Porter Susannah M
Department of Earth Science, University of California at Santa Barbara, Santa Barbara, CA 93106, USA.
Science. 2007 Jun 1;316(5829):1302. doi: 10.1126/science.1137284.
The first appearances of aragonite and calcite skeletons in 18 animal clades that independently evolved mineralization during the late Ediacaran through the Ordovician (approximately 550 to 444 million years ago) correspond to intervals when seawater chemistry favored aragonite and calcite precipitation, respectively. Skeletal mineralogies rarely changed once skeletons evolved, despite subsequent changes in seawater chemistry. Thus, the selection of carbonate skeletal minerals appears to have been dictated by seawater chemistry at the time a clade first acquired its mineralized skeleton.
文石和方解石骨骼在18个动物类群中的首次出现，这些类群在埃迪卡拉纪晚期至奥陶纪（约5.5亿至4.44亿年前）独立演化出矿化作用，分别对应于海水化学有利于文石和方解石沉淀的时期。尽管海水化学随后发生了变化，但骨骼矿相一旦演化出来就很少改变。因此，碳酸盐骨骼矿物的选择似乎在一个类群首次获得矿化骨骼时就由当时的海水化学所决定。
