6. From Meso- to Cenozoic

Triassic 250-205Pangaea

Jurassic 205-140Laurasia and Gondwana

Cretaceous 140-65Formation of present day continents

Hot and dryPolar regions moist

and temperate

Warm and dryNo ice caps at poles

Very warm no ice caps at poles. Ocean temperatures

about 15-20º higher than today

Pangaea

Cretaceous 140-65Formation of present days continents

Very warm no ice caps at poles. Ocean temperatures about 15-20º higher than today

From Müller et al. 2008)

Saurischia

Ornithischia

Stegosauria

Ceratopsia

Pterosauria

Sauropoda

Therapoda

ArchaeopteryxMicroraptor gui

Aves

Archosauromorpha

Triceratops

Stegosaurus

Diplodocus

Dinosauria

Herbivores

Herbivores

Mainly Carnivores

Triassic 250-205Pangaea

Jurassic 205-140Laurasia and Gondwana

Cretaceous 140-65Formation of present days continents

Iguanodon

Oviraptor

Carnivores

(Flight / display feathers)Paraves

Nemicolopterus crypticus

Thyranosaurus rex(Down feathers)

0

100

200

300

400

500

600

Late Triassic EarlyJurassic

MiddleJurrasic

Late Jurrasic EarlyCretaceous

LateCretaceous

Maastrichtian Total

Epoch

Num

ber o

f kno

wn

gene

ra

zMesozoic dinosaur diversity

0

100

200

300

400

500

600

700

Late Triassic EarlyJurassic

MiddleJurrasic

Late Jurrasic EarlyCretaceous

LateCretaceous

Maastrichtian Total

Epoch

Num

ber o

f gen

era

z

Estimated diversity

Data from Wang, Dodson (2006), Sullivan (2006)

Total 1844 genera

RecentBirds: 1200 generaMammals: 1135 genera

ACE

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

Percent species observed

Per

cent

spe

cies

est

imat

ed

z

Jurassic 205-140Laurasia and Gondwana

Cretaceous 140-65Formation of present days continents

Basal Theropoda

Archaeopteryx

Confuciusornis

Yixianornis

Jinfengopteryx

Rahonavisprobably flight

Troodon(large brain, stereoscopic sight, nocturnal

Mahakala

Deinonychus

Velociraptor

Aves

ParavesFlight / display

feathershomoiotherm,

Pneumatic bones

10 – 80 kg

< 1 – 50 kg

1 – 5 kg

< 1 kg<1 – 60 kg

<1 – 20 kg

< 1 kg

Downfeathers

Dromaeosauridae

Avialae

Cretaceous 140-65 Paleogene 65-23 Neogene 23-

Evolution of birds

Palaeognathae

Neognathae

Anseriformes

Galliformes

Passeriformes

Psittaciformes

Apodiformes

Falconiformes

Others

Tinamiformes

Struthioniformes

Strigiformes

Adaptive radiation

Triassic250-205

Jurassic205-140

Cretaceous140-65

Cycadophyta

Gingkophyta

Permian290-250

Pinophyta

Carboni-ferous

355-290

Cordaitales GnetophytaWelwitschia mirabilis

Magnoliophyta

Archaefructus liaoningensis

Gingko

Nymphaeaceae„Dicotyls”„Monocotyls”

Amborella trichopoda

Adaptive radiation

Adaptive radiation

Cretaceous 140-65Cenozoic 65-

Paleogene 65-23 Neogene 23-Mesozoic 250-65

Monotremata

Marsupialia

Afrotheria Elephants

Elephant shrews

Xenarthra Ant eaters

EuarchontogliresPrimates

Tree shrews

RodentiaLagomorpha

LaurasiatheriaChiroptera

Cetarthiodactyla

Perissodactyla

Carnivora

Adaptive radiation

Genetic diversification

Extant mammalian lineages

Adaptive radiation

Adaptive radiation

Adaptive radiation

Cetacea

Devonian TriassianPermianCarboniferous CretaceousJurassic Tertiary to recent

PalaeodictyopteraOdonata

EphemeropteraDictyopteraPlecopteraZorapteraEmbiopteraIsoptera

GrylloblatodeaDermaptera

PhasmidaOrthopteraMallophagaPsocopteraThysanopteraHeteropteraHymenopteraNeuropteraColeoptera

