< p >无可争议的最古老化石是叠层石,细菌垫,< a href = " https://www.ncbi.nlm.nih.gov/pubmed/27580034 " rel = " nofollow noreferrer " >古老< / >约会ay 37亿年前。关键项是无可争议的,可能有其他的化石,但很难有确定的化学或细胞的化石。不确定的最古老化石可追溯至< a href = " https://www.nature.com/articles/nature21377 " rel = " nofollow noreferrer " > < / >, 42.8亿年是可能的细菌被困在深海热液喷口的产品。< / p > < p >最古老化石的生物大脑是奇怪。它实际上是几个生物从< a href = " https://en.wikipedia.org/wiki/Ediacaran_biota " rel = " nofollow noreferrer " >埃迪卡拉生物群< / >。这些也是最古老的多细胞生物化石,没有任何困难部分石化早期的小动物是非常罕见的事件甚至已经考虑到罕见的石化。有一些双边对称的动物运动的能力,结合事实他们是两个以上的细胞厚几乎肯定意味着他们的大脑。< / p >Kimberella and Spriggina and their relatives are both almost certainly mobile, with some form of nervous system based on phylogenetic bracketing, others are also likely since the ancestor of chordates may in there somewhere. We know there were moving creatures from the ediacara because we actually have trace fossils that are consistent with a muscular moving organism like anemone.