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Introduction: The purpose of this lab is to introduce you to the cranial and dental morphology
of early hominins. By examining the suites of primitive and derived traits present in different
hominins and comparing those traits with modern Homo sapiens and Pan troglodytes, you will
gather the evidence necessary to address questions of relationships and behavior.
To complete this lab, you will be examining virtual specimens available through the NMNH, Smithsonian 3D Digitization website:
https://3d.si.edu/explore/museum/natural-history-museum
. This site allows you to view casts of fossil specimens in 3D and to rotate the specimens to view them from different angles. There are also a series of tools that will allow you to measure, zoom in and out, and change lighting, material, and view. Feel free to play with the settings/tools. In some cases, minor adjustments to the lighting and/or materials can make it easier to see details on the specimens. While there are links accompanying the specimens that you should view in completing this lab (see below), there are many additional specimens available with this digital collection. Feel free to explore.
Part 1 – Data Collection: On each of the following pages is a data collection table for seven fossil hominin species the modern human, and the chimpanzee. For each species, collect the following data. Enter your data directly into the tables. Links to specimens are provided with each species.
1) Foramen magnum location – moved forward or toward the rear; pointing straight down or
angling to the rear?
2)
Crests
– Is there a sagittal crest (running front to back along the top of the skull)?
Is there a nuchal crest (running horizontally along the back of the skull)?
3)
Prognathism
– Is the face more prognathic (projecting) or orthognathic (flat)? Is there alveolar
prognathism (projecting at the teeth)?
4)
Robusticity
– Is the skull heavily built or lightly built? Is the face dish-shaped? Is the jaw
rugged and deep or smooth and shallow? Are there heavy muscle markings?
5) Supraorbital torus (brow ridges) – present or absent; size
6) Brain size (relative to face) – Is it larger? Smaller? The same?
7)
Teeth
– What are the relative sizes of the teeth (incisors, canine, premolars, molars)? Is the
last molar (M3) reduced? Do the premolars look like molars, or are they small with few
bumps? Does the canine extend beyond the tooth row?
NOTE:Damage to specimens sometimes prevents complete data collection. However, you might be able to infer characteristics from the surrounding bone. For example, if a specimen is missing a tooth (or teeth) you might be able to estimate the size of teeth from the roots, the size of the jaw, or the tooth sockets.
Australopithecus afarensis: 4.0 – 2.9 million years old
Specimen # A.L. 444-2
https://3d.si.edu/object/3d/australopithecus-afarensis-cranium:6faf8121-250c-47cb-a5cc-139d7b16c570
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Foramen Magnum Location |
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Supraorbital Torus |
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Brain Size (relative to face) |
Homo habilis: 2.4 – 1.7 million years old
Specimens # OH 24 & KNM-ER 1813
https://3d.si.edu/object/3d/homo-habilis-cranium:4c474d9f-72b2-49ab-bdd2-9f4b9d250cd2
https://3d.si.edu/object/3d/homo-habilis-cranium:de47a0c6-20c6-4d70-bcc8-4992d5f4ff66
Foramen Magnum LocationCrestsPrognathismRobusticitySupraorbital TorusBrain Size (relative to face)Teeth
Paranthropus robustus: 1.8 – 1.0 million years old
Specimens # SK-46 (male) and DNH 7 (female)
https://3d.si.edu/object/3d/paranthropus-robustus-cranium:70125300-c184-494d-9a05-3b4b8ba3977f
https://3d.si.edu/object/3d/paranthropus-robustus-cranium:8bc77140-b75c-4f96-9899-bf275b5d43dd
