Lab 9- History of life Assignment (2) (1) (1)
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Lab 9- History of Life and Geologic Time
GEOL 1122
Watch all iCollege videos and use the handout to answer these questions, plus the questions in the PowerPoint file.
Learning Objectives
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Understand how geologists divide geologic time
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Understand what environments on Earth preserve geologic history and how we use them to piece together the history of Earth
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Learn major events in geologic time and how they have driven the evolution of life
Part 1: Depositional Environments (handout)
1a) Ancient remains of corals and clams were found in limestones across Kansas. What does this
indicate about the paleoenvironment of that area? (1 pt)
With corals and clams found in limestones, this could indicate that this paleoenvironment could be from marine and shallow sea origins. b) The limestones contained shattered and broken shell fragments. What might this indicate about the energy of that paleoenvironment? (1 pt)
This could indicate that the energy of the paleoenvironment was extremely high. 2a) How does coal form? (1 pt)
Coal is formed through the deposition of plants and other organic matter, b) What does the appearance of coal indicate about an area's paleoenvironment? (1 pt)
The appearance of coal indicates that the paleoenvironment has a terrestrial area because coal is typically formed from the deposition of terrestrial plants. c) What fossils might you find represented in coal deposits? (1 pt)
Most likely plants since that's how coal forms. Part 2: Geologic Timescale (handout)
3) What percent of geologic time does the Precambrian represent? (1 pt)
About 88% of geologic time does the Precambrian represent.
Part 3: History of Life (handout and videos)
4a) This is a stromatolite fossil. Based on the eon you identified when stromatolites firs appeared, why were stromatolites so important for the development of other organisms and Earth as a habitable planet? (Hint: Think about how they lived via photosynthesis). (1 pts)
Stromatolites were important for the development of other organisms because they produced a lot of oxygen and were a leading mechanism for future organisms.
b) What does the discovery of these fossils tell geologists about the depth of paleoenvironments in which stromatolites were formed? Explain your reasoning. (2 pts)
The discovery of these fossils provided geologists with a more accurate timeline of paleoenvironments. 5) Did dinosaurs and humans co-exist on Earth? Explain your reasoning. (1 pt)
No, dinosaurs and humans did not co-exist on Earth. Dinosaurs became existed around 65 million years ago while humans only started existing around 7 million years ago. The timing doesn’t add up. 6) Plants invaded land before animals. Why might the colonization of plants be important as a precursor to animals on land? (1 pt)
The colonization of plants is as important as precursors to animals on land because of the oxygen
they provide as well as their ability to become food for those animals. 7) Did mammals co-exist with dinosaurs? If so, how and why did the extinction of dinosaurs affect the evolution of mammals in the era following that extinction? (2 pts)
Unlike humans, mammals did co-exist with dinosaurs. Those mammals became prey for the dinosaurs, which delayed their evolution and ability to grow in masses, so when the dinosaurs stopped existing, those ancient animals were able to finally adapt and change. 8)
This is a fossilized Archaeopteryx.
a)
In which era did it appear? (1 pt) This fossilized Archaeopteryx appeared in the Mesozoic era. b)
Why is it important as a fossil that “links” change between different groups of organisms? (1 pt)
A fossil that link change between different groups of organisms are important because they show
geologists the timeline of life, and can be able to detect where some organisms share common traits which can help understand how organisms went through evolution. c)
Using this recreation of Archeopteryx
, what evidence can
you see that relates to this connection? (1 pt)
An archeopteryx looks like a mix between a bird and a dinosaur. The wings have feather-
like covering just like modern-day birds, however, its head/beak area is very dinosaur-
looking. The claws are also very reptile looking as well as its long tail. 9) Archaeopteryx
is preserved in a lagerstätten deposit in Germany. What is a lagerstätten? Name another similar deposit from the Paleozoic that contains evidence of diverse early multi-
cellular life. (2 pts)
A lagerstätten is a type of deposit that contains extremely well-preserved fossils. Another similar
deposit from the Paleozoic era is the Burgess Shale.
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10) This is an artist’s rendition of Tiktaalik
. What features does the organism possess and what does that provide evidence for with respect to evolution? (2 pts)
The Tiktaalik has very similar facial features to many amphibians and has many different features that are very fish-like as well as land animals. The fins that this organism has are long enough to touch the floor which gives off the idea that the organism is walking. The thin, slim body is very fish-like with the addition of the singular fin at the end. 11) The Precambrian has fewer fossils preserved in the fossil record than later eras. Explain why
there are fewer fossils from the Precambrian era. (1 pt)
The reason why there were fewer fossils from the Precambrian era was because there were more softer organisms living during this time which didn't fossilize as well as harder organisms. 12) Pollen grains are sperm-carrying reproductive bodies of seed plants, such as angiosperms (flowering plants). The last row on the era ID chart displays a pollen fossil. What sort of information might fossil pollen provide about paleoenvironments? (1 pt)
Pollen grains help provide the climate at the time, and the timeline/period and give hints to any of the other life that was living around the same time and area. 13) The Cenozoic was characterized by many ice ages. List geologic changes that contributed to cooling and ice ages in this era. (2 pts)
Some geologic changes that contributed to cooling and ice ages during the Cenozoic era are the shifting of plate tectonics, ocean currents, and changes in the Earth’s orbit. 14) The extinction of many large grazers, such as Wooly Mammoths occurred late in the Cenozoic. What is a possible explanation for such an extinction? Explain your reasoning. (2 pts)
They could’ve become extinct due to a lack of food or a serious change in weather that happened
too quickly for these animals to adapt. 15a) Many scientists agree that we are currently undergoing a sixth extinction. Why? What might be causes of the sixth extinction? (2 pts)
The reason why many scientists believe that we are currently undergoing a sixth extinction is because of the massive change in our climate, specifically in 2019 when climate change started
to get quite serious. Also, human-made problems such as overfishing, deforestation, or hunting is
causing many animals to go extinct. b) List 2 species that are extinct or endangered that you know of and provide an explanation for their status. (4 pts)
The two species that I chose are the Dodo and the Amur Leopard. The Dodo is extinct and has been for years. They became extinct due to habitat loss, hunting by humans, and invasive animals like rats that preyed on their eggs and babies. Amur Leopards are critically endangered because human activities like logging or infrastructure and habitat loss.