Chapter 22 - Synapsida & Origin of Mammals

three

How many lineages of synapsids persist to the present?

cenezoic

this is era is known as the age of mammals

Monotremes, Metatherians, and Eutherians

What are the three extant lineages of synapsids?

masseter muscle

closes the jaw with a corresponding increase in temporal fenestra,

zygomatic arch

cheek bone

malleus

part of the ear called the hammer

incus

part of the ear called the anvil

stapes

part of the ear called the stirrup

pinna

external ear

flow of sound

tympanum to the malleus, incus, stapes, and then finally to the cochlea

cretaceouss

this is period is also known as the “age of mammals”

fovea centralis

where the cones are concentrated in the eye

heterodont teeth

teeth that have different forms, which carry out different tasks

diophyodonty

two sets of teeth

incisors, canines, and premolars

What are the types of teeth that are involved in the first set of teeth?

precise occlusion

interlocking arrangement of upper and lower teeth

keratin

forms many appendages of mammalian skin (claws, nails, hooves, quills)

apocrine glands

“sweat” glands, also form anal glands in skunks; chemical communication; milk-producing mammary

cells; armpits & groin

eccrine glands

entire body (primates) or surface of hands & feet; improve adhesion or tactile perception; nervous = sweaty palms = for escaping

sebaceous glands

oily secretions of sebum for lubrication or scent marking (lanolin in sheep, our oily hair, most anal glands)

holocrine gland

sebaceous glands of the skin = only true example

lactation

females of all mammals feed their young on milk (nursing) produced by mammary glands

monotremes

this group has milk that seeps from pores in the skin and the young suck the milk from the mother’s fur

vibrissae

special hairs that have a sensory function

3rd phalanx

the terminal bone of the toe

antlers

deer family; extension of the animal's skull, generally only males; true bone and are a single structure; shed and regrown each year

horns

Bovine; two-part structures; interior of bone (also an extension of the skull) is covered by an exterior sheath of keratin grown by specialized hair follicles, as are your fingernails; never shed (there is an exception) and continue to grow throughout the animals life

adipose tissue

brown fat, that is specially adapted to generate heat

brown fat

breaks down lipids and glucose to produce heat and can generate as much as 10X as much heat as an equivalent mass of muscle

torpor

allow body temp to fall during short periods of inactivity (i.e. night, cold periods

hibernation

deep torpor over an extended periods of time; comatose condition; generally larger mammals

thermogenic opportunity model

basal mammals were nocturnal, so selection for increased body temperature at night to maintain metabolism to find food, etc

aerobic scope model

higher metabolic rates can only be achieved with higher resting metabolic rates and higher internal heat production when at rest as well as when it is active, thus increased activity and metabolic rates increase survival and lead to endothermy.

parental care model

warmer body temperatures allow for faster embryonic development rate, increase viability of embroyos, thus increased reproductive success leads to endothermy

tidal ventilation

what type of respiration do mammals do?

True

True or False: Mammals have exceptionally large brains and, as a group, most depend more heavily on olfaction and hearing rather than vision (except primates who primarily depend on vision)

visual sensitivity

being able to form images in low light

visual acuity

being able to form detailed images

rod cells

these cells are very sensitive to low light, but relatively poor at acute vision and do not produce color vision

True

True or False: Most mammals have dichromatic vision (two types of cones)

trichromatic vision

provides a big advantage for animals, because it (most likely) enables them to spot ripe fruit and identify the newest and most tender leaves