All of the major animal groups of the Ordovician oceans survived, including trilobites, brachiopods, corals, crinoids and graptolites, but each lost important members.
Widespread families of trilobites disappeared and graptolites came close to total extinction.
What type of organisms were dominant after Ordovician extinction?
Brachiopods, bivalves, echinoderms, bryozoans and corals were particularly affected. Before the late Ordovician cooling, temperatures were relatively warm and it is the suddenness of the climate changes and the elimination of habitats due to sea-level fall that are believed to have precipitated the extinctions.
What organisms lived in the Ordovician period?
The Ordovician is best known for its diverse marine invertebrates, including graptolites, trilobites, brachiopods, and the conodonts (early vertebrates). A typical marine community consisted of these animals, plus red and green algae, primitive fish, cephalopods, corals, crinoids, and gastropods.
What survived the Devonian extinction?
Placoderms, for example, did not survive, acanthodians were decimated, and almost all agnathans vanished. Numerous brachiopods became extinct, conodonts all but disappeared, and only one family of trilobites survived. In total, over 70% of species living in the Devonian no longer existed in the Carboniferous Period.
How did the Ordovician end?
443.8 (+/- 1.5) million years ago