二疊紀(jì)末期距今已有約2.5億年,，發(fā)生了有史以來最嚴(yán)重的大滅絕事件，地球上大約有96%的物種滅絕,，占領(lǐng)海洋近3億年的主要生物衰敗并消亡,，新生物開始出現(xiàn)，地球生態(tài)系統(tǒng)發(fā)生徹底更新,。如今,，研究人員在日前在線出版的《自然—地球科學(xué)》期刊上報告，由海綿和微生物構(gòu)成的暗礁出現(xiàn)在這次大滅絕之后的150萬年,。此前的研究認(rèn)為,，由動物遺體構(gòu)成的暗礁在大滅絕之后的第一個500萬年內(nèi)就已經(jīng)消失了。
Arnaud Brayard和同事報告了采集自美國猶他州和內(nèi)華達州的化石,，認(rèn)為這些化石是由海綿和微生物群落組成的暗礁,。他們在暗礁沉積物中發(fā)現(xiàn)各種各樣的軟體動物、海膽脊椎和已滅絕的頭足綱軟體動物菊石,。他們指出,，暗礁中的這些沉積物應(yīng)該形成于大滅絕之后150萬年內(nèi)，含有這一時期海底棲息動物的豐富記錄,。以前的研究認(rèn)為,，這一時間沒有海底棲息動物。(生物谷 Bioon.com)
doi:10.1038/ngeo1264
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Transient metazoan reefs in the aftermath of the end-Permian mass extinction
Arnaud Brayard, Emmanuelle Vennin, Nicolas Olivier, Kevin G. Bylund, Jim Jenks, Daniel A. Stephen, Hugo Bucher, Richard Hofmann, Nicolas Goudemand & Gilles Escarguel
Recovery from the devastating Permian–Triassic mass extinction about 252 million years ago is usually assumed to have spanned the entire 5 million years of the Early Triassic epoch. The post-crisis interval was characterized by large-scale fluctuations of the global carbon cycle and harsh marine conditions, including a combination of ocean acidification, euxinia, and fluctuating productivity. During this interval, metazoan-dominated reefs are thought to have been replaced by microbial deposits that are considered the hallmark of the Early Triassic. Here we use field and microscopic investigations to document Early Triassic bioaccumulations and reefs from the western USA that comprise of various sponges and serpulids associated with microbialites and other eukaryotic benthic organisms. These metazoan-rich reefs were formed only 1.5 million years after the extinction, in contrast to previous suggestions of a much delayed recovery of complex benthic communities. We conclude that the predominance of microbial reefs following the mass extinction is restricted to short intervals of the earliest Triassic. We suggest that metazoan reef building continued throughout the Early Triassic wherever permitted by environmental conditions.
