Mammal Paleontology

always remember when & where..

What is Sinodelphys

First known Marsupial relative, Early Cretaceous, China

What is Eomaia

First known Placental relative, Early Cretaceous, China

What is Juramaia

oldest (true) tribosphenic mammal, Late Jurassic

Speciation processes

Allopatric: spatial separation

Peripatric: separation of small population

Parapatric: overlapping with hybrid zone

Stasipatric: same area, polyploids isolated

Sympatric: same area

Dual origin of tribosphenic mammals

Boreosphenida: northern continents ("true")

Australosphenida: southern continents (convergent)

Oldest prismatic tooth enamel

Dryolestidea

Haldanodon characteristics

enlarged femur and humerus for digging

shortened phalanges

occluding molars

diphyodont replacement of antemolars

Late Jurassic, Portugal

Hints at endothermy

Nose turbinals

arguments for aerobic capacity first

sustained activity: reposition of limbs and diaphragm for better breathing

juvenile provision: metabolic activity needed to produce milk

Arguments thermoregulation first

miniaturisation

increased brain size

ecological: becoming nocturnal, need to stay warm at night

growth of offspring: higher incubation temperature

Therocephalia characteristics

mostly carnivorous

secondary palate

possibly warm blooded

middle Permian - middle Triassic

Gorgonopsida characteristics

dominant carnivores

saber-like canines

legs underneath the body

Middle-Late Permian

earliest herbivorous tetrapod

Edaphosauridae

Late Carboniferous-Early Permian

Holarctic

Edaphosaurus sail function

unclear, thermoregulation, display

Dicynodontia characteristics

enlarged tusks, other teeth reduced

horny beak

herbivorous

Southern Pangea, Permian

developments in Cynodontia

secondary palate forms

precise tooth occlusion

dentary main part of lower jaw

Therapsida apomorphies

reduction of palatal teeth

forward position of jaw joint

enlarged temporal fenestrae

oldest Synapsid

Archaeothyris

Late Carboniferous

Extinction events Synapsida

Permian-Triassic

Triassic-Jurassic

mammalian characters

mammary glands

hair

endothermy

secondary jaw joint

diaphragm

increased brain size

limbs under body

specialised dentition

secondary palate

reduced ribs

Phylogeny of Mammalia

Synapsida

Therapsida

Cynodontia

Mammaliamorpha

Mammaliaformes

Mammalia

jaw bones turning into middle ear ossicles

Hyomandibula → stapes

Quadrate → incus

Articular → malleus

secondary jaw joint

squamosal + dentary

primary jaw joint

quadrate + articular

when did the secondary jaw joint evolve?

Triassic

Morganucodon had double jaw joint

oldest Eutherians

Eomaia - Cretaceous

Juramaia - Jurassic

what are Therians

Metatherians (marsupials) + Eutherians (placentalia)

Allotherians jaw movement

vertical (orthal) or directed backwards (palinal)

