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Mammalogy > Lectures 5 and 6 > Flashcards

Lectures 5 and 6 Flashcards

1
Q

Monotreme Reproduction

A

Cloaca present

Testes are abdominal

Mammae lack nipples

Long lactation periods

Female echidnas have folds of skin along the abdomen in place of typical pouch

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2
Q

Order Monotremata
Family Tachyglossidae
Etymology

A

Tachy = fast speed
Gloss = tongue
Fast tongued

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3
Q

Order Monotremata

Family Tachyglossidae

A

Thick bodies covered with short spines

Rostrum slender and beak-like

Rostrum bears electro-receptors in Tachyglossus
-Can detect very faint electric signals

Slender, delicate dentary bones

Long protrusible tongue

Limbs powerfully built for digging
-Need to be able to break into ant/termite mounds

AKA “spiny anteaters”

Little hairs on tongue help pick up ants

Electro-receptors on distal tip of beak (only about 200-300 electroreceptors)

Spines protect against predators, do NOT dislodge like porcupine quills

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4
Q

Echidna Love Train

A

Males awaken from hibernation before females

Smell out females and wait for her to wake up

Sometimes will nudge females to try to wake her up

Female awakens from hibernation and is not immediately ready to mate, she will smell around while males follow her

Males will make hierarchy

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5
Q

Order Monotremata
Family Ornithorhynchidae
Etymology

A

Ornitho = bird
Rhynch = beak
Bird-like beaked mammal

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6
Q

Order Monotremata

Family Ornithorhynchidae

A

Semi-aquatic lifestyle

Dense velvety pelage and wooly underfur

Eye and ear openings covered by skin folds when submerged

Webbed feet

Inhabits streams, rivers, and lakes

Primarily hunts on bottom for crustaceans, insect larvae, and other food

Take refuge in burrows in stream banks

Primarily NOCTURNAL mammals

Monotypic family: Only ONE species

Young have teeth, but teeth are absent in adults

Egg tooth used for hatching

Gums covered by horny plates

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7
Q

Platypus Bill

A

40k electroreceptors

60k mechanoreceptors

Mechanoreceptors detect by touch

Electroreceptors detect faint electric signals (i.e. heartbeat); platypus finds food by sweeping head back and forth like a mine sweeper or metal detector

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8
Q

Platypus Spurs

A

Males have medially directed spurs on ankles

Connected to venom glands

Venom production increases during breeding season

Function:

  • True answer UNKNOWN
  • Intraspecific competition (fight other males)
  • Subdue females for mating (not supported well, venom pretty strong and could potentially cause damage)
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9
Q

Adaptive Radiation of Crown Mammals

A

Monotremes: 5-7 extant species

Marsupials

Placentals

Class Mammalia
 Subclass Prototheria
 Subclass Theria
  Infraclass Metatheria
  Infraclass Eutheria
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10
Q

Metatherians and eutherians diverged in ___________

A

late Jurassic

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11
Q

Infraclass Metatheria

A

Known as marsupials for the marsupium
-Only ~50% living marsupials have marsupium

Give birth at early stage of development

  • Short gestation, long lactation
  • Choriovitelline placenta (lack villi)

2 Centers of diversification:
Modern centers of diversity are the Australian region and the Neotropics (S and C America)

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12
Q

Metatherian Morphology

A

Function of palatal vacuities is to allow for extra vascularization

Palatal vacuities present on cranium (Good way to ID marsupials)

Medially inflected angular process on dentary

Hindfeet may be specialized
-e.g. for arboreal or saltatorial (leaping) locomotion

Epubic bones present

Marsupium may be present

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13
Q

Koala Toes

A

Big toe opposable

Used to grasp branches (common in arboreal mammals)

Syndactyly: 2nd and 3rd digits fused

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14
Q

Bandicoot toes

A

Hopping like kangaroos

Long plantorial surface (common in hopping animals)

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15
Q

Tree kangaroo toes

A

Secondarily adapted to arboreal habit

No opposable big toe, evolved primitive grasping function

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16
Q

Epipubic bones in Virginia opossum

A

Paired epipubic bones: Come off pubis/pelvic girdle

Role:

  • Initially thought to support pouches, but ALL marsupials have epipubic bones, NOT all have pouches; bones are present in males, too (most don’t have pouches, a few males do)
  • ACTUAL purpose: Point of origin for muscles involved in locomotion

