Answer to Question 1After the Permian extinction, roughly 50 of all marine invertebrate families and about 90 of all
marine invertebrate species were extinct. Scientists think global warming caused the ocean to become
highly stratified. Since there was little or no circulation of oxygen-rich surface waters into the deep
ocean, deep-water organisms died out. Stagnant waters covered the shelf region, causing shallow water
organisms to die out. Widespread volcanism also added carbon dioxide into the atmosphere, causing
climatic instability and ecologic collapse.
Answer to Question 2ANS:Transgressing
seas opened up environments that allowed marine organisms to evolve into new species
and increase their numbers. During the following regression, environments would be lost, and there
would be a mass extinction of many invertebrate species. The mass extinction was then followed by
transgressing seas and a rediversification of species and an increase in numbers. The life forms did not
always come back in the same way; for example, large organic reefs that were common in the early
Paleozoic were replaced by small patch reefs in the Late Paleozoic.
The Passenger Pigeon—a Recent Extinction Example
Carrie Mae Weems, A Negroid Type, from the series From Here I Saw What Happened and I Cried.
The sensing wire in a typical hot wire mass air flow sensor.
There has been a widespread loss of glacier mass globally
Acquisition and Extinction of a Salivary Response
For toluene (shown below), you would expect to see which m/z fragment in the mass spectrum?