Silurian
Post-Ordovician geologic era
Silurian refers to a geological period roughly 440 to 420 million years ago, when the first land plants and jawed fish appeared.
The name comes from the Silures, an ancient Celtic tribe of Wales, where rocks from this period were first studied.
As an adjective, it describes fossils, formations, or life from that era: Silurian coral reefs, Silurian shale deposits.
Paleozoic geological period
- DevonianGeologic period, 419-359 million years ago
- LudlowShropshire market town
- PaleozoicEarly complex-life epoch
- geologicOf Earth's physical structure
stratigraphy · geochronology · stage · epoch · era · system · boundary · type section
Ancient southern supercontinent
- orogenyGeological mountain formation
- CaledonianOf or from Scotland
- tectonicsStudy of crustal deformation
- continental driftGradual landmass repositioning
Hinged-shell marine invertebrate
- trilobiteExtinct segmented marine arthropod
- coralMarine skeletal formation
- nautiloidChambered cephalopod subclass
- bryozoanColonial aquatic invertebrate
tabulate · rugose · articulate · paleontology · preservation · fossil record
Time-traveling alien series
- prehistoric civilizationSociety before written records
- cold-bloodedUnfeeling or externally heated
- hibernationProlonged winter dormancy
- awakeningReturn to consciousness
Extinct aquatic arthropod predator
- reefUnderwater rock or coral formation
- carbonateAdd dissolved gas
- shallow seaMarine area with penetrable depths
- cephalopodTentacled marine mollusk class
jawless fish · marine ecosystem · benthic · pelagic · marine invertebrate · transgression · regression
Foreign territorial takeover
- millipedeMulti-segmented leggy invertebrate
- arachnidEight-legged wingless arthropod
- ozone layerAtmospheric UV filter
- recoveryRegaining what was lost
Ordovician
Paleozoic geological period
- DevonianGeologic period, 419-359 million years ago
- LudlowShropshire market town
- PaleozoicEarly complex-life epoch
geologic · stratigraphy · geochronology · stage · epoch · era · system · boundary · type section · Wales
Gondwana
Ancient southern supercontinent
- orogenyGeological mountain formation
- CaledonianOf or from Scotland
- tectonicsStudy of crustal deformation
continental drift · ironstone · formation · outcrop · Wales
brachiopod
Hinged-shell marine invertebrate
- trilobiteExtinct segmented marine arthropod
- coralMarine skeletal formation
- nautiloidChambered cephalopod subclass
bryozoan · tabulate · rugose · articulate · paleontology · preservation · fossil record
Doctor Who
Time-traveling alien series
- prehistoric civilizationSociety before written records
- cold-bloodedUnfeeling or externally heated
- hibernationProlonged winter dormancy
sea scorpion
Extinct aquatic arthropod predator
- reefUnderwater rock or coral formation
- carbonateAdd dissolved gas
- shallow seaMarine area with penetrable depths
cephalopod · jawless fish · marine ecosystem · benthic · pelagic · marine invertebrate · transgression · regression
colonization
Foreign territorial takeover
- millipedeMulti-segmented leggy invertebrate
- arachnidEight-legged wingless arthropod
- ozone layerAtmospheric UV filter
SilurianHolocene
Current geological epoch
Anthropocene · Quaternary · Cenozoic · Permian · Precambrian