Topic 33 Mammals Flashcards
Mammals
4-legged terrestrial animals, amniotes that have hair and produce milk
shared derived traits of mammals
mammary glands (feed milk to offspring), hair (cylindrical keratin fibers), three middle ear bones (higher detection of sounds), endothermy supports a high metabolic rate (4-chambered heart and hair), dentary squamosal jaw joint, larger brain, kidneys
the function of differentiated teeth
more complex and differentiated, greater diversity of teeth morphology, greater diversity of teeth, teeth occlude more closely and allow food to be ground up more finely, two sets of teeth in lifespan
the function of kindey
efficiently conserve water while filtering waste metabolites from blood
Other characteristics of mammals
the vertical placement of limbs beneath the body, diaphragm contributes to lunch ventilation, copulate intromittent organ for internal fertilization
mammals evolved from
synapsids
The evolution of mammals showed a progressive enlargement of the _________ in the jaw of therapsids
dentary bone
secondary palate
bone partition between nasal and oral cavities and permits simultaneous chewing and breathing
By the early Cretaceous, the three
extant lineages of mammals that had
descended from the synapsid
clade
Monotremes, Marsupials, and Eutherians
Following __________, mammals
diversified into large- and small-bodied herbivores, carnivores, and
insectivores (adaptive radiation)
Cretaceous mass extinction (65 mya)
three clades of mammals
monotremata, mersupiala, and eutheria
Monotremes
a small group of egg-laying mammals consisting of echidnas and the platypus, lay eggs and provide milk to young (no nipples), have cloacas, lack teeth
cloacas
Single opening for digestive, urinary, and reproductive systems
Shared, derived traits of Marsupials + Eutherians clade
Viviparous development of the embryo inside the body, Placenta provides initial nourishment to embryo, Post-birth nursing on milk from nipples
Marsupials
opossums, kangaroos, and koalas. − Marsupials born as partially developed embryos. sexes of marsupials possess a cloaca
Why are most marsupials restricted to Australia
In the absence of eutherian mammals, Australian marsupials evolved to fill specific ecological niches
Eutherians
non-marsupial mammals, have a more complex placenta that nourishes placenta until well developed, Post-birth the young suckle milk from nipples, no cloaca
_____ underwent extensive adaptive radiation
Eutherians
Clade Afrotheria
underwent diversification in Africa when it was separate from the other continents
Clade Xenarthra
eutherians are typically South American forms and lack teeth
Clade Euarchontoglires
includes rodents, primates, and related groups
Clade Laurasiatheria
typically Eurasian and North American forms including Terrestrial hooved animals, marine animals, and bats
Colugos
(order Dermoptera) are closely related to primates
primates
- include lemurs, tarsiers, humans, monkeys, and apes
- arose from ancestors that lived in the trees of tropical forests
- most arboreal (live in trees)
- all species possess adaptations for climbing trees
SHared derived traits of primates
Hands and feet adapted for grasping (thumb widely separated for grasping and flat nails), large brain and short jaw, forward-looking eyes (depth perception), complex social behavior and parental care
Three main groups of extant primates
- Lemurs, lorises, and bush babies.
- Tarsiers.
- Anthropoids
hominoids
non-monkey anthropoids, lack tails, relatively large brains, include lesser apes and great apes
hominoids versus hominids
apes versus great apes
Hominids
great apes, Seven species of non-human great apes, critically endangered due to habitat loss and illegal hunting
