• Durability (hard vs soft) •
Burial (saturated sediment)
• Lack of oxygen
ultimately - need to
form ROCK
How good is it?
± 250 000 described
fossils (not a lot)
Lineages are
separated by long
periods of time
Gaps of many thousand years
Fossil species are
only known from a
few specimens
Bias
Geographic
(sampler
and habitat)
Annotations:
Any sort of preservation dependent
on location relative to lowland and marine habitat.
The animal/plant has to have the
opportunity to be covered by
sediment
Taxonomic
Annotations:
- Marine organisms dominate the
fossil record BUT make up only 10%
of extant species
- 2/3rds of all animal phyla
underrepresented as do not have
mineralised hard parts
- Soft reproductive structures of
plants (flowers) not generally
preserved
Temporal
Annotations:
- The Earth’s crust is being constantly recycled
- Both tectonic activity and erosion of rock surfaces has/will lead to the loss of fossils
Rock Strata
Rocks arranged in
a predictable
pattern with strata
found in the same
relative position
Assemblages of
fossils from older to
younger rocks
Layers of sediment
contain distinctive suites
of fossils
Radiometric
dating provides a
time sequence
Fossil record provides
evidence of changes
that have occurred in
the history of life
BIOGEOGRAPHY \ PLATE TECTONICS
Paleography
continental drift
Wallace – studied animal
distributions whilst collecting
specimens in Asia and Indonesia
Discovered different
suites of species on
different islands with the
same climate
Darwin and Wallace believed
the only plausible explanation –
Natural selection
Biogeography – similarities and
differences between geographic
regions
Drivers of biogeographic distribution
Annotations:
All drive macroevolutionary patterns of species
distribution
1. Movement of the
landmasses and formation of
continents