Topic 15 - Squamates and Tuatara

What are Squamates and their History?

This is the biggest order of reptiles. It includes all lizards and snakes. The term lizard is not monophyletic due to snakes (which makes them paraphyletic). It is unknown whether they have a Gondwana origin (older) of South East Asian origin (invaded Australia).

Characteristics of Squamates

• scales

• kinetic skulls (upper jaw can move)

• paired copulatory organs (hemipenes - 2 penis like structures)

• egg laying (most species)

• live bearing (some species)

• asexual (few species)

• limb reduction and body elongation

• communication through

  • colour

  • pheromones

Key Groups in Squamates

1. Geckoes

2. Skinks

3. Dragons (Agamids)

4. Goannas/monitors (Varanids)

What are Tuatara and their History?

They are not lizards or dinosaurs. They are their own order. They were widespread 220 - 100 mya. Now only one/two species in NZ. Characteristics include:

• mating by cloacal contact

• two rows of teeth on top jaw

• photoreceptive ‘parietal eye’

• no external ear

• long lived

• slow reproduction