About Aussie Reptiles
The term “reptile” is, in fact, a misnomer. It is the habit of scientists to group all life-forms in terms of their evolutionary lineage – or if you like, their family tree. In this way, we can attempt establish who evolved from whom, and who is most closely related to whom. This branch of science is termed phylogeny.
However, “reptile” lumps together three very separate groups of animals:
- the Crocodilia, which includes crocodiles, alligators and caimans
- the Testudines, being the turtles and tortoises
- and, together, the Squamata (including all lizards, worm-lizards and snakes) and the Sphenodontia (the only living representative being the Tuatara, a unique, dragon-like reptile from New Zealand).
Contrary to appearances, these three groups do not belong to the same evolutionary lineage, and are only very distantly connected. For example, crocodiles and their kin are much more closely related to birds than to other so-called “reptiles”. So, never judge a book by its cover…
At SnakeSense, we concentrate on group number three. Snakes evolved from lizads around 120 million years ago, in the early Cretaceous. Due to their small, fragile skeletons, fossils of early snakes are few and far between, but the latest research indicates that they evolved on land from a burrowing, lizard-like ancestor, which gradually lost its limbs in order to better slip between cracks in the soil. Due to their burrowing lifestyles, the eyes of ancient snakes also became greatly reduced through lack of use; hence modern snakes had to, as it were, re-evolve functional eyes in order to take up life on the surface. For this reason, the eyes of a snake are structurally very different from other animals.
There are approximately 3000 species of snake worldwide, the genetic interrelationships of which are still challenging researchers. Put simply, snakes can be roughly divided into six broad categories: blindsnakes; pythons and boas; mobile front-fanged snakes; fixed front-fanged snakes; filesnakes; and colubrids.
Australia boasts members from each category other than the mobile front-fanged venomous snakes, belonging to the families Viperidae (vipers, rattlesnakes and the like) or Atractaspididae (asps, mole-vipers and stiletto snakes), even though the Death Adder has evolved to look and behave in a very similar fashion. When wholly unrelated species evolve to become alike in this way, it is termed ‘convergent evolution’.
In total, Australia is home to nearly 200 species of snake, and over 600 species of lizard. Sporting great morphological variety than snakes, lizard taxonomy is rather more clearcut; with today’s species neatly divisible into five families: Skinks, Dragons, Monitors, Geckoes and Legless-Lizards.