Hominid Skull Lab
David Pierce
Group Members: Jacob Sher, and Daniel Roberts
Mr. Guzzi
Period 6
Started: 3/15/10
Submitted: 3/25/10
Purpose:
The purpose of this lab was to see the evolutionary relationships of human relatives, by
looking at skulls of living and extinct relatives. While looking at the different skulls,
measurements were to be made of certain parts of each skull and the data was to be collected.
When the data was complete, it would be used to create a Phylogenetic Tree.
Materials:
Primate Skulls, ruler, calipers, protractor, human evolution chart, calculator, and computer with
Microsoft Word and Excel.
Procedures:
1. Forehead: The forehead is the part of the skull that extends vertically above the eyes area.
This was measured in relative terms. These terms were absent, small, medium, and large.
The forehead was measured by using the human forehead picture provided in the Humans vs.
Apes handout. The human forehead would be an example of a large forehead, so therefore
measurements were based off of that principle. If the skull did not extend above the eyes the
forehead was classified as absent.
2. Chin: The chin is a protrusion from the bottom of the jaw.
The four categories for
measurement were absent, small, medium, and large. Similar to the forehead, the chin was
also measured by comparing the specimen’s chin to the human chin. Humans have very
large chins, and therefore, a human’s chin would be classified as large. However, an ape’s
chin would be absent.
3. Sagittal Crest: The Sagittal Crest is a pointy obtrusion on the top of the skull to which
chewing muscles attach. The Sagittal Crest was measured by observing the definition of and
the size of the crest at the top of the skull. If the Sagittal Crest protruded outwards and
resembled a Mohawk, then the specimen would have a large Sagittal Crest. If the head was
rounded and had no protrusions, then the Sagittal Crest would be absent. Measurement terms
for the sagittal crest were absent, small, medium, and large. Humans have an absence of a
Sagittal Crest, while apes have a large Sagittal Crest.
4. Prognathism: The prognathism is a snout on the skull or a large protrusion around the nose
and mouth area. The prognathism was measured by seeing how much the face sloped into
the snout. The ape, for example, had a large and exceptionally pronounced Prognathism. On
the other hand, a human has no snout; so therefore, the Prognathism was absent. The four
categories for measurement were absent, small, medium, and large.
5. Facial Slope: The facial slope is the angle of the face from the bottom of the upper teeth to
the top of the skull. Facial Slope was measured using degrees. A ruler was laid flat against
the face and a protractor was placed on the side of the head. Then whichever degree lined up
with the ruler was the measurement. Humans have a nearly ninety degree facial slope, while
apes have a more gradual, less steep Facial Slope.
6. Supra-orbital Ridge: The Supra-orbital Ridge is the part of the skull in some animals that
protrudes from the head above the eyes. The Supra-orbital Ridge was measured by
comparing human and apes’ skulls to the specimen. For example the human has no Supraorbital Ridge, so the Supra-orbital Ridge would be absent. Furthermore the Supra-orbital
Ridge was large in apes, so an ape would be classified as large. The four categories for
measurement were absent, small, medium, and large.
7. Dental Arcade: The Dental Arcade is the alignment of the last three teeth in the mouth. The
Dental Arcade was measured by seeing if the three back teeth on both sides were parallel to
each other. Humans, for example, have non-parallel teeth, while apes have “U” shaped
alignment. The description for this was either V-shaped (non-parallel) or U-shaped) parallel.
An intermediate rating could have been granted, if the alignment was in between.
8. Canines: Canines are the third teeth from the center of the mouth, whose purpose is to bite or
tear. The Canines were measured by looking at the size of the Canines and their flatness. If
a Canine was flat, it would be dull. If the Canine was sharper and in a v-shape, it would be
sharp. Additionally if the Canine was large, than it would be classified as large. However if
the Canine was small, it would be classified as small. The descriptions were small or large
and flat or dull. Human canines are small, yet sharp. Apes have larger, duller canines.
9. Molar width: Molar width is the measurement in centimeters of the last molar on the upper
jaw. Molar width was determined by taking the ruler/caliber tool to measure the width of the
top-right and farthest back molar. Human Molars are relatively small in width. Ape Molars
are generally larger in width, due to their greater need to grind items in their diet.
