Bio 123: PP18 Material Flashcards
What is the Reptile class known for?
Having an amniotic egg
What orders fall under reptiles?
-Testudines (turtles)
-Squamata (lepidosauria)
-Crocodilia
What are the sub orders of squamata?
-Serpentes (snakes)
-Lacertilia (Lizards)
What animals are Amniotes?
-Includes the reptiles, birds, mammals, and amniotes
What are the derived features of amniotes?
- They have an amniotic egg now that they are in terrestrial ecosystems which have been fully colonized by them
-They have waterproof skin
-Have costal ventilation using paired lungs (which is movement of the ribs)
What is the most ancient reptile order?
Testudines
Egg characteristics of amniotes
They retain their eggs inside without laying it out
Skin characteristics of amniotes
They now have scales, feathers, fur and waterproof skin
Costal Ventilation
It enhances their respiration by using their ribs to expand the space in the lungs to allow extra oxygen to come in. This is important b/c reptiles take on a much larger form and need more oxygen.
Parts of the Amniotic Egg
-Leathery Shell
-Chorion
-Allantois
-Yolk sac
-Embryo
What are the 4 major chambers of the amniotic egg?
- Amnion
- Allantois
- Chorion
- Yolk Sac
Purpose of the Amnion
Purple sac that directly cushions the embryo and provides protection and support
Purpose of the allantois
Where the developing embryo stores its waste
Purpose of the Chorion
Thin white layer that allows for gas exchange to occur with the external environment
Purpose of the Yolk Sac
Where the embryo receives its nutrition from
Characteristics that Reptiles have that distinguishes them from amphibians
- Better developed lungs
- Tough, dry scaly skin that offers protection against desiccation and physical injury
- Amniotic egg permits rapid development of large young in relatively dry environments
- Have an efficient and versatile circulatory system and higher blood pressure than amphibians
- Have efficient strategies for water conservation
- Nervous system is much more complex
Desiccation
Drying out
Why have turtles been so successful?
B/c of their hard shells and low metabolic needs. Turtles, crocodiles, and birds have been the only species that have survived mass environmental catastrophes.
What is the earliest known turtles?
The eunotosaurus africanus which lives 260 mya during the permian (before the age of the dinos)
What are the two extant lineages of turtles?
-Pleurodires
-Cryptodires
Pleurodires
-Known as side-necked turtles
-Live in the southern hemisphere
Neck Mechanism of Pleurodires
Can bend their neck to the side to afford their protections yet it is not as efficient b/c is still leaves their neck exposed
Cryptodires
-Hidden necked turtles
-Live in the Northern Hemisphere
-about 350 species total
Neck mechanism of cryptodires
Their cervical vertebrae allows them to bend it so that the turtles can fully pull their neck into their shell.
Evolutionary contraint of a turtles shell
There has been no selective pressure for turtles to get rid of their shell and therefore have not evolved any other traits that we commonly see such as being able to glide, slide, or live high up on trees.
Bone breakdown of a turtle
-Neck
-Ribs
-Fused Vertebrae
-Carapace
-Plastron
Carapace
The top of a turtles’s shell
Plastron
The bottom of a turtles shell
What are the classifications of amniotes based on temporal fenestration?
- Anapsid (turtles)
-Synapsid (mammals)
-Diapsid (other reptiles/birds)
Temporal Fenestration
Posterior to the orbit
Anapsid
Has no opening posterior to its orbit
Synapsid
Has 1 opening posterior to its orbit