埃迪卡拉纪（），又称艾迪卡拉纪、震旦纪（）、文德纪（），是元古宙最後的一段时期，其後緊接著便是顯生宙的開端──古生代的寒武紀。埃迪卡拉纪一般指6.35-5.41億年前。学者曾用这个名字指稱不同阶段，直到2004年5月13日，國際地質科學聯盟明確定義其年代，这是这个组织120年來首次對其加时期定义。最古老的動物遺跡可追溯至十億年前，但最早的動物化石出現於埃迪卡拉纪。

埃迪卡拉紀和震旦纪、文德紀 
埃迪卡拉生物群因為發現於南澳洲的而得名。1946年，一位澳洲地質學家在古代的沙岩板中留意到一曾在这里发现顯生宙以前的化石。研究这些化石的科學家認为这是珊瑚、水母和蠕虫的先驱。以后几十年，南澳洲还找到很多的隐生宙化石，其他各大洲也找到一些。这些化石都叫作埃迪卡拉动物。一開始，人們認為埃迪卡拉動物是寒武紀的動物，但經過仔細的觀察，埃迪卡拉生物群比寒武紀還久遠，應屬於埃迪卡拉纪。

本纪曾被一些人称为震旦紀（Sinian）。震旦纪的名称来源于中国，“震旦”是中国的古称。由于古印度人称中国为Cinisthana，在佛经中被译为震旦，故名震旦纪。时至今日，中国学者仍经常这么称呼，中国教科书上一直称此纪为震旦纪。俄国人又把埃迪卡拉纪称为文德纪（Vendian），他们在这一时期的地层中又发现了一些古线虫动物的化石。

上下邊界

細分

絕對年代

生物群

埃迪卡拉生物群（）是1946年发现于南澳洲的末远古系庞德石英岩中的化石群，这类化石群已在世界30多个地点被发现。它們是迄今已知最早的複雜多細胞生物。

埃迪卡拉动物和今天的大多數動物截然不同，牠們既沒頭、尾、四肢，也無口部和消化器官，因此牠們大概只能從水中攝取養份。大多的埃迪卡拉动物固著在海底，和植物十分相近，其他的則平躺在淺海處，等待營養順水流而送上門來。埃迪卡拉动物化石出土越多，反而越没有规律。有一些化石比较像后来动物的先驱。

在埃迪卡拉紀末期，埃迪卡拉动物分成兩支，牠們有的成功演化成更有活力，更具進攻性的動物，並在之後的寒武纪大爆发中大放異彩，成為現今大多數動物門的祖先。而有的則走向滅亡，牠們的特徵也永遠消失於歷史舞台上。

天文因素

參見 
 
 
 埃迪卡拉紀末期滅絕事件

參考資料

脚注

书目
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新元古代