Ch 34 Chordates - Mammals Flashcards
Synapsids were the first what?
Amniote group to diversify widely into terrestrial habitates
What were the dominant amniotes during the Permian period?
Synapsids
Anapsid
No temporal openings in the skull for muscle attachment
Diapsids
Two temporal openings in the skull for muscle attachment
Are reptiles anapsids, diapsids, or synapsids?
Diapsids
Were the earliest amniotes anapsides, diapsids, or synapsids?
Anapsids
Synapsids
One temporal opening in the skull for muscle attachment
Are mammals anapsids, diapsids, or synapsids?
Synapsids
Shared derived characteristic of mammals
Hair
How do mammals nourish their young?
Milk produced by mammary glands
Are mammals endothermic or exothermic?
Endothermic
What modification in mammals transmits sound in the middle ear?
Three bones of the skull
Mammals have what kind of heart?
Four-chambered
Mammals have what kind of metabolic rate?
High
Hairs
Composed of dead, keratin packed cells of the epidermal skin layer
How does hair grow?
By proliferation of cells at its base in the hair follicle
Molt
The shedding of all hairs at once
Benefits of hair
1) Buoyancy
2) Concealment
3) Insulation
4) Protection
5) Sensing
6) Signaling
7) Waterproofing
Guardhairs
Long, coarse hairs that overlie underhair
Underhairs
Dense, soft, insulating hair
Horns
Bones extension of the skull
What covers horns?
A sheath of keratin
Antlers
Solid bone
What covers antlers?
Velvet
Velvet
A highly vascular, soft skin
When are antlers covered by velvet?
During their growth phase
Are antlers shed?
Yes, annually
Are horns shed?
No
Sweat glands
Produce a watery fluid that cools the skin surface
Sebaceous glands
Consist of cells that rupture to release sebum that conditions skin and hair
Mammary glands
Produce nourishing milk
Scent glands
Have various function in chemical signaling including territoriality and mating
Heterodont
Teeth differentiated to perform specialized functions
Advances in mammalian locomotion
1) Limbs positioned under, rather than to the sides, of the body
2) Muscular diaphragm for inhalation, loss of abdominal ribs
3) Enlarged cerebrum for greater coordination
Three groups of mammals
1) Marsupials
2) Monotremes
3) Eutherians
Monotremes
Mammals that reproduce by laying eggs
Female monotremes possess what?
An abdominal pouch within which offspring complete their development after hatching
How are monotreme young fed?
From milk secreted by the mother’s skin within the pouch
Marsupials
Pouched, viviparous mammals
When are marsupial young born?
At the embryonic stage of development
Where do marsupial young complete development?
In the abdominal pouch
How are marsupial young fed?
From the mother’s nipples
Are most mammals, marsupials, monotremes, or eutherians?
Eutherians
How are eutherian young nourished during embryonic development?
Via a placenta
Placenta
A vascular connection within the uterus between the mother and embryo
Gestation
The period of development in the uters
How long can gestation last?
One to twenty-two months
What is seen between marsupials and eutherians?
Evolutionary convergence
Digitigrade
Mammals that walk on their digits (toes)
Are ungulates considered digitigrades?
Yes
Perissodactyla
The odd-toed ungulates
Ungulates
Hooved mammals
Characteristics that distinguish humans from other apes
1) Upright posture and bipedalism
2) Larger brains
3) Reduced jawbones and jaw muscles
4) Shorter digestive tract
The larger brains of humans are capable of what?
1) Language
2) Symbolic thought
3) Artistic expression
4) Manufacture and use of complex tools
Are living primates a part of the human ancestral lineage?
NO
