Flashcards in Lecture 9 RH - Reptiles Deck (54)
What kind of grouping are amniotes?
Monophyletic group within tetrapods.
What lifestyle do amniotes have?
A terrestrial lifestyle; some colonised air and some returned to water
What type of fertlization do amniotes have?
What kinds of animals are the amniotes?
What are the general features of amniotes?
Thicker and more waterprood skin
Rib-ventilation of the lungs
High-pressure cardiovascular system
Water-conserving nitrogen excretion
Expanded brain and sensory organs
What are the layers of membranes surronding the amniotic egg?
Yolk sac: Contains nutrients
Chorion: Allows gas exchange with environment
Amnion: Surrounds and cushions embryo with the help of fluid
Allantois: Stores wastes and allows gas exchange
Why is the shell of an egg porous?
Shell contains pores so that the embryo could breath
What does the layer between the egg's shell and the chorion contain?
In what order does everything happen with egg production?
fertilization -> membranes around embryo -> shell
What are the general features of reptiles?
Tetrapods with 5 digits per limb
Amniotic with calcareious or leathery shelled egg
No aquatic larval stage
Respiration by lungs
Ectothermic and poikilothermic (birds are homeothermic and enothermic)
Epidermal keratin forms scales (this forms feathers in birds and hair in mammals)
Skull with one occipital condyle
How many occipital condyles do reptile skulls have?
1; compared to 2 in mammals
Are reptile and fish scales homologous?
No, reptilian scales are epidermal whereas fish scales are mesodermally derived (from the dermis of the skin)
What is the function of reptile scales?
Physical protection and prevention of dessication
Some reptiles have bony dermal plates with added strength
What do reptile hearts look like?
All reptiles have a septum between left and right atria.
Most reptiles have a partial septum dividing the ventricle into 2 chambers.
Crocodilians have a complete septum between left and right ventricles.
What are the developments in locomotion seen in reptiles?
Improved body structure and support and limbs.
Ancestral form of locomotion is by lateral undulations of trunk which compresses lungs alternatingly in order to run.
Improvements include bipedal locomotion, movements of ribs, pelvis, organs, and limb movement independent of trunk bending.
What are the developments that reptiles have in order to respire more efficiently?
Larger and more efficient lungs
Lungs are inflated by negative pressure by enlarging body cavity (without using a diaphragm)
Turtles move their visceral organs around in order to create the negative pressure.
Lizards ventilate the lungs by compressing and expanding the rib cage
Crocodiles inhale by expanding the rib cage and pulling the liver back and rotating pubic bones.
What developments in the reptiles have allowed more efficient metabolism to take place?
More effient circulatory system with 4 chambered hearts.
What are the advantages and disadvantage of ectothermy?
Efficient conversion of food into biomass
Can thrive in ecosystems of low productivity
Can survive with low metabolic rate
External temperature limits activity
Requires behavioural adaptations for finding thermal microenvironments
Becoming inactive for part of the year
Limitations on latitudinal range
How long ago did amniotes arise from amphibians?
What are the 3 groups of amniotes?
Anapsids: No temporal bone holes posterior to orbits. (earliest reptiles)
Synapsids: One pair of temporal holes posterior to orbits for attachment of jaw muscles. (gave rise to therapsid reptiles and mammals.
Diapsids: 2 pairs of temporal holes posterior to orbits for attachments of jaw muscles. They gave rise to all other reptiles including dinosaurs and birds. Turtles secondarily lost these openings
What basis is there for amniote division?
Are turtles considered anapsids, synapsids, or diapsids?
Crocodilians are more closely related to birds than to other reptiles
What are the 3 main clades of reptilians?
Snakes, lizards, tuataras
Crocodiles, birds, dinosaurs
What order are tortoises/turtles?
Where does the shell attach to the turtle body?
Shell is fused to the ribs and vertebrae of the thorax
How is the lung ventillated in turtles?
Muscular contractions of the thorax, abdomen, and limbs.
Viscera are moved in a way where pressure is created to open the lungs for ventillation
What are tortoises referring to?
Turtles are endangered
What is the turtle's life cycle?
Egg buried in the sand
Sand travels to the water and hatchlings must travel to the water
What determines the sex of a turtle?
Nesting temperature of the egg
How are turtles guided between feeding and nesting grounds?
What order are snakes and lizards a part of?
Which reptiles are the most recently evolved?
Why can snakes open their mouth so wide?
They have a kinetic skull with movable quadrate bone which allows large mouth opening.
Very strong jaw muscles
Are squamates viviparous?
Some are by retaining egg in oviduct until it hatches
What suborder of squamata are lizards?
Which are more primitive, lizards or snakes?
How are sauria eyes different to snakes?
Lizards have movable eyes and very good vision
Where are saurians typically found?
low productivity environments such as dry forests, deserts, or grasslands
What are worm lizards?
No limbed lizards that burrow in soil and are poorly studied
Which suborder are snakes?
What are the features of snakes?
Excellent olfactory and vibration senses (olfactory organs in roof of mouth known as jacobson's organs
Pit vipers have a pit organ which senses temperature with 0.003 degrees sensitivity
Fused, transparent eyelids
No external ear openings (unlike worm lizards)
How can worm lizards be excluded from snakes?
Worm lizards have external ear openings
What type of diet do snakes have?
What percentage of snakes are venomous?
80% of Australian snakes are venomous
Are snakes ovi or viviparous?
Most are oviparous
Which snake has the most toxic venom of all land snakes?
What superorder are snakes a part of?
What order are tuataras a part of?
What are the features of tuataras?
1 genus remains
Nocturnal, live in burrows associated with nesting sea brds
Most primitive living reptiles, similar to 200 million year old fossils
Have a primitive third eye on the top of their head used to regulate sun exposure
What are the differences between alligators and crocodiles?
Crocodiles have a broader snout and visible upper teeth when mouth is closed
Alligators have a narrow snouth and both upper and lower teeth visible when mouth is closed
What are the largest crocodilians?
Salties; they extend up to 7m