the aftermath of the end-Guadalupian extinction and continued following the end-Permian extinction. Ammonites were affected substantially by the Triassic-Jurassic extinction. Ceratitidans, the most prominent group of ammonites in the Triassic, became extinct at the end of the Rhaetian after having their diversity reduced significantly in the Norian. Other ammonite groups such as the Ammonitina, Lytoceratina, and Phylloceratina diversified from the Early Jurassic onward. Bivalves experienced high extinction rates at the early and middle Rhaetian. File shell bivalves experienced the Brobdingnag effect, the reverse of the Lilliput effect, as a result of the mass extinction event. There is some evidence of a bivalve cosmopolitanism event in the aftermath of the mass extinction. Plankton and gastropod diversity was barely affected at the T-J boundary, although there may have been local extinctions in radiolarians. Brachiopods slowly declined in diversity during the late Triassic before re-diversifying in the Early Jurassic. Conulariids seemingly completely died out at the end of the Triassic. There is good evidence for a collapse in the reef community, as corals practically disappeared from the Tethys Ocean at the end of the Triassic and would not return to their previous abundance until the late Sinemurian (the 2nd of 11 Jurassic stages). This reef collapse was likely driven by ocean acidification resulting from supplied to the atmosphere by the CAMP eruptions. Other studies point to a fast recovery from the mass extinction; British Early Jurassic benthic marine environments display a relatively rapid recovery that began almost immediately after the end of the mass extinction despite numerous relapses into anoxic conditions during the earliest Jurassic. Marine vertebrates Fish did not suffer a mass extinction at the end of the Triassic. The late Triassic in general did experience a gradual drop in actinopterygiian diversity after an evolutionary explosion in the middle Triassic. Though this may have been due to falling sea levels or the Carnian pluvial event, it may instead be a result of sampling bias considering that middle Triassic fish have been more extensively studied than late Triassic fish. Despite the apparent drop in diversity, neopterygiians (which include most modern bony fish) suffered less than more "primitive" actinopterygiians, indicating a biological turnover where modern groups of fish started to supplant earlier groups. Conodonts, which were prominent index fossils throughout the Paleozoic and Triassic, finally became extinct at the T-J boundary following declining diversity. Like fish, marine reptiles experienced a substantial drop in diversity