2007-10-16 11:03:46 · 7 answers · asked by Katie C 1 in Science & Mathematics ➔ Zoology
There are anatomic criteria: a diaphragm dividing thorax from abdomen, 7 cervical vertebrae (except for one species of sloth that has 6), single lower jaw (mandible or dentary) bone, true hair (not bristles or setae, has to do with embryologic origin), mammary glands.
2007-10-16 12:51:54 · answer #1 · answered by Howard H 7 · 0⤊ 0⤋
NOT ALL MAMMALS GIVE LIVE BIRTH
There are three types of mammals. Placentals, marsupials, & monotremes.
All have milk glands, vertebrates, hair/fur, and are warm blooded.
Placentals carry their young in the uterus until highly developed.
Marsupials give birth much earlier and carry their young in a pouch.
Monotremes lay eggs. There are only two forms...the Platypus and Echidna. They have a cloaca like reptiles instead of seperate openings...for urination, defacation, and reproduction. They also have no nipples but do excrete milk. "Monotreme" is Greek for one-opening.
2007-10-16 12:32:37 · answer #2 · answered by Flyer 4 · 0⤊ 0⤋
MAMMALS have MAMMARY glands, with which the females produce milk to feed their young.
2007-10-16 17:50:47 · answer #3 · answered by The First Dragon 7 · 0⤊ 0⤋
They give birth to live young, they feed their young milk, and are warm-blooded.
2007-10-16 12:31:57 · answer #4 · answered by Anonymous · 0⤊ 2⤋
Warm blooded, hair or fur (some don't have much), and live birth.
2007-10-16 11:12:40 · answer #5 · answered by Knowledge 3 · 1⤊ 2⤋
live birth (live young opposite to eggs) and mammary glands I think
2007-10-16 11:07:58 · answer #6 · answered by Elke B 4 · 0⤊ 2⤋
live birth, nurse their young, have tails, fur or hair on bodies, warm-blooded,
2007-10-16 11:15:35 · answer #7 · answered by wendy_da_goodlil_witch 7 · 0⤊ 2⤋