Hominoid Skull Comparison s1

YEAR 10 EVOLUTION HOMINID SKULL COMPARISON

Introduction

You are an Anthropologist in a team (ie 2 or 3) who are investigating the evolutionary relationships among living and extinct human relatives. You will work as a group to collect data for this project. It is your responsibility to keep all the data together. (This will be submitted as your rough draft.) You will use this data to write individual practical reports.

Materials per team: 1 skull cast of each of the following: 1. Homo sapiens (modern human) 2. Pan troglodytes (modern chimpanzee) or Gorilla gorilla (modern gorilla) 3. Two of : Homo neanderthalensis (Neanderthal), Homo erectus (Peking Man), Homo floresiensis (Hobbit), Homo habilis (Handy Man), Australopithecus boisei (Nutcracker Man) Australopithecus afarensis (Lucy) and Australopithecus africanis (Taung Child), Homo rudolphensis, Homo heidelbergensis.

Materials per team: 1 metric ruler 1 protractor 1 caliper Photographs, and other visuals of humans, chimpanzees, and gorillas

Procedure: PART A – Comparison of Modern Apes and Humans

Using skull casts, photographs, and other visuals of humans, chimpanzees, and gorillas, your teacher will engage you in a discussion during which you compare these modern hominids. During this discussion, you should make a list of the features these hominids share and those features that make them differ. Use “Chart 1 - A Comparison of Modern Apes and Humans” to record your observations.

Procedure: PART B – Comparing Modern and Extinct Hominid Skulls

In this part of the activity you will make detailed observations and measurements of skull casts of one modern and two extinct hominids. You will then use your data to determine if the extinct hominids are more ape-like or more human-like in appearance. Your data will also provide a basis for drawing some conclusions about patterns of hominid evolution.

1. Your team will examine the skull casts chosen. For each skull you will need a metric ruler, protractor, and caliper. A few “rules” should be followed:  Do not make pencil or pen marks on the skulls.  Be careful with the skulls. They are expensive reproductions that are breakable.  Be sure to take turns in making the measurements.  Measure in millimeters (mm). Round off to whole numbers.

2. Complete the “Chart 2 - Hominid Skull Comparison Data Table” as you examine your chosen skulls. Refer to the “Hominid Skull Comparison Checklist” for a description of each hominid characteristic you observe.

1 YEAR 10 EVOLUTION

Analysis Using observations and measurements from your completed Chart 2- Hominid Skull Comparison Data Table, answer the following question.

Question 1. Which traits distinguish modern humans from other modern apes?

Question 2. Are your chosen extinct hominids more closely related to modern humans or other modern apes such as gorillas?

Question 3. Briefly describe how the following characteristics have changed in hominid evolution from ape-like ancestors to modern humans. a. Size of cranium/brain. b. Size of brow ridge. c. Presence of sagittal crest. d. Facial prognathism (protrusion of snout). e. Size of chin. f. Facial slope. g. Size of canines. h. Dental arcade. i. Position of foramen magnum. j. Forehead shape.

Question 4. Suggest reasons for the changes you described in Question 3. Only give answers to the following (a, b, g, i, j).

Question 5. In terms of natural selection, describe how modern humans evolved a large brain from ape-like ancestors that had a smaller brain.

Question 6. Draw a phylogenetic tree that shows the position of the various hominids studied in this practical activity. (Carry out an Internet Search)

Question 7. Are modern apes ancestors to modern humans?

2 YEAR 10 EVOLUTION Chart 1 – A COMPARISON OF MODERN APES AND HUMANS

Structure Description in Modern Humans Description in Modern Apes

Hands and feet

Arms and legs

Skull/cranium/brain/face

Pelvic region

3 YEAR 10 EVOLUTION

HOMINID SKULL COMPARISON CHECKLIST

1. FOREHEAD: Does the forehead (frontal bone) look more vertical or does it slope backward?

2. CHIN: Does the chin stick out or does it recede back?

3. SAGITTAL CREST: A sagittal crest is a bony ridge that runs from front to rear on top of the cranium. Is it small, medium, large, or absent?

4. FACIAL PROGNATHISM: How much does the snout protrude when looking at the skull from the side? Is the protrusion large, medium, small or absent?

5. BROWRIDGE: The brow ridge is a heavy mass of bone directly over the eye orbits. Rate it large, small, medium.

6. DENTAL ARCADE: This refers to the shape of the arrangement of the teeth in the jaw when looking directly at the chewing surface of the teeth. Does the arrangement form a parabolic (rounded) shape with a relatively continuous outward curvature or is the arrangement rectangular with the premolars and molars in parallel rows?

7. CANINE TOOTH: What is the length in millimeters of the exposed part of the upper canine tooth?

8. DENTAL FORMULA: Record the number of incisors, canines, premolars and molars present in the upper jaw. (ICPM)

9. CANINE DIASTEMA: Is there a gap present on the upper jaw between the canines and incisors?

10. FORAMEN MAGNUM: The foramen magnum is a large opening in the back or bottom of the skull through which the spinal cord enters the cranium. Determine if it is more to the rear or towards the bottom of the skull.

11. WIDTH OF CRANIUM: Use the caliper and ruler to determine the maximum width of the brain case. Measure from temple-to-temple and record your answer in millimeters.

12. LENGTH OF CRANIUM: Use the caliper and ruler to determine the maximum length of the brain case. Measure from the forehead to the back of the skull.

13. FACIAL SLOPE: Use the protractor to measure the angle make by the face and the upper jaw when viewed from the side.

4 YEAR 10 EVOLUTION CHART 2 - HOMINID SKULL COMPARISON DATA TABLE

A B C D FEATURES Modern Modern Extinct Extinct Human Ape Hominid 1 Hominid 2

Scientific Name of Chosen Specimen

Age of Specimen

Location and Date of Fossil Discovery

1.Forehead: more vertical or slopes back

2.Chin: sticks out or recedes back

3.Sagittal Crest: large, small, medium or absent

4.Facial Prognathism: (snout protrusion) large, small, medium, absent

5.Browridge: large, small, medium

6.Dental Arcade: rows of molars parallel or parabolic

7.Canine Tooth: length of exposed upper canine tooth in mm

8.Dental Formula: number of incisors-canine-premolars-molars in upper jaw (ICPM)

9.Canine Diastema: gap between upper incisors and canines present or absent

10.Foramen Magnum: towards rear or underneath

11.Width of Cranium: maximum width of brain case in mm

12.Length of Cranium: maximum length of brain case in mm

13. Facial Slope: the angle made by the face and the upper jaw viewed from side

5 YEAR 10 EVOLUTION