Biostratigraphy

Question 1

Biostratigraphy:

Answer 1

-Sectioning of rock layers based on the fossils they contain

Question 2

Evolution is the basis of biostratigraphy

Answer 2

Fossils evolve so we can use them to build up the relative timescale . Fossils that define our different assemblages

Question 3

Biostratigraphic unit

Answer 3

• a body of rock defined by its fossil content
• basic unit is the biozone
• a biozone should be/have: fossils contemproaneous with the body of rock that contain them i.e. no reworking (need to keep an eye out for sediment that has been reworked), independent from lithostratigraphic units and independent from chronostratigraphic units

Question 4

Interval Zone

Answer 4

• Based on 1 or 2 taxa only (Taxon = a species, a genus or a family)

Question 5

FAD

Answer 5

First Appearance Datum

Question 6

LAD

Answer 6

Last Appearance Datum

Question 7

Concurrent range zones:

Answer 7

Overlapping ranges of two or more taxa

Question 8

Lineage Zones

Answer 8

• Defined by evolutionary FAD, or related taxa
• Use evolution to advantage
• Species A went extinct and was replaced by B

Question 9

Characteristics of useful marker fossils

Answer 9

• Broad global or environmental distribution
• Short range zones
• Are part of a long lived lineage with clear morphological changes
• Are easily fossilised
• Are small (so that numerous individual specimens can be collected from on rock sample).

Question 10

Abundance Zone

Answer 10

Zones are based on the relative importance of different taxa

• Do not rely on evolutionary change
• What environments/age was this suited to