10. Number of teeth: The number of teeth is the amount of teeth each hominid had. The number
of teeth was calculated by adding both the teeth on the top and bottom. Adult humans have
32 teeth. Apes also have 32.
11. Cranium Volume: Cranium Volume is the measurement of the capacity of each skull. The
cranium volume was measured by taking the length at the widest point, height at the smallest
point, and width at the thinnest point. Human’s have a larger Cranium Volume than apes.
Data Chart:
Specimen
Name
Gaston
Forehead
Small
Chin
N/A
Sagittal
Crest
Absent
Prognathism
Small
Facial
Slope
70°
Supraorbital
Ridge
Medium
Dental
Arcade
U-shaped
Canines
N/A
Molar
# teeth
Cranium
Cranium
Width
top/bottom
L,W, H
Volume
1.3 cm
Top: N/A
12.9 cm
686.28 cm3
Bottom: N/A
7 cm
7.6 cm
Beast
Small
N/A
Small/
Large
69°
Medium
U-shaped
N/A
N/A
Absent
Top: N/A
12.5 cm
Bottom: N/A
7.4 cm
832.500 cm3
9 cm
Belle
Small/
Small
Absent
Medium
66°
Medium
U-shaped
Absent
Large and
1.2 cm
Dull
Top: 16
12.5 cm
Bottom:16
6.6 cm
734.250 cm3
8.9 cm
Lumiere
Small/
Small
Absent
Medium
71°
Large
Intermediate
Absent
Small and
1 cm
Dull
Top: 14
12.5 cm
Bottom:12
8.5 cm
903.125 cm3
8.5 cm
Mrs. Potts
Absent
N/A
Large
Small/
75°
Absent
Medium/
U-shaped
Large
Small and
1.8 cm
Dull
Top: 16
13.5 cm
Bottom: N/A
8.5 cm
1147.500 cm3
10 cm
Maurice
Large
Large
Absent
Absent/
86°
Absent
V-Shaped
Small
Large and
1.1 cm
Sharp
Top:16
14.3 cm
Bottom: 16
12.2 cm
2006.290 cm3
11.5 cm
LeFou
Medium
N/A
Absent
Small
78°
Small
N/A
N/A
N/A
Top: N/A
13.2 cm
Bottom: N/A
7.4 cm
761.904 cm3
7.8 cm
Cogsworth
Small
Small/
Absent
Small
Small
70°
Medium/
U-shaped/
Small and
Large
Intermediate
Dull
1.3 cm
Top: 16
14 cm
Bottom:16
8 cm
9.1 cm
1019.200cm3
Graphs:
Facial Slope in Degrees
100
86°
90
80
66°
70
69°
70°
70°
71°
Beast
Gaston
Cogsworth
Lumiere
75°
78°
60
50
40
30
20
10
0
Belle
Mrs. Potts
LeFou
Maurice
Cranial Volume
100
1147.5 cm3
90
Cranial Volume
80
70
734.25 cm3
686.28 cm3
832.5 cm3
3
903.125cm3 1019.2 cm
761.904 cm3
60
50
40
30
20
10
0
Beast
Gaston
Cogsworth
Lumiere
Homimid Skulls
Mrs. Potts
LeFou
Maurice
Analysis and Conclusion:
1. The Cranium size graph shows the maximum capacity of each Hominid skull, which also
gives the maximum size of the brain of each Hominid. This would imply that Hominids
with a higher Cranial Volume would have larger brains, thereby making them more
intelligent relative to the other Hominids. From this graph it can also be implied that the
Hominids with the higher Cranial Volume were the ones that were the most recent
Hominids. From this it can also be implied that the Hominids with higher cranial
volumes were closer to humans.
2. The Facial Slope of each Hominid skull is portrayed on the Facial Slope graph. Facial
Slope shows you the Bipedal abilities of each animal. If the Facial Slope was steep, the
Hominid most likely had an upward posture. If the slope was gentle, than the Hominid
most likely had a more “leaned over” posture. The facial slope would also dictate that
longer snouts would have a high Facial Slope.
