GEL 12 Midterm 4

Summer Sessions

What are not dinosaurs

Marine Reptiles and flying reptiles

Aquatic adaptions

Long skull

conical teeth

long or short neck, squat

streamlined bodies

tails laterally compressed, short

paddle-like limbs

Ichthyosaur

Plesiosaur

Mosasaur

Mosasaur

Marine varanoids

Mid to late Cretaceous

Well-designed for a diet of fish

Fed on various invertebrates, including ammonites

Plesiosaurs

Late Triassic to Late Cretaceous

Ranged in size 2-14m

strong limb girdles

Powerful paddle-like limbs

Long necks

Flippers are more like wings than oars

Joints allow up-and-down movement

downstroke more powerful

Ichthyosaurs

Highly derived marine reptiles with streamlined

fusiform bodies

large dorsal fins

elongated skull

large eyes

Late Triassic to Late Cretaceous

go extinct before the end of the Cretaceous

Strealined body form with doplphins

propel with tail; steer with paddles

dolphins-up and down- mammals

Ichthyosaurs- side to side- reptile

Ichthyosaur reproduction

Fully adapted for life in sea

did NOT lay eggs on land

gave birth to live young in sea

Pterosaurs

Flying reptiles

NOT DINOSAURS

semi-erect posture

Pterosaur features

enlarged sternum

elongated 4th digit

pteroid bone

Rhamphorhynchids

hook-beak

small bodies

long tails

no crests on head

Pterodactyloids

Wing finger

larger bodies

no tails

crests on head common

Archaeopteryx like birds

Feathered wings and feathered tail

backward-pointing pubis

backwards-pointing pedal digit I hallux on foot

Archaeopteryx different from birds

Long bony tail instead of a pygostyle

Unfused digits with unguals (claws)

Teeth in the skull

Archaepterx lacks

toothless beak

keeled sternum

no claws on their wings

a pgostyle

Other dinosaurs

many other clearly NON-avain dinosaurs had pygostyles

Wings

Climbing a steeper slope

flap wings from head to tail

Gives extra traction to bird while climbing

WAIR

Wing assisted incline running

Flight and Wair

Angle of attack of wing in WAIR and flight stroke are VERY similar

Trees down Model arboreal hypothesis

Ancestors of birds were tree dwellers bird went through a gliding stage

Ground up model terrestrial hypothesis

No aboreal (tree dwelling) phase, nor gliding stage

The Compromise hypothesis

Wings evolved first to aid young in running up sides of trees, cliffs, etc later modifications allowed true flight

Functions of feathers

Thermoregulation

colorations/mates

sensory

Extinctions

Most species become extincit after a few millions years

Background of extinction

Constantly going on, but is during static periods of biodiversity, it is balanced by the origination of new species

Mass extinction

The extinction rate far outweighs the origination rate for new species

Global climate change

Intrinsic factors (GC)

Atmospheric composition

Global climate change

rates of carbon burial

rates of volcanism

Plate tectonics

Continental configuration

distribution/shape of the ocean basins

ocean circulation

Global climate chnage

Sea level changes Intrinsic

Area/size relationship of continents

effects on habitable area

effects on climate

Potential Contributing biological factors INTRINSIC FACTOR

Competitions

predator-prey interactions

epidemics

Extrinsic factors

orbital changes

solar system evolution

cosmic factors

orbital changes

changes in axial tilt and shape of the earths orbit

Solar system evolution

Rates and sizes of impactors

Cosmic facots

Radiation from supernovae

Evidence for dinosaur killing asteroid

Iridium anomaly

shocked quartz

tsunami deposits

fern spore spike

crater

Animals that survived

Early mammals

avain dinosaurs

reptiles and amphibians

aquatic invertebrates

Why animals survived

Small didn’t need a lot of food to survive

High reproduction rates grew large populations fast

Subterranean and aquatic animals lived in burrows and swamps and deep rivers