Primate Evolution Virtual Lab

5.03 Primate Evolution Virtual Lab Instructions

Skull Analysis

Safety Notes:

◾Skull casts are fragile, so always handle with care.

Materials:

◾Skull casts: 4 known species and 1 unknown

◾Calipers

Purpose:

◾Observe and compare physical features of primate skulls.

◾Examine possible relationships based on the observed features.

Hypothesis:

Predict the species of your skull based on first observation, giving an explanation for your prediction.

Procedure:

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: 1.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?

2. Face: Is the shape of the face sloped or flattened and vertical?

3. 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 according to the formula: (BC/AC) × 100 = Supraorbital Height

4. Record the skull’s supraorbital height in the data table.

5. Take the same measurements for each of the skulls, recording the...