Sedimentology and Palaeontology Lecture 1: Fossilization and Trilobites Flashcards
Define a fossil
The remains of an ancient organism, preserved within geological strata.
Define and explain the differences between body fossils and trace fossils
Body fossils are fossils of a body part of an organism, body part was directly fossilized.
Trace fossils are non body part fossils, for example fossilized footprints.
What must happen for an organism to fossilize/become a fossil?
An organism must be mineralised to become a fossil, rather than decay.
Organisms will only become fossils if they are protected from processes of decay, meaning scavenging and microbial decay.
Microbial decay is affected by; temperature, Ph and availability of oxygen. (+type of organic carbon present in tissues)
For an organism to fossilise, mineralisation must be rapid.
What are the majority of fossils made up of?
The hard part of plants and minerals; mineralised or tough organic tissue.
Often internal and external skeletons and biomineralized shells.
Define Taphonomy
The study of the processes of transition of organic tissues from the biosphere to the lithosphere./
Or what happens to organisms after their death.
What is Arthropoda?
Arthropoda is a phylum including trilobites, crustaceans, cheliceratans
(spiders and others) and uniramians
(insects and others).
What is the Trilobite/Trilobita
Very successful marine arthropod.
Features a calcite exoskeleton
High diversity and abundance for 290 million years
What is the time range of the Trilobita?
Lower Cambrian – Late Permian distribution (540 – 250 Ma).
What are the three anatomical sections of the trilobite and what actually are they?
Cephalon (Head)
Thorax (Body)
Pygidium (Tail Plate)
Describe the trilobites eyes
First organisms to evolve sophisticated eyes.
Feature Calcite lenses.
Two types:
- Holochroal eyes: tightly packed lenses
- Schizochroal eyes: large, separated lenses.
Go into detail about the trilobites diet and method of consuming and digesting food
A trilobites diet mainly consisted of worm like invertebrates as well as scavenging.
They have no mandibles or teeth, but use
thick, spiny legs for subduing and
processing prey.
Glabella houses
stomach, while
axial lobes contain
digestive tract.
What is the trilobites main defensive strategy?
Rolling up into a ball.
True or false; trilobites species have very similar and consistent morphologies
False, trilobites species have a vast array of different morphologies, as well as sizes and other different physical differences (e.g. Atheloptic/Blindness).
