GEL 12 Final UC Davis

What are pterosaurs - feature, time and space?

Pterosauria = winged lizard

features: wing supported by one finger (ring finger), long or short tail without much muscle, hair covering body to keep warm, short torso with fused backbones

Time: Late triassic - later than dinosaurs, but did the best in Cretaceous

Space: mainly in Europe, but fossils in American Southwest/Texas, appeared near bodies of water

What are the major groups of Pterosaurs?

Eudimorphon (early form): late triassic, bones were paper thin, tusk like teeth which probably ate insects or catching fish, Short tail: early form, Pterodactyls

Vhamphoryncus (intermediate form): Jurassic, long bony tail, no muscle, elongated teeth for capturing fish

How different are Pterosaurs, bat and bird wings?

Pterosaurs: No feathers, use one finger attached to wing, biggest hands

Bats: Use membrane, so no feathers, use three fingers attached to wing, smallest hands

Birds: Flap, force field, going up and down for flight, no hands or fingers attached

What kind of fliers were pterosaurs?

High AR = less drag but weaker

Low AR = more drag but stronger

High WL = increase in weight to carry/area

Low WL = less weight to carry per area

Large Pterosaurs: high AR - flew like birds but used the air for movement and limited flapping

Low WL - do not flap

How did pterosaurs breathe?

Balloons/air sacs inside body of the bird, lung flow is unidirectional - inhale/exhale

What were the smallest and largest pterosaurs?

Nemicolopterus - smallest pterosaur wing span = 250mm (early cretaceous)

Quetzalcoatlus - Largest Pterosaur, size of giraffes (late cretaceous)

What did pterosaurs eat and what ate them?

Pterosaurs ate: Sordes (small fish) - Rhamphoryncus, Aspidornychus

Some pterosaurs were eaten by fish, Velociraptor, Quetzalcoatlus - ate meat, carnivore

What are marine reptiles?

Marine Tetrapods: 4 limbed vertebrates that re-invaded the sea ex: Acanthostega gave rise to the Petrolacosaurus

Marine: swimming in the sea, and feeding in the sea

What are the major groups of marine reptiles?

Sauropterygians: flattended animal

Icthyosaurs: started as a lizard and then changed to a fish

Mososauridae: good swimmers and sharp teeth

What was the largest Mesozoic marine reptiles?

Archelon: biggest sea turtle up to 4m

Mososaurs: up to 12-15m

Long/short neck Plesiosaurs

Shastasauridae: state fossil of Nevada

How do modern tetrapods give birth?

Tend to give birth tail first, but some occasionally give birth head first

Ex: Bottle nose dolphin and sea snake (tail first)

Harbor Seal (head first)

How do modern reptiles give birth?

Archosaurs (crocodiles, turtles, birds) - all lay eggs

Oviparity: lay eggs

viviparity: give birth

Ovoviviparity: baby in egg

lecithotrophy: nutrient from yolk

Matrotrophy: nutrient from mother

Partial Placentotrophy: Placenta

How did Mesozoic marine reptiles give birth?

Sauripteryia: embryo evidence

Icthyopterygia: tail first (Early Jurassic)

Chaochusaurus: head first (early Triassic)

When did plants appear and what plants were around by the time dinosaurs appeared?

Ordovician- Paleozoic - first plant - hornworts or liverworts - short plants/primitive/spores - first green algae

Vascular plants: water and nutrients go up the stem and energy and waste go down the stem, CO2 comes in and 02 comes out

Late Devonian - tall trees

Very soft plants, Carboniferous - when they die they leave carbon behind as a carbon field

Devonian and Permian - seed plants

Which new plant groups appeared as dinosaurs evolved in what form and when?

Tracheids: vessels in the xylem

Cretaceous: new forms appeared - grasses/flowering plants good for grazing animals

Where were the land masses placed?

220 ma - dinos first appeared/ triassic ended with mas extinction

170 ma - middle jurassic started

150 ma - Archaeopteryx lived

120 ma - microraptor lived

105 ma - world was warming up

90 ma - world was the warmest

65 ma - dinosaurs became extinct

Continents started with Pangea, then Dinosaurs came, Pangea broke apart, carrying dinosaurs, separated species and lineages

Was the sea level high or low?

