Global cooling at the (*) Frasnian-Famennian boundary late in this period led to the extinction of seventy percent of marine vertebrates, particularly reef builders, which would not fully recover until the Mesozoic.
This era saw the emergence of species such as Cladoselache, Prototaxite, and the Placoderm Dunkleosteus , which at up to three meters in length was one of the largest organisms in existence at the time. A notable Lagerstatten for this period is the Rhynie Chert in Scotland, discovered in 1912 by Dr. William Mackie. During this period the continents of Laurentia and Baltica collided, and the supercontinent Gondwanaland migrated north. Global cooling at the (*) Frasnian-Famennian boundary late in this period led to the extinction of seventy percent of marine vertebrates, particularly reef builders, which would not fully recover until the Mesozoic. For 10 points, name this geologic time period preceding the Carboniferous, and which was named for a county in southwestern England.
This era saw the emergence of species such as Cladoselache, Prototaxite, and the Placoderm Dunkleosteus , which at up to three meters in length was one of the largest organisms in existence at the time.
{Devonian}