Monotremes also have epipubic bones

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17
Q

Hopping marsupials have ___________ pouches

A

Anterior-facing

Allows for CURSORIAL locomotion

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18
Q

Burrowing marsupials have ____________ puches

A

Posterior-facing

Protects young from dirt

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19
Q

Metatherian Paleontology

A

Fossil record dates to early Cretaceous of Asia (140-130Mya)
-But diverged from Eutheria much earlier than this

Souther continents served as centers of metatherian radiations

Metatherians reached Australia via Antarctica

Antarctica and Australia contiguous until about 55Mya

S America (mostly) isolated

S American radiation rivaled that in Australia
-Diversification about 140Mya in Asia

Most living metatherians found in Australia

Evolved from basal insectivorous or omnivorous mammalian stock

Lots of convergence with eutherians

Over 130 living and fossil genera
-Not a very diverse group now, historically diverse group

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20
Q

Examples of Convergence

A

Borhyaenidae
-Convergent with canids and bears

Thylacosmilidae
-Convergent with saber-toothed cats

Argyrolagidae
-Convergentw ith kangaroo rates and jerboas

21
Q

Metatherians vs. Eutherians

A

Are modern metetherians adaptively and competitively inferior to eutherians?
-NO, different approach to solving evolutionary problems

22
Q

Metatherians less diverse today than eutherians

A

No flying or marine metatherians

Some extremely productive food sources not part of metatherian diet (e.g. marine plankton and flying insects)

23
Q

Metatherians far more conservative morphologically

A

No marsupials with fins or wings

24
Q

Metatherians have not exploited great size

A

Largest living metatherian is the red kangaroo (100kg)

25
Q

Metatherians have never evolved highly social behavior

A

No herding metatherians

-Kangaroos eat together, exploit same food source, do NOT travel as a unit

26
Q

Metatherians are less diverse than eutherians

A

About 6% of living mammals are metatherians

~390 species of metatherians

~6500 living species of mammals

27
Q

Metatherian mode of reproduction is probably more ancestral than that of eutherians

A

Very brief gestation period

Bear almost embryonic young

Forelimbs are most developed part of this embryonic young, UNABLE to develop into other specializations because they’re needed for climbing to nipples

28
Q

Extended gestation of eutherians produces young that are far more endothermic

A

Eutherians seem better able to exploit colder climates

29
Q

Investment of energy by the mother is probably lower in metatherians

A

Adcantage in unpredictable environments;

  • Can replace young quickly
  • Able to go into estress much more quickly, not too much energy lost
30
Q

South American metatherians

A

Superorder Ameridelphia
Order Didelphimorphia
Family Didelphidae

Includes opossums in S America and common/Virginia opossums

31
Q

Order Didelphimorphia

Family Didelphidae

A

Southeastern Canada to southern Argentina

Braincase long and narrow

Prominent sagittal crest

50 total teeth! (5/4 incisors)

Marsupium may be present or absent

Tail usually prehensile

Some are immune to snake venom

32
Q

South American metatherians

Superorder Ameridelphia
Order Paucituberculata
Family Caenolestidae

A

Monotypic family

Shrew-like marsupials

Disconnected/disjunct distribution on Andes mountains

No marsupium

Lower incisors procumbent (stick out anteriorly)

Elongate heads and small eyes

Large olfactory bulbs
-Indicates that it relies heavily on sense of smell

33
Q

South American Metatherians

Superorder Australidelphia
Order Microbiotheria
Family Microbiotheriidae

A

Only member of Superorder Australidelphia found in S America, NOT found in Australia

Monotypic family

Monito del monte
-“Little bush monkey”

3-5in; ~20g

Southern Andes Mountains

Scansorial/Arboreal
-Scansorial = spends a lot of time on ground

Primarily insectivorous

  • Sole disperser of misteltoe seeds
  • If they go extinct, the mistletoe would, too

May undergo hibernation

Goes between ground and trees

34
Q

Superorder Australidelphia
Order Microbiotheria
Family Microbiotheriidae

Why is it found in S America?

