Editing Coral (section)

===Modern corals===
The currently ubiquitous stony corals, [[Scleractinia]], appeared in the [[Middle Triassic]] to fill the niche vacated by the extinct rugose and tabulate orders and is not closely related to the earlier forms. Unlike the corals prevalent before the Permian extinction, which formed skeletons of a form of calcium carbonate known as [[calcite]], modern stony corals form skeletons composed of the [[aragonite]].<ref name=Ries>{{cite journal | vauthors=Ries JB, Stanley SM, Hardie LA | date=July 2006 | title=Scleractinian corals produce calcite, and grow more slowly, in artificial Cretaceous seawater | journal=Geology | volume=34 | issue =7 | pages=525–28 | doi=10.1130/G22600.1 | bibcode=2006Geo....34..525R }}</ref> Their fossils are found in small numbers in rocks from the Triassic period, and become common in the [[Jurassic]] and later periods.<ref>{{cite web|title=Evolutionary history |url=http://coral.aims.gov.au/info/evolution.jsp |archive-url= https://web.archive.org/web/20181013124550/http://coral.aims.gov.au/info/evolution.jsp |archive-date= 13 October 2018 |website=AIMS |access-date=25 April 2015}}</ref> Although they are geologically younger than the tabulate and rugose corals, the aragonite of their skeletons is less readily preserved, and their fossil record is accordingly less complete.

{{Coral fossil record timeline}}