Reptiles Flashcards
When did amniotes arise?
370mya in the Late Devonian
What do archosaurs consist of?
Dinosaurs, crocodiles, birds
What time period did archosaurs dominate?
Mesozoic
What two groups did dinosaurs consist of?
- Saurischia: contained a group called Theropsids that gave rise to birds
- Ornithischia
What was the difference between saurischia and ornithischia?
The shape of their pelvis
Ornithischians have a bird shaped hip, but birds didn’t arise from them
Why are reptiles not a class? What are they instead?
They’re a group that includes an ancestor but not all of its descendants
Paraphyletic group
How many chambers is the heart divided into?
3 for most, 4 for crocodilians
What environment are crocodylia confined to? And what habitat do they spend most of their time?
Tropical and warm temperate environments
Spend much of their time in the water but build nests on land
What do testudines consist of?
Turtles and tortoises
What is the testudines primary characteristic?
A shell
What does the shell consist of?
A carapace and a plastron
What are the two groups in testudines?
Cryptodires
Pleurodires
What are cryptodires and how many species are there?
They retract their head vertically
Consists of snapping turtles, marine turtles, tortoises and terrapins
200 species
What are pleurodires and how many species are there?
They retract their head horizontally and have snake heads
Consist of matamata
50 species
What type of ventilation do testudines use? Why?
Diaphragmatic ventilation
Because shell breathing and respiration cannot be carried out through chest expansion
Aquatic species use pharyngeal and cloacal respiration
What temperatures determine which sex?
Cool temperatures: males
Warm temperatures: females
What are the two groups of lepidosaurs?
Sphenodontida (tuatara)
Squamata (lizards and snakes)
What is the sister group to lizards?
Tuatara
How many species of tuatara exist today?
2 species on 30 small islands off New Zealand
What does the subclass Squamata consist of?
Lizards
Snakes
Amphisbaenians
What is lost in a snake in order to accommodate its long shape?
Left lung reduced or absent
Gall bladder posterior to the liver
Kidneys aren’t arranged side by side
What are the different types of locomotory specialisations in snakes?
Lateral undulation
Rectilinear
Concertina: pushing against solid surface to move forward
Side winding: allows the snake to have limited contact with hot sand
What are the 3 morphologies of venomous snakes?
- Opisthoglyphous: “back fanged”
- Proteroglyphous: hollow fangs on the front of the maxilla, fangs are permanently erect
- Solenoglyphous: only teeth on maxilla are long hollow fangs
