50 terms

mammals

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diversity
29 orders: 1 order of monotremes (Prototheria), 7 orders of marsupials (Methatheria), and 21 orders of placentals (Eutheria)
synapsids
Mammals evolved from --- that have a pair of temporal
openings in the skull
therapsids
One of the early carnivorous synapsids gave rise to the---. were the only synapsid group to survive beyond the
Paleozoic. first to have efficient erect gait, upright limbs under body. high metabolic rate, specialized jaw, skeletal changes for greater agility. heterodont teeth
secondary bony palate
A --- separates the food chamber from the respiratory passage in skull. Permits breathing while holding prey or chewing food. Important later to mammal evolution by allowing young to breathe while suckling
Turbinate bones
these bones in the nasal cavity reduces water loss.
On inspiration
air is heated and humidified because water and heat moves from the turbinate surfaces to the air
on expiration
the warm, moist air passes over the cooled turbinate condensing the water lost during inspiration.
Malleus, incus, and stapes
Transformation of three middle ear bones. Originated from articular and quadrate bones that previously served as jaw joint but became reduced in size to better transmit sound vibrations
dermis and epidermis
Mammal's skin generally thicker than in other vertebrates. Composed of A and B. A is thicker than B
keratin
In regions subject to much contact and use, outer layers of epidermis become thicker and filled with a type of fibrous protein called
Hair follicle
is an epidermal structure, but lies in dermis of skin. A hair grows continuously by rapid proliferation of cells in the ---
undercoat and guard coat
Mammals have two kinds of hair forming their pelage (fur coat)
Vibrissae
"whiskers" are sensory hairs. Provide a tactile sense for nocturnal mammals
quills
Porcupine, hedgehog, and echidna have these that are barbed and break off easily
true horns
Occur in ruminants such as sheep and cattle. Hollow sheaths of keratinized epidermis. Surround a core of bone arising from skull. Normally not shed and are usually not branched, but may be curved. Grow continuously and occur in both sexes. May be longer in males
antlers
Occur in the deer family. Are branched and composed of solid bone when mature. Develop beneath an annual spring covering of highly vascular soft skin or velvet. Velvet removed by rubbing shed after breeding season
Rhino horn
Hairlike keratinized filaments arise from dermal papillae and are cemented together. Not attached to the skull
heterodont teeth
mammals have this kind of teeth Differentiation of teeth for cutting, seizing, gnawing
diphyodonts:
Mammals are --- their teeth replaced only once. Generally, incisors, canines, and premolars are deciduous. Molars are a single permanent set
polyphyodont
Most vertebrates are --- meaning that their teeth are continually replaced.
Omnivores
feed on both plant and animal tissues
Insectivores
feed primarily on arthropods
herbivores
browsers and grazers, gnawers. reduced or absent canning. eat plant tissue
carnivores
feed mostly on herbivores, claws and canning specialized for killing prey. molar and premolars into carnassial teeth
Incisors
Sharp edges for snipping or biting
canines
Specialized for piercing
Premolars
Compressed crowns with one or two cusps for shearing , slicing, crushing and grinding
Molars:
Larger bodies and variable cusp arrangements for shearing , slicing, crushing and grinding
coprophagy
Rabbits and other non ruminant herbivores eat their fecal pellets
digestive tract
Herbivores, which cannot produce cellulases, use anaerobic fermentation chambers so microorganisms can metabolize cellulose. In non-ruminants, a side pocket or cecum may also serve as a fermentation chamber and absorptive area. The cecum is posterior to the small intestine where most of the absorption occurs so much of the nutrients liberated by fermentation are lost.
midgut fermenter
Ruminants use their stomach for fermentation and are the most specialized fermenters. They have a stomach with four chambers
rumen and reticulum
Plants are moistened and fermented in the
abomasum
Further digestion occurs in the omasum and microbes are digested in the
Echolocation,
along with flight, allows bats to navigate and eat insects in total darkness
heat or estrus
Female usually restrict mating to a fertile period commonly called
monotremes
the duck-billed platypus, lay eggs with one breeding season per year. embryos develop after 10-12 days in uterus, then think leathery shell is secreted around the egg before it is layer. incubated for 12 days, use mom milk
marsupials
ouched, viviparous mammals. have primitive choriovitelline or yolk sac placenta. gestation is brief and marsupials give birth to tiny young that are still embryos
Eutherians
placental mammals, embryo nourished in uterus, yolk sac placenta replaced by chorioallantoic placenta. gestation is longer,
primitive order
humans belong to this order, primates have grasping fingers, flat fingernails and forward pointing eyes
anthropoids
three major groups of---, new world monkeys, old world monkeys, and apes
family hominidae
humans, orangutangs, gorillas and chimps all placed in single family
Sahelanthropus tchadensis
hominins, 6.5 million years ago, most ancient hominid yet discovered
Ardipithecus ramidus
dates to 4.4 million years ago, both ape and humanlike traits
Australopithecus afarensis
short bipedal hominid, brain size slightly larger that that of a chimp, numerous fossils have been discovered
Hominins
The first species of Homo and the definition of the genus are both controversial. TheApesmorecloselyrelatedto humans than to chimps are
Homo habilis
had a larger brain than australopithecines. used stone tools
Homo erectus
low but distinct forehead, strong brow ridges. intermediate between the brain capacity of H.habilis and modern humans. we diverged from this about 8000,000 years ago
out of africa theory
H.erectus gave rise to H.neanderthalensis in Europe/Asia. H. erectus gave rise to H. sapiens in Africa around 200 000 years ago. H.sapiens dispersed out of Africa around 100000 years ago. About 30,000 years ago, they replaced H. neanderthalensis
homo sapiens
we are unique among animals because we have, a non-genetic cultural evolution that provides constant feedback between our past and future experience. Symbolic languages, Conceptual thought, Knowledge of history, and The ability to manipulate our environment
Ruminants
antelopes, deer, cattle, sheep, goats, camels, buffalo, llamas