what is the postdentary trough

hollow behind molar teeth, where postdentary bones and Meckel’s cartilage sit

→ mezosoic mammals

Meckels groove

opening on inner surface of mandible

modern eutherians don’t have it

Biotic interchanges

FABI - Late Cretaceous/Paleocene

GABI - Pliocene

Faunal regions

Nearctic + Palearctic - Holarctic

Ethiopian

Oriental

Australian

Neotropic

Pangea breakup

into Laurasia and Gondwana, Tethys ocean forms

Middle Jurassic

land bridges

Bering - North America/Eurasia

Gomphotherium-Eurasia/Afro-Arabia

Panama - North America/South America

land partitions

Turgai Strait - Europe, Asia

South America old immigrants

South American ungulates

Xenarthra

Marsupialia

Late Cretaceous-Paleocene

second phase South America

primates

stem caviamorph rodents

Eocene-Oligocene

third phase South America

hamsters, raccoons, elephants

Late Miocene

What are Xenarthra

Cingulata (armadillos) - Eocene

Pilosa

• Vermilingua - Miocene

• Folivora - Eocene-Oligocene

when did the GABI happen

Pliocene

Anthropoidea origin

Myanmar, Eocene

Tapiroidea distribution

Eocene: Holarctic

migrated from North- to South America in GABI

now South America and South-East Asia

Equidae dispersal

Early Eocene - North America

over Bering to Asia, Europe and Africa

Equus with humans back to North America

Rhinocerotoidea dispersal

early Eocene: holarctic

middle Eocene: Asia

Miocene from Asia to Africa

Ursidae dispersal

early Miocene: Asia, Europe, North America

Late Miocene: Africa

Pleistocene: South America

Canidae dispersal

Eocene: North America → main evolution and radiation

Miocene: Europe

Pliocene: Asia, Africa, South America

Felidae dispersal

Oligocene: Europe, Asia

Miocene: Africa, North America

Pliocene South America

Bovoidea dispersal

Early Miocene: Europe, Asia, Africa

Late Miocene: North America

Giraffoidea dispersal

Miocene: Africa, Asia, Europe

extant only Africa

Cervoidea dispersal

Oligocene: Europe

Miocene: Asia, North America

Pleistocene: some in South America

Camelidae dispersal

Eocene: North America (extinct there in Holocene)

Miocene: Asia, Africa, South America

Proboscidea dispersal

Eocene: Africa

Miocene: over Gomphotherium landbridge to Eurasia

Deinotheriidae first ones out of Africa

Mammutidae dispersed to North America

Gomphotheriida dispersed to South America

Elephantidae recent

Phocidae dispersal

Miocene: Atlantic (Palearctic origin)

Pliocene: Pacific

recent worldwide

Mustellidae disersal

Oligocene: Northern Hemisphere

recent worldwide, except for Australia, Antarctica, Madagascar

Proboscidea lineage

Tethytheria

Proboscidea + Sirenia

Paleocene

Tapiroidea dispersal routes

Beringia - when there was no arctic ice cap

Thulean - North America to Britain to Europe

De Geer - North America to Northern Europe

caviamorph rodent mandibles

Felidae teeth

premolars and postcarnassial teeth reduced

Ursidae teeth

molars flattened and enlarged, premolars reduced in size

Canidae carnassials

Carnassials

P4/m1, cutting blade

Rhinocerotoidea & early Tapiroidea teeth

upper lophodont, lower bilophodont

vertical Hunter-Schraeger-Bands → ridges

evergrowing

Equidae teeth

lophodont

increasingly hypsodont (high-crowned)

cervid teeth

selenodont

Hippopotamus teeth

tetracuspid

early Artiodactyla teeth

molars brachyodont

bunodont/buno-selenodont

chiroptera teeth

dilambdodont

blood-feeding: blade-like incisors

soricidae (shrews) teeth

dilambdodont, “classic” tribosphenic molars

enlarged incisors

unicuspid teeth

lamellodont

bilophodont

bunoselenodont

lophodont

dilambdodont

selenodont

bunodont

secodont

different tooth crowns

hypsodont - high crowned

brachydont - low crowned

euhypsodont - evergrowing, rootless

tooth component hardness

enamel > dentin > cementum

internal structure of mammalian teeth

chewing movements, who uses them

orthal - up/down - carnivores, to use saws

transversal - left/right - herbivores, to grind on crests

palinal - pushing back - haramyidans, multituberculates, gondwanatherians

proal - pushing forward - proboscidea

catarrhini dentition

2.1.2.3./2.1.2.3

bunodont or bilophodont

Deinotheriidae dentition

bilophodont

tusks only on lower jaw

Tapiroidea dentition

upper lophodont

lower bilophodont

different lophs

Ruminantia dentition

mostly selenodont

Bovidae hypsodont

sus dentition

three incisors

enlarged canines

bunodont

Anthropoidea groups

Catharrini (old world simians) - two premolars

Platyrrhini (new world simians) - three premolars

different wear types

abbrasion - from food

attrition - from tooth-tooth contact

Platyrrhini dentition

2.1.3.3/2.1.3.3

bunodont

Tribosphenic upper molar

Tribosphenic lower molar

simians teeth

tetracuspid/pentacuspid

Arvicolinae (voles) teeth

prismatic enamel triangles

most derived rodent teeth

hypsodont, evergrowing

Hyracoidea teeth

convergent to Rhinocerotoidea

lophodont

Phocidae teeth

canines enlarged

homodont cheek dentition

Rodentia teeth

one pair of enlarged, evergrowing incisors

decidious, don’t get replaced

large Diastema

Elephant teeth

lamellodont

transversal tooth replacement (three molars that push forward)

lagomorpha teeth

enlarged incisors

peg-like I3 behind upper pair

What cusp occludes into the talonid basin?

Protocon