对笔石
对笔石属 化石时期：奥陶纪
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| Didymograptus murchisoni | |
科学分类 
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| 界： | 动物界 Animalia |
| 门： | 半索动物门 Hemichordata |
| 纲： | 羽鳃纲 Pterobranchia |
| 目： | †正笔石目 Graptoloidea |
| 科： | †均分笔石科 Dichograptidae |
| 属： | †对笔石属 Didymograptus McCoy, 1851[1] |
| 种 | |
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见内文 | |
| 异名 | |
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对笔石属（学名：Didymograptus）是正笔石目下的一属笔石，生存于奥陶纪的海洋中，是一种群居性浮游生物。[2]其化石分布于美洲、欧洲、亚洲、澳大利亚和新西兰等地。
特征
对笔石群体的形状与音叉相似，大小从1至10公分不等，两条枝在接近末梢处逐渐变宽。胞管构造简单。[2]
物种
本属包括以下物种：[1]
- Didymograptus (Expansograptus) abnormis Hsu, 1934
- Didymograptus (Expansograptus) acriculus Keble & Harris, 1934
- Didymograptus (Expansograptus) adamantinus T.S.Hall, 1914
- Didymograptus (Didymograptus) artus Elles & Wood, 1901
- Didymograptus (Expansograptus) asperus Harris & Thomas, 1938
- Didymograptus (Expansograptus) aureus T.S.Hall, 1914
- Didymograptus (Expansograptus) balticus Tullberg, 1938
- Didymograptus bartrumi Benson & Keble, 1935
- Didymograptus (Didymograptellus) bidens Keble, 1927
- Didymograptus (Expansograptus) constrictus J.Hall, 1865
- Didymograptus (Expansograptus) cuspidatus Ruedemann, 1904
- Didymograptus demissus (Törnquist, 1901)
- Didymograptus (Expansograptus) dilatans T.S.Hall, 1914
- Didymograptus distinctus Harris & Thomas, 1935
- Didymograptus (Expansograptus) ellesae Ruedemann, 1908
- Didymograptus (Expansograptus) elongatus Harris & Thomas, 1914
- Didymograptus ensjoensis Monsen, 1937
- Didymograptus eocaduceus Harris, 1933
- Didymograptus euodus Lapworth, 1875
- Didymograptus (Expansograptus) extensus J.Hall, 1858
- Didymograptus filiformis (Tullberg, 1880)
- Didymograptus hemicyclus Harris, 1933
- Didymograptus holmi (Törnquist, 1901)
- Didymograptus (Expansograptus) latus T.S.Hall, 1907
- Didymograptus (Corymbograptus) mundus T.S.Hall, 1914
- Didymograptus (Expansograptus) nicholsoni Lapworth, 1875
- Didymograptus (Expansograptus) nitidus J.Hall, 1858
- Didymograptus pacificus Ruedemann, 1947
- Didymograptus paraindentus Berry, 1960
- Didymograptus (Expansograptus) perditus T.S.Hall, 1914
- Didymograptus (Expansograptus) procumbens T.S.Hall, 1914
- Didymograptus protobalticus (Monsen, 1937)
- Didymograptus (Didymograptellus) protobifidus Elles, 1933
- Didymograptus pusillus (Tullberg, 1880)
- Didymograptus (Expansograptus) similis J.Hall, 1865
- Didymograptus spinulosus Perner, 1895
- Didymograptus (Didymograptus) stabilis Elles & Wood, 1901
- Didymograptus (Didymograptus) stavus Legg, 1976
- 瑞典对笔石 Didymograptus (Expansograptus) suecicus Tullberg, 1880
- Didymograptus (Expansograptus) superstes Lapworth, 1876
- Didymograptus taylori T.S.Hall, 1899
- Didymograptus turgidus (Lee, 1974)
- Didymograptus undulatus (Törnquist, 1901)
- Didymograptus uniformis Elles & Wood, 1901
- Didymograptus (Corymbograptus) v-deflexus Harris, 1924
- Didymograptus (Expansograptus) validus Toernquist, 1901
- Didymograptus (Expansograptus) vicinus Harris & Thomas, 1938
参考文献
- ^ 1.0 1.1 Fossiilid.info: Didymograptus. [2017-11-25]. （原始内容存档于2020-11-27） （英语）.
- ^ 2.0 2.1 Walker, Cyril; Ward, David. Fossils. Smithsonian Handbooks revised, illustrated. Dorling Kindersley. 2002: 48. ISBN 0789489848.