BIRDS & MAMMALS

1. BIRDS & MAMMALS The platypus is a mosaic of mammalian, avian and reptilian traits.

2. BIRDS & MAMMALS • EX: The duck-billed platypus has a flat, fury tail that resembles a mammal, the beaver; resembles turtles & birds in that it has a cloaca, an enlarged duct through which faeces, excretions from the kidneys & gametes pass. • Female platypus has mammary glands but lays shelled eggs (Monotreme-an egg laying mammal), as turtles and birds do. • Normally found in lagoons in Australia and Tasmania.

3. BIRDS & MAMMALS PLATYPUS

4. BIRDS & MAMMALS BIRDS The ability to fly evolved in four groups, Insects, pterosaurs (extinct), birds and bats • Birds apparently evolved from reptiles during the Jurassic. 1. The oldest known bird (Archaeopteryx) resembled reptiles in limb bones and other features. (avian traits, including feathers).

5. BIRDS AND MAMMALS Archaeopteryx

6. BIRDS & MAMMALS Pterosaur

7. BIRDS & MAMMALS 2. Birds still resemble reptiles: horny beaks, scaly legs, and egg-laying. 3. There are greater than 9,000 named species of birds. The smallest known birds weigh 2.25 gm (0.08 ounces), while the largest bird, the ostrich, weighs about 330 lbs.

8. BIRDS & MAMMALS AVIAN

9. BIRDS & MAMMALS 4. The first birds evolved from reptiles during the Mesozoic era. The feathers were a highly modified reptilian scale.

10. BIRDS & MAMMALS • The body plan of birds is unique. 1. The body is covered with feathers – helpful in flight and insulation. Elastic sacs connected to the lungs help dissipate excess heat as they force warmed air out of the body.

11. BIRDS & MAMMALS 2. Construction meets the requirements of flight: low weight and high power. a. The bones are lightweight because of air cavities within them. There is a honey combed structure and an efficient mode of respiration and circulation.

12. BIRDS & MAMMALS b. Powerful muscles are attached at strategic places on the bones for maximum leverage. c. The heart is four-chambered, and the lungs are highly efficient because of their “flow- through” design.

13. BIRDS & MAMMALS AVIAN HEART

14. BIRDS & MAMMALS 3. Flight in general and migratory movements in particular are amazing feats that birds seem to accomplish with ease. FLIGHT: PG 459 gives some explanation of the mechanics. Birds that are migratory move frequently from region to region in response to environmental rhythms. Seasonal change in day length is a cue, that influences internal timing mechanisms and biological clocks. Consequently, causes physiological and behavioral changes which induce birds to make round trips to different regions in different climates.

15. BIRDS & MAMMALS The Rise of Mammals Range from: Kitti’s hog-nose bat 1.5 gm to 100 ton whales • Mammalian Traits 1. Brain capacity is increased, allowing more capacity for memory, learning, and conscious thought.

16. BIRDS & MAMMALS 2. Milk-secreting glands nourish the young. 3. Hair covers at least part of the body (whales are an exception). 4. Dentition is extensive and special- ized to meet dietary habits.

17. BIRDS & MAMMALS Other amniotes typically swallow their prey whole, but most mammals secure, cut and sometimes chew their food before swallowing it. Four distinctive types of upper and lower teeth serve this purpose – incisors, canines, premolars, and molars.

18. BIRDS & MAMMALS The amniotes are a microphylum of tetrapod vertebrates that include the Synapsida (mammals) and Reptilia (reptiles and dinosaurs, including birds).

19. BIRDS & MAMMALS B. Mammalian Origins and Radiations 1. During the Triassic, divergence from the small, hairless reptiles called synapsids gave rise to the therapsids. The early ancestors of mammals.

20. BIRDS & MAMMALS Synapsids

21. BIRDS & MAMMALS 2. By Jurassic times, mouse-sized therians with jaws and hair had evolved. This was a diverse group of plant and meat eating mammals that co-existed with the dinosaurs. They began to flourish as the dinosaurs began to vanish.

22. BIRDS & MAMMALS 3. They (therians) had major changes in the jaws, teeth and body form. Their four limbs were positioned upright under the body’s trunk. It made it easier to walk upright. Stability however had not yet arrived. The cerebellum, the region of the brain, concerned with balance and spatial positioning was only beginning to expand.

23. BIRDS & MAMMALS 4. With the demise of the dinosaurs, diverse adaptive zones opened up for monotremes (egg-laying mammals), marsupials (pouched mammals), and eutherians (placental mammals).

24. BIRDS & MAMMALS Monotremes – “Spiny Anteaters” (egg-laying)

25. BIRDS & MAMMALS Monotremes – Duck-billed Platypus

26. BIRDS & MAMMALS Marsupials - kangaroos, koalas, wallabies, wombats, bandicoots, and opossums

27. BIRDS & MAMMALS Eutherians – placental mammals

28. BIRDS & MAMMALS 5. Egg laying mammals – Platypus/Spiny Anteater Compared with the monotremes and marsupials – placental mammals had a competitive edge (i.e., higher metabolic rates, more precise regulation of body temperature, and a new way of nourishing their developing embryos).

