鸟类与哺乳动物【英文】

BIRDS & MAMMALS
AVIAN
BIRDS & MAMMALS
4. The first birds evolved from reptiles during the Mesozoic era. The feathers were a highly modified reptilian scale.
BIRDS & MAMMALS
AVIAN HEART
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.
BIRDS & MAMMALS
B.
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.
Tasmania.
BIRDS & MAMMALS
PLATYPUS
BIRDS & MAMMALS
BIRDS The ability to fly evolved in four groups, Insects, pterosaurs (extinct), birds and bats
A.
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).
BIRDS AND MAMMALS
Archaeopteryx
BIRDS & MAMMALS
Pterosaur
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.
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 “flowthrough” design.
BIRDS & MAMMALS
The platypus is a mosaic of mammalian, avian and reptilian traits.
BIRDS & MAMMALS
EX: The duck-billed platypus has a flat, fury tail
that resembles a mammal, the beaver; resห้องสมุดไป่ตู้mbles 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
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.