Foramen Magnum LocationCrestsPrognathismRobusticitySupraorbital TorusBrain Size (relative to face)Teeth
Paranthropus boisei: 2.3 – 1.2 million years old
Specimens # KNM-ER 406 (male); OH 5 (male); KNM-ER 732 (female)
https://3d.si.edu/object/3d/paranthropus-boisei-cranium:081d5e0b-7181-4ccb-bfbd-9f906930c620
https://3d.si.edu/object/3d/paranthropus-boisei-cranium:f71256ba-fb5d-4a26-b44d-3d4cc2a8b533
https://3d.si.edu/object/3d/paranthropus-boisei-cranium:1257a10e-a0a5-448c-9d1e-db0c4d775ec0
Foramen Magnum LocationCrestsPrognathismRobusticitySupraorbital TorusBrain Size (relative to face)Teeth
Australopithecus africanus: 3.0 – 2.0 million years old
Specimens # STS 5 and STS 71
https://3d.si.edu/object/3d/australopithecus-africanus-cranium:ea4abc35-be8e-4787-aec4-ab7e34298f9b
https://3d.si.edu/object/3d/australopithecus-africanus-cranium:987cb78e-29f6-41da-be16-71a3ff2b8324
Foramen Magnum LocationCrestsPrognathismRobusticitySupraorbital TorusBrain Size (relative to face)Teeth
Homo rudolfensis: 2.4 – 1.8 million years old
Specimen # KNM ER 1470
https://3d.si.edu/object/3d/homo-rudolfensis-cranium:6d2ecbf8-0d42-4277-a475-4a3d9208ecd3
Foramen Magnum LocationCrestsPrognathismRobusticitySupraorbital TorusBrain Size (relative to face)Teeth
Sahelanthropus tchadensis: 7.0 – 6.0 million years old
Specimen # TM 266-01-060-1
https://3d.si.edu/object/3d/sahelanthropus-tchadensis-cranium:9730a62f-a649-44fb-8494-aa7c9b6eb1f8
Foramen Magnum LocationCrestsPrognathismRobusticitySupraorbital TorusBrain Size (relative to face)Teeth
Homo sapiens: 200,000 years ago to present
Specimens: Qafzeh 6; Cro-Magnon 1; and Skhūl V
https://3d.si.edu/object/3d/homo-sapiens-cranium:52610788-8e81-4b0b-8d3a-8d19828236ec
https://3d.si.edu/object/3d/homo-sapiens-cranium:09d681b2-5ae9-44a8-b444-8e31bb40305e
https://3d.si.edu/object/3d/homo-sapiens-cranium:7821efd3-6af6-4306-8063-228489aa497d
Foramen Magnum LocationCrestsPrognathismRobusticitySupraorbital TorusBrain Size (relative to face)Teeth
Pan troglodytes: 200,000? years ago to present
https://3d.si.edu/object/3d/pan-troglodytes-troglodytes-cranium:3dc12b5f-e7df-48cc-84a7-be5e6ec7fa90
Foramen Magnum LocationCrestsPrognathismRobusticitySupraorbital TorusBrain Size (relative to face)Teeth
Part 2 – Data Analysis: Refer to the table that you completed in Part 1 to complete this
section.
1) What differences do you see between the genus Paranthropus and the other genera (fossil and
modern)? What do you think the dietary differences might be?
2) Looking at the size of the brain case (neurocranium) relative to the face (splanchnocranium), rank the species from smallest to largest relative brain size (ties are permitted).
3) Using the data from the table (Part 1) construct a hypothesis of relationships between all of the
species (including Pan troglodytes and Homo sapiens). Draw your hypothesis in the form of a cladogram and give an explanation for why you position each species as you do. Insert a picture of your hypothesis below (or attach an image as a separate file).
Note: To receive full credit, the position of each species must be justified on the basis of the data that you collected (i.e. on the basis of morphology [shape]), and you must be specific!
To consider in making your tree:
- There are no right or wrong answers to this. Use the data to come up with a hypothesis of relationships. You will be assessed on your ability to interpret your data and to use it to support your hypothesis – Don’t worry about having the “correct” evolutionary tree!
- Anything that you consider to be a hominin should share a more recent common ancestor with Homo sapiens than with Pan troglodytes.
- Time is not usually a good organizing factor. It is not uncommon for highly derived organisms to occur early in the evolutionary history of a group. You will lose points if you use time as the sole justification for your hypothesis of relationships.
