Exercise 1: Australopithecine Worksheet
Instructions
In this lab, you will compare sets of fossil casts and record your comparisons on a chart. The term specimen in the chart refers to the specific fossil or primate species being studied. The name of the species is filled in at the head of the column. Individual fossil specimens are usually identified by an abbreviation indicating the name of the site from which the fossil comes and a number given to each fossil from the site. For example, OH 5 stands for the fifth hominin fossil from Olduvai Gorge: Olduvai Hominin 5. The fossil casts for your class may or may not be labeled this way.
The early hominins include a diverse group of African fossils that include the genera Sahelanthropus, Orrorin, Ardipithecus, Australopithecus, and Paranthropus. The many species represented by these genera lived from about 7 million years ago (mya) to almost 1.0 mya. Early hominin fossils are found in South Africa, East Africa, and Chad (north central Africa). None are found outside of Africa.
- The early hominins are those that show many transitional features between the apes and later hominins. They include Sahelanthropus tchadensis, Orrorin tugenensis, Ardipithecus ramidus, and Ardipithecus kadabba. These species lived between 6.8 and 4.4 mya.
- Three of the well known gracile Australopithecines are Australopithecus anamensis and Australopithecus afarensis from East Africa, and Australopithecus africanus from South Africa. They lived between 4.2 and 2.1 mya.
- Many paleoanthropologists classify the robust Australopithecines in the genus Paranthropus. There are three known species: Paranthropus aethiopicus and Paranthropus boisei from East Africa and Paranthropus robustus from South Africa. They lived between 2.7 and 1.0 mya and were contemporary with the genus Homo.
Part 1. The Gracile Australopithecines
While Sahelanthropus, Orrorin, and Ardipithecus are considered transitional genera, the gracile Australopithecines (Australopithecus africanus and Australopithecus afarensis) are clearly hominins. In Exercise 1, you will look closely at some of these species.
In this lab, we will analyze skulls from the four categories (pick one individual from each category):
- Ape:
- Anatomically Modern Human:
- Gracile Australopithecine
- Australopithecus Afarensis: https://3d.si.edu/object/3d/australopithecus-afarensis-cranium:6faf8121-250c-47cb-a5cc-139d7b16c570
- Au. Africanus: https://3d.si.edu/object/3d/australopithecus-africanus-cranium:ea4abc35-be8e-4787-aec4-ab7e34298f9b
- “Robus” Australopithecine (Paranthropus) :
- Paranthropus Bosei: https://www.efossils.org/page/specimens/Paranthropus%20boisei
I have included recommended individuals above, but you may pick another fossil. Note: Many of the fossils have been photographed/3D modelled MULTIPLE times. So if you find another website with a better image of “Lucy” or you are more than welcome to use them! I recommend checking out the following websites: https://africanfossils.org/, http://efossils.org/, https://www.eskeletons.org, https://sketchfab.com/, https://3d.si.edu/collections/hominin-fossils
You will note your observations in the table below. There are four ways to fill in a cell, depending on how the statement of feature is phrased.
- Present or absent: When a feature is either there or not, you can use a + for present and – for absent. For example, “presence of sagittal crest” can be answered + or –.
- Describe: When you are asked to describe a feature, do so with a few words or short phrase. For example, “shape of dental arcade” can be answered “U-shaped.”
- Compare: When you are asked to compare, you need to ask “compare to what?” If there are three skulls being compared, you might say X and Y are smaller than Z. Or X is smaller than Y and Y is larger than Z.
- Measure: Since this is online, you will not be asked to measure anything today. But refer to the Condylar Index and Facial Index diagrams in the PowerPoint to see how to take the measurements and calculate the indexes.
| Type | Ape | Human | Gracile Australopithecine | “Robust” Australopithecine Paranthropus |
| Species name & Specimen ID | ||||
| Location of occipital condyles on base of skull | ||||
| Presence and degree of postorbital constriction in superior view | ||||
| Size of neurocranium relative to size of facial skeleton as seen in the lateral view | ||||
| Degree of prognathism as seen in the lateral view | ||||
| Presence and degree of development of supraorbital torus | ||||
| Robustness of zygomatic arch | ||||
| Presence of a sagittal crest | ||||
| Relative size of incisors vs. molars (M > or < or = I) (Bigger, smaller, same size) | ||||
| Size of canines to other teeth (C > or = ) |
Part 2. Bipedal Adaptations: Pelvis and Foot
Our earliest hominin ancestors were essentially bipedal apes. The first hominins walked on two legs but had small brains and retained adaptations for climbing trees. When a new fossil is discovered, paleoanthropologists spend a great deal of time and care studying the remains to determine the locomotor pattern for that species. It is not a straightforward process and claims that recent discoveries such as Sahelanthropus, Orrorin, and Ardipithecus species are bipedal have generated a lot of discussion.
