Intro to Paleoanthropology: Fossils, Bipedality, and Human Evolution

What is a fossil?

A fossil is mineralized remains or traces of animals, plants, or other organisms that lived in the past.

What are the two major types of fossils?

Body fossils (bones, teeth, shells, skull fragments) and trace fossils (footprints, burrows, coprolites, cut marks on bones).

What is the fossil record?

The totality of all fossils ever discovered, which is incomplete, biased, and fragmentary.

What are some biases in the fossil record?

Most organisms do not fossilize, soft tissues decay quickly, and certain environments preserve fossils better than others.

What is paleoanthropology?

The study of ancient humans and human ancestors using fossil evidence, stone tools, and signs of habitation.

Why is burial important for fossilization?

Rapid burial prevents scavengers from destroying remains, weather from breaking bones, and bacteria from causing decay.

What are the steps in the fossilization process?

1. Organism dies near water, 2. Body sinks, 3. Soft tissue decays, 4. Sediment covers remains, 5. Minerals replace bone, 6. Fossil is buried deeper, 7. Uplift & erosion expose fossil.

What conditions are ideal for fossil preservation?

Volcanic ash, lava, tar, tree resin (amber), freezing, and extremely dry environments.

What is the reality of fossil findings?

Most fossils are partial skeletons; complete skeletons are rare.

What are hominoids?

Hominoids include humans, chimpanzees, bonobos, gorillas, orangutans, and gibbons.

What defines hominins?

Hominins include humans and extinct ancestors, defined by habitual bipedality and split from chimpanzees ~6-7 million years ago.

What are key fossils in the study of hominins?

Toumaï (Sahelanthropus tchadensis), Taung Child, and Lucy (Australopithecus afarensis).

What characterizes a hominin?

Any species more closely related to humans than chimpanzees, characterized by habitual bipedality and skeletal adaptations for upright walking.

What is the significance of the foramen magnum?

The foramen magnum is the large hole at the base of the skull where the spinal cord passes through; its position indicates bipedality.

How does the pelvis differ between humans and apes?

Humans have a short and broad ilium, while apes have a tall and narrow ilium.

What is the shape of the human spine compared to apes?

Humans have an S-shaped spine, while apes have a C-shaped spine.

What is the angle of the femur in humans?

Humans have a valgus angle (angled inward) to keep knees under the center of mass.

What are the differences in foot structure between humans and apes?

Humans have an arch and aligned big toe, while apes have grasping feet and a divergent big toe.

What should you assess when examining a fossil?

Check the position of the foramen magnum, shape of the pelvis, spine curve, femur angle, and foot structure.

What is the core takeaway regarding bipedality?

Bipedality evolved before big brains.