A

Backwards migration hypothesis:
-Relict of an Australidelphian radiation back into S America (i.e. back-migration)

Accepted hypothesis:

  • Relict of the lineage that colonized Australia via Antarctica
  • -Shares common ancestor with all of the other Australian metatherians
35
Q

4 Extant Orders of Metatherians

A

Dasyuromorphia
Peramelemorphia
Notoryctemorphia
Diprotodontia

36
Q

Order Dasyuromorphia

Family Dasyuridae

A

Marsupial Carnivores

Diversity in sizes
-Shrew-sized to size of small dog

Carnivorous and insectivorous forms

  • Specialized teeth reflect diet
  • Upper molars have sharp cusps for slicing

Tasmanian devil

  • Formerly widespread in Australia
  • Now restricted to Tasmania
  • Devil Facial Tumor Disease
  • -80% decline in population
37
Q

Order Dasyuromorphia

Family Myrmecobiidae

A

Monotypic family: (Myrmecobius fasciatus)

Numbat

Eats termites

  • Long, protrusible tongue
  • Teeth small

Diurnal

38
Q

Order Dasyuromorphia

Family Thylacinidae X

A

“Thylacine” or Tasmanian wolf

EXTINCT

Widespread over Australia until about 3500 years ago when dingos were introduced

Last known thylacine died in a zoo in 1936

Females and males both had pouches

Features convergent to dogs

39
Q

Order Notoryctemorphia

Family Notoryctidae

A

Marsupial moles

Fossorial adaptations

  • Eyes vestigial and lenseless
  • Ears lack pinnae
  • Cornified skin on nose
  • Enlarged claws for digging
  • Marsupium opens posteriorly
40
Q

Order Peramelemorphia

Family Peramelidae

A

Bandicoots

Large ears, pointed snout

Omnivorous

Hind feet specialized for cursorial locomotion:
-2nd and 3rd toes fused (syndactyly), a feature shared with Diprotodontia

Dig shallow burrows
-Pouch present, facing posteriorly

41
Q

Order Diprotodontia

A 
Family Vombatidae (wombats)
Family Phascolarctidae (koalas)
Family Phalangeridae (possums and cuscuses)
Family Tarsipedidae (noolbenger, honey possum)
Family Macropodidae (kangaroos, euros, wallabies)

Diprotodonts have 2 procumbent lower incisors

42
Q

Order Diprotodontia

Family Vombatidae

A

Stocky bodies up to 36kg

Limbs short and powerful

Tail vestigial

Excavate extensive networks of tunnels

Marsupium opens POSTERIORLY

Zygomatic arches robust

Cranium flattened

Wide mastoid process

Wide diastema (anterior premolars lost)

incisors 1/1

Conspicuous depression in jugal and maxillary (origin of masseter)

Biliphodont cheekteeth

Syndactylous

Lower incisors diprotodont

43
Q

Wombats are

A

herbivores

44
Q

Order Dipotodontia

Family Phascolarctidae

A

Monotypic family - koalas

8-12kg

Specialized arboreal herbivore

  • Eucalyptus
  • -Low-quality diet: No protein, takes a lot of energy

Fairly sedentary (low quality diet)

Microbial fermentation in caecum
-Caecum is first part of intestine

Single young dependent on mother for 1 year

Cellulase breaks down cellulose; mammals lack this, they need some sort of bacteria to break down cell wall of plants

45
Q

order Diprotodontia

Family Phalangeridae

A

Cuscus and possums

Large-ish possums

Includes cuscusses and brushtail possums

Omnivorous

Some have adapted to living in suburban areas

Primarily arboreal

  • First 2 digits of front foot (pollex) opposable
  • Prehensile tail
  • Bare skin on part of tail (on distal-most end)
  • Opposable first toe
46
Q

order Diprotodontia

Family Tarsipedidae

A

Monotypic family

Honey possum, or noolbenger

nectivorous

Long-p prehensile tail

Long, bristled tongue used to extract nectar

jaw muscles and teeth reduced

47
Q

Mammal with liquid diet?

A

Honey possum

Vampire bats

Modifications: Long tongue to lap up/suck things

48
Q

Order Diprotodontia

Family Macropodidae

A

Kangaroos, wallabies, quokka

900g to 90kg

Marsupium opens anteriorly

Broad diastema

Highly specialized for bipedal jumping

  • Hindlims elongate (especially 4th metatarsal)
  • Digits 2 and 3 small and syndactylous

Digit 1 ABSENT

Macropods CONVERGENT with ungulates

  • Cursorial
  • Browsing/grazing
  • Specialized digestive system for microbial fermentation of plant material (foregut fermenters)

Mammalogy (11 decks)

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