfamily Gavialinae

Gavialis

27 to 20 upper and 25 or 26 lower teeth on each side, anterior largest, laterals subequal, not received into interdental pits; the first, second, and third mandibular fitting into notches in the upper jaw. Snout extremely narrow and elongate, dilated at the end; nasal bones comparatively short, widely separated from the premaxillaries; nasal opening smaller than the supratemporal fossae; lower anterior margin of orbit (jugal) raised; a very small anterior bony plate in the upper eyelid. Mandibular symphysis extremely long, extending to the 23rd or 24th tooth, comprising the splenial bones. A dorsal shield formed of four longitudinal series of juxtaposed, keeled, bony scutes: no bony ventral scutes. [SOURCE: Boulenger]

Gavialis gangeticus

Indian Gavial

Indian subcontinent, Burma

13½' [21']

An easily recognisable species thanks to its long snout full of teeth. Formerly these were common animals in the river systems of the subcontinent and Burma but are now seriously endangered and mostly confined to the Chambal, Girwa, Rapti and Narayani rivers of the Ganga river system. For most of the year they inhabit deep pools at river junctions and bends and deep gorges in hilly country, but spread out with the monsoon flood waters, only to return to their normal habitat at the end of the season. They are not good movers on land and stay close to the river. Diet is mainly fish but opportunistically take other creatures, including corpses. Description: the jaws have 27-29 undifferentiated teeth on each side of the upper jaw and 25-26 on each side of the lower: anterior largest, laterals subequal, not received into interdental pits; the first 3 of the mandibular teeth fit into notches in the upper jaw. Snout extremely narrow and elongate, dilated at the end ; nasal bones comparatively short, widely separated from the premaxillaries; nasal opening smaller than the supratemporal fossae; lower anterior margin of orbit (jugal) raised; a very small anterior bony plate in the upper eyelid. Mandibular symphysis extremely long, extending to the 23rd or 24th tooth, comprising the splenial bones. A dorsal shield formed of four longitudinal series of juxtaposed, keeled, bony scutes: no bony ventral scutes. Males can be distinguished by a large cartilaginous mass on the end of the snout. Coloration: adults are dark- or brownish olive, ventrally white or yellowish white. The young are greyish brown with 5 irregular transverse bands on the body and 9 on the tail. Reproduction: mating takes place December-January in the water. Nesting follows in March-April, the nests usually being sited on sand: the nesting season is said to not vary each year by more than 10 days, with all females in an area nesting within a week [Daniel]. A clutch may consist of anything between 10-96 eggs but is on average 40: incubation lasts 72-92 days. Sexual maturity is reached in females at lengths of 2½m and males at 3m. [SOURCE: Boulenger, Daniel]

Tomistoma

20 or 21 upper and 18 or 19 lower teeth on each side, the laterals received into interdental pits ; fifth maxillary tooth largest *; mandibular teeth, first and fourth fitting into notches in the upper jaw. Snout very narrow and elongate ; nasal bones not extending to the nasal opening, bnt in contact with the premaxillaries; nasal opening smaller than the supratemporal fossae; a small anterior bony plate in the upper eyelid. Mandibular symphysis very long, extending to the 14th or 15th tooth, comprising the splcnial bones. A dorsal shield formed of four longitudinal series of juxtaposed, keeled, bony scutes. [SOURCE: Boulenger]

Tomistoma schlegelii

False Gavial

S Thailand, Malaysia, Sumatra and Borneo

9-11½'

Description: snout very narrow and elongate; jaws have 20-21 upper and 18-19 lower teeth on each side; lateral teeth received into interdental pits; 5^th maxillary teeth larges; mandibular teeth, 1^st and 4^th fitting into notches in upper jaw; nuchal and dorsal scutes form continuous shield, composed of 22 transverse rows, of which the largest contains 6 scutes, the anterior (nuchals) only 2: all keeled: 2 small postoccipital scutes. Anatomy: nasal bones do not extend to nasal opening but in contact with premaxillaries; nasal opening smaller than supratemporal fossae; smaller anterior bony plate in upper eyelid; mandibular symphysis very long, extending to 14^th or 15^th tooth, comprising the splenial bones.[SOURCES: Boulenger]