Upward Bound Math/Science 2010
Mr. McDowell
Name:
HOMINOID SKULL COMPARISON
Introduction:
In this activity you will make detailed observations and measurements of skull casts of seven modern
and extinct hominoids. You will then use your data to determine if the extinct hominoids are more
ape-like or more human-like in appearance. Your data will also provide a basis for drawing some
conclusions about patterns of hominoid evolution.
Materials per class:
1 skull cast of each of the following: Homo sapiens (modern human), Pan
troglodytes (modern chimpanzee), (Gorilla gorilla (modern gorilla),
Homo neanderthalensis Neanderthal), Homo erectus, Australopithecus
boisei, and Australopithecus afarensis
Materials per team:
1 metric ruler
1 protractor
1 caliper
Procedure:
1. Your team will move from station-to-station as you examine the skull casts. At each station you
will find a skull, 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 “Hominoid Skull Comparison Data Table”, as you move from station-to-station.
Refer to the “Hominoid Comparison Checklist” for a description of each hominoid characteristic you
observe.
3. Using observations and data from your completed “Hominoid Skull Comparison Data Table”,
answer the analysis question on the “Analysis of Hominoid Skulls” chart.
HOMINOID 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?
a = incisors
b = canines
c = premolars
d = molars
Parallel Arcade
Parabolic Arcade
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. ANGLE OF INCISOR: Do the incisors rise vertically from the lower jaw or do they slant out?
11. 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.
12. 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.
13. 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.
14. FACIAL SLOPE: Use the protractor to measure the angle make by the face and the upper jaw when viewed from the
side.
Angle of facial slope
Length of cranium
Width of
cranium
HOMINOID SKULL COMPARISON DATA TABLE
FEATURES
A
Gorilla
gorilla
Gorilla
Modern
B
Pan
troglodytes
Chimpanzee
Modern
C
Homo
sapiens
Human
D
Homo
Neanderthalensis
Neanderthal
E
Homo
erectus
F
Australopithecus
boisei
G
Australopithecus
afarensis
Modern
30,000 YA
.4 -.5 MYA
1.8 MYA
2.9-3.6
MYA
France
1908
China
1920’s
Tanzania
1959
Africa
1975
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: # of
incisors-canine-premolarsmolars in upper jaw (ICPM)
9.Canine Diastema: gap
between upper incisors and
canines present or absent
10.Angle of Incisor:
vertical or slanted out
11.Foramen Magnum:
towards
rear or underneath
12.Width of Cranium:
maximum width of brain
case
in mm
13.Length of Cranium:
maximum length of brain
case
in mm
14. Facial Slope: the angle
made by the face and the
upper jaw viewed from side
ANALYSIS OF HOMINOID SKULLS
What evidence indicates that modern humans and the extinct hominids you examined
evolved from a common ancestor?
List and Discuss several SPECIFIC pieces of anatomical evidence that support your
answer.
Explain the significance of each piece of evidence. In other words, what function does
the anatomical feature have, and how has that function changed as humans evolved?
How does the shape and location of the anatomical feature support your answer?