Chap.34 (2) Flashcards
Amniotes
are a group of tetrapods whose living members are the reptiles, including birds, and mammals
Derived Characters of Amniotes (5)
- Amniotes are named for the major derived character of the clade, the amniotic egg, which contains membranes that protect the embryo
- The extraembryonic membranes are the amnion, chorion, yolk sac, and allantois
- The amnion encloses the embryo in a fluid-filled sac that reduces the dependence of tetrapods on an aqueous environment for reproduction The amniotic egg was a key adaptation to life on land
- The amniotic eggs of most reptiles and some mammals have a shell
- Amniotes have other terrestrial adaptations, such as relatively impermeable skin and the ability to use the rib cage to ventilate the lungs
The reptile clade includes (6)
the tuataras, lizards, snakes, turtles,
crocodilians, birds, and some extinct groups
Reptiles characteristics (5)
- Reptiles have scales that create a waterproof barrier
- Most reptiles lay shelled eggs on land
- Fertilization occurs internally, before the eggshell is secreted
- Most reptiles are ectothermic
- some are endothermic
Birds are endothermic
capable of maintaining body temperature through metabolism
ectothermic
absorb external heat as the main
source of body heat
Derived Characters of Birds (5)
- Weight-saving adaptations for flight
- wings with keratin feathers
- elaborate courtship rituals
- Fertilization is internal
- Eggs and the developing embryos inside must be kept warm through brooding by one or both parents
bird Weight-saving adaptations (4)
lack of a urinary bladder, females with only one ovary, small gonads, and loss of teeth
Flight requires (3)
a great expenditure of energy, acute vision, and fine muscle control
The Origin of Birds (3)
- Birds probably descended from small theropods, a group of carnivorous dinosaurs
- Feathers evolved long before powered flight
- Early feathers might have evolved for insulation, camouflage, or courtship display
Living birds belong to
the clade Neornithes
* Several groups of birds include one or more flightless species
* The ratites are all flightless birds
ratites
are all flightless birds
Mammals are
amniotes that have hair and produce milk
Mammals are class….
mammalia
Mammals derived characters (8)
- Mammary glands, which produce milk
- Hair and a fat layer under the skin for insulation
- Kidneys, which conserve water from wastes
- Endothermy and a high metabolic rate
- Efficient respiratory and circulatory systems
- A large brain-to-body-size ratio
- Extensive parental care
- Differentiated teeth
By the early Cretaceous (140 million years ago), the three living lineages
of mammals emerged:
monotremes, marsupials, and eutherians
Monotremes are
a small group of egg-laying mammals consisting of
echidnas and the platypus
* Females lack nipples and secrete milk from glands on their bellies; the
baby sucks milk from the mother’s fur
Marsupials (4)
- include opossums, kangaroos, and koalas
- The embryo develops within the mother’s uterus and is nourished by the placenta
- A marsupial is born very early in its development
- It completes its embryonic development while nursing in a maternal pouch called a marsupium (in the front or rear of mother)
eutherians (2)
- Compared with marsupials, eutherians have a more complex placenta
- Young eutherians complete their embryonic development within a uterus, joined to the mother by the placenta
Derived Characters of Primates (4)
- Most primates have hands and feet adapted for grasping, and flat nails instead of
claws - A large brain and short jaws
- Forward-looking eyes close together on the face, providing depth perception
- A fully opposable thumb (in monkeys and apes)
The mammalian order Primates includes
- lemurs, tarsiers, monkeys, and apes
- Humans are members of the ape group
three main groups of living primates
- Lemurs, lorises, and bush babies
- Tarsiers
- Anthropoids (monkeys and apes)
Apes
includes gibbons, orangutans, gorillas, chimpanzees, bonobos, and humans
* Apes diverged from Old World monkeys about 25–30 million years ago
monkeys (2)
- evolved in the Old World (Africa and Asia)
- In the New World (South America), monkeys first appeared roughly 25
million years ago
Humans are (2)
- mammals that have a large brain and bipedal locomotion
- The species Homo sapiens is about 200,000 years old, which is very
young, considering that life has existed on Earth for at least 3.5 billion
years
Derived Characters of Humans (5)
- Upright posture and bipedal locomotion
- Larger brains capable of language, symbolic thought, artistic expression, and the manufacture and use of complex tools
- Reduced jawbones and jaw muscles
- Shorter digestive tract
- The human and chimpanzee genomes are 99% identical