MecopteraSiphonaptera

Diptera

LepidopteraTrichoptera

Genetic diversification

Genetic diversification

In the Triassic period all extant taxa already existed

The rise of insects

Adaptive radiation

HymenopteraNeuropteraColeoptera

MecopteraSiphonaptera

Diptera

LepidopteraTrichoptera

The rise of holometabolous insects

Jurassic

Cretaceous

0

100

200

300

400

500

600

700

-600 -500 -400 -300 -200 -100 0

Num

ber o

f fam

ilies

K O S D C P T J Kr Pa NE

InsectsVascular plants

Terrestrial Tetrapoda

Num

ber o

f gen

era

Cretaceous 140-65

Photos from: http://www.fossilmuseum.net/Fossil_Galleries/Insect_Galleries_by_Order/

Paleogene 65-23

The earliest ants

An early bee

A swarm of midgesThe earliest moth

An early lacewing An early weevil A weevil in amber

The Cretaceous –Tertiary impactK-T boundary

The K-T boundary. The arrow indicates a layer of Iridium rich ash.

Iridium is rare on the surface of the earth but much more common in Chondrite meteors

Luis Alvarez 1911-

Walter Alvarez 1940-

The Chicxulub Impact structure buried beneath the Yucatan Peninsula has 150 -

300 km in diameter

Age dates of melt rock in the structure have at date of 65 Ma.

The K-T layer is divided into two parts, the Magic Layer (3 mm thick) and the Ejecta Layer (2 cm thick). They contain

• Siderophiles contain the rare Earth Elements Os, Au, Pt, Ni, Co, Pd, and Ir. Iridium (Ir) has been found in the K-T layer around the world (New Zealand, Denmark, and Italy). The layer is about 100,000-years-thick.

• Tektites are abundant in the K-T layer.They are quartz grains which are vaporized under intense heat and pressure, and cool into glass beads with no crystalline structure. Tektites were probably formed during a meteorite or comet collision.

• Shocked quartz - When quartz is put under extremely high pressure, it can cleave in parallel planes. Shocked quartz is found at nuclear bomb sites and known meteorite impact areas. Shocked quartz is abundant in the K-T layer.

• Stishovite (Silicon Dioxide) - a form of quartz created under conditions of high heat and pressure. It is used as an indicator of meteor impact. It has been found in abnormally high abundance in the K-T layer.

• Glass beads - Kenneth Miller has discovered a two-inch layer of glass beads in the K-T layer near the Bass River in New Jersey, USA, supporting Alvarez' theory.

Extinctions at the K-T boundary were not evenly distributed across taxa

15% of all marine families went extinct, 50 % at generic level, maybe 80-90 % of all species.

Affected were mainly plankton, marine predators, and shallow water communities.

25 % of terrestrial families and 56 % at generic level went extinct.

Nothing bigger than 25 kg survived (predators and herbivores).

Unaffected were higher plants (10% extinction), mammals (rise of 20%), and birds.

However, dinosaur diversity declined even before the impact.

Probably the impact wiped out the last survivors.

Cretaceous and Paleogene sawan enormous diversification of

• Angiospermes• Holometabolic insects (Coleoptera, Hymenoptera,

Lepidoptera, Diptera)• Mammals

• Birds• Gastropods

a decline in diversity of• Gymnospermes

• Brachiopods

the extinction of • Ammonites• Belemnites• Dinosaurs

0

20

40

60

80

100

120

607080

Time (mya)

Num

ber o

f tax

a

zSpecies

Genera

K-T boundary

Global species richness of dinosaurs

Data from Sullivan (2006)

Today’s reading

The Mesozoic era: http://www.palaeos.com/Mesozoic/Mesozoic.htm http://www.palaeos.com/Mesozoic/Mesozoic2.htmlThe Cenozoic era: http://www.palaeos.com/Cenozoic/Neogene.html

http://www.palaeos.com/Cenozoic/Paleogene.html