Types of fossils Flashcards
Skolithos
Vertical burrow
Diplocraterion
U-shaped burrow
Thallasinoides
Branching burrow
Rusophyctus
Trilobite resting trace
Cruziana
Trilobite walking trace
Trinucleus
Infaunal Trilobite
Sensory pits instead of eyes
Large genial spines
Small thorax
Calymene
Epifaunal Trilobite
Large thorax to spread weight
Eyes on top of head to see predators
Agnostus
Planktonic Trilobite Blind Pygidium same size as Cephalon for balance Inflatable glabella Small thorax Fins on pygidium to steer
Deiphon
Nektonic Trilobite Thoracic segments separated and not jointed to spread weight Large genal angle Inflatable glabella Fin like pygidium Eyes in front of head to look for prey
Rugose
Horn shaped Coral (Lithostotian) Large corallites Sometimes dissepiments Bilateral symmetry Columella always present Major septa at 6 points and Minor septa at 4 points
Tabulate
Honey comb shaped coral (Halysites) Well developed tabulae Small corallites No dissepiments or columella Radial symmetry Septa sometimes present but not well developed May have mural pores
Scleractinian
Modern coral (Thecosmilia) Small corallites Always contains dissepiments Radial symmetry Columella may be present Major septa at 6 points
Terebratulid
Brachiopod
Smooth shell
Large pedicle foramen, suggest epifaunal + sessile
Lived in high energy environment
Speriferid
Brachiopod
Wide shell to spread weight on sediment
Sessile epifaunal
Productid
Brachiopod
Large spines used for anchoring in the ground
Convex pedicle valve also for anchoring
Rhynchonellid
Brachiopod
Ribs for strength in high energy environments
Crenelated commisure to prevent sediment getting into the shell
Mytilus
Bivalve - Epifaunal
Byssus (thread like structure for attachment to substrate)
Layer of periostracum protects from acidic water
Strong, streamlined shell and large adductor muscles for high energy environment i.e. Littoral zone
Ostrea
Bivalve - Epifaunal
Cement used for attachment
Thick shell and strong adductor muscle for high energy environment
Larger left valve cemented to sediment, smaller right valve acts like a lid
Gryphaea
Bivalve - Epifaunal
Larger left valve to spread weight on the sediment as no attachments
Small right valve like a lid (small so not caught like a sail in current)
Thick shell for high energy environment
Cytherea
Bivalve - Infaunal
Ribs
Small pallial sinus and no gap between valves
Short retractable siphon
Smooth shell for easy burrowing
Large adductor muscle scar lived in high energy environment i.e. Littoral zone
Solen
Bivalve - Infaunal
Large pallial sinus for long siphon
Smooth and elongated shell for easy movement in burrow
Small adductor muscle scars because no reason to open valves in burrow
Anterior and posterior gapes because siphon and foot can’t be retracted fully
Pecten
Bivalve - Nektonic
Thin corrugated valves to be strong but light
Ears making hinge line straight improves stability and speed while swimming
Lots of tiny eyes in the edge of the mantel sense shadows of predators
Buccinum
Gastropod
Short siphon to respire in clean water as ploughs through sediment
Carnivorous, radula scraps soft tissue off prey
Planorbis
Gastropod
Thin shelled as lived in low energy environment
Flat coil, little to no spire
Sinistral
Turritella
Gastropod
Large spire to anchor in sediment (small apical angle)
Infaunal filter feeder
Tetragraptus
Graptolite Uniserial Pendent Four stipes Simple Theca
Didymograptus 1
Graptolite Uniserial Pendent Two stipes Simple Theca
Didymograptus 2
Graptolite Uniserial Pendent Horizontal Two stipes Simple Theca
Dicellograptus
Graptolites Uniserial Reclined Two stipes Sigmoidal Theca
Diplograptus
Graptolite Biserial Scandent Single stipe Simple Theca
Monograptus
Graptolite Uniserial Scandent Single stipe Simple or lobated Theca
Ostracods
Microfossil
Complex crustaceans with 2 valves, teeth and muscles
Made of chitin
Paleoenvironment indicator as varied in salinity
Foraminifera
Microfossils
Single called creature with protective test
Captured food using thread like structures
Excellent stratigraphic (dating) tool, used by oil companies
Conodonts
Microfossils
Teeth of soft bodied creature
Made of calcium phosphate
Found in Precambrian rocks
Radiolaria
Microfossils Planktonic animals Made of silica Found below CCD (carbon compensation depth - below which calcite is unstable so dissolves) Easy to recover