II. Primate and Human Derived Characteristics

Primates are the order of mammals that includes all monkeys and apes. The apes include gorillas, orangutans, chimpanzees, and humans. Characteristics of both primates and humans can be found in Table 3.

An indication of the larger brain size is evidence found from cranial bones in skull fossils of different taxa. Here are some representatives.

Activity 2: Skull Fossil Exercise

Pre-lab

Your instructor might direct you to view this short video from the American Museum of Natural History before lab.

In the lab

It is estimated that the chimpanzees diverged from the lineage that gave rise to the human lineage about 6 mya (including Australopithicenes such as Lucy and later, other Homo species such as Homo neanderthalensis, the Neanderthals). Modern humans (Homo sapiens) evolved approximately 200,000 years ago (0.2 mya). Examine the replica skulls on the demonstration table closely, which are similar to the ones in Figure 2. View the cranial bones as well as the facial bones. Consider the following attributes:

1. the length of the jaw
2. the size of the cranium
3. the morphology of the bridge of the nasal bone
4. the morphology of the eyebrow ridge
5. teeth number and specialization

What patterns do you notice for i–v from the most primitive to the advanced organism? Refer to Figure 2, which is organized from the most primitive (left) to advanced (right), to help your analysis. Record your observations in a table like Table 4 below.

Answer the following questions.

a. What can you conclude from your observation of the size of the cranium?

b. What can you conclude about the differences observed in the number and morphology of the teeth?