3. The specimens that are most apelike were Mrs. Potts and Belle. These specimens both
had apelike Prognathism. Another observation is that Mrs. Potts had the largest Sagittal
Crest which apes also have.
Another similarity is the Supra-orbital Ridge which is
clearly present in apes and the two specimens. Finally, all of them had 16 teeth on the
top and a U-Shaped Dental Arcade.
4. The most humanlike specimens were Maurice and Cogsworth. All of them have a high
Cranium Volume, above 1,000 cm3, with thirty-two total teeth. Another observation is
all of them had V-shaped Dental Arcades. Small to absent Prognathism were present in
all of the specimens, as were chins. Finally, the molar widths were relatively close.
5. From this lab I learned that humans had many diverse and distinct relatives. I also
learned that it is very hard to judge the relative size of certain Hominids. Another
important thing I learned is that the skulls have not been fully recovered yet, due to the
missing lower jaws. Finally I learned the different parts of human and ape skulls, along
with their purpose and how they are used to categorize Hominids.
Phylogenetic Tree
Maurice
Cogsworth
Lumiere
Gaston
Belle
Beast
wonka
LeFou
Mrs. Potts
Phylogenetic Tree Explanation:
The Phylogenetic Tree started off with the Hominid Mrs. Potts. Mrs. Potts was easily the
most primitive looking due to her large Sagittal Crest, pronounced Prognathism and medium to
large Supra-orbital Ridge. A possible theory, but certainly not concrete, is that there is no lower
jaw which could imply that this fossil is older and therefore harder to find. Next the diagram
branched off into LeFou, Lumiere, and Belle. Three hominids branched off of this tree, because
they were all unique in a certain way. LeFou had a very flat face with a Supra-orbital Ridge, a
slight Sagittal Crest and a Supra-orbital Ridge. Belle had a Supra-orbital Ridge, slightly less of a
Prognathism than Mrs. Potts and an almost Humanoid face. Finally Lumiere was the last branch,
because he had a medium Supra-orbital Ridge and a slight Prognathism. LeFou was the most
diverse out of the other two skulls, so he likely went extinct first, not having the adaptations
needed for his environment. After that, Belle’s existence happened. However, her extinction
may have been accelerated by a changing environment and the need for greater adaptations.
Soon after, the advent of Lumiere came into existence. Lumiere was there at the time of
Cogsworth, because he was the most human. A major staple of his diet was meat, like that of
humans. Lumiere’s diet also proved to be like humans, because he had no Sagittal Crest for
chewing muscles to attach to. Finally Lumiere had the fourth largest Cranial Volume. The next
branch of descendants encompassed the rest of the hominids. LeFou broke off into Gaston and
Beast. These two shared the same facial design as LeFou. Most of them had a medium sized
Supra-orbital Ridge and relatively close Cranial Volumes, which were also the lowest group. All
of the skulls were missing lower jaws which was earlier theorized to be caused by these
hominids being relatively old compared to others. With the exception of LeFou, this entire
group had U-Shaped dental arcades (LeFou’s teeth were unavailable). The forehead of this
group was also smaller. It is believed that Beast went extinct a bit faster than Gaston, because
Gaston has teeth starting to appear, a higher facial slope, and less of a Prognathism. Lumiere
was still alive, a short while after the appearance of Cogsworth; but he went extinct marginally
quicker. Lumiere not only had a major meat eating diet, but an intermediate Dental Arcade.
However, Cogsworth had a higher Cranial Volume and less of a Supra-orbital Ridge. He also
had more teeth.
Finally Belle split off into Cogsworth and Maurice. Maurice was the most
human in all the fields. He was also the most human-looking. The assumption was that he was a
human. Therefore he is the highest part of the tree. Cogsworth was slightly less human with
wider teeth, smaller and duller canines, a more U-shaped Dental Arcade, a medium Supra-orbital
Ridge, less of a facial slope, and less of a chin and forehead. These two Hominids were
descendants of Belle, because they possessed smaller Molars, smaller Prognathisms, and thirtytwo teeth. Maurice, Cogsworth, and Belle all resembled each other more closely than any of the
other organisms.