"Extinction" of the Dinosaurs

What are some reasons why climate change could have been induced?

- Asteroid impact -Extreme volcanic activity -Changes in Earth's orbit -Methane released into atmosphere (Clathrate release) -Supernova or gamma ray burst nearby -Massive solar storms -Plate tectonics

Fossil record shows:

- Decline in dino # over millions of years <40% BEFORE asteroid impact. - Sudden disappearance of dinos in some parts of the world at K-T boundary.

What could have been some biological influences?

- mammals competing for food & eating dinosaur eggs -Disease -Egg shell changes (example in video we watched of embryos not forming due to environment) - Diversification of flowering plats changed food chain & insect word

What were the changes that egg shells underwent

-Shell thickness may have decreased at end of Mesozoic, fewer babies survived to hatch, environmental stress- estrogen decreases- thin egg shells, Multi-layer egg shells - suffocate embryo.

65 Ma extinction

70% of all species go extinct - ecological collapse

• Increased atmospheric sulfuric & hydrochloric acid, methane, nitric oxide, CO2 → acid rain, ozone layer damage & greenhouse effect increasing global temperature by ___ C.

8 Degrees Celcius

What are the Indian Deccan Traps?

Basaltic lava eruption. 200k miles ^2 and 6,500 feet thick. 0.5-3 million years BEFORE 65 Ma extinction events.

How did disease spread in dinos?

Decreased sea level opened up more land, dinos who had evolved apart began to mingle, spreading disease that other species weren't immune to.

Generally volcanic activity was decreasing at the end of the Cretaceous.. T/F?

False! It was decreasing, (decreasing greenhouse effect)

What was the Climate during the Cretaceous?

Global temperature decrease & drop in sea level

The angiosperms took over, why were they a major influence in the extinction of dinosaurs?

Many dinosaurs only ate gymnosperms, the angiosperms changed biological habitat, brought new insects who brought disease.

Caterpillar evolution- hyp says:

NO EVIDENCE, first of all. This hyp says that the diversifying caterpillar sate all the plants causing dinosaur starvation..

Were dinos the only species that went extinct in 65 Ma?

No, theres also other animals like ammonites, marine reptiles, pterodactyls, some turtles & crocs, most birds & many mammals.

Mammals competition during end of Cretaceous

Packs of small mammals competed for food with dinoss, preyed on dino babies & eggs (evidence).

What did climate change cause

Starvation! Dying vegetation depleted by herbivores which were depleted by carnivores.

A good hypothesis must be..

Testable & able to explain all aspects of the event.

There is evidence of global warming ~1-2 million years before the impact, T/F?

True

Iridium is found only found in what type of rocks?

Volcanic rocks. ALWAYS attributed to volcanic rocks/ asteroid impacts.

Climate change is absolutely the main reason why dino's went extinct.. Right?

WRONG. It's not the main reason, but it does give reason to why 40% died before the impact event.

What is seasonality and what did more seasonability during the Cretaceous have impacts on?

Winter was colder, summer was hotter. It was caused by greater temperature differences through year. Lower temp caused tropical plants to die- herbivores starve, etc. Plankton decrease- lower temp, acidification. Methane release by clathrates, or deep sea algae.

Change in global ocean circulation..

it has happened before, killing sea life as food chain is disrupted