BIOL 1442 Ch 29 Mammals

Mammals are vertebrates that possess

hair and mammary glands

Modern mammals belong to 3 clades:

monotremes, marsupials, and eutherians

hair is composed of the protein

keratin

The functions of hair include

insulation, vibrissae (sensory mechanisms), protective coloration, and social signaling

The integument of animals include

sebaceous glands, eccrine glands, apocrine glands, and mammary glands

Mammary glands most likely evolved from

sebaceous or eccrine glands

The jaw of mammals, unlike other vertebrates, only consist of one bone, the

dentary

In mammals, the quadrate and articular bones moved into the

middle ear

The adductor muscles that close the jaw include

temporalis and masseter

Most mammals have ( ) teeth

heterodont

Most mammals are ( ), which means they have two sets of teeth

diphyodonts

Mammals posses a ( ) heart

four-chambered heart

Mammalian erythrocytes are not

nucleated

The kidneys of mammals have

a portion of the nephron loop called the loop of Henle, which allows mammals to produce urine with a higher concentration of solutes

Mammals lack a ( ) port system

renal

The skulls of mammals have

two occipital condyles

Turbinate bones are located in the nasal cavity of mammals and help

warm and moisten air as it is inhaled

The pelvic bone in mammals is

fused

Mammals typically have ( ) cervical vertebrae

7

Mammalian brains have a

highly convoluted and folded cerebral cortex and two optic lobes that are divided into two parts

Eutherian mammals have a ( ), which link the cerebral hemispheres together

corpus callosum

Mammals are synapsids, meaning

the have a single, ancestrally fused, postorbital opening in the skull

A key characteristic of all synapsids is

endothermy

In the appendicular skeleton, the shoulder girdle of mammals is modified in that

it does not possess a procoracoid bone or an interclavicle, and the scapula is the dominant bone

Monotremes include

platypus and four species of echidnas

Ornithorhynchidae include

the leathery-beaked platypus

Monotremes retain their eggs

through about 2/3rds of the developmental period and then lay them in the nest

In monotremes, babies hatch in a

fetal state and complete development in the nest

Marsupials are found in

Australia and the Americas

Most marsupials possess a pouch in which

the very premature young reside

Eutherians all possess a

chorioallantoic placenta

Eutherian mammals are divided into two clades:

Atlantogenata and Boreoeutheria

Atlantogenata include

Afrotheria (elephants, hyraxes, and manatees) and the Xenarthra (anteaters, armadillos, and sloths)

The Boreoeutheria contain two large groups:

Euarchontoglires and Laurasiatheria

Orders in the Euarchontoglires are

scandentia (tree shrews), Rodentia (rats, mice, squirrels, porcupines), Lagomorpha (rabbits, hares), and Primates (including humans)

Laurasiatherian orders include

Perissodactyla (horses and rhinos), Cetartiodactyla (cows, giraffes, pigs, hippos, and whales), Carnivora (cats, dogs, bears), and chiroptera (bats, flying foxes)