Topic 2 - Phylogeny and Diversification of Mammals

Two subclasses of mammals

Prototerhia

Theria

What order is in subclass prototheria?

monotremata

What infraclasses are in subclass Theria?

Metatheria: marsupials

Eutheria: olacental mammals

Two extant suborders of order monotremata

1) platypoda: platypus

2) tachyglossa: echidna or spiny anteaters

Suborder platypoda: family? genus? species?

family: ornithorhynchidae

genus: ornithorhynchus

species: ornithorhynchus anatinus

What is unique about platypus bill?

It has electroreceptors to help it locate food

Tachyglossa: family? 2 genus? 4 species?

family: tachyglossidae

genera: tachyglossus and zaglossus

species: 1 tachyglossid, 3 zaglossids

What are the features of echidna?

borrowing insectivores; covered in spines dorsally; found in Australia and New Guinea

Two unique features of monotremes

• oviparous laying eggs

• maintain much lower metabolism and average internal temperature

Do monotremes have mammary glands?

Yes; but they are simpler and lack nipples

What animals are in infraclass metatheria?

marsupials

Differences between marsupials and placental mammal development

• mode of reproduction: shorter gestation time

• offspring will crawl into pouch after gestation

  • will latch onto nipple to complete development in pouch

Anatomical term for pouch

marsupium

7 orders of infraclass metatheria

• didelphimorphia

• paucituberculata

• microbiotheria

• dasyuromorphia

• peramelemorphia

• notoryctemorphia

• diprotodontia

Order Didelphimorphia

• american opossums

• 87 species

Order Paucituberculata

• shrew, rat, opossums

• 6 species

Order Microbiotheria

• 1 extant species: monito del monte

Order Dasyuromorphia

• numbat, dasyures, extinct tasmanian wolf

• 70 species

Order Peramelemorphia

• bandicoots

• 21 species

Order Notoryctemorphia

• marsupial “moles”

• specialized burrowers

• 2 species

Oder Diprotodontia

• koala, wombat, kangaroos, most australiasian possums

• 144 species

What orders are part of superorder Australidelphia?

all orders expect didelphimorphs

Where did superorder Australidelphia originate?

South America, traveled to Australia by way of Antartica

Short beaked echidna? Long beaked echidna?

Short beaked: Tachyglossus

Long beaked: Zaglossus

One of most notable features of eutherians

development of placenta

3 Unique features of Eutharians

• mode of reproduction (viviparous & neonate development fully in uterus)

• higher metabolism

• more intelligent & complex socially/behaviorally

How many Eutharian orders? Superorders?

20 orders

4 superorders

4 superorders

• Afrotheria

• Laurasiatheria

• Xenartha

• Euarchontoglires

Where did each superorder originate from?

Afrotheria: africa

Xenartha: south america

Laurasiatheria: northern hemisphere (carnivores)

Euarchontoglires: northern hemisphere (rodents and primates)

7 extant orders of afrotheria

• tubulidentata

• afrosoricida

• eulipotyphla

• macroscelidea

• hyracoidea

• proboscidea

• sirenia

Order Tubulidentata animals

aardvark

Order Afrosoricida animals

tenrecs & golden moles

Order Eulipotyphla animals

shrews, moles, hedgehogs, gymnures, selenodons

Which 2 orders were previously thought to be one order “insectivora”?

afrosoricida and eulipotyphla

Order Macroscelidea animals

elephant shrews

Order Hyracoidea animals

hyraxs

Order Proboscidea animals

elephants

Order Sirenia animals

manatees and dugongs

Superorder Xenartha orders

• cingulata

• pilosa

Order Cingulata animals

armadillos

Order Pilosa animals

sloths and anteaters

5 extant orders of Euarchontoglires

• rodentia

• lagamorpha

• dermoptera

• scandentia

• primates

Order Rodentia animals

rodents (most species rich order)

Order Lagamorpha animals

rabbits and hares

Order Dermoptera animals

culogos (group of gliding mammals)

Order Scandentia animals

tree shrews

Order Primates animals

apes & monkeys

Which two superorders are more closely related than the others? Why?

euarchontoglires and laurasiatheria due to both originating on northern supercontinent Laurasia

5 extant Laurasiatheria orders

• chiroptera

• pholidota

• carnivora

• cetatriodactyla

• perissodactyla

Order Chiroptera animals

bats (second most species rich order)

Order Pholidota animals

pangolins

Order Carnivora animals

cats, dogs, weasel, bears

Order Cetatriodactyla animals

• pigs

• goats

• antelopes

• deer

• whales

• dolphins

Order Perissodactyla animals

• odd-toed ungulates such as horses and rhinoceri

What did mammals evolve from?

group of reptiles called synapsids

Evolution order from synapsids to mammals

synapsids → therapsids → cynodonts → mammals

Crown group

collection of species that consists of: living group, their ancestors, and their common ancestor

What gave rise to the crown group of mamals?

therapsid reptiles

Why are monotreme fossils rare?

They often look like reptilian fossils; especially if there is not a head