Exam 3 - Fossils

Laggerstatten

A sedimentary record with exceptionally well preserved records; particularly fine fossil deposits where sometimes parts of the organism don’t typically fossilize, including the soft parts

What are fossils biased towards?

Organisms with hard parts and organisms that lived in sedimentary environments as these are more likely to fossilize.

Why is organismal incompleteness inevitable?

Because typically only hard parts are fossilized

Kinetic Isotope Effect

The geochemical footprints in living systems: ex: rubisco, the enzyme that introduces CO2 into photosynthesis preferentially processes the C12 isotope over the C13 one

What is stratigraphic incompleteness?

The result of inconsistent patterns and rates of sedimentation

Stratigraphic incompleteness can cause artifactual evolutionary patterns which are:

Jumps between one fossil form to another because there was a hiatus in sedimentation (an no fossil record of the intermediates between the two forms

Pull of the Present

Because ancient rocks are more likely to be eroded (or undergone some form of destruction, including plate subduction) than relatively recent ones, there is bias in the fossil record towards more recent material

Anagenesis

Change within a lineage

Chronospecies

A fossil species that represents a stage in a single, non-branching evolutionary lineage where one form gradually turns into another over time

If organismal incompleteness in evitable, what tools can we use to maximize the amount of bio info we can get from scattered, 2-D materials?

Track fossils such as footprints and burrows

The Great American Interchange

When the Isthmus of Panama formed, connecting the continents of North and South America

Why was the Great American Interchange important? 

It allowed for the migration of plants, animals, and other organisms between two previously isolated continents, leading to a massive mixing of their distinct faunas

Why do we see such asymmetry in the Great American Interchange?

While North American mammals successfully migrated south, a greater number of South American mammals died out, leading to more diversification for North American species in South America

Paleozoic Eras (recent to ancient)

Permian, Carboniferous, Devonian, Silurian, Orovician, Cambrain

Mesozoic (recent to oldest)

Tertiary, Crutaceous, Jurassic, Triassic

What’s the KPg Event?

The Crustaceous-Paleogene Event was a mass extinction event that occurred 66 million years ago which wiped out 75% of all species on Earth and non-Avian dinosaurs

Cope’s Law

The evolutionary theory stating that the body size of organisms within a lineage tends to increase over geological time

Ediacaran Biota

The first complex, multicellular organism to appear 600 million years ago

What can be said about the radiation that characterizes the Cambrian Explosion?

The sudden radiation is not due to poor fossil records but rather a lack of complex trace fossils. Plenty come after

What significant transitions are documented in the fossil record?

Fish-tetrapods (Tiktaalik), reptile mammals, ants from wasps, birds from feathered dinosaurs, whales as first tetrapod group to return to water

Passive trend

The starting state is maintained

Active trend

The starting state is no longer present in later phases

Red Queen Hypothesis

The idea that all species are evolving all the time in order to keep up with the species that they interact with

According to the RQH, what did paleo observations suggest?

That the probability of extinction for a species is more or less constant throughout its entire life

Stasis

A period of little to no evolutionary change which is reflected in the fossil record

Stabilizing selection

Negative selection against extremes where the average individual is preferred

Punctuated Equilibrium

A theory of evolution that proposes that species experience long periods of little/no change (stasis) followed by short, rapid bursts of evolution

Phyletic gradualism

A theory of evolution that new species arise through the slow and steady accumulation of small genetic transformations over long periods of time, leading to the gradual transformation of an ancestral species to a new one.

What are the additional effects of the KPg event? (outside of the dinos)

Rapid diversification and adaptive radiation of mammals

What can stasis be explained by?

Stabilizing selection