cambrian. anomalocaris marella hallucigenea
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Cambrian
Anomalocaris
Marella
Hallucigenea
Jellyfish?
Shrimp?
Sponge?
Parts of Anomalocaris were at first thought to be three separate animals.
Anomalocaris
Wiwaxia corrugataWiwaxia corrugata
Wiwaxia corrugata
Marrella splendens
HallucigeniaHallucigenia
GLB in the Paleozoic EraGLB in the Paleozoic Era
Central North America experienced Central North America experienced repeated transgressions and regressions of repeated transgressions and regressions of shallow, tropical seas during Paleozoicshallow, tropical seas during Paleozoic
Midwest is below equatorMidwest is below equator
Large areas of tropical coral reefsLarge areas of tropical coral reefs
Seas deposited layers of materials that became Seas deposited layers of materials that became sedimentary rockssedimentary rocks Limestone, shales, sandstone, gypsumLimestone, shales, sandstone, gypsum Thornton Quarry, Sagawau Canyon limestoneThornton Quarry, Sagawau Canyon limestone
Ordovician PeriodOrdovician Period 490 - 443 Million Years Ago Shallow, shifting seas covered most of North
America Biodiversity increasing rapidly
Corals, bryozoans, crinoids, cephalopods, a great variety of new brachiopods, trilobites
First fish appear in fossil record Squid-like cephalopods were the largest creatures in
Ordovician seas. Cone-shaped shells sometimes reached a length of 5 meters
(about 16 ft.).
Ordovician PeriodOrdovician Period
Sea floor covered by calcium carbonate mud produced by the breakdown of "stony" algae and animal remains.
Bryozoans and algae trapped the sediment to form small mounds. Mounds protected animals, such as brachiopods,
corals, crinoids, starfish, mollusks, and trilobites.
Receptaculitids are common in the rocks from this area.
Ordovician Ordovician FossilsFossils
Ordovician PeriodOrdovician Period
Algae with Skeletons• Receptaculites appeared
around 488 million years ago in the Lower Ordovician and disappeared 250 million years ago in the Lower Triassic.
• Their modern-day cousins, the Dasycladaceae, are algae that also form calcareous skeletons.
BrachiopodsBrachiopods
Onniella meeki
Illinois
Rhynchotrema dentatum
Illinois
BrachiopodsBrachiopods300 living species 300 living species
of brachiopodsof brachiopods
Brachiopods-Brachiopods-LampshellsLampshells
CrinoidCrinoid
Pycnocrinus dyeri
Cincinnati, Ohio
Nautiloid CephalopodNautiloid Cephalopod
Plectoderas undatus
Illinois
CoralsCorals
tabulate coral Favistella alveolata
Illinois
rugose coral Grewingkia canadensis
Cincinnati, Ohio
Coral ReconstructionsCoral Reconstructions
Rugose coral
Tabulate Coral
Tentaculites -Tentaculites - mollusc mollusc
Tentaculites incurvus
Cape Girardeau, Missouri
Tentaculites oswegoensisTentaculites oswegoensis Waubonsee Creek in Oswego, IL
Rock called Brainerd Formation
Shale and thin dolomite
Upper Ordovician and Silurian
Tentaculites oswegoensisTentaculites oswegoensis
Fossils found only known in Fossils found only known in Illinois Illinois
Animal ranged from Oswego, Animal ranged from Oswego, IL (Kendall County) to possibly IL (Kendall County) to possibly Kankakee River State Park in Kankakee River State Park in Will County.Will County.
TrilobiteTrilobite
Isotelus iowensis
Missouri
Graptolites ‘‘Graptolite' means 'writing in rock‘Graptolite' means 'writing in rock‘ Hemichordate – related to echinoderms & chordatesHemichordate – related to echinoderms & chordates Most graptolites are thought to have been Most graptolites are thought to have been
planktonic, floating or slowly sinking through the planktonic, floating or slowly sinking through the water. water. The spiral shape of some was probably an adaptation to The spiral shape of some was probably an adaptation to
slow sinking. slow sinking. Other graptolites may have been connected to gas-filled Other graptolites may have been connected to gas-filled
sacs, keeping them buoyant. sacs, keeping them buoyant. Lived in water with low oxygen levelsLived in water with low oxygen levels
Fed on planktonFed on plankton
GraptolitesGraptolitesHemichordatesHemichordates
Phyllograptus archaios Phyllograptus archaios
SpirograptusSpirograptus
Graptolite ReconstructionsGraptolite Reconstructions
Silurian PeriodSilurian Period 443 - 417 Million Years Ago — Silurian Period443 - 417 Million Years Ago — Silurian Period Shallow, tropical sea covered Illinois (then south of the Shallow, tropical sea covered Illinois (then south of the
equator) equator) Reefs, corals, crinoids, and shelled invertebrates flourished Reefs, corals, crinoids, and shelled invertebrates flourished Delicate corals, bryozoans, and crinoids were in protected Delicate corals, bryozoans, and crinoids were in protected
pockets and along the sides of the reefs. pockets and along the sides of the reefs. Brachiopods, snails, clams, and trilobites were hidden in the Brachiopods, snails, clams, and trilobites were hidden in the
tangle of the complex branches of these animalstangle of the complex branches of these animals These shelled animals were eaten by predatory, squid-like These shelled animals were eaten by predatory, squid-like
cephalopods. cephalopods. Largest animals of the time were 2-meter-long (6.5 ft.) sea Largest animals of the time were 2-meter-long (6.5 ft.) sea
scorpions called eurypteridsscorpions called eurypterids
Eurypterids
A group of eurypterids (sea scorpions) from group of eurypterids (sea scorpions) from Upper Silurian rocks of the Niagara Peninsula.Upper Silurian rocks of the Niagara Peninsula.
