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THE FIRST VERTEBRATES ~530 million years

Vertebrates are members of the subphylum Vertebrata, chordates with backbones or spinal columns. About 58,000 species of vertebrates have been described. Vertebrata is the largest subphylum of chordates, and contains many familiar groups of large land animals. Vertebrates comprise cyclostomes, bony fish, sharks and rays, amphibians, reptiles, mammals, and birds. Extant vertebrates range in size from the carp species Paedocypris, at as little as 7.9 mm (0.3 inch), to the Blue Whale, at up to 33 m (110 ft). Vertebrates make up about 5% of all described animal species; the rest are invertebrates which lack backbones.

The grouping sometimes includes the hagfish, which have no vertebrae, but are genetically quite closely related to lampreys, which do have vertebrae. For this reason, the sub-phylum is sometimes referred to as "Craniata", as all members do possess a cranium. (click to see all the article on Wikipedia)

脊椎動物出現 ~53千萬年前

脊椎動物是脊椎動物亞門的一員,是有脊柱或脊骨的脊索動物。大約58000種的脊椎動物被記載下來。脊椎動物是脊索動物中最大的亞門,包含了許多常見的大型陸地動物群。脊椎動物包括了圓口類,硬骨魚,鯊魚,魟魚,兩棲類,哺乳類,以及鳥類。現存的脊椎動物範圍,尺寸小從7.9mm0.3吋)的鯉魚種的Paedocypris,大到33m(110)的藍鯨。脊椎動物約占所有有紀錄的物種的5%,其他的都是沒有脊椎的無脊椎動物。

(譯者註:Paedocypris是新品種的魚,沒有確定的中文譯名(似乎叫做原生壤鯉),詳情見此連結)

有時候盲鰻被算在其中,牠沒有脊椎,但在基因上十分接近其親戚,具有脊椎的八目鰻。因為如此,這分門被稱為有頭類,此類動物均帶有明顯的頭骨。 

(維基連結:脊椎動物)

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