Name:______Period:___
Background: One of the pieces of evidence for evolution is looking at bones of living things to see if there are similarities or differences. This can tell us if there have been changes in organisms and to see the relationships of living things. In this lab you will be comparing replica models of various hominid skulls and looking for these similarities and differences through measurement and observation. You will be introduced to many new terms that will be explained in the procedure section. This is your chance to become an anthropological expert!
Materials (These will be at each station): rulers, scratch paper, calipers, and a protractor.
Procedure:
1. Use your chronology lab that we have previously done to help you.
2. There are five stations with a total of seven skulls. You do all of them! Fill in your data table as you go. PLEASE BE CAREFUL WITH THE SKULLS! IF YOU BREAK THEM OR DRAW OR WRITE ON THEM YOU WILL REPLACE THEM!
3. Follow the hominid checklist as you look at each skull. There are 11 items you need to look for on each skull. Read each item! It describes exactly what to do! All of the skulls are numbered.
4. Answer the questions after you have looked at and measured each skull.
Post Lab Questions:
1. How are the skulls different? Similar? Explain.
2. Do you see changes though time in the skulls? Is this a piece of evidence for evolution?
3. List in order from oldest to most recent the names of the species of each skull.
4. Of the skulls you examined, which are now extinct? Still alive?
5. By looking at the teeth of the skulls, could you make a guess as to what they may have eaten or what they eat? List four examples.
HOMINOID SKULL COMPARISON CHECKLIST
First fill in the name of each skull on your data chart. Then follow the checklist below to fill in the characteristics of each skull on the data chart. Record all measurements in millimeters!
1. Forehead: Does the skull extend above the eyes? Is the forehead large, small, or medium?
2. Chin: How pronounced is the chin? Does it stick out like yours or slope back?
3. Zygomatic bone: This is the cheekbone on the skull to which large chewing muscles attach. Are there Zygomatic bones? Is it large, small, or medium?
4. Prognathism: Examine the skull for existence of a "muzzle" or snout - a protrusion of parts of the face below the eyes. Gorillas (and dogs) have pronounced prognathism. Humans do not.
5. Facial slope: Use a ruler and protractor to measure the angle of the face as shown in diagram below.
6. Supraorbital browridge: Look for a bony ridge protruding above the eyes. Large, small, or medium?
7. Dental arcade: The arch, or shape of the jaw will be either box shaped (sides parallel), "U"-shaped
(parabolic sides), " V " -shaped, or intermediate.
8. Canines: The canine is the third tooth from the center of the top and bottom jaw. Describe them. Are they long, or short, sharp, or dull? Is there a diastema present (a gap between the upper incisors and canines)?
9. Foramen magnum: This is the large opening in the base of the skull through which the spinal cord passes. The position of this hole reflects the body posture (and indirectly the locomotor pattern) of a hominoid. Is the foramen magnum located toward the rear or more forward?
10. Number of teeth: Top/Bottom: Count the number of teeth in the upper and lower jaw. Record number of incisors: canine: premolars: molars in one-half of the upper jaw as the numerator and the same count for one-half of the lower jaw as the denominator.
11. Cranial Module: Calculating the cranial module provides a rough numerical value for the size of the cranium. 1. Measure the maximum length by placing one end of a caliper on the most forward projecting point of the forehead and the other end on the most posterior point at the back of the skull. 2. The maximum width is determined with the calipers on the sides (temples) of the skull at the widest point. 3. The maximum height is measured by putting the skull on its side; then hold one end of the calipers on the midpoint of the anterior of the foramen magnum and the other end at the intersection of the coronal and sagittal sutures on top, in the midline. Add these and divide by 3: