5.03 Biology or English Thing PDF

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5.03 Primate Evolution - Skull Analysis Virtual Lab Report Instructions: As you complete each slide of the Skull Analysis Virtual Lab Activity, please fill in this lab report with the appropriate information and data. Title: Identifying an Unknown Skull Objective(s): Observe qualities of skulls of several different species in comparison to the unknown skull. Hypothesis: If the unknown skull and the skull of the Australopithecus afarensis have the most in common, physically, then the unknown skull shares the most recent ancestor with Australopithecus afarensis out of all of the other skulls. Variables: Independent: The qualities of the known skulls. Dependant: The species classification of the unknown skull. Control: The species and qualities of the known skulls.

Materials: ● Skull casts: 4 known species and 1 unknown ● Calipers Procedures: Qualitative Observations: 1. Line up each of the skulls on the lab table, facing to the left, with the Frankfurt planes parallel to the ground. 2. Observe each skull from the side, recording your observations about the following features (use the table below to record your observations): A. Forehead: Is the angle of the forehead sloping or more vertical? Is the brow ridge above the eyes small, medium, or large? Does the forehead extend out above the eyes? B. Face: Is the shape of the face sloped or flattened and vertical? C. Teeth: Are the teeth long or short? Sharp or dull? 3. Observe each skull from the bottom view and locate the foramen magnum. This is the hole that connects the brain stem to the spinal cord. Record your observation of the location of each skull’s foramen magnum. Is it located toward the front or the rear of the skull? 4. Observe each skull from the top and record your observations of the shape of the brain cavity. Is it more round or oval? Are the edges more squared off or pointed? Make comparisons between the skulls. Quantitative Observations: Determine Supraorbital Height 1. Use the calipers to measure the distance AC (from point A to point C on the skull). 2. Use the calipers to measure the distance BC (from point B to point C on the skull). 3. These measurements will be used to calculate the skull’s supraorbital height index according to the formula: (BC/AC) × 100 = Supraorbital Height Index (note: The unit of measurement is SHI.) 4. Record the skull’s supraorbital height index in the data table. 5. Take the same measurements for each of the skulls, recording the supraorbital heights index in the data table.

Data and Observations: Create a data table to record your observations and measurements for each skull: Skull

Forehead

Face

Teeth

Foramen Magnum

Brain Cavity

Supraorbital Height (SHI)

Pan troglodytes (modern chimpanzee)

Vertical

Sloped

Long dull

Rear

Oval

.549

Homo sapiens (modern human)

Vertical

Vertical

Short, dull

Front

Round

.677

Homo erectus (extinct hominid)

Sloped

Vertical

Short, dull

Front

Oval

.619

Australopithecus afarensis (extinct hominid)

Sloped

Sloped

Long, sharp

Rear

Round

.532

Unidentified Fossil Skull

Sloped

Sloped

Short, dull

Rear

Oval

.514

Conclusion: Answer the following in complete sentences: ● Was your hypothesis correct? Which of the four species does the unidentified skull most resemble? Predict how you think it may relate to the other species in terms of evolution. Justify your answer with specific observations. My hypothesis was correct. Australopithecus afarensis is the most similar to the unidentified skull. Their SHI is the closest, and their forehead, face, and foramen magnum results are the same. ●

How do the shapes of the face, forehead, and teeth differ between the various species?

The skulls of species that have lived recently have a more vertical forehead, foramen magnums that are near the front, vertical face, and shorter, duller teeth. Questions: Answer the following questions in complete sentences: 1. What do you think accounts for these differences? How might some of these differences be possible adaptations? Since the first primates, we have been drifting from reliance on smell and more toward reliance on eyes and brain power. This means that faces have become more flatter, recently, because we no longer need large noses. Instead, the cranial skulls expand, to be able to hold more brain matter and therefore, becomes more capable of powerful thought processes. 2. In what way do you think the location of the foramen magnum relates to the movement of each species?

If the foramen magnum is closer to the front of the skull, it indicates that the species was bipedalism or at least that the species had a more upright posture. This is due to the center of mass shifting toward the median of the body. 3. What might the shape of the skull and the supraorbital height tell us about each species? The larger the skull and SHI, the more brain matter a species could hold. This indicates more intelligence than a species with smaller skulls and SHIs....