W
|
riting
this article made me realise just how complicated classification can be in the
animal kingdom. The class Reptilia is certainly diverse and at times, a
bit unclear. But that’s the nature of biology – we’re constantly finding new
evidence for evolutionary relationships which continuously modifies our current
understanding of phylogenies. But with what I’ve learnt from my lectures in Australian
Wildlife Biology, I’ve put together a diagram of reptile diversity which
will give us the big-picture of where reptiles sit in and amongst each other!
Reptile
diversity
The class
Reptilia includes many four main orders (red in the diagram):
· Rhynchocephalia – tuataras
(New Zealand)
· Squamata – lizards,
snakes, worm lizards
· Crocodilia – crocodiles
and alligators
· Testudines
–
turtles and tortoises
Tuataras,
lizards, snakes, and worm lizards belong to the subclass Lepidosauria.
The
crocodilians belong to the clade Archosauria which they also
share with birds and all the dinosaurs! Yes, technically birds are reptiles but
usually you would classify them as class Aves.
This
diagram does not include every family of reptile, certainly not any of the
extinct groups of reptilians. But it gives a satisfying overview of all the
modern reptiles we see today.
Below is
some extra on each of the four orders above…
TUATARAS
Tuataras
are only found in New Zealand. These reptiles have pointed spines running down
their back and there is only one living species, Sphenodon punctatus.
SQUAMATES
The
squamates (order: Squamata) include the worm lizards, lizards, and snakes.
Worm
lizards
Worm
lizards, of the group Amphisbaenia, are generally limbless. Only members
of the genus Bipes still have forelimbs. Examples of amphisbaenians are
the Mexican mole lizard and the red worm lizard.
Lizards
Lizards
belong to the order Squamata, along with snakes and worm lizards.
There are
many families; below is not the complete list!
Dragon
lizards e.g. Frill-neck lizard, Bearded dragon
Geckoes e.g.
Burrow-plug gecko
Flap-footed
lizards e.g. excitable delma
Hind
limbs reduced to flaps.
Skinks e.g.
Blue-tongued lizard
Goanna,
monitor lizard e.g. Lace monitor, Perentie
Iguanas e.g.
Green iguana
Chameleons e.g.
Veiled chameleon
True
lizards e.g. Common wall lizard
+ more!
Snakes
Snakes (Serpentes)
belong to the order Squamata, along with the lizards.
There are
many families; not all have been included in the diagram.
Blind/worm
snakes e.g. Blind snake
They have
poorly developed eyes. Non-venomous.
Pythons e.g. Carpet
python
Has
spur-like vestigial hind limbs. Non-venomous.
File
snakes e.g. Acrochordus species
They are
aquatic and have scale sensilla which are sensory spots behind their eyes.
Colubrids
e.g.
Green tree snake
Venomous
and non-venomous species.
Elapids e.g.
Southern Death Adder, Eastern Brown snake
VENOMOUS.
Have fangs.
Sea
snakes e.g. Yellow belly sea snake
VENOMOUS.
Have fangs. Semiaquatic and have paddle-like tail.
Sea
kraits e.g. Yellow-lipped sea krait
VENOMOUS.
Have fangs. Marine and have paddle-like tail.
Vipers e.g.
Western Diamondback Rattlesnake
VENOMOUS.
Boas e.g. Boa constrictor
VENOMOUS.
+ more!
CROCODILIANS
Crocodilians
are members of the order Crocodilia comprising crocodiles, alligators,
caimans, and gharials. There are three families:
Crocodylidae
–
crocodiles e.g. Saltwater crocodile, Freshwater crocodile
Alligatoridae
–
alligators e.g. American alligator, and caimans e.g. Black caiman
Gavialidae
–
gharials e.g. Gharial, False gharial
TURTLES
The order
Testudines includes the turtles and tortoises. Below is some of the
families (not all):
Snake-necked
turtles e.g. Bellinger River Snapping Turtle
Freshwater
Pitted-shelled
turtles e.g. Pig-nosed turtle
Freshwater
Leatherback
– one
extant species (Leatherback sea turtle)
Marine,
have leathery carapace made of osteoderms not scutes
Sea
turtles e.g. Hawksbill turtle, Green sea turtle, Loggerhead sea
turtle,
Marine
Tortoises
e.g.
Galápagos
tortoise
Terrestrial
+ more!
That’s
all for reptile diversity! See you in my next article Xx
Sources:
Thompson, E
2019, BIOL2032 Australian Wildlife Biology, lecture: Reptiles Diversity,
lecture PowerPoint slides, Taronga Institute of Science and Learning, The
University of Sydney
Wikipedia
2019, Reptile, Wikipedia The Free Encyclopedia, viewed 08 January 2020
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