Lab Quiz 4

a plaque titled "Lake Pit: Buried Oil Makes Great Goo". Why is there a "lake" here? Where are those smelly bubbles in the water coming from?

- a pit left over from asphalt mining operations in late 1800s - bubbles are of methane, a colorless and odorless gas, and hydrogen sulfide

What was the diet/foraging behavior of Mastodons? and what type of teeth do they have?

- diet of twigs and leaves - pointier teeth

What chemical compounds are responsible for the bubbles, and how do they form?

- methane and hydrogen sulfide - forms with crude oil when marine organisms break down due to heat & pressure

How did the California Saber-Toothed Cat take down its prey? How is this different from modern cats, such as the African Lion?

- modern cat -> African Lion: attacks neck/throat of prey - saber-tooth cat: pulled down prey, stabbed unprotected soft underside

How much time does it typically for fossil excavators to extract all the fossils from one 3 ft cube of sediment/tar? What does this tell you about the concentration and number of fossils found here at the Tar Pits?

- takes about 1 month - the concentration is high because they've found up to 1,000 fossils from a single chunk

Why do you think there is an overrepresentation of birds of prey at La Brea, instead of other types of birds? What is drawing these birds to the pits (and to their eventual demise)?

- the case of the birds of La Brea is unique because bird bones were surrounded by protective coating of tar and were preserved well - over 100 species of bird found - 3,000 = birds of prey ---> probably nested near the pits or were attracted to animals caught in tar

What is ONE mammoth behavior the sculpture depicts that contradicts what the science tells us? What is the scientific evidence that informs us of this contradiction?

- the sculptures show a mammoth family consisting of a male (standing), a baby, and a female (becoming trapped in tar) - scientists believe columbian mammoths lived in female-led herds, with adult males living apart except for mating season. Asian elephants live this way now.

What is precession?

- the slow change in the direction in which Earth's axis tilts - the revolution of a planet in its orbit around the sun

describe the geologic process of the La Brea Tar pits

1) large oil field lies 1,000 feet below 2) pressure forces oil field through cracks in overlying rocks 3) asphalt form shallow pools when it reaches surface. Animals and plants may be trapped

The eccentricity of the Earth's orbit follows a long ________________ year cycle.

100,000

The precession of the Earth follows a _______________ year cycle.

20,000

The Earth's tilt is currently _______ degrees.

23.5

The obliquity of the Earth's orbit follows a _________________ year cycle.

41,000

Beyond the sheer number of fossils, what are some of the new fossil finds that make Project 23 so unique?

baby animals!

List three greenhouse gases:

carbon dioxide, methane, water vapor

Compare the daily dietary intake (in pounds) of adult Columbian and Pygmy Mammoths. Why do you think Columbian Mammoths were unable to exist sustainably on the Channel Islands?

columbian ---> 500 lbs food/day pygmy ---> 50 lbs food/day - unable to exist due to limited food

Name one current project that fossil preparators are working on, what scientific information that project is hoping to uncover.

currently working on repairing partial rib of Paramylodon harloni (harlon's ground sloth)

How is the columbian mammoth tooth different from that of a Mastodon?

curved tooth, bigger

the 3 movements of milankovitch are

eccentricity, axial tilt, and precession

List 3 extinct animals and 3 extant animals that are found at the La Brea Tar Pits.

extinct: California condor, camel, western horse extant: mountain lion, coyote, deer mouse

List 3 small fossils found at Pit 91 and what each fossil tells us about the environment in Ice Age L.A.

fossil 1: rainbow trout bones ---> streams once flowed here all year long fossil 2: Monterey cypress cones ---> lived only when cool & rainy so it was cold and wetter back then fossil 3: jaw of a fence lizard ---> still alive today

What evidence do the short-faced bear fossils at La Brea preserve that indicate it may have eaten plants, in addition to meat?

had cavities which could indicated starch (from plants) in their diet

How can plants be used as a proxy for temperature?

high CO2 ---> low stomata density low CO2 ---> high stomata density

What chemical compound is responsible for that "rotten egg" smell?

hydrogen sulfide

what is climate?

is the average of weather in a given location over many years (at least 30 years). So, regardless of weather, it's safe to say that the climate of Antarctica is much cooler than the climate of a tropical island. Similarly, hot days are quite typical of summer in many regions of the world, even without the effects of global warming. Climate is fundamentally more predictable than weather.

what is weather?

is the sum of events that happen every second in our atmosphere including temperature, rainfall and wind. Perhaps it is dry and sunny today where you live, but just upstate it is cloudy, raining or even snowing. Weather is chaotic, which means that it cannot be forecast very far into the future.

