# 盾皮魚綱[编辑]

| 盾皮魚綱 化石时期：志留紀早期至泥盆纪末期
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| 邓氏鱼头骨
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| 科学分类  |
| 界： | 动物界 Animalia |
| 门： | 脊索动物门 Chordata |
| 演化支： | 嗅球類 Olfactores |
| 亚门： | 脊椎动物亚门 Vertebrata |
| 下门： | 有颌下门 Gnathostomata |
| 纲： | **†盾皮鱼纲 Placodermi** |
| 目
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| * †胴甲鱼目 Antiarchi
* †节颈鱼目 Arthrodira
* †叶鳞鱼目 Phyllolepida
* †褶齿鱼目 Ptyctodontida
* †硬鲛目 Rhenanida
* †瓣甲鱼目 Macropetalichthyida
* †假瓣甲鱼目 Pseudopetalichthyida
* †棘胸鱼目 Acanthothoraci
* †布林达贝拉鱼目 Brindabellaspis
* †史天秀鱼目 Stensioella（?）
 |

**盾皮鱼纲**（學名：Placodermi）是一类已经滅绝的史前鱼类，出现于4.39億年前的古生代志留纪早期，在泥盆纪成为水域生态系统的优势物种，共繁衍了近7000萬年，最终於3.59亿年前的泥盆纪晚期灭绝事件中全部绝灭。盾皮魚類是最早占据顶级生态位的脊椎动物，因头部和胸部覆盖骨甲故得名。盾皮鱼类也是最原始的有颌鱼类，其颌骨是由嘴部后方的第一对鳃弓演化而来的。

2005年8月，约翰·A·朗（John A. Long）及其野外考察队对戈戈（Gogo）站高地草地的考察中，发现带有矿化脐带及胚胎的盾皮鱼化石，这个发现颠覆了以往對繁殖和体内受精起源的認識。

## 化石纪录

粒骨鱼（*Coccosteus*）的身體構造示意圖
副雲南魚，一種發現於雲南的胴甲魚
最早的可确认的盾皮鱼生活在晚期志留纪。盾皮鱼在泥盆纪末全部灭绝。最早一批志留纪盾皮鱼化石发现于中国，主要是节颈鱼目和胴甲鱼目。显然盾皮鱼起源分化于泥盆纪以前，可能在志留纪早期或中期，尽管更早的盾皮鱼化石还没有被发现。志留纪的盾皮鱼化石往往是一些骨甲碎片，有些种的分类命名也十分不可靠。

有些古生物学家认为志留纪盾皮鱼的生活环境可能不利于化石保存，并不是真的很少。这个假说也解释了在泥盆纪早期大量盾皮鱼的出现。

与志留纪形成反差的是，在泥盆纪，盾皮鱼在各种水生生态系统中占优势，包括海水和淡水。尽管如此，盾皮鱼在泥盆纪末全部灭绝，没有一个种存活到石炭纪。

中国的盾皮鱼化石较为丰富，主要是节颈鱼目、胴甲鱼目和瓣甲鱼目。在中国还发现了许多早期的盾皮鱼化石，尤其是在泥盆纪早期地层中发现了属于基干胴甲鱼目的云南鱼类（Yunanolepiformes）和始突鱼类（Procondylopeformes），这在世界其他地方没有发现过。近来又在云南发现了志留纪的胴甲鱼目化石，说明胴甲鱼目起源于东亚。

## 生活方式

盾皮鱼类是泥盆纪最占优势的水生脊椎动物。许多盾皮鱼都是掠食者。大多數盾皮鱼生活在底部，因为骨甲实在太重。有些盾皮鱼，主要是节颈鱼目生活在中上层水域，是敏捷的掠食者。目前已知最大的节颈鱼目，邓氏鱼（*Dunkleosteus telleri*），有8米长，被认为在全球范围内有分布。目前在欧洲、北美、摩洛哥等地区发现了它的化石。有一些小型的节颈鱼目，比如说Fallacosteus和Rolfosteus，有弹头型的头部骨甲，说明许多节颈鱼目都擅长游泳。

## 分類

对于将盾皮鱼类的分类，有多种说法。有些学者认为盾皮鱼属软骨鱼类，所以将其置于软骨鱼纲下，作为一个亚纲。也有将其置于鱼纲（Pisces）下。更多的是将盾皮鱼纲直接置于脊椎动物亚门或是有颌下门（Gnathostomata）之下。

