Anth-105 Exam 3: Early Hominin Evolution

What is the significance of the Great Rift Valley in paleoanthropology?

It is a major region in Africa where many early hominin fossils have been discovered.

What important hominin species was found in Tugen Hills, Kenya?

Orrorin tugenensis.

Which species is associated with Chad?

Sahelanthropus tchadensis.

Name three other significant paleontological sites for early hominins.

Olduvai Gorge (Tanzania), Laetoli (Tanzania), Hadar (Ethiopia).

What is unique about all the early hominin species listed except possibly Australopithecus afarensis?

All are bipedal, found only in Africa, and none are clearly associated with stone tools.

Characteristics of Sahelanthropus tchadensis?

Small-brained, no post-cranial remains.

What do we know about Orrorin tugenensis fossils?

Only fragmentary remains such as teeth and femur; cranial capacity cannot be reconstructed.

What is notable about Ardipithecus ramidis?

Small brained.

Australopithecus afarensis (Lucy and "Lucy's baby") had what features?

Small-brained, possibly associated with simple stone tools.

Describe Paranthropus robustus and P. bosei.

Massive teeth and jaws; highly specialized for chewing; small-brained relative to their size; not ancestral to modern humans.

Define bipedalism.

Walking upright on two legs, a key feature of early hominins.

What is the foramen magnum?

The large opening at the base of the skull where the spinal cord enters; its position indicates upright walking.

What anatomical term refers to the connection between the thigh bone and the pelvis?

Neck of femur.

What pelvic differences distinguish bipeds from knuckle-walkers?

Bipeds have broader, shorter pelves adapted for upright walking.

What is the bicondylar angle?

The angle of the knee that helps bipeds balance their weight over one leg at a time.

Cranial capacity in early hominins remained close to that of which animal until Homo?

Chimpanzees.

What does the Geological Time Scale represent?

A system for dating events and fossil remains by placing them within Earth's history.

Define adaptive radiation.

The process by which organisms rapidly diversify into new forms, especially when a change in the environment makes new resources available.

What is stratigraphy?

The study of rock layers (strata) and how they are arranged.

Explain the Law of Superposition.

In undisturbed strata, the oldest layers are at the bottom and younger layers on top.

What does the Law of Original Horizontality state?

Layers of sediment are originally deposited horizontally.

What is the Law of Concealed Stratification?

Layers may be hidden or rearranged by geological processes after initial deposition.

List three dating techniques used in paleontology.

Paleomagnetic dating, faunal dating, potassium-argon dating.

What is taphonomy?

The study of what happens to organisms from death to discovery as fossils.

Which body parts are most likely to fossilize?

Hard parts like bones and teeth.

What is a True Form Fossil?

Fossils that preserve the actual organism or its parts.

Define body fossil.

Fossils that consist of the actual remains of an organism.

What is a trace fossil?

Evidence of an organism's activity, such as footprints, burrows, or feces.

What is a mold fossil?

An impression left by an organism in sediment that then hardens into rock.

What is a living fossil?

Species that have remained unchanged over millions of years and resemble ancient ancestors.

Define paleontology.

The scientific study of fossils and ancient life forms.

What does paleoanthropology study?

The origins and predecessors of modern humans using fossil evidence.

What is phylogeny?

The evolutionary history and relationships among species.

How is Occam's Razor applied in paleoanthropology?

Prefer the simplest explanation that fits the evidence.

Who was James Ussher?

A scholar who calculated the age of Earth using biblical chronology.

Who is Charles Lyell?

A geologist who established principles of geology crucial for understanding Earth's history.

Who was Kamoya Kimeu?

A renowned fossil hunter in Africa, identified several hominin fossils.

Who were Louis and Mary Leakey?

Pioneers in paleontology; discovered Homo habilis and many other important fossils.

Who discovered Australopithecus afarensis ("Lucy")?

Donald Johanson.

Who discovered "Lucy's baby" (Selam)?

Zeresenay (Zeray) Alemseged.

Who discovered Orrorin tugenensis?

Kiptalam Cheboi.

Who led the team that discovered Orrorin tugenensis?

Pickford and Senut.