Lecture 5. Animal Diversity II: Tetrapods and Human Evolution Flashcards
What are craniates ?
Chordates with a head
What are vertebrates ?
- Chordates
- Craniates
- With a backbone
What are gnathostomes ?
- Chordates
- Craniates
- Vertebrates
- With jaws
What are osteichthyans ?
- Chordates
- Craniates
- Vertebrates
- Gnathostomes
- With lungs or swim bladders
What are lobe fins ?
- Chordates
- Craniates
- Vertebrates
- Gnathostomes
- Osteichthyans
- With lobe fins
What is interesting about coelacanth ?
Evolved before tetrapods but still exist today
What do lobe fins have ?
Rod shaped bones projecting into their fins
What are tetrapods ?
- Chordates
- Craniates
- Vertebrates
- Gnathostomes
- Osteichthyans
- Lobe fins
- 4 limbs with 5 digits
What tetrapods still exist today ?
- Amphibians
- Reptiles
- Birds
- Mammals
What are the different classes of reptiles ?
- Parareptiles
- Turtles
- Crocodilians
- Pterosaurs
- Omithischian dinosaurs
- Saurischian dinosaurs other than birds
- Birds
- Plesiosaurs
- Ichthyosaurs
- Tuataras
- Squamates
What are birds technically a type of ?
Dinosaur
Why did tetrapods move to land ?
- Empty niches
- Avoid competition
- Safer places to lay eggs
- Avoid predators
What is needed to survive on land ?
- Skeletal support
- Lungs
- Limbs
- A neck
What is unique to lungfish ?
Use their fins to walk across the bottom of the water
What do lobe finned fishes show ?
Adaptations which pre-adapted them to life on land
What are fishapods ?
Part fish, part tetrapod
When did tetrapods move to land ?
Devonian perio
What was once thought about the Acanthostega ?
Once thought to be a land dweller but its skeleton could not have supported it on land
What is Romer’s gap ?
The era 360-345 million years ago where there are very few fossils
What did most tetrapods have before Romer’s gap ?
8 digits
What is humans closest relative ?
The Pan troglodytes
Why are humans special ?
- They have opposable thumbs
- Virtually hairless
- Use language to communicate
- Make and use tools
- Bipedal
- Foramen magnum is beneath the skull so we can hold our heads upright
- Our spine has a lumber curve which pulls our body weight over our pelvis
- Balance on one foot
- Large brains
What allows us to articulate words ?
Unattached hyoid bone
How do humans balance on one foot ?
The iliac blades of the human pelvis are tilted inwards to support internal organs
Why do modern humans have larger brains than our ancestors ?
Linked to changing climate
How did lactose tolerance evolve ?
A mutation in the lactase gene
When does the ability to digest lactase disappear ?
Before adulthood in mammals