In this exercise we will examine the pelves of an ape, Au. afarensis, and a modern human, and consider changes that occurred as our ancestors evolved from quadrupeds to bipeds. We will also look at, and compare, the feet of an ape, Ardipithecus, and modern human.
The pelvis underwent significant changes as part of this process, but other parts of the postcranial skeleton were also affected by selection for bipedality. It is also important to remember that bipedal locomotion in the earlier hominins was not identical to the way we now move. This will be apparent as we compare pelves today. You may want to review the textbook descriptions of the modern human pelvis and ape pelvis, as well as descriptions of Australopithecine pelvis and feet.
Answer the questions and record your answers in the chart.
| Ape | Au. afarensis | Modern human | |
| Specimen label | |||
| General shape of pelvis | |||
| Relative position of sacroiliac and acetabular joints | |||
| Position of iliac blade relative to spine | |||
| Shape of pelvic inlet | |||
| Relative size of anterior inferior iliac spine | |||
| Relative length of ischium bone |
| How are modern humans and Au. afarensis similar? How are they different? What inferences can you make about bipedality in Au. afarensis? |
Part 3. Paranthropus “Robust” Australopithecines
Between three and one million years ago, some hominins begin to exhibit larger posterior dentition, changes in dental enamel, and cranial evidence that suggest variation in dietary strategies among hominins. The large-molared hominins can be referred to as “robust” Australopithecines (in contrast to “gracile” Australopithecines like Au. africanus), though many researchers have placed them into a separate genus: Paranthropus. Some have speculated that they developed specializations in the jaws and teeth that allowed for processing tough, fibrous material such as grasses and hard seeds. The relationship between the two groups is unknown, but both have been found in the same sites, although at different time periods.
Paleoanthropologists recognize three species of robust Australopithecines or Paranthropus:
- Paranthropus aethiopicus is known from East Africa. It is the oldest of the group, dated at 2.7 – 2.3 mya, and is somewhat more primitive than later forms. It was discovered in 1984.
- Paranthropus robustus is a species that existed in South Africa between 2.3 and 1 mya. It was first discovered between 1936 and 1939 by Robert Broom.
- Paranthropus boisei is a species that existed in East Africa between 2.4 and 1.4 mya. It has larger posterior teeth and more developed jaw musculature than those living in the south. It was first discovered by Mary Leakey at Olduvai Gorge in 1959.
Examine the Paranthropus fossil casts and then answer these questions.
- List three anatomical features suggest that Paranthropus ate a diet of tough, fibrous plant material.
- In contrast, what might have been the diet of gracile Australopithecine species? How do you know?
Exercise 2: Your Inner Monkey Video
Video Information:
PBS Your Inner Fish Episode 3: Your inner Monkey (54:40 minutes)
PBS Link (with Captions): https://www.pbs.org/video/your-inner-fish-your-inner-monkey/
An MP4 version of the video will be uploaded to Canvas but it does not have subtitles.
Video Questions: Fill out the worksheet as you watch the watch the video
- The early primate creature found in Wyoming territory, was called ___________________, and lived some _____ million years ago.
- The _____________ was the most significant anatomical characteristic of this early primate.
- About ________ million years ago, a group of primates became able to see colors, which helped them see ______________ and find the most nutritious _________________.
- Special proteins called ___________________ are used to detect color. These are housed in the eye’s _______________________.
- Lucy is _______ million years old. And was about _______ feet tall.
- Lucy’s knees were ______________________, which made it easier for her to ______________________________.
- Lucy’s is of the species ___________________________________________.
- “Ardy” or ___________________________ was found only 50 miles from the site where Lucy was discovered.
- “Ardy’s” bones had been buried for _______ million years.
- Based on studies of the paleo-environment, Dr. White and his team determined that “Ardy” probably lived in a ____________________ environment.
- The most critical bone for bipedality is the ____________________.
- The top part of “Ardy’s” pelvis is short and broad, like a ____________ pelvis, but the bottom of the pelvis is ________________, which is useful for _________________________.
- Ardy also had a _________________ foot that could ______________.
- The tool Don Johanson found was made by _________________ _____________, a human ancestor that lived about ____________ million years after Lucy.
- All brains have a fundamental architecture, and contain a _________________, a __________________, and a _____________________.
