Lab 13 Primate Evolution

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California State University, Los Angeles *

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2600

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Anthropology

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Oct 30, 2023

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Concept Review Questions 1. Define fossil. A fossil is defined as the trace or remains of an organism preserved in rock. Fossils are formed when organic materials decay and are slowly replaced by minerals, or when impressions left by living organisms, such as footprints, are preserved. 2. Compared with living primates, ancient plesiadapiforms were more likely to have: Grasping hands and feet 3. Compared with adapiforms, omomyoids: Are usually more nocturnal. 4. Describe one trait found in Aegyptopithecus that suggests it was an early catarrhine. Narrow nose 5. I lived in Africa around 15 mya. I had bilophodont molars and a frugivorous diet. I had some adaptations for terrestrial quadrupedalism. What fossil primate am I? Victoriapithecus 6. Proconsul lived in Africa around 20 mya. It had Y-5 molars and a frugivorous diet. It also had some adaptations for arboreal quadrupedalism and was tailless. What living primate group is its closest living relative? Apes 7. What is the genus assigned to the largest primate that ever lived? Gigantopithecus 8. Which category of dating methods provides a more precise numerical age for fossil sites: relative dating or chronometric dating? Chronometric dating 9. According to the law of superposition, are deeper geological layers older or more recent than layers near the surface? Deeper geological layers are older than layers near the surface. 10.What type of material would you need to conduct radiocarbon dating? Organic material, such as bone, shell, or wood.

Exercise 1: PLESIADAPIFORMS 1. Describe at least one feature that Carpolestes shares with other plesiadapiforms such as Plesiadapis. One feature that Carpolestes share with other plesiadapiforms is having a front tooth gap that is similar to the mouth of the Plesiadapis. 2. Describe at least one feature that makes it different from most other plesiadapiforms. One feature that makes Carpolestes different from most other plesiadapiforms is grasping hands and feet. Carpolestes seem to have this trait, whereas Plesiadapis do not. 3. Do you think this new find forces us to reconsider the relationship between plesiadapiforms and primates? Why or why not? Yes, I believe that this new find forces us to reconsider the relationship between plesiadapiforms and primates because the trait of the grasping hands and feet demonstrate that there is a more recent common ancestor than the Plesiadapis. Exercise 2: ADAPIFORMS AND OMOMYOIDS 1. Which of these mystery fossils is an adapiform? Mystery fossil A is the adapiform. 2. Which of these mystery fossils is an omomyoid? Mystery fossil B is the omohyoid. 3. Describe at least two traits you used to make these identifications. (Be sure to describe how each trait differs between the two mystery fossils—for example, fossil A has this trait, but fossil B does not.) Fossil A has smaller eyes than the omohyoid, which has much larger eyes. Omomyoids also have a smaller body size than adapiforms, which can be seen in the images provided.

Exercise 3: DARWINIUS 1. Describe at least two features that Darwinius shares with living haplorhines. Two features that Darwinius shares with the living haplorhines is a short snout and a deep jaw, which are similar to apes, monkeys, and tarsiers. They both also have nails instead of claws. 2. Describe at least two features that the fossil shares with living strepsirhines. Two features that Darwinius shares with living strepsirhines are grasping hands with opposable thumbs and nails instead of claws. 3. Would you classify Darwinius as a haplorhine relative or a strepsirhine relative? Why? Seeing as Darwinius shares features with both haplorhines and strepsirrhines, I would consider it to be a relative of both. Exercise 4: FOSSIL NEW WORLD AND OLD WORLD MONKEYS 1. Which of these mystery fossils is a fossil Old World monkey? Mystery fossil A is the Old World monkey. 2. Which of these mystery fossils is a fossil New World monkey? Mystery fossil B is the New World monkey. 3. Describe at least two traits you used to make these identifications. (Be sure to describe how each trait differs between the two mystery fossils—for example, fossil A has this trait, but fossil B does not.) Mystery fossil A has bilophodont molars and fossil B does not. Additionally, mystery fossil A only has 2 premolars (which correlates to Old World monkeys) and fossil B has 3 premolars (which correlates to New World monkeys).

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Exercise 6: SIVAPITHECUS 1. Is Sivapithecus more similar to living Asian great apes or to living African great apes? Sivapithecus is more similar to Asian great apes than African great apes. 2. Describe at least two traits you used to make this distinction. The orangutan shown in the pictures appears to have similar dental adaptations for hard foods. Unlike chimps, Orangutans also have long fingers and toes, and these are similar to Sivapithecus. Exercise 7: DATING METHODS 1. Draw a star next to the oldest layer. F is the older layer. 2. Circle the youngest (most recent) layer. A is the youngest (most recent layer).

3. In layer B, you find an unfossilized bone. What chronometric dating method could you use to date this layer? For what date range would this method be appropriate? To date the fossil in layer B, I would use radiocarbon dating and it would be appropriate to date the range of 2 and 50 KYA. 4. In layer D, you find a fossilized bone. Layer C and layer E are made of volcanic rock. Given what is available at the site, what strategy will you use to determine a chronometric date for layer D? In layer D, you find a fossilized bone. Layer C and layer E are made of volcanic rock. Given what is available at the site, the dating strategy for layer D would be argon-argon dating because it would give the date of the specific layer, not just the layers around the rock.