Started out low in the Triassic but gradually became higher and higher by the time of dinosaur extinction

What fluctuations of average temperature occurred through the age of dinosaurs?

Temperature in the Age of Dinosaurs was always higher than today and little bit of drop in the middle, but temperature eventually rose again

What is the metabolic rate?

energy expenditure per unit time

- Usually measured by how much oxygen is respired per unit of time

How does the metabolic rate change with temperature in reptiles?

Using external heat to warm up and minimize heat loss (blood flow pattern change, additional insulation) - goes up through the day

What does warm blooded mean?

ability to regulate body temperature

What is gigantothermy?

the ability of an extremely large animal to maintain a constant and relatively high body temperature due to its low surface/volume ratio

What 'equipment' is needed to maintain constantly high metabolic rates?

Decrease in heat loss and moisture loss

-nasal turbinate bones, air sac system

Were dinosaurs warm-blooded?

Nasal Turbinates - Not warm blooded

Insulation - evolving toward homeothermy (constant body temp)

growth rates - grew very fast but does not suggest warm blooded

body temp- high temperature because of gigantothermy but not warm blooded

Therefore not warm blooded

How do we estimate the speed of dinosaurs?

Track way and foot print, stride length and leg length... fastest dinosaur = 30mph

Did T. Rex run?

T. rex could not run easily because it needed lots of muscle to stand and it actually walked slowly

Do footprint shapes indicate taxonomy only?

Can preserve foot motion, and shapes from a single individual could vary drastically so taxonomic require caution

How strongly do dinosaurs bite?

T. Rex - strong head for biting/tearing

Allosaurs- strong head for slashing and uses entire jaw as a knife

broad crown- stronger biting/tearing

narrow crown- weaker biting

Do bird hips bite differently than lizard hips?

IGS - inter globular porous space

Orithschian- do not have IGS

Saurischian - have IGS

What type of animals forage in the dark - even if they are not nocturnal?

Large animals forage in the dark because they are big and need to fill bodies at all hours of the day

Cathemeral activity - day and night

crepuscular - dawn and dusk

Diurnal - day activity

Did any dinosaurs forage in the dark?

Small carnivores were nocturnal, bird were diurnal, pterosaurs were crepuscular

How many kinds were here and did dinosaurian diversity constantly increase?

1800 general species of dinosaurs but increased twice throughout history

How do we estimate the body mass of dinosaurs?

Physical Model - measured the volume in water and estimated the density

Regression - circumference of humerus and femur

3D Computer Modeling - fit a convex hull onto 3D scans of dinosaur skeleton

What is Cope's rule?

body size in a lineage tends to increase over evolutionary time

Did dinosaurs evolve larger and larger body sizes through the Mesozoic?

Cope's rule cannot be sustained through big groups of dinosaurs because there was no big increase in size throughout time

Did the geographic distribution of dinosaurs change throughout the Mesozoic?

Dinosaurs were spread worldwide throughout evolution, but early forms were in Argentina

What is the K/pg or K/T boundary?

K/T is outdated term referring to the Cenozoic before the Quaternary

K/Pg is the first segment of Cenozoic/Paleogene

At this boundary is the very rare Indium Spike deep in the earth

Was there a gradual decline of dinosaur diversity before the K/T boundary?

No gradual decline before the K/Pg mass extinction

What are the Deccan Traps?

A massive flood basalt in India.

What is the Chicxulub Crater?

- Evidence of a asteroid or comet impact on Earth in Carribean Sea near Yucatan Penninsula

- largest impact structure on Earth

What is an instantaneous kill?

It was not but the process was long:

Crater hit

Molten rock in the air

Fires started

acid rain from sulfur in ejecta

nuclear winter from sunshield

many thing could not survive the sudden changes and green house gas effect of temps getting warmer and warmer

What survived and what did not?

Survivors: amphibians, reptiles, birds, mammals

Losers: dinosaurs, marine reptiles

icthyosaurs became extinct before the extinction

Were all mass extinctions similar to the K/Pg extinction?

P/T extinction was the largest and took the longest to recover

Each mass extinction has a unique set of potential causes