1. Amniotes through Eutherians Chapter 34.6-34.8
By: Francisco Berrios and Siria Arzuaga

2. Amniotes
A group of tetrapods that trace back to the same common ancestor.
The only animals that have amniotic eggs.
pods that retain water for vertebrates to complete their life cycles on land.
Developed the ability to use the ribcage to ventilate lungs
Early amniotes were herbivorous.
Examples: Reptiles, birds, and mammals

3. Phylogeny of amniotes

4. The Amniotic Egg
Exists inside mother’s belly or in a shell outside the mother.
Extraembryonic membranes provide protection and nourishment
4 layers: Allantois, chorion, amnion, yolk sac
Develop through tissue layers
Has a shell

5. Amniotic Egg

6. Similarities and Differences
Some Tetrapod's evolved and became 2 footed.
Reptiles are ectotherms (cold blooded), while mammals and birds are endotherms (warm blooded)
– Ectotherms have body temperatures determined by their environment.
– Endotherms use metabolic heat to keep tissues warm.

7. Circulatory systems 4 chambered heart 3 chambered heart
Provides high metabolism rate
Mammals and birds
3 chambered heart
Reptiles

8. Reptiles Traced back to the diapsids and anapsids.
Parareptiles- dermal plates
Proposed linkage with turtles
All reptiles have:
3 chambered hearts
ectothermic
Covered with hard dry scales
prevent dehydration
amniotic eggs
Rely on lungs for gas exchange

9. Reptile Anatomy

10. Diapsids Pair of holes behind eye socket Lepidosaurs Archosaurs
Lizards, snakes, tuatara
Marine reptiles (plesiosaurs)
Archosaurs
Crocodilians, dinosaurs
Pterosaurs – first tetrapods to fly
Presence of muscles, blood vessels, and nerves in the wing membranes

11. 3 main groups of reptiles
Turtles (Archosaurs)
Over 200 species
May live on sea or on land
Huge shells to protect their bodies
Crocodilians (Archosaurs)
23 species
Semi-aquatic predators
Huge teeth to attack big prey
Lizards and Snakes (Lepidosaurs)
Thousands of species
Flexible skulls
shed skin frequently
Sea and land habitats

12. Last Living Dinosaurs There are 8,600 species of birds in the world.
Similarities:
Hollow bones
Feathers
V-shaped wishbone
only 3 fingers
Differences:
Beak shape
Feet/talons
Feather structure

13. Why Can Birds Fly? Unique features Wings to produce flight
Strong flight muscles to move the wings
Active metabolism that provides energy to the muscles.
Hollow bone structure to minimize weight.
Lack a urinary bladder
A wing is a remodeled version of the tetrapod forelimb.

14. Exceptions Ratites (non-flying) Flightless because…
Ex: emu, ostrich, rhea, kiwi
Flightless because…
Sternal keel (bone) is absent, and the pectoral muscles (wing control) are not greatly enlarged.

15. Mammals (Synapsids) 3 types of mammals:
Active, large-brained, endotherms with complex social, feeding, and reproductive behaviors.
5 characteristics:
Hair to retain heat
Mammary glands
Milk production
Middle ears
Temporal fenestra
Single jaw bone for faster and stronger chewing
3 types of mammals:
Monotremes, Marsupials, Eutherians

16. Monotremes (egg-laying)
Found in Australia and New Guinea
Very unique:
Offspring fully develop within egg.
Lack nipples.
After hatching, the baby sucks the milk from the mother’s fur.
Echidna and platypus

17. Marsupials (pouch) Opossums, kangaroos, and koalas
Young born very early in development
Continue development in the pouch of the mother, called a marsupium.
Produce milk and have nipples, higher metabolic rates
Placenta
nutrients diffuse into the embryo from the mothers blood when inside the mother

18. Eutherians (placental)
Same characteristics of a marsupial but consists of a more complex placenta
Longer pregnancy and stays inside the mother’s uterus.
Primates are the most common.
Include:lemurs, monkeys, apes (humans), and tarsiers.

19. Phylogeny of Ancestral Mammal

20. Primates Earliest primates lived in trees
Had a thumb that was able to grasp
Large brain, short jaw, flat face, forward looking eyes
No claws but flat nails
Omnivorous
The 3 main groups of living primates
lemurs, lorises, pottos; the tarsiers; and the anthropoids.
Anthropoids include hominoids and monkeys
opposable thumbs.
more diversity

21. Cerebral Cortex
Thought processes, consciousness perception, language, memory

22. Phylogeny of the Ancestral Primate

23. Apes Hominoids branch off of anthropoids.
Include humans, gorillas, orangutans, and chimpanzees
Have bigger brains compared to their size and their behavior is more flexible.

24. Sources: http://www.bio.sdsu.edu/faculty/archibald/Archibald05ELS.pdf