GEOSC 10 - ROCK ON #11

You are a famous scientist, renowned for the well-accepted idea you developed over the last 15 years. A new idea suddenly appears from some upstart junior scientist. For the new idea to overthrow your well-accepted idea and gain widespread scientific acceptance, what must happen?

The new idea must explain the things that your old idea explained, and do a better job than your old idea in predicting the outcomes of many new experiments designed by various people to test the ideas.

The extinction of many types of dinosaurs occurred about:

65,000,000 years ago. FEEDBACK: Humans were trotting around 65,000 years ago, and met dinosaurs only in The Flintstones. 650,000 years is barely enough time for evolution to have changed large animals a bit, and although 6,500,000 years is enough time for noticeable change of large animals—increase in maximum size of members of the horse family, for example—the huge changes since the dinosaurs needed 65,000,000 years. 650,000,000 years goes back before any land creatures, and before all but the simplest of multi-celled organisms.

The picture above shows:

A right-side-up dinosaur track. FEEDBACK: This is a dinosaur track, from dinosaur ridge, and the dinosaur stomped down into the mud, so the track is right-side-up.

What cause probably was not important in contributing to extinction of most species on Earth, including the dinosaurs, in a very short interval of time at the end of the Mesozoic Era?

Cold from the change in Earth's orbit caused when the meteorite shoved the planet farther from the sun. FEEDBACK: Robert Frost once wrote "Some say the world will end in fire, some say in ice". For the dinosaurs, both were probably true, with acid thrown in. But the meteorite was not nearly big enough to change the planet's orbit noticeably. Frost went on "From what I've tasted of desire, I hold with those who favor fire, But if it had to perish twice, I think that for destruction ice, Is also great, and would suffice."

Considering long-term averages, and assuming that we don't deploy space-based defenses against incoming meteorites, a reasonable estimate of the chance of an average U.S. citizen being killed by the effects of a meteorite or comet impact is that this risk is about the same as the chance of being killed by:

Crash of a commercial airplane. FEEDBACK: Nobody that we know eats Pepsi cans, and while there are still meteorites in the solar system that can hit and kill, there are no dinosaurs left except on "The Flintstones". A reputable study found that a meteorite impact might not occur for millions of years (or might occur next year...) but then might kill billions of people; plane crashes usually kill a few to a few hundred each year. Add up the deaths over a sufficiently long time, and plane crashes and meteorite impacts likely are similarly dangerous. But car crashes, smoking, and being fat and lazy are way more dangerous to us.

Evolution produces new types, and extinction gets rid of them. The scientific evidence summarized in the text and in class shows that:

Evolution and extinction are usually more-or-less in balance, but occasional mass extinctions reduce biodiversity, and subsequent evolution faster than extinction increases biodiversity until a new balance is reached. FEEDBACK: Numerous extinctions have occurred over the history of the planet, but extinctions have been especially rapid during the short "mass extinctions" including the one that killed the dinosaurs. After mass extinctions, evolution fills the empty niches, increasing biodiversity back to a more-or-less stable level.

Evolutionary theory is used in the real world for:

Fighting diseases, and in other practical ways including guiding some techniques in computer science. FEEDBACK: As antibiotic resistance appears in disease organisms, evolutionary biologists are helping doctors find better strategies to keep us healthy. The processes behind evolution—try new things, keep the ones that work, repeat—has been used intentionally for guidance in many human endeavors, including "evolutionary computing" in computer science. Ecologists trying to rescue ecosystems are informed by understanding of the evolutionary processes that made, and are changing, those ecosystems. Even regulations for sport fishing are guided by our understanding of evolution. In the same way as other successful ideas in science, evolution is useful in many practical ways in the real world.

Which of the following is not part of the evidence that the odd layer marking the extinction of the dinosaurs was caused by a large meteorite impact?

High concentrations of silica found in the layer. FEEDBACK: We have seen several times that silica is very common, so its presence in a layer would not indicate much of anything. Features really observed in the layer that are associated with meteorites but not common elsewhere in rocks include shocked quartz from the impact, soot from wildfires, iridium from the meteorite, and a giant-wave deposit because the meteorite hit water as well as land at the edge of the Yucatan Peninsula.

