Reptiles

This information was obtained from the Queensland Museum's Database on Reptiles and Amphibians of Queensland

Reptiles are scaly, ectothermic, egg-laying, vertebrates.

Crocodilia

Testudines

Saltwater Crocodile
Saltwater crocodile (Crocodylus porosus)

Saltwater Crocodiles

Identification: 

The Saltwater or Estuarine Crocodile is a broad-snouted species that grows to a large size (up to 7 metres but rarely more than 5 metres).  This is the largest of all living crocodiles. 

Distribution: 

Islands of the western Pacific, India, south-east Asia, New Guinea and northern Australia.  In Queensland, Saltwater Crocodiles may be encountered in the sea or any coastal waterway north of Rockhampton.  Individuals are occasionally seen as far south as the Mary River (Gympie).

Habitat: 

Coastal rivers, swamps and lagoons – will readily enter the ocean.

Danger: 

Dangerous.  Due care should be taken when approaching the water or undertaking water-related actives within the known distribution of this species.
Crocodile warning signs are posted on many northern waterways and these should be heeded at all times.
Problem crocodiles should be reported to the Department of Environment and Resource Management , phone 1300 130 372.

Food: 

A broad range of crustaceans, fish, reptiles, birds and mammals.  Large crocodiles can overpower large mammals such as pigs, horses and cattle.  Humans are also occasionally taken.

Breeding: 

As many as 60 hard-shelled eggs are laid in a mound of vegetation and soil during the wet season.  These take around three months to hatch and are guarded by the female throughout this time.


Flatback Turtle, Natator Depressa

Sea turtles

The coastal waters of Queensland are important breeding and feeding habitat for marine turtles.  Six of the world’s seven marine turtle species are known from Queensland.  Leatherback Turtles are seasonal visitors arriving in the waters of south-eastern Queensland in the late winter months.  The other species (Green Turtle, Loggerhead Turtle, Hawksbill Turtle, Flatback Turtle and Olive Ridley Turtle) have resident feeding and breeding populations in Queensland.

These turtles are long-lived and take 30 to 50 years to reach breeding age.  They have complicated life histories and show high levels of fidelity to both breeding and feeding areas.

All marine turtles have strong, paddle-shaped flippers, nostrils positioned high on the snout and a bony shell.  In all species, except the Leatherback and Flatback Turtles, the shell is covered in large plates.  Marine turtles, unlike freshwater turtles, pull their heads directly back (cryptodirous).


Leatherback Turtle, Dermochelys coriacea.

Freshwater Crocodiles

Johnston Freshwater Crocodile
The narrow-snouted Freshwater Crocodile, Crocodylus Johnstoni

Identification: 

The freshwater crocodile is a narrow-snouted species that grows to 3 metres. 

Distribution: 

Far northern Australia.  In Queensland, this species is usually found in western-flowing rivers that drain into the Gulf of Carpentaria.  It also occurs in some eastern-flowing rivers on Cape York Peninsula where the headwaters are narrowly separated from western-flowing rivers.

Habitat: 

Usually found in freshwater rivers and lagoons but will also enter brackish water.

Danger: 

Inoffensive.  Humans are occasionally bitten but such attacks are likely to be accidental, occurring in water with low visibility.

Food: 

A broad range of crustaceans, fish reptiles, birds and small mammals.

Breeding:

Around 20 eggs are laid during the dry season in a hole dug into a sandbank.

For more information, please see the Queensland Department of Environment and Resource Management crocodile website .

Freshwater turtles

Freshwater turtles are commonly seen in most Queensland waterways.  There are about 14 species (and a number of subspecies) recognised from Queensland, all belonging to the family Cheluidae.


The Eastern Snake-necked Turtle, Chelodina longicollis

There are two basic body forms, the short-necked turtles ( Elseya spp., Elusor macrurus , Emydura spp., Rheodytes leukops and Wollumbinia spp.) and the long-necked turtles ( Chelodina spp. and Macrochelodina spp.), which have extremely long, snake-like necks. Unlike the sea turtles and many foreign freshwater turtles, the Australian cheluids fold their necks side-ways under the protective edge of the shell (pleurodirous).  They have clawed, webbed feet and most species have distinct barbels on the chin. 

Most freshwater turtles leave the water to lay their eggs.  One species, Macrochelodina rugosa , has developed an unusual nesting strategy.  This turtle lays its eggs underwater, in a nest dug into the bottom of a shallow pool.  The pool then recedes during the dry season until the nest is on land.  The eggs delay development while submerged and laboratory tests have shown that even when they are submerged for 12 weeks they will still develop normally when removed from the water.  The significance of this behaviour is not fully understood but it may prevent the eggs being eaten by terrestrial predators.  By the time the nest is above the water level, the signs and odour of the nesting turtle will be largely gone.

