of, denoting, or formed in the third period of the Palaeozoic era, between the Ordovician and Devonian periods, which lasted for 25 million years, during which fishes first appeared
2.
of or relating to the Silures
noun
3. the Silurian
Silurian in American English
(sɪˈlʊriən; saɪˈlʊriən)
adjective
1.
of the Silures
2. [sometimess-]
designating or of the third geologic period of the Paleozoic Era, characterized by the development of coral reefs and small land plants, the first fish with jaws, and the first land arthropods
Idioms:
the Silurian
Word origin
(sense 2) because the rocks were first found in an area in SE Wales: see Silures