The pictures labeled I and II show fossils from a sediment core collected from the floor of the Atlantic ocean, east of South Carolina. The sediment has not been disturbed by landslides or mountain building or other processes. The pictures were taken by Brian Huber, of the Smithsonian Institution, using a scanning electron microscope. The two samples in the sediment core were separated by the unique layer marking the extinction that killed the dinosaurs.Which is correct?

I is older than the unique layer, and thus sat below the unique layer in the sediment on the sea floor. FEEDBACK: Before the impact, biodiversity was high, as shown in I, which includes fossils from below the unique layer and thus deposited before the meteorite hit. After the impact, most of the living types were killed, giving rise to the limited diversity seen in II from above the unique layer after the impact.

Which of the following is part of the modern theory of evolution?

If a reproductive "experiment" is successful, it will be passed to more and more children in successive generations until all members of a population have it. FEEDBACK: No matter how hard you and your friends wish that your children will be born with the ability to fly unassisted, the kids will have to use airlines like the rest of us. You can get a tattoo without worry that your children will be born with that same tattoo. A hopeful monster would have no one to mate with. And while sometimes bigger or more-complex kids do better, sometimes smaller or simpler ones do better. But, a successful reproductive "experiment" is one that is passed to more and more children in successive generations, and all members of a population are likely to have that successful experiment sometime in the future.

Reasons why fossils of transitional forms are missing in some lineages that humans especially care about include:

Rapid evolution often occurred in small populations, and fossilization is less likely in smaller populations. FEEDBACK: Although more searching could be valuable, lots of scientists have looked for transitional forms, which are expected based on evolutionary theory. The common occurrence of transitional forms in commonly fossilized types shows that "Ford-Mustang-type" catastrophism did not occur, but the data also show that evolution often occurred rapidly in small, isolated populations that are hard to find, and that might not be fossilized in rarely-fossilized types.

Sometimes, people with scientific backgrounds say bad things about religion, and sometimes people with religious backgrounds say bad things about science. This is because:

Religion and science do not need to disagree, but sometimes science-background and religion-background people choose to disagree.

There are many large mammals on Earth today. This is because:

Small mammals were not able to outcompete the dinosaurs for big-animal jobs, but after the dinosaurs were killed, some large mammals evolved from small mammals to fill the large-animal jobs. FEEDBACK: There are "big-animal" jobs—eating tall trees, eating smaller animals, etc. But the total number of big-animal jobs is limited. The dinosaurs filled the big-animal jobs before mammals really got going, and mammals were not able to displace the dinosaurs. Some small mammals survived the meteorite that killed the dinosaurs, and then evolved to give big mammals over millions of years and longer. There were almost no big mammals before the dinosaurs were killed off, volition has nothing to do with evolution, and running away doesn't avoid acid rain.

In Pennsylvania today (or at most other places on the world's land surface):

The land surface is accumulating sediment in a few small places, building up records of geologic history, but most places are eroding. FEEDBACK: Today in Pennsylvania (and across most of the land surface of the planet), sediments are accumulating in a few human-made lakes, a few natural wetlands or natural lakes, along some streams and in some caves, but almost everywhere else is eroding. This is the typical state of affairs, so you need to correlate events across large regions to get a good geologic record.

Araucarioxylon arizonicum was a beautiful tree of the Mesozoic, and is the most common tree found fossilized in Petrified Forest National Park. A spectacular specimen is shown above.Based on the discussions of evolution in the textbook and lectures, it is likely that:

Trees alive today are related to Araucarioxylon arizonicum, but even those modern trees most similar to Araucarioxylon arizonicum are recognizably different from it. FEEDBACK: Evolutionary theory indicates that living things change from generation to generation, but that all living things are related. Consistent with this, Araucarioxylon arizonicum is recognizably similar to, yet different from, Araucaria trees such as monkey puzzle that are native to southern South America today.