In some of the short-neck turtles ( Rheodytes and Elusor ), the cloaca is lined with numerous finger-like projections that act in a similar manner to the gills of a fish.  By drawing water into its cloacal cavity, the turtle can satisfy much of its oxygen needs.  The turtles armed with this 'bum-breathing' system need surface only infrequently for air.

The Common Snake-necked Turtle ( Chelodina longicollis ) is often seen crossing roads during or after rain.  This turtle is highly mobile and moves away from permanent water bodies to feed in seasonal lagoons that, for a time, offer a rich abundance of food.  These turtles are often killed by traffic and there is evidence that they are declining in heavily settled areas.  They were once common in Brisbane waterways but are now rarely seen.

Squamata

Rhynchocephalia


Blue-tongued skink, Tiliqua Scincoides

Squamates (Squamata) are the most diverse of all the reptile groups, with approximately 7400 living species. Squamates include lizards, snakes, and worm lizards.

There are two characteristics that unite the squamates. The first is that they shed their skin periodically. Some squamates, such as snakes, shed their skin in one piece. Other squamates, such as many lizards, shed their skin in patches. In contrast, non-squamate reptiles regenerate their scales by other means—for example, crocodiles shed a single scale at a time while turtles do not shed the scales that cover their carapace and instead add new layers from beneath.

The second characteristic shared by squamates is their uniquely jointed skulls and jaws, which are both strong and flexible. The extraordinary jaw mobility of squamates enables them to open their mouths very wide and in doing so, consume large prey. Additionally, the strength of their skull and jaws provides squamates with a powerful bite grip.

The closest living relatives of the squamates are the tuatara, followed by the crocodiles and birds. Of all living reptiles, turtles are the most distant relatives of the squamates. Like crocodilians, squamates are diapsids, a group of reptiles that possess two holes (or temporal fenestra) on each side of their skull.

Key Characteristics

The key characteristics of squamates include:

  • the most diverse group of reptiles
  • exceptional skull mobility

Tuatara, Sphenodon punctatus

Laurie J. Vitt, Janalee P. Caldwell, in Herpetology (Fourth Edition), 2014

Rhynchocephalians as a group are considered the sister taxon to squamates, and, together, they comprise the Lepidosauria. Lepidosaurs share numerous derived characteristics, including a transverse cloacal opening (the vent); tongue notched distally and used to capture prey (lingual prehension); full-body ecdysis; imperforate stapes; teeth attached superficially to the jaw bones; pelvic bones fused in adults; fracture planes or septa in the caudal vertebrae; and numerous other anatomical traits. However, one study shows that sperm morphology of extant rhynchocephalians (Sphenodon) is more similar to that of crocodylians and turtles than to squamates, which argues against a sister relationship with squamates. Chromosomal and gene sequence data indicate that Sphenodon is sister to squamates. Based on the assumption that rhynchocephalians and squamates are each other’s closest relatives, they apparently diverged early in the Late Triassic, and the rhynchocephalians seemingly have always been a group with moderate or low diversity.

Rhynchocephalians differ from squamates by the presence of gastralia; a narrow quadrate with greatly reduced or lateral concha; lower temporal fenestra enclosed or partially so; jugal in the mid-temporal arch touching the squamosal posteriorly; prominent coronoid process on the mandible; several anterior teeth of the palatine series enlarged; dentary and mandibular teeth generally enlarged, regionalized, and fused to dorsal margin of bone; and the premaxillary teeth replaced by chisel-shaped extensions of the premaxillary bones that have given rise to the tuatara’s other vernacular name, half-beaks. Most of the rhynchocephalian radiation occurred during the Triassic and Jurassic, and by the Cretaceous, most had disappeared from the fossil record, suggesting that lizards may have outcompeted them. However, the recent discovery of the extinct rhynchocephalian Priosphenodon avelasi in Cretaceous beds of Patagonia suggests that competition with lizards may not have been the only factor resulting in the disappearance of early rhynchocephalians. Priosphenodon avelasi was more abundant than any other tetrapod group in the Cretaceous beds of Patagonia, indicating that rhynchocephalians were the dominant tetrapods of the Cretaceous fauna of South America.

The only extant rhynchocephalians are the tuataras, which occur only on small islets off the main islands of New Zealand.