Silurian PeriodSilurian Period
Ocean reefs occurred in a band 30 degrees to Ocean reefs occurred in a band 30 degrees to the north and south of the equator. the north and south of the equator.
Most widespread distribution of reefs in the Most widespread distribution of reefs in the history of North America during Silurianhistory of North America during Silurian
Reefs ranged fromReefs ranged from less than a meter (3.3 ft.) to several kilometers in less than a meter (3.3 ft.) to several kilometers in
diameter anddiameter and
less than 3 meters (about 10 ft.) to nearly 304 meters less than 3 meters (about 10 ft.) to nearly 304 meters (about 1000 ft.) high. (about 1000 ft.) high.
Silurian PeriodSilurian Period
Rich fossil deposits in Illinois and lower Rich fossil deposits in Illinois and lower Midwest from this periodMidwest from this period Many fossils from ancient Silurian reefsMany fossils from ancient Silurian reefs
e.g. Trilobites, Ammonites, Eurypterids, Corals, e.g. Trilobites, Ammonites, Eurypterids, Corals, Crinoids, Brachiopods, Jawless Fish, Primitive Sharks Crinoids, Brachiopods, Jawless Fish, Primitive Sharks
Be sure to visit the online Silurian Reef exhibit from Be sure to visit the online Silurian Reef exhibit from the Milwaukee Public Museum!the Milwaukee Public Museum!
Plants and wingless insects arosePlants and wingless insects arose But GLB fossils of these are rare since entire region But GLB fossils of these are rare since entire region
was under water was under water
Silurian PeriodSilurian Period
Silurian rocks are exposedSilurian rocks are exposed
Along the Kennedy Expressway at Addison Along the Kennedy Expressway at Addison (southbound lanes) (southbound lanes)
In the Thornton Quarry at Homewood In the Thornton Quarry at Homewood
In the Sag Bridge abandoned quarries (Cook County In the Sag Bridge abandoned quarries (Cook County Forest Preserves) Forest Preserves)
Along Rock Creek in the Kankakee River State Park Along Rock Creek in the Kankakee River State Park
Along the Illinois River Along the Illinois River
Near the towns of Lemont, Romeoville and Joliet. Near the towns of Lemont, Romeoville and Joliet.
Silurian Seat at Navy PierSilurian Seat at Navy Pier
Thornton Quarry: Then and Thornton Quarry: Then and NowNow
Chicago is built upon a vast Chicago is built upon a vast Silurian Reef.Silurian Reef.
Silurian Reef Diorama at the Field Silurian Reef Diorama at the Field Museum of Natural History in ChicagoMuseum of Natural History in Chicago
Fossil Crinoids, Brachiopods, Trilobites, Fossil Crinoids, Brachiopods, Trilobites, Ammonoids, Gastropods and Corals are found Ammonoids, Gastropods and Corals are found in Thornton Quarry rock. in Thornton Quarry rock.
Modern reef environments are found in warm, Modern reef environments are found in warm, shallow oceans. shallow oceans. The water is usually clear of silt and wind-blown The water is usually clear of silt and wind-blown
sediments. sediments. Many of the reef inhabitants are filter feeders and Many of the reef inhabitants are filter feeders and
sediment prevents feeding.sediment prevents feeding.
Scene from a Silurian seaScene from a Silurian sea
Silurian FossilsSilurian Fossils
BryozoanBryozoan
Fenestrellina elegans
Chicago
CrinoidsCrinoids
Eucalyptocrimus crassus
Indiana
Scyphocrinites sp
Diorama of a Silurian Reef
Living CrinoidsLiving Crinoids
CephalopodsCephalopods
Nautaloid Cephalopod
Michelinoceras
Illinois
Ammonoid
Living Chambered Living Chambered NautilusNautilus
Silurian TrilobitesSilurian Trilobites
Calymene celebra
Milwaukee
Slab of Upper Ordovician Tyndall Limestone at the quarry in Garson, north of Winnipeg showing a large Receptaculites (calcareous algae) and mottles produced by Thalassinoides burrows.
SpongesSponges
Astylospongia praemosa
Modern SpongesModern Sponges
Sponge Fossils
Corals Corals
tabulate coral Cladopora reticulata
Louisville, Kentucky
Tabulate Coral
Living Corals
Living Coral Polyps
TrilobitesTrilobites
Dicranurus monstrosus Dicranurus monstrosus
Note: defensive spinesNote: defensive spines
In the late Silurian, the first-known land In the late Silurian, the first-known land plants (plants (CooksoniaCooksonia) and air-breathing ) and air-breathing animals (millipedes, centipedes and animals (millipedes, centipedes and scorpions) appeared. scorpions) appeared.
Cooksonia
Psilotum
Arthropleura Pleurojulus steuri Myriopoda millipede
Pleurojulus steuri