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40 Cards in this Set
- Front
- Back
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1. What were the first tetrapods?
Do we have fossil evidence? |
Amphibians were first tetrapods
Have fossil tadpoles of some of the adult species |
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2. What are amniotes?
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They lay eggs
At some point amphibians began laying eggs on land and we call these amniotes Today includes birds, reptiles, mammals |
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3. Does egg-laying ability preserve?
What features of amniotes do we use to trace back? |
Egg-lying ability does not preserve
Use characteristic features of skulls |
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4. What is one key difference of amniotes?
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Number of holes in the skull behind the eyes
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5. What are anapsid, diapsid, and synapsid?
What is an example of each? |
Anapsid: no holes (amphibians and early reptiles)
Diapsid: two holes (reptiles) Synapsid: one hole (mammal-like reptile, precise term for our ancestors) |
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6. What era where the first tetrapods in?
What about the first mammal-like reptiles and reptiles? |
Tetrapods: Devonian
Mammal-Like Reptiles: Late Mississippian Reptiles: Late Pennsylvanian |
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7. Where did the earliest synapsid reptiles and diapsid reptiles live?
What was this conducive for? |
Lived in damp, swampy forests
Perfect setting to evolve terrestrial egg laying |
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8. What was the first major group of synapsids?
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Pelycosaurs
They were 70% of all genera by Early Permian |
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9. What was the second major group of synapsids?
What are the last and only surviving group? |
Therapsids
Mammals |
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10. Who is the most famous synapsid ancestor?
What was his characteristic feature? How did he walk? |
Dimetrodon
Fin used for thermal regulation (tentative evidence for primitive warm-blooded metabolism) Walked like reptile (retained skeletal features and sprawling lizard-like walk of earlier primitive reptiles) |
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11. What was Dimetrodon's skull like?
What were his teeth and jaw like? Was he a carnivore or vegetarian? |
Tall skull (not flat like amphibian)
Varied teeth and jaw does not hinge like modern mammal's Carnivore |
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12. What is another pelycosaur who was a vegetarian?
What were his teeth and body like? |
Edaphosaurus
Teeth were short pegs (not sharp or broad) and palate was studded w/ many teeth Had large body and tiny head (typical of vegetarians) |
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13. Who took over as the chief vegetarian after Edaphosaurus?
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The Caseids (pelycosaur group)
Had large, bulky body and tiny head like many vegetarians |
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14. What was the posture of Theraspids like?
What did this allow for? What are two examples of Therapsids? |
More erect (less lizard like)
Enabled more efficient breathing and strides Titanophoneus and Moschops |
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15. What were Titanophoneous?
What were Moschops? What was special about them? |
Carnivores
Herbavores, had earliest known mating ritual behavior (head-butting contests) |
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16. What era were the pelycosaurs?
What were they again? Where they warm-blooded? |
Late Pennsylvanian/Early Permian
They were reptiles Essentially were cold-blooded (large fin...need morning sun for warmth) |
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17. What era were the first Therapsids?
Were they warm-blooded or cold-blooded? Why do we think this? |
Late Permian and Russian
(highly evolved) They started to develop warm-bloodedness Think this b/c they tended to live at higher latitudes (cooler temps and longer nights) |
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18. What drove the gradual evolution of hot blooded creatures?
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The expansion to cooler environments
They expanded to these areas b/c there was less competition |
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19. Who are the most abundant herbivors of the Late Perimian/Triassic?
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Dicynodonts
They are common Theraspids |
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20. What was Dicynodont's body like?
Why was it designed this way? |
Fat, compact bodies with short tail
Designed to slow heat loss (evidence for warm-bloodedness?) 'Fangs' for display |
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21. Who were the most mammal-like of the Theraspids?
What kind of fossil record is there for them? |
The Cynodonts
Rich fossil record of cynodonts that goes from ones with more reptilian fetures to those that are fully mammal |
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22. Which was the first mammal?
What do we say the first mammals have by definition? |
Extensive debate about which was the first since evolution predicts no clean slit
First mammal has fully mammalian jawbone (dates back to to late Triassic) |
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23. How was the lower jaws of mammal-like reptiles?
What happened over time? |
Several bones fused together (seen in reptiles)
Over time the dentary expanded |
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24. What is the jaw of a mammal like?
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One bone with large coronoid process for muscle attachment
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25. What is the oldest, well-preserved mammal?
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Megazostrodon
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26. How big were cynodonts originally?
What were they like by Early Jurassic? |
Were larges as modern dogs
Reduced to mouse to possum size Most likely all were nocturnal (large eye sockets) and warm-blooded |
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27. Why do we think they were warm-blooded?
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It's cold at night and these animals were small
To be active at night, they'd have to be warm-blooded Probably covered by fur now |
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28. Who appeared first, mammal-like reptiles (synapsids) or regular reptiles?
Who was more diverse? |
Mammal-like reptiles
Synapsids were more abundant and diverse than diapsid reptiles during Late Caroniferous and Permian |
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29. Who dominated the Permian?
What happened at the end of the Permian? |
Herbivore and carnivore roles were dominated by our synapsid ancestors
Greatest extinction event of all time: 90-95% of all marine invertebrates species were wiped out |
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30. What happened on land to many vertebrates groups during the End-Permian Extinctions?
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75% that entered last 5 Myr of Permian didn't live to see Triassic
Most of the synapsid carnivores died |
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31. With the death of synapsid carnivores what was able to occur?
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Important ecological niches for carnivores opened up
Triassic diapsid carnivores rapidly diversified **(evolutionary radiation) |
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32. Who were the main synapsid survivors?
Who were the main reptile survivors? |
Dicynodonts & Cynodonts
(synapsids) Ancestors of dinosaurs (archhosaurs) & lizards (lepidosaurs) |
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33. What happened during the Late Triassic extinctions?
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1. Wiped out veggie dicynodonts & most cynodonts
2. Mammals emerged 3. Reptile groups now radiated fastest to fill new ecological positions |
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34. Who were many of the big Triassic carnivores related to?
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Corcodiles
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35. How did dinosaurs progress through the Triassic period?
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At start of Late Triassic, they were 1-2% of fossil vertebrates
By end of Triassic, they dominated both the herbivore and carnivore role |
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36. What common pattern do we see with extinctions?
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The dominant groups (i.e. synapsids) are wiped out and one or more of the marginal groups (i.e. dinos)are spared
There is now opportunity for marginal groups to fill newly vacated ecospace |
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37. Since dinosaurs filled most major niches, what ecospace was left for small, rodent-sized mammals?
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The night
Cold-blooded creatures find it hard to operate at night |
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38. What were some characteristics or features of Mesozoic mammals?
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1. Rodent-sized
2. Large eyes and brains for size 3. Agile climbers and jumpers 4. Mostly at worms and bugs |
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39. Mammals have larger brains, why?
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Not Clear, some ideas are....
1. Being warm blooded and having high metabolism is necessary precondition for large, expansive brain 2. Sharp hearing can aid nocturnal animals and sound is a lower grade signal that needs more processing than vision 3. Life in trees can be complex so large brain can help (also diet of fruits, nuts, & insects = brain food) |
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40. Why don't mammals have good color vision?
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Lost color vision during 140 Myr of living in dark
Color vision wasn't important and wasn't maintained *Also mammals display more muted colors than do birds or fish (wasn't used for attracting mates or conveying threats) |
