Macroevolution, Evidence, Fossil Record & Earth’s History

Flashcards covering macroevolution, evidence for evolution, the fossil record, and Earth's history based on lecture notes.

What is macroevolution?

Large-scale evolutionary change above the species level, including originations and extinctions.

What is the Law of Succession?

Fossil species in a region resemble living species from that region; evidence for descent with modification.

What are vestigial structures?

Reduced or functionless traits inherited from ancestors (e.g., whale pelvis).

Why do vestigial structures support evolution?

They show ancestry even when the trait no longer has a function.

What are transitional forms?

Fossils that show intermediate traits between ancestral and derived groups.

Why is Tiktaalik important?

It bridges fish and tetrapods, showing features like fins with wrist bones.

What is homology?

Similarity due to shared ancestry.

What is homoplasy?

Similarity not due to shared ancestry but convergence or reversal.

What are the two types of homoplasy?

Convergence (independent evolution of similar traits) and reversal (loss of derived traits).

How do pseudogenes show homology?

Shared nonfunctional DNA sequences in closely related species indicate common ancestry.

What evidence shows the Earth is old?

Uniformitarianism, radiometric dating, and stratigraphy.

What is a half-life?

Time required for half of a radioactive isotope to decay.

Approximate radiometric age of Earth?

~4.5 billion years.

What are the four major eons?

Hadean, Archean, Proterozoic, Phanerozoic.

What are the major periods of the Phanerozoic?

Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic, Cretaceous, Paleogene, Neogene, Quaternary.

What is the Burgess Shale?

A Cambrian fossil site preserving soft-bodied organisms, revealing early animal diversity.

What is the Cambrian Explosion?

A period of rapid diversification of animal body plans ~540 mya; not truly "sudden" but relatively fast.

What conditions favor fossilization?

Rapid burial, hard body parts, low oxygen environments.

What biases affect the fossil record?

More likely to preserve abundant, widespread, and hard-bodied organisms.

What are stromatolites?

Layered microbial mats that provide some of the oldest evidence of life.

What were banded iron formations?

Sedimentary layers formed when early photosynthesis released oxygen that bound with iron.

What is the endosymbiotic theory?

Mitochondria and chloroplasts originated as symbiotic bacteria within early eukaryotes.

What is Darwin’s “abominable mystery”?

The rapid and unexplained rise of flowering plants (angiosperms).