Ch.12, KT Extinction, and NKY Fossils
most land masses were close or joined to Gondawa. Glaciers started to appear and caused a mass extinction.
What happened at the end of the Ordovician? What specific groups were affected?
Alvarez' publish impact theory in Science in 1980. They propose that 10-km asteroid hit 65 million years ago. The impact created a "nuclear" winter that exterminated the dinosaurs. Scientists don't like catastrophism and think that its contrary to uniformitarianism.
What has been the reaction to catastrophism from the scientific world?
plants were evolving from ancestor green algae. Between 500 to 400 million years ago some algae made the transition to land, becoming plants by developing a series of adaptations to help them survive out of the water
What was happening to the evolution of plants during the Ordovician period?
Shocked Quartz and tectites
Where's the crater?
they hadn't evolved yet
Why didn't animals have backbones?
theory
a proposed idea that is supported by well-researched evidence
abnormal measurements
anomalies
the graph
bottom shows normal amount of iridium. Yellow shows iridium spike-sudden dramatic increase. Typically iridium is close to zero but at the top the amount had increased. It occurs at the same time that dinosaur extinction takes place
evidence
facts discovered through investigation by the scientific method: experiments and observations
time scale; the complete history of life on earth; divided into eras, period and epochs
geologic records
Shoemaker Levi Asteroid
hit Jupiter and caused an explosion
finds tsunami deposits in Texas
Alan Hildebrand
K-T boundary
line separating what is known as the Cretaceous period (lots of dinosaur fossils) to the Tertiary Period (no dinosaur fossils)
represent modern day clam and oysters, have rigid pattern, some types are extinct, but some are extant.
Brachiopods
similar to octopi and the squid. They have shells and are extant
Cephalopods
confirmed impact site of the crater
Chicxulub
thought to be early vertebrates, also thought to be the mouthparts of worms. Know known to be part of the teeth of an early vertebrae fish
Conodonts
have spirals, star like shape at the tip. Related to the starfish. Spiral part makes up the fossil, extant
Crinoidea
Gene and Caroline Shoemaker
noted up to 1500 earth-orbit crossing asteroid
found only at impact and nuclear explosion sites
shocked quartz
droplets of molten eject and frozen into form
tectites
means three-part-body, lines indicate the numbers of days alive
trilobite
Luis Alvarez
worked on the Manhattan project
Walter Alvarez collects rock and strata samples at Gubbio, Italy. He wasn't looking for dinosaurs or fossils. He was examining reversals in the Earth's magnetic field. He notices unusual clay layer at K-T boundary. Brought samples back to share with famous father, Luis Alvarez.
State the events leading to the Alvarez theory
shape of shells are unique because they are coiled. Common name of the group is snails and slugs.
Gastropoda
finds gravity and magnetic anomalies in Yucatan Peninsula in Mexico
Glen Penfield
area that resulted in the breakup of Pangea
Gondwana
numerous studies support instantaneous extinction, K-T boundary, Shoemaker Levi Asteroid
How do we know that the dinosaurs didn't die out slowly?
Peter Wars finds corresponding extinction of ammonites, 75% of life was killed off the earth
If the steroid did so much damage, why did it only kill the dinosaurs?
time period began 488.3 million years ago and ended 443.7 years ago
Ordovician
Ordovian period
Paleozoic era
live in a cup called a calyx. The septa are radially aligned ridges or grooves. Extinct.
Rugose Corals (horn Corals)
