Fossil types Flashcards
What 6 fossil examples do I need to know?
Corals
Cephalopods
Trilobites
Graptolites
Brachiopods
Bivalves
What are corals?
Creatures closely related to a sea anemone, with hollow, bag-like bodies with a mouth at the top surrounded by tentacles
What do coral tentacles do?
catch and paralyse small organisms which are then pushed into the mouth
What is the role of the coral mouth?
Feeding - mostly at night
removing undigested food
What is the polyp?
The soft part of the coral
What is the corallum?
The calcareous skeleton which is built by the polyp, and is where the polyp sits
What are the two types of corals?
Solitary corals
Colonial corals
What is a colonial coral?
lots of polyps all living in a group (colony), all attached to the same corallum
What is a solitary coral?
A single polyp on a cup-like skeleton
What do corals have living inside them?
algae, zooxanthellae
What is the function of the algae inside corals? Why do they have a symbiotic relationship?
they photosynthesise during the day, producing nitrogen and carbon for the polyp, and in return, it gets oxygen and a sunny position
they also give the coral its colour
What are the 7 specific conditions that reef building corals need?
- latitudes of between 30 degrees N/S of equator
- depth of above 30m where there is plenty of light
- marine - salinity 30-40ppt
- temperature - 23-27 degrees C
- clear waters for photosynthesis
- no sediment which may clog the polyps
- high energy levels or wave action as it incorporates more oxygen and circulates nutrients
Name the features of solitary corals
- septa
- columella
- tabulae
- calice
- dissepiments
- epitheca
CORAL - What is the septum? (septa)
radial partitions
CORAL - What is the columella?
rod like axial structure
CORAL - What are tabulae?
horizontal partitions
CORAL - What is the calice?
cup shaped hollow which the polyp sits in
CORAL - What are the dissepiments?
small, downward curving plates between the septa
CORAL - What is the epitheca?
outer wall
What are the 3 subclasses of cephalopod?
Nautiloid
Ammonoide
Coleoid
What kind of shell does a nautiloid have?
Simple chambered
What kind of shell does an ammonoide have?
What else is special about ammonoids?
Complex chambered
EXTINCT
What sort of shell does a coleoid have?
THEY ARE SOFT BODIED
Doesn’t have a shell - at best they have an internal shell that is more like a skeleton for muscle attachment and buoyancy
- cuttlebone/gladius
a) Give characteristics of a nautilus
b) Give characteristics of an ammonoide
c) What characteristics do they share?
a)
- marine creature
- lives close to the sea bed
- swims using jet propulsion
b)
- extinct cephalopod
- similar shell to the nautilus but the outside of their shell has ribs
c)
they both have chambered shells with chamber walls called SUTURE LINES separating the chambers
- though ammonoids have more complex suture lines than nautiloids
What time periods did
a) nautilus
b) goniatite
c) ceratite
d) ammonite
live in?
a) Cambrian - Quaternary
b) Devonian - Permian
c) Carboniferous - Triassic
d) Permian - Cretaceous
What are trilobites?
Extinct marine arthropods
What does planktonic mean?
Give an example
free-floating and drifting
- little or no effective swimming capacity
e.g. jellyfish
What does nektonic mean?
able to swim efficiently against the ocean current for prolonged periods
What does benthic mean?
Give an example
those organisms that live on or in the sea floor
e.g. MOBILE - crabs and starfish, IMMOBILE - barnacles
What does pelagic mean?
living in the water column
What does substrate mean?
the surface or material on which an organism lives, grows, or obtains its nourishment
Give the body parts of a trilobite
Glabella
Thoracic segment
Thoracic spines
Thorax
Eye
Genal spines
Genal angle
Cephalon
Pygidium
TRILOBITE - what is the glabella for?
What could it suggest?
Size dictates size of stomach
large = carnivore
small = filter feeder
OR
for buoyancy
large = pelagic
TRILOBITE - what is the genal spine for?
What could it suggest?
increase surface area, or maybe protection
- could suggest pelagic and planktonic to stay in the water column, or benthic to stop it sinking in the mud
TRILOBITE - what are the thoracic segments for?
What could it suggest?
- each segment has a pair of legs
- under the legs is pair of gills, for respiration, produces energy
more thoracic segments = more legs = more gills = more respiration = more energy
could suggest nektonic, pelagic, carnivorous
TRILOBITE - What is the pygidium?
The tail bit
TRILOBITE - what are the thoracic spines for?
Big = increased surface area, or maybe protection
could suggest they stop it sinking in the mud. Benthic (mud) or planktonic so it stays the right level in the water column (pelagic)
So anything really
TRILOBITE - what is the cephalon?
The head bit
TRILOBITE - what is the genal angle?
The bit where the cephalon meets the genal spine
TRILOBITE - what is the thorax?
The body bit
TRILOBITE - how can eye shape suggest the trilobites way of life?