29. BIRDS & MAMMALS Existing Mammals Evolutionary distant, geographically isolated lineages often evolved in similar ways and in similar habitats and came to resemble each other in form and function. • The lineages of mammals are examples of convergent evolution.

30. BIRDS & MAMMALS 1. The platypus and spiny anteater, which survive today in Australia, differ from other mammals in these ways: a. They are practically toothless b. Metabolic rates are lower c. They lay eggs but suckle their young.

31. BIRDS & MAMMALS 2. The marsupials found in Australia and in North America are distinc- tive in that the young are born tiny, blind, and hairless but find their way to the mother’s pouch where they are suckled and finish their development. 260 species of marsupials are native to Australia. The Tasmanian devil the largest carnivorous marsupial.

32. BIRDS & MAMMALS 3. The descendants of therians, placental mammals are found in virtually every aquatic and terrestrial environment. a. The young are nourished within the mother’s uterus by the placenta – a composite of maternal and fetal tissue. b. It is the organ of exchange of oxygen, nutrients and wastes between the maternal blood and the fetal blood.

33. BIRDS & MAMMALS We have journeyed about 570 million years, starting from tiny bag like animals to craniates, from jawless and jawed fishes having a backbone. Arriving at the end of the Devonian era we saw the emergence of tetrapods, that possessed skull bones, jaws, a back bone, lungs, walking on four limbs that evolved from fleshy lobed fins, to amniotes – reptiles and mammals to primates and then to humans.

34. BIRDS & MAMMALS Trends in Primate Evolution A. Primates include a wide variety of animals: 1. Prosimians (literally: before apes) are small tree dwellers (arboreal) that use their large eyes to advant- age during night hunting.

35. BIRDS & MAMMALS Prosimians – Mongoose Lemur

36. BIRDS & MAMMALS 2. Tarsiers (tarsioids) are small primates with features inter- mediate between prosimians and anthropoids. 3. Anthropoids include monkeys, apes and humans. Hominoids include apes and humans, where Hominid refers to human lineages only.

37. BIRDS & MAMMALS Tarsiers – Spectral Tarsier (S.E. Asia)

38. BIRDS & MAMMALS Anatomically and biochemically apes are closer to humans than monkeys, but chimps are most closely related. GA Tech conducted a genetic analysis of approximately 63 million base pairs of DNA – 99.4%

39. BIRDS & MAMMALS Ape and Man – 98 -99% genetic similarity

40. BIRDS & MAMMALS • Primate evolution displays key trends: Five features set primates apart from other mammals: 1. Less reliance on sense of smell and more on enhanced daytime vision: a. Early primates had an eye on each side of the head.

41. BIRDS & MAMMALS b. Later ones had forward-directed eyes resulting in better depth perception and increased ability to discern shape, movement in three dimensions, color, and light intensity.

42. BIRDS & MAMMALS • Apes - Forward-facing eyes for binocular vision (allowing depth perception) reliance on vision: reduced noses, (smaller, flattened), color vision

43. BIRDS & MAMMALS 2. Skeletal modification promoted Bipedalism – upright walking a. Bipedalism is possible because of of skeletal reorganization in primates ancestral to humans. This freed the bonds for novel tasks.

44. BIRDS & MAMMALS b. A monkey skeleton is suitable for a life of climbing, leaping, and running along tree branches with palms down. c. An ape skeleton is suitable for climbing and using the arms for carrying some body weight; the shoulder blades allow the arms to swivel overhead.

45. BIRDS & MAMMALS d. Compared to the ape, humans have a shorter, S-shaped and somewhat flexible backbone. Skeletal change favoring bipedalism was a key innovation that evolved in ancestors of hominids.

46. BIRDS & MAMMALS 3. Bone and muscle changed led to refinements in hand movements. 4. Power grip and precision grip: Early mammals spread their toes apart to support the body. Primates still spread fingers and toes. Tree-dwelling primates had modifications to handbones which allowed them to wrap their fingers around object. Prehensile Movement

47. BIRDS & MAMMALS a. Opposable thumb and fingers allowed more refined use of the hand. b. The precision and power grip movements of the human hand allowed for toolmaking.

48. BIRDS & MAMMALS 4. Teeth became less specialized. Jaws and teeth in early mammals suitable for eating insects and fruits and leaves later evolved long\ canines, in monkeys and apes and humans to rip flesh. 5. changes in the brain became inter- locked with changes in behavior and the evolution of culture.

49. BIRDS & MAMMALS 6. Brain, behavior, and culture: is the sum of behavior patterns of a social group, passed on to generations through learning and symbolic behavior. a. Brain expansion and elaboration produced a brain of increased mass complexity, especially for thought, language, and conscious movements.

50. BIRDS & MAMMALS b. Human brain development promo- tion of new neural connections, led to patterns of human behavior known collectively as culture. Maternal core became intense and offspring started to acquire longer periods of dependency and learning.