GCSE - Fossil Summary
Fossil Group
Exam Emphasis
Zone Fossil
Use
Morphology related to mode of life
Trilobite
1-2009
2-2008
Features Essential to Know
Parts to Label
Symmetry
When Lived
Cambrian to P/T
extinction event
Cephalon
Thorax
Pygidium
Eye (compound)




Lengthwise
Flat, eyes in middle = sea floor
Streamlined, eyes forward/big = swimmer
Small and/or no eyes = floater
None specific
Other Information
Moults its exoskeleton –
see cluster of juvenile,
adult and mature sizes
Fossilise – mineral
replacement
Environment –
Coral
1-2006
2-2009



Silurian
still alive
Septa
Tabula
Corallite
Radial
Warm – tropical latitudes
Clear marine
Light (<20m)
Shallow (<20m) and high energy to be
oxygenated by turbulent waves
Restricted
environment
None specific
Colonial or Solitary
Fossilise – replacement by
calcite
No, but good
as
environmental
indicator
Rapid evolution of land
plants during Devonian
changed Earth’s
atmosphere (> O2).
Spawned the evolution of
land animals (amphibians) =
oxygenated air and food
Excellent –
evolved
rapidly
Floated throughout marine
environments. Delicate, so will
not survive intact if died in
turbulent waters. Always
found in a death assemblage
Excellent –
evolved
rapidly
Coiling (whorls touch or almost
hidden by next whorl) significant, but not date
dependent
Died out with dinosaurs
Environment
Plants
1-2006
Land plants evolved
in the Silurian



Root
Stem
Leaf
N/A
Indicative of terrestrial environment
Dating and Evolution
Graptolite
1-2009
1-2007
Mid/Late Cambrian
to Carboniferous


Stipe
Thecae
N/A
Stipes – reduced through time (4 to one)
Thecae - shape changed through time (> complex)
Thecae – Pendant (down) → Scandent (up)
Thecae - Inside → Outside
Thecae - Uniserial → Biserial
Dating and Evolution
Ammonoid
1-2008
1-2006
Devonian to K/T
Boundary




Coiling
Keel
Ribs
Suture lines
N/A
Suture pattern changes from simple to complex
through time.
Goniatite – Devonian to Permian (Paleozoic)
Ceracite – Triassic only
Ammonite – Jurassic/Cretaceous
GCSE - Fossil Summary
Fossil Group
Trilobite
Features Essential to Know
Parts to Label
Symmetry
When Lived
Cephalon
Thorax
Pygidium
Eye (compound)
Glabella
Genal Spine
Thoracic Segments







Exam Emphasis
Morphology related to mode of life
Zone Fossil
Use
Other Information
Moults its exoskeleton –
see cluster of juvenile,
adult and mature sizes
Fossilise – mineral
replacement
Environment
Coral
Septa
Tabula
Corallite



Colonial or Solitary
Fossilise – replacement by
calcite
Environment
Plants



Root
Stem
Leaf
N/A
Rapid evolution of land
plants during Devonian
changed Earth’s
atmosphere (> O2).
Spawned the evolution of
land animals (amphibians) =
oxygenated air and food
Dating and Evolution
Graptolite


Stipe
Thecae
Floated throughout marine
environments. Delicate, so will
not survive intact if died in
turbulent waters. Always
found in a death assemblage
N/A
Dating and Evolution
Ammonoid




Coiling
Keel
Ribs
Suture lines
N/A
Coiling (whorls touch or almost
hidden by next whorl) significant, but not date
dependent
Died out with dinosaurs