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mammalogy > Basal Eutheria > Flashcards

Basal Eutheria Flashcards

1
Q

How did explosion of plant diversity contribute to increasing presence of early eutherians?

A
  • angeosperm starts to appear (flowering plants)
  • produces pollen = explosion of insects
  • early mammals are insectivores (lots of food for them to eat in Cretaceous = diversification)
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2
Q

What kind of molariform teeth are characteristic of basal eutherians?

A
  • 3 tribosphenic molars with high, sharp cusps
  • last PM clearly distinguishable from first M
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3
Q
A

Duplex uterus:

  • 2 uteri, each with cervix opening into vagina
  • rabbits, rodents, hares, aardvarks, hyrax
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4
Q
A

Bicornuate uterus:

  • uterine horns Y-shaped but fused forming a chamber opening into the vagina through a single cervix
  • whales, carnivores
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5
Q
A

Bipartite uterus:

  • horns of uterus are separate but enter the vagina by a single cervix
  • most widespread
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6
Q
A

Simplex uterus:

  • no separation between the uterine horns, opens into the vagina through one cervix
  • some bats, higher primates
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7
Q

baculum

A
  • bony structure in penis
  • some mammals have it (very reduced in great apes, carnivores usually have one)
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8
Q

Choreoallantoic placenta

A
  • characteristic of all eutherian mammals
  • develops from embryonic membranes
  • long-lived and vascular (vs. metatherians)
  • villi provide increased surface area for exchange of nutrients, gases, and waste
  • nutrients passed along walls and capillaries but no actual blood exchanged
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9
Q

Types of chorioallantoic placenta

A

-differ in distribution of villi, efficiency of nutrient/gas/waste exchange

  1. Diffuse: villi scattered evenly throughout uterus
  2. Cotyledonary: evenly spaced patches of villi
  3. Zonary: continuous band of villi around the placenta
  4. Discoid: villi organized into 1-2 disc shapes
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10
Q

Epitheliochorial chorioallantoic placenta

A
  • villi rest in pockets of endometrium
  • least efficient type of chorioallantoic placenta
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11
Q

Endotheliochorial chorioallantoic placenta

A
  • maternal capillary in direct contact with chorion of fetus
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12
Q

Hemochorial chorioallantoic placenta

A
  • no maternal epithelium
  • no distinct maternal capillaries
  • mother’s blood is bathing villi directly
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13
Q

Endothelioendothelial chorioallantoic placenta

A
  • no connective tissue in between mother and embryo
  • second most effective chorioallantoic placenta
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14
Q

Hemoendothelial chorioallantoic placenta

A
  • fetal capillaries (cells) bathed in maternal blood
  • most direct/effective chorioallantoic placenta
  • some rodents, rabbits, hares
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15
Q

Golden moles

A

s.C. Theria

I.C. Eutheria

S.O. Afrotheria

O. Afrosoricida

  • resemble marsupial moles
  • no pinnae, eyes covered with skin and fur
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16
Q

Tenrec

A

s.C. Theria

I.C. Eutheria

S.O. Afrotheria

O. Afrosoricida

  • very diverse group
  • found mostly in Madagascar
  • panniculus carnosus muscle to roll into a ball
  • several have spines
17
Q

Elephant shrew

A

s.C. Theria

I.C. Eutheria

S.O. Afrotheria

O. Macroscelida

  • small insectivores
  • diverse
  • Africa
  • bipedal hopping
18
Q

Aardvark

A

s.C. Theria

I.C. Eutheria

S.O. Afrotheria

O. Tubulidentata

  • myrmecophagy
  • use smell to find ant/termite prey = fleshy tentacles on nose
  • teeth surrounded by cementum instead of enamel (make of dentine prisms) = not true teeth
19
Q

Paenungulates

A
  • elephant, hyrax, manatee
  • shared characteristics:
    • no clavicles
    • short nails, 4 digits on forefeet
    • all nonruminating, herbivorous, hindgut fermenters with a large caecum
    • bicornuate uterus, males have no scrotum or baculum
20
Q

Proboscidea

A

elephants (African and Asian)

s.C. Theria

I.C. Eutheria

S.O. Afrotheria

O. Proboscidea

Synapomorphies:

  • graviportal limbs = bone vs. muscle supports large weight
  • proboscis
  • tusks grow throughout life
  • heavy skull with air pockets

widespread by Oligocene

21
Q

Manatees and Dugongs

A

s.C. Theria

I.C. Eutheria

S.O. Afrotheria

O. Sirenia

  • only herbivorous aquatic mammals
  • live in warm water due to poor thermoregulation and low metabolism
  • fusiform
  • only fur is vibrissae
  • no ear pinnae
22
Q

Hyraxes

A

s.C. Theria

I.C. Eutheria

S.O. Afrotheria

O. Hyracoidea

  • hypsodont or lophodont teeth
  • two cecums to aid with digesting veg
  • diastema with super weird upper incisors and tricuspid lower incisors
23
Q

Xenarthra

A

s.C. Theria

I.C. Eutheria

S.O. Xenarthra

-sloths, anteaters, armadillos

Synapomorphies:

  • at least 2 intervertebral articulations (xenarthrales) on lumbar and some thoracic vertebrae
  • reduced/simplified dentition
    • no incisors/canines
    • cheekteeth single-rooted, no enamel
  • extra rigidity in axial skeleton
    • Limbs specialized for digging, climbing
    • Well-developed processes on scapula and expanded ischium
  • Low metabolic rates, body temps: limited to warm areas, move slowly
24
Q

Anteaters and sloths

A

s.C. Theria

I.C. Eutheria

S.O. Xenarthra

O. Pilosa

  • anteaters and sloths
  • N and S America

Anteater:

  • edentate
  • myrmecophagous

Sloth:

  • algae in fur
  • low metabolic rate
  • 2- or 3-toed
25
Q

Armadillos

A

s.C. Theria

I.C. Eutheria

S.O. Xenarthra

O. Cingulata

  • Jointed armor: bands and bony plates = dermal, scales on top = epidermal
  • Vertebrae modified for attachment of carapace
  • C2 and C3 are fused for extra support
  • Peg-like molars: small, open-rooted, homodont, no enamel
26
Q

Hedgehogs and gymnures

A

s.C. Theria

I.C. Eutheria

S.O. Laurasiatheria

O. Erinaceomorpha

Hedgehogs:

  • spines
  • panniculus carnosus = roll into ball

Gymnures:

  • no spines
  • nasty anal glands
27
Q

Solenodons, shrews, and moles

A

s.C. Theria

I.C. Eutheria

S.O. Laurasiatheria

O. Soriciomorpha

Selenodons: toxic saliva

Shrews: nonshivering thermogenesis

Moles: fossorial = unusual pectoral adaptations

28
Q

Pangolin

A

s.C. Theria

I.C. Eutheria

S.O. Laurasiatheria

O. Pholidota

  • myrmecophagous
  • covered in protective scales

mammalogy (5 decks)

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