•Fossils Flashcards
What is a fossil?
What do they include?
Preserved evidence of pre-historic life
Hard parts of an organism
Tracks, footprints, burrowers and feeding trails
What are the seven main taxonomic ranks in order?
Kingdom Phylum Class Order Family Genus Species
What environments are fossils preserved in?
Fine grained sediment
Low energy environments
Best preserved in shale, mudstone and micritic limestone
What are the hard parts of organisms called?
Invertebrates = shells of exoskeletons
Vertebrates = endoskeletons
How are derived fossils formed?
Organisms in older rock are eroded
Then transported
And deposited in younger rocks
What is a life assemblage ?
What are their characteristics?
Assemblage of fossil remains found where animals had lived
While fossils
Range of sizes
No orientation
What is a death assemblage?
What are it’s characteristics?
Assemblage of fossils formed because they were brought together after death not because of their habitats
Not in living position
Fragmented through transport
Similar in size
Have orientation
What is the process of petrification?
A shell is buried in sediment
Original material is dissolved leaving a mould
The mould is I filed with calcite, silica, iron oxide and iron sulphide
Creates a cast
What is hard body preservation?
The soft body decomposes leaving the skeleton or shell
Gap is replaced with crystallised deposits (petrification)
What is soft body preservation?
How can it be preserved?
Soft body rapidly decomposes
Process of petrification
Anaerobic environments
Frozen in glacier
Preserved in Tundra
Incorporated into wood sap
What is a Trilobite?
What are it’s parts?
Oldest creature found with eyes
From the Cambrian to the Permian
Cephalon Thorax Pygidium Glabella Facial suture Eyes Genial spines Thoracic segments Legs
Which characteristics classify a trilobite?
Size of cephalon Size of pygidium Shape of facial suture Number of thoracic segments Size of glabella Shape of glabella Size of genal spines
Morphological characteristics of a trilobite: pelagic (swimmer) lifestyle
Large eyes
Large glabella
Elongated body
Large pygidium
Morphological characteristics of a trilobite: burrower lifestyle
Smooth cephalon Poorly developed/ no genal spines Elongated body Poorly developed genal spines Small/ no eyes Rushes on pygidium
Morphological characteristics of a trilobite: Benthic (mud grubber) lifestyle
Large cephalon Reinforced fringe Small/ no eyes Wide body Large genal spines
Morphological characteristics of a trilobite: predatory lifestyle
Large eyes
Large body
Large glabella
Thoracic spines
What is cruziana?
Chevron like trails caused by a trilobite crawling, ploughing, shovelling or burrowing through soft sediment
What is Rusophycus?
Surface scours
Implies that a swimming trilobite has landed, made a temporary nest then swim away
Occur at the end of cruziana trails
What are asaphoidichnus?
Diagonal sets of walking trails
Crab like sideways motions as animals try to steady itself on slippery mud
What are diplichnites?
Walking or striding tracks with individual leg impressions.
Series of paired markings
What is a graptolite?
What are it’s parts?
A fossil that is only preserved in low energy environments & shale
Lived from Ordovician to Silurian
Nema
Stipes
Thecae
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What is this?
What are it’s characteristics?
Dictyonema
Early Ordovician
Multiple pendant stipes
Simple thecae
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What is this?
What are it’s characteristics?
Tetragraptus
Early Ordovician
4 pendant stipes
Simple thecae
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What is this?
What are it’s characteristics?
Didymograptus
Early Ordovician
2 pendant stipes
Simple thecae
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— —
What is this?
What are it’s characteristics?
Leptograptus
Middle Ordovician
2 reclined stipes
Fairly complex thecae
_|_/
What is this?
What are it’s characteristics?
Dicellograptus
Late Ordovician
2 Scandentia stipes
Complex thecae
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What is this?
What are is characteristics?
Climograptus
Late Ordovician
2 scadent stipes
Complex and elaborate thecae
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What is this?
Monograptus
Silurian
1 Scandent stipe
Complex and elaborate thecae
When was the time span of an ammonoid?
What are it’s parts?
Devonian- Cretaceous
Well- developed eye
Shell cavities
Septa
Soft bodies creature- siphon
Goniatite
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Upper Palaeozoic- Carboniferous
Simple loves and saddles
Relatively wide shell
Ceratite
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Mesozoic- Triassic
Rounded saddle & frilled lobe
Relatively thin and streamlined
Ammonite
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Mesozoic- Cretaceous
Complex septa and highly frilled lobes and saddles
Narrow and streamlined
What is the time span of a Brachiopod?
What are it’s parts?
Cambrian to Today
Pedicle opening Foramen Umbo Growth lines Bilateral symmetry Unequal valves Commissure Pedicle valve Brachial valve
What are the two brachiopod valves?
What are their parts?
Pedicle valve: Pedicle opening Hinge- teeth & sockets Abductor- close Diductor- open Muscle scars
Brachial valve:
Brachidium
Lophophone
What is a time span of a bivalve?
What are it’s parts?
Ordovician- Today
Umbo Teeth and sockets Hinge line Muscle scars Pallial line Pallial sinus
What are the bivalve valves?
What are their parts?
Dorsal
Anterior Posterior
Ventral
No bilateral symmetry
Equal valves
What is an Infaunal (deep burrowing) bivalve?
Flat elongated shell
Large pallial sinus
Equal valves
Anterior and posterior valves
20cm below the sediment surface
E.g Mya
What is an epifaunal (attached by a byssus) bivalve?
Secrets threads of protein collagen Upright position Elongate shells Equal valves Flattened surface Anterior muscle scar is smaller than posterior
Rocky surfaces submerged at high tide
E.g mytilus mussel
What is an infaunal (shallow burrowing) bivalve?
Equal convex valves
Small pallial sinus
Adductors similar size
Strong shell
Just below beach surface
Cockle (cardium)
What is an epifaunal (cemented) bivalve?
High energy environments
Thick unequal valves
Single adductor muscle
Attached to bedrock
Rocky surfaces on the seabed
Oyster (Ostrea)
What is a free-lying bivalve?
Convex valves for stability
One large valve
Lying on seabed
Gryphaea
What is a swimming bivalve?
Low freely Vigorously clap valves Unequal sized valves One adductor Almost bilaterally symmetrical Large muscle scars
Open sea and on sea bed
Scallop (pecten)
What is the time span of a plant?
Devonian to Today
3000ma in the sea
400ma on the land
Common in terrestrial rocks
What are the hard parts of a plant?
Leaf
Branch
Trunk
What is the time span of a coral?
Pre-Cambrian to Today
What are the parts of a coral?
Colonial:
Septa
CaCo3 exoskeleton (Corallite)
Solitary:
Septa
What are the best conditions for coral?
Warm water (25 degree)
Shallow and light (no deeper than 20m)
Still water (no sediment)
Oxygenated water
Marine water (away from river mouth)
Neutral PH (7)
