Goodbye to All That

From Biol301

• ...life is an odd thing. It couldn't wait to get going, but then, having gotten going, it seemed in very little hurry to move on.
• lichen are a partnership between fungi and algae. The fungi excrete an acid that digests the rock enough for the algae to use the minerals enough for food for both the algae and the fungi.
• ...life even at its simplest level occurs, apparently, just for its own sake.
• John McPhee demonstrates Homo sapien's youth by imagining all of time as the expanse of one arms and the mere rub of a nail file would remove us from the recent end.
• lots of change had to occur for animals to move onto land. They may have been encouraged during the time of Pangea as the coastal area would have been crowded causing increased pressure to escape predators.
• First plants moved onto land accompanied by mites and small instects.
• Probably the first mobile land animals were like wood mites and grubs.
• There was a 35% concentration of oxygen in the air back then (they know from isotope geochemistry).
• Huge amount of oxygen encouraged huge growth --over sized animals and plants indeed.
• Small (house cat size) rodent like animals came about and their small size would be their salvation when the 3rd megadynasty ended (bye-bye dinosoars) to usher in Megadynasty 4.
• 30 billion is the suggested number of species that have inhabited the earth since the beginning; 99.99% is the suggested number that are now extinct.
• Average lifespan for many species is about 4000 years (just about where we are now :/ ).
• There have been 5 major extinctions (Ordovician, Devonian, Permian, Triassic, and Cretaceous) which each wiped out at or over 70% of living species at their time; the Permian wiped out over 95%!
• It is thought that 52% of all families were destroyed by the permian extinction.
• Interesting to note that a solar flare would leave no trace of itself other than mass extinction!
• We see that it is particularly difficult to wipe out species --the KT event (aka the Manson event; a huge meteor hitting the earth) was equivalent to setting of a Hiroshima bomb for every person on earth, and then some
• The KT event probably produced sulfuric acid ridden rains and winds from the sea bottom laced with sulfur.
• KT destoryed 90% of land animals but only 10% of fresh-water living animals. Many questions to be answered about how those that survived did indeed survive.
• After KT was the perfect time to be small, warm-blooded and cautious.
• Fewer than 1k species are known from the dinosaur time. About 300 specimens have lead us to these species which makes us think dinosaurs may have been on their way out when KT occured.
• But then Sheehan meticulously sifted through Hell's Creek in Montana and came up with lots of stuff that had been passed over. He suggests that the huge amount of material they found suggests dinosoars were prevalent right up until KT.
• Four generic points:

1. Life wants to be.
2. Life doesn't always want to be much.
3. Life from time to time goes extinct.
4. Life goes on.