40 Questions
What is the Phanerozoic eon characterized by?
The abundance of fossils of high diversity
What was the mother continent at the start of the Phanerozoic eon?
Pangea
What happened to the CO2 levels in the atmosphere during the Phanerozoic eon?
It decreased
How many eras are the Phanerozoic eon divided into?
3
When did the Cambrian Explosion occur?
541 m.y. ago
What is characteristic of the Paleozoic era?
The evolution of fish, amphibians, and reptiles
What is characteristic of the Mesozoic era?
The evolution of lizards, crocodiles, snakes, turtles, mammals, and dinosaurs
When did life remain mostly small and microscopic?
Until 580 m.y. ago
What was the primary location of the mass extinction during the Devonian Period?
Oceans
What type of organisms persisted during the Mississippian Period?
Crinoids and sea lilies
What type of fossil is particularly useful for indexing the Carboniferous Period?
Fusulinid
What characteristic did the first land-dwelling vertebrates, tetrapods, possess?
Four limbs
What was the climate like during the Mississippian Period?
Warm and moist
What type of coral formed colonies during the Mississippian Period?
Rugose
What type of organisms became extinct at the end of the Permian Period?
Fusulinids
What type of appearance did some tetrapods resemble?
Crocodiles or salamanders
What was the dominant group of marine animals during the Permian Period?
Trilobites
What was the climate like during the Permian Period?
Dry and desert-like
What was the result of the environmental changes during the Permian Period?
The extinction of some species
What group of animals prospered and increased in number by the late Permian Period?
Reptiles
What was the primary food source for land animals during the Permian Period?
Terrestrial plants
What type of animals evolved from large amphibians during the Permian Period?
Reptiles
What was the environment like during the Late Permian Epoch?
Unsuitable for the growth of organisms
What type of fossils are common in Permian deposits?
Reptile fossils
What type of plants first appeared on land during the Ordovician period?
Non-vascular plants
What was the second largest mass extinction event in Earth's history?
The O/S First Mass Extinction
What is believed to have triggered the mass extinction event at the end of the Ordovician period?
The onset of an ice age
What percentage of existing species was lost during the Permian extinction?
90% of existing species
What was the approximate duration of the ice age during the Ordovician period?
0.5 to 1.5 million years
What was the climate like during the Cambrian period?
Warm and wet
What formed on the supercontinent Gondwana during the Ordovician period?
Ice caps
What happened to atmospheric carbon dioxide levels before the extinction event?
They decreased from 7000ppm to 4400ppm
What type of organisms flourished in offshore environments during the Devonian period?
Corals and stromatoporoids
What type of cephalopod appeared during the Devonian period?
Ammonites
What type of marine invertebrate occupied surface waters during the Devonian period?
Dacryoconarids
What type of vertebrates were abundant in many Devonian marine facies?
Conodonts
What is the reason why the Devonian period is called the Age of Fishes?
The dominance of fish in aquatic ecosystems
What type of fish evolved early in the Devonian period?
Lobe-finned fish
What type of animal was derived from fishes near the middle of the Devonian period?
Tetrapods
What type of animal appeared in the Devonian period?
Sharks
Study Notes
Phanerozoic Eon
- Characterized by the evolution of life in different multicellular animals with complex ecological systems
- Marked by the abundance of fossils of high diversity and the occurrence of several phyla
- Land plants and animals developed, and fishes evolved
Proterozoic-Phanerozoic Boundary
- Occurred 541 million years ago
- Classic point of the first trilobites and reef-building animals (archaeocyatha) appearance
- Complex multicellular life arose and developed over time, culminating in the Cambrian Explosion
Eras of the Phanerozoic
- Divided into three eras: Paleozoic, Mesozoic, and Cenozoic
- Each era further subdivided into 12 periods
Paleozoic Era
- Featured the evolution of fish, amphibians, and reptiles
- First plants (non-vascular plants) and terrestrial arthropods appeared on land
- Primitive plants and fungi occurred, along with spreading algae
Ordovician Period
- Ended with a mass extinction event due to global cooling and glaciation on Gondwanaland
- Second-largest mass extinction in Earth's history, with approximately 60% of Ordovician organisms disappearing
- The event was likely triggered by the onset of an ice age, which was probably no longer than 0.5 to 1.5 million years
Silurian Period
- Followed the Ordovician Period and marked the beginning of a new era in Earth's history
- Warm and wet climate of the Cambrian continued until near the end of the Ordovician
Devonian Period
- Known as the Age of Fishes, with a remarkable proliferation of primitive fishes in both fresh and marine waters
- Early fish evolved into various forms, including armored fish, jawless "agnathans", and jawed placoderms
- The first lobe-finned fish evolved early in the Devonian, and by the end of the period, had evolved into the first amphibian-like animals
- Sharks appeared in the Devonian Period
Carboniferous Period
- Saw the continuation and prevalence of bryozoan, brachiopods, and coral reefs
- Sea invertebrates, such as crinoids, echinodermata, and cephalopods, persisted
- Spreading of benthic foraminifera, particularly the Fusulinids, which became extinct at the end of the Permian Period
- Trilobite became less common and headed for extinction
Mississippian Period
- Marked the evolution of the first land-dwelling vertebrates, such as tetrapods
- Tetrapods were well-adapted to life on land, where they could breathe air and escape predators
Permian Period
- Known as the Age of Reptiles, with the decline of trilobites and the abundance of ammonites with complex sutures
- Reptiles prospered and continued to increase in number and variety by the late Permian period
- Terrestrial life was closely keyed to the evolution of terrestrial plants, which were the primary food source for land animals
This quiz covers the Phanerozoic Eon, characterized by the evolution of complex life forms, abundance of fossils, and geological changes. It includes the formation of Pangaea, diversification of life, and changes in the Earth's atmosphere.
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