海因茨氏斯坦鱼（*Stensioella heintzi*）

| 目 | 特征
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| --- | --- |
| **†胴甲魚目** | 頭和軀幹前部被有骨甲，頭甲和軀甲均由對稱排列的甲片組成；頭甲以關節同軀甲相連；眼位於頭的背面，兩眼靠近；胸鰭呈槳狀，分成兩節或不分節，表面被有甲片，以活動關節同軀甲相連；尾歪型；一或兩個背鰭；感覺管為開溝式，位於甲片表面。
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| **†节颈鱼目** | 頭部與胸部皆覆蓋有堅硬的骨甲，颈部骨甲有关节联接。
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| **†葉鱗魚目** | 擁有堅硬的甲冑，但是型態與硬鮫目相異。眼睛生於頭頂，可能已經退化。
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| **†褶齒魚目** | 頭部與眼睛大，胸鰭發達，齒板厚且呈鳥喙狀，脊索發達。
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| **†硬鲛目** |  |
| **†瓣甲鱼目**  |  |
| **†假瓣甲鱼目** |  |
| **†棘胸鱼目** |  |
| **†布林达贝拉鱼目** |  |
| **†史天秀鱼目**（?） |  |
| **†**奇迹秀山鱼
 | 奇迹秀山鱼（*Xiushanosteus mirabilis*）是目前已知时代最早的、头尾完整保存的有颌鱼类。化石发现于中国重庆市兰多维列统特列奇阶，距今约4.36亿年，是探究颌起源和有颌鱼类早期演化最重要的化石证据之一。
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## 分支圖

以下支序圖基於 Carr et al.等人2009年的研究:

*Homostius* and *Pterichthys*
*Diandongpetalichthys*

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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
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史天秀魚屬 *Stensioella*  |
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| **盾皮魚綱** |

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假瓣甲魚屬 *Pseudopetalichthys*  |
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布林達貝拉魚屬 *Brindabellaspis*  |
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Acanthothoraci

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硬鮫目 Rhenanida  |
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雲南魚屬 *Yunnanolepis*  |
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真胴甲魚類 Euantiarcha  |
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瓣甲鱼目 Petalichthyida  |
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褶齒魚目 Ptyctodontida  |
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| 節甲魚目
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烏塔古納魚屬 *Wuttagoonaspis* |
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輻紋魚科 Actinolepidae  |
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葉鱗魚目 Phyllolepida

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菲里克特魚目 Phlyctaeniida  |
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| 短胸魚亞目
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|  | *Holonema* |
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|  | *Antineosteus* |
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巴坎魚科 Buchanosteidae

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| 真短胸魚類
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|  | *Pholidosteus*  |
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|  | *Tapinosteus* |
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粒骨魚屬 *Coccosteus*  |
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托羅魚屬 *Torosteus* |
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|  | *Plourdosteus* |
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鄧氏魚屬 *Dunkleosteus*  |
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|  | *Brachyosteus* |
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|  | *Erromenosteus* |
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|  | *Gorgonichthys*  |
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霸魚屬 *Titanichthys*  |
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| Eubrachythoraci
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| Brachythoraci
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| Arthrodira
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| **Placodermi** |

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然而，這些年來盾皮魚的分類發生了變化，現在人們認為盾皮魚綱是並系群，, 其中一些比另一些更接近有颌下门。更新後的分支圖（Zhu et al., 2016）:

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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
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| --- | --- |
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頭甲魚綱 Cephalaspidomorphi  |
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| 有颌下门
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| --- | --- |
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胴甲魚目 Antiarchi  |
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| --- | --- |
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瓣甲魚目 Petalichthyida  |
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| --- | --- | --- | --- | --- | --- | --- | --- |
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| --- | --- |
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節甲魚目 Arthrodira  |
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褶齒魚目 Ptyctodontida  |
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| --- | --- |
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麒麟魚屬 *Qilinyu* |
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| --- | --- |
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全頜魚屬 *Entelognathus* |
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| --- | --- |
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雅努斯魚屬 *Janusiscus* |
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| --- | --- | --- | --- | --- | --- | --- | --- |
| 真有頜類
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| --- | --- |
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軟骨魚綱 Chondrichthyes (包括棘魚綱)  |
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硬骨魚高綱 Osteichthyes  |
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| Gnathostomata
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## 滅绝

什么彝民鱼
罗佛鱼
格陵兰鱼
一般認為，盾皮鱼类是在與新進化出的硬骨鱼类和软骨鱼类的競争中衰弱並滅绝的。也有認為是環境变化所致。和非鸟恐龙一样，盾皮鱼在泥盆纪末的全部灭绝也有诸如小行星撞击等说法。

坡塘鱼
* Janvier, Philippe. *Early Vertebrates* Oxford, New York: Oxford University Press, 1998. ISBN 0-19-854047-7
* Long, John A. *The Rise of Fishes: 500 Million Years of Evolution* Baltimore: The Johns Hopkins University Press, 1996. ISBN 0-8018-5438-5
* 中国大百科全书·生物卷 ISBN 7-5000-0345-5
* 化石网
* Annetta Markussen-Brown, "Devonian Armoured Fish" 2000 （页面存档备份，存于互联网档案馆）
* Introduction to the Placodermi Extinct armored fishes with jaws（页面存档备份，存于互联网档案馆）
* PALAEOZOIC FOSSILS UK
* Placoderms
* Placodermi: Overview
* Evolution of Teeth (archived item) （页面存档备份，存于互联网档案馆）

* 維基物種上的相關信息：盾皮魚綱
* 维基共享资源上的相關多媒體資源：盾皮魚綱