mammals Flashcards
monomermes
egg laying; e.g. platypus
marsupial
pouched e.g. kangaroos
placentals
e.g. gorilla
mammalia development from synamsid
post orbital opening merges with orbit
synapsids are
mammal like reptiles
characteristics of mammals
mammary glands hair endothermic homeothermic diapgram, 4 chambered heart, red blood cells without nuclei live birth (minus monotrmes) heterodton teeth disphydonty determinate growth secondary palate single jaw bone 3 middle ear bones repsirotory turbinates large brains double articulations upright posture
mammal characteristics derived from fossilr ecord
heterodton teeth disphydonty determinate growth secondary palate single jaw bone 3 middle ear bones repsirotory turbinates large brains double articulations upright posture
heterodont teeth
different types of feeth
dyphydonty
two sets of teeth
secondary palate
seperate breating and feeding passages
pelycosaurs
first synapsids mammal ancestors in fossil record 306 mya had sprawling gait quadrate articular jaw joint nasal passages open into mouth
synasid evolution
pelycosaurs therapsids cynadonts mammal like reptiles mammals
what traits evolved into mammals
- posture (sprawling to upright)
- respiration (formation of secondary palate)
- post dentary jaw bones to middle ear elements
therapsids
275/200 mya
more upright stance
quadrate articular jaw joint but dentary expanding up and back
some taxa with partial or complete secondary palata
cynodonts
255-170 mya
more upright posture
still quadrate articular jaw joint but post dentary jaw reduced
partial or complete secondary palate in all taxa
only two sets of complex teeht
earliest mammals
210 mya; mainly small and insectivorous and nocturnal
upright gait
complete secondary palate
at first; both quadrate articular and squamosal jaw joint
e.g. harocosium (mous like)
what did the articular and the quadrate evelop into
malleus and incus
cenzoic
age of mammals
meozoic
reptile age
palezoic
synapsid age
jurassic
mammalia evolution of shrews
creatacous
large animals start evoling
age of mammals
after k/pg extinction 65 mya;
mammals that made it through diverisifed quickly in terms of body size especially and specialization
what are mammal clades based on
reproductive strategies
placentals
long gestataion period, 5000+ species (95% of mammals)
diverse in numbers and types and biographic division
e.g. pangolins, armadillos, humans
monotremata
egg laying earlist fossils from creatcous teeth in beke mammary glands without teets no placenta
e.g. platapus echina duckbill
marsupials
pouched animals
early createacous
south america and australia mainly
anticlockwize radiation around world
e.g. koala kangaroos oppposums
4 major clades of placentals
- laurosiatheria
- eurochontoglieres
- xenartha
- afrotheria
laurosiatheria
shrews bats carnivores
eurochontoglieres
rabbits rodents primates
xenartha
anteaters sloths south america
afrotheria
elephants manatee africa
atriodactyl
morphology of limb; nails to toes to feets; prupose to elongate limbs to move faster
e.g. whales closely repalted to hippos (ceetartiodatylus)
angulates
tapirs, horses and rhinos, and whales
- walk on toes
whatl developments
pakicetus to choohacetus to basilosaurus to modern whale
pakicetus
50 mya wolf like mammals with enlogated skull and simplified teeth
roohacetus
46 mya more specialized for water
webbed feed and elongated digits
basilosaurs
37 mya
very whale like and elongated
hippos to whales
transitional fossils show that teeth and balen devloved from hippo to modern whale ancesotrs