NONE
- lived in dark
- buried in mud
- planktonic
CRESCENT
- see behind
- potentially prey, looking out for predators
ON STALKS
- buried in mud
SEE BELOW
- swam
LARGE
- predators
What niches did trilobites occupy?
Nearly every one available
swim (nekton)
float (plankton)
crawl/walk
burrow
What methods did different trilobites use to feed?
- filter - either water, or mud (mud grubber)
- herbivore
- carnivore
- predator
- prey
- scavenger
What is the anatomy of a trilobite?
- soft parts are covered with an exoskeleton
- have compound eyes made of many lenses
- many were 3-6cm long, some were up to 60cm
What body shapes did trilobites tend to be?
How did each one suggest something different?
Streamlined - swam or buried
Spines - snow shoe effect to stop sinking into the mud
Spikes - protection (on top too), or maybe to attract a mate
TRILOBITES - why did some enrol?
some could roll themselves up, maybe for protection
What is a bivalve?
a mollusc that lives in both marine and freshwater
- the creature lives inside the shell, or valves
- 2 valves = bivalve
How do bivalves feed?
when it is in water and safe, it opens its shell and uses its siphon to feed
- filter feeders: filtering the water for bits of food
How many species of bivalve are there?
over 20,000 now and many more in the fossil record
What are some bivalve ways of live?
Give examples for each
SESSILE - fixed in one place
e.g. mussels and oysters
BURROWERS - the deeper they burrow, the longer the siphon they have
e.g. cockles
SOME SWIM!
e.g. scallops
BIVALVE - what is a pallial sinus?
What does it show?
Where the siphon goes when the shell closes
- denotes a burrower
- no pallial sinus = not a burrower
- the bigger the pallial sinus, the bigger the siphon and the deeper it burrowed
BIVALVE - what anatomical structures should I look for?
- tooth and socket
- ligament pit
- muscle scars
- pallial sinus
- pallial line
Where are the lines of symmetry in a bivalve?
between the two shells
Where are the lines of symmetry in a brachiopod?
Down the front of a shell
Where are brachiopods found?
Exclusively marine
What anatomical features should I be looking out for in a brachiopod?
- foramen
- pedicle
- pedicle valve
- brachial valve
BRACHIOPOD - what is the pedicle?
the stalk attaching the brachiopod to the substrate
BRACHIOPOD - what is the foramen?
the hole that the pedicle comes through
BRACHIOPOD - what is the pedicle valve?
The valve with the foramen in
BRACHIOPOD - what is the brachial valve?
the other valve - the one without the foramen in
How do brachiopods feed?
They open their shells to let water in and filter it through their feeding filter, the lophophore
What are the similarities and differences between brachiopods and bivalves?
BRACHIOPODS:
- lophophore for feeding
- commisure
- now rare
- line of symmetry from top to bottom
- opens with muscles
- pedicle and foramen
- don’t move
- exclusively marine
BIVALVE:
- freshwater and marine
- symmetrical from the side
- opens with ligaments
- mobile
- common
- siphuncle
BOTH:
- 2 valves
- marine
- have lines of symmetry
What is a graptolite?
The trace of a fragile skeleton consisting of a series of cup-like thecae arranged in a series along a branch called a stipe
What anatomical features should I look for in a graptolite?
- nema
- sicula
- stipe
- thecae
GRAPTOLITES - what is the sicula?
The initial cup/thecae from which the other thecae bud
GRAPTOLITES - what is the nema?
the thread from the sicula
(the top bit)
GRAPTOLITES - what is the stipe?
The branch along which the cup-like thecae are arranged
What is a rhabdosome?
The network of branches
How did graptolites through the geological periods?
- The earliest graptolites had many branches
- The number of stipes was reduced in the Ordovician and Silurian until the last graptolites had only 1.
- They died out at the end of the Silurian possibly due to the rise of fished in the Devonian
How did graptolites change over the Ordovician and into the Silurian?
ORDOVICIAN:
4 pendant stipe then
2 pendant stipe then
2 flatish stipe then
2 scandent stipe with the nema inside then
2 scandent together in a rod then
SILURIAN:
1 stipe, monograptus
GRAPTOLITES - what does
a) pendant
b) scandent
c) monograptus
mean?
a) Hanging stipe, nema on the top
b) Upwards stipe, nema inside
c) One stipe, whole new animal?
How have thecae evolved?
Larger, fewer, more complex as time goes on`
What characteristics do graptolites have and what can they tell us?
- GRAPTOLITES EVOLVED QUICKLY
- easy identified
- can be used to come up with relative age for the rocks they are found in - NOT SESSILE
- floated freely = found all over the world, widespread - VERY FRAGILE
- only preserved in very low energy environments
- facies dependent = they are only found in a particular facies which is the environment in which shales are deposited - THEY ARE MARINE
- oceans used to be there
Where are graptolites often found?
black shales
Give some characteristics of black shales
- fine grained = formed in low energy environment
- black = high carbon content
- lots of dead material
- lack of oxygen = anoxic environments
- deep see marine
