後生動物 (metazoa) 屬於動物類，雖然在最早期的化石研究記錄裡顯示在埃迪卡拉紀時代的水母(刺细胞动物 Cnidaria)已經出現，但是海棉(海棉動物 Porifera)有可能比水母還要更早進化。 (依據化石的研究記錄) 大多數已被礦化的動物門類之骨骼首先出現在寒武紀時期, 其年代已超過5億年之久，而且還有另一種聽似有理的說詞，多數的生物門可能在寒武紀生物爆發 (Cambrian explosion) 時已經進化，但是並没有留下任何化石記錄。凱文・彼得森認為最早期的後生動物大概出現在5億7300-6億5600萬年前。
友誼網頁連結
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The Museums of Cape Town have a marvelous introduction to the kingdom of animals (Metazoa) with photographs and descriptions of the various phyla.
- A page from U Cal Berkeley about the Metazoa fossil record suggests it may be possible that nearly all the phyla of metazoa evolved in the Cambrian aside from
the Cnidaria, which evolved earlier, in the Ediacaran (Vendian).
- Were the Cnidaria present in the Ediacaran Era, or did they evolve later, in the Cambrian. This article from the New York Times discusses fossil and DNA evidence that seem to suggest conflicting dates for Cnidaria (600 MYA or 540 MYA).
- The Museum Victoria in Australia has a page about the oldest evidence of life, including the earliest animal life.
- Another possible ancestor of early metazoa would be the bilaterians who lived 580-600 million years ago.
後生動物 (metazoa) 屬於動物類，雖然在最早期的化石研究記錄裡顯示在埃迪卡拉紀時代的水母(刺细胞动物 Cnidaria)已經出現，但是海棉(海棉動物 Porifera)有可能比水母還要更早進化。 (依據化石的研究記錄) 大多數已被礦化的動物門類之骨骼首先出現在寒武紀時期, 其年代已超過5億年之久，而且還有另一種聽似有理的說詞，多數的生物門可能在寒武紀生物爆發 (Cambrian explosion) 時已經進化，但是並没有留下任何化石記錄。凱文・彼得森認為最早期的後生動物大概出現在5億7300-6億5600萬年前。
友誼網頁連結
- The Museums of Cape Town have a marvelous introduction to the kingdom of animals (Metazoa) with photographs and descriptions of the various phyla.
- A page from U Cal Berkeley about the Metazoa fossil record suggests it may be possible that nearly all the phyla of metazoa evolved in the Cambrian aside from
the Cnidaria, which evolved earlier, in the Ediacaran (Vendian).
- Were the Cnidaria present in the Ediacaran Era, or did they evolve later, in the Cambrian. This article from the New York Times discusses fossil and DNA evidence that seem to suggest conflicting dates for Cnidaria (600 MYA or 540 MYA).
- The Museum Victoria in Australia has a page about the oldest evidence of life, including the earliest animal life.
- Another possible ancestor of early metazoa would be the bilaterians who lived 580-600 million years ago.