Given the locations of the fossils, and given your prior knowledge of the geology of the La Brea Tar Pits, what was the depositional energy in pit 91?

medium

Is the "tar" in the Tar Pits actually Tar? How does this substance form?

no, it's asphalt left over after crude's oil lighter elements have evaporated

you reach the fenced-off area containing Project 23. If you're lucky, you'll be able to see actual fossil excavators working through blocks of sediment contained in the wooden crates! Do you think this is normally how paleontologists find fossils in the field? Why or why not?

no, usually requires much more research & investigation but here they got lucky to find so many fossils. They also won't have much help from carpenters and volunteers as other paleontologists.

On the fence surrounding Pits 3, 4, 61/67 is a plaque titled "Tar seeps form Ice Age time capsules". You will learn that Pits 3, 4, and 61/67 are all different ages. Name one fossil from of each of these pits that showcases the changes in flora and fauna that occurred over the past 55,000 years at La Brea.

pit 3: juniper tree fossil pit 4: saber-toothed cat bones pit 61/67: dog

What is a major trait that Ice Age animals still alive today have in common? How would this trait make these animals more likely to survive extinction?

small-bodied animals had a better chance of surviving

Along the way to Stop 4, you may notice that there are neon cones placed seemingly randomly around the grassy areas of the park. Why do you think those cones are placed there? Did the park's maintenance crew just forget to take some of them back, or is there something larger (and more interesting) going on here? Knowing what you now know about the geologic processes in this area, what do you think these cones are warning visitors about?

tar oozes up in different places so the cones are there to warn people not to step in that area

A Milankovitch cycle is related to

the Earth's orbit around the Sun.

Given what you have learned so far in class, how do you think the fossils and data at La Brea would be helpful in assessing how plants and animals alive today respond to future changes in climate (e.g. global warming)? Explain your reasoning.

the extinct animals' relatives might have same response that they did in a climate change

What organisms do scientists use to obtain o18O? why?

the shell proxies to get ratio of 18o/16o of past oceans

What evidence do we have that suggests that Antique Bison were only seasonal visitors to the La Brea Tar Pits when they were alive?

there are only certain ages found of bison evidence. There are a bunch of gaps that are missing which indicates they were seasonal visitors

If the obliquity were zero degrees what would happen to the seasons?

they wouldn't exist

Chinook winds (snow eaters) are

unseasonably warm winds that can cause extreme increases in temperatures within a few hours. As these winds move east, they rise over the western slopes of the mountains then descend, becoming extremely dry and much warmer. Temperature change caused by the Chinook winds is so drastic, sometimes warming as much as 40 degrees in a matter of minutes causing snow to literally vanish.

which greenhouse is the most abundant?

water vapor

Mammoths, mastodons, and elephants only have how many teeth on their lower jaw?

ONE

How do the precession and eccentricity affect climate?

Precession determines timing of Seasons relative to the position of the Earth eccentricity Along its orbit around the Sun

What is eccentricity?

The shape of Earth's orbit around the sun

What is obliquity?

The tilt of the Earth's axis that controls season extremes

Why should we care about climate change?

We care about our loved ones, careers, material things, and living a purposeful, successful life. Yet, all the things we care about most are at risk as the world gets warmer. As Earth heats up, people across the globe are experiencing more intense rainstorms, severe droughts, powerful tropical cyclones, and extreme heat waves. Unless we act, it gets worse

What do the three most commonly- found fossil animals at Pit 91 have in common in terms of diet?

all carnivores