坎布里亚时期的管状肠
Jean-Bernard Caron1, Simon Conway Morris, Christopher B Cameron
1Department of Natural History (Palaeobiology), Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada. jcaron@rom.on.ca
Nature
|March 15, 2013
概括
一个新发现的坎布里亚化石,Spartobranchus tenuis,揭示了从类似虫的祖先进化的半弦动物. 这一发现澄清了肠体和枝体之间的进化联系,阐明了早期的双胞胎体发育.
科学领域:
- 古生物学的古生物学
- 进化生物学 进化生物学
- 海洋生物学 海洋生物学
背景情况:
- 包括肠体和体在内的半弦体,是了解早期动物进化过程的关键的海洋双弦体.
- 在 hemichordates 内的遗传关系和 enteropneusts 和 pterobranchs 之间的过渡一直在历史上争论.
- 半弦动物,特别是肠动物的化石记录稀少,阻碍了进化洞察力.
研究的目的:
- 为了描述一个新的中堪布里亚时期的肠化石,Spartobranchus tenuis,来自伯吉斯页岩.
- 通过化石证据,研究肠动物和枝动物之间的进化联系.
- 提供关于半弦状动物的起源和早期演变的见解.
主要方法:
- 关于化石Spartobranchus tenuis的详细形态描述和分析.
- 化石形态的比较与现存的半弦状动物群体 (enteropneusts和pterobranchs).
- 基于形态特征和推断的进化过渡的植物遗传学解释.
主要成果:
- 斯帕尔托布兰克斯 (Spartobranchus tenuis) 与现存的哈里曼尼德 (harrimaniid) 类肠虫有着显著的相似之处.
- 化石与一根纤维管有关,被解释为枝皮的前体.
- 这些发现支持了这样一个假设:甲虫是通过小型化和食触手的发展从更大,类似于肠肺的祖先进化而来的.
结论:
- 斯帕托布朗克斯 (Spartobranchus tenuis) 提供了哈里曼尼德 - 枝转变的关键证据,表明枝从肠杆菌衍生出来.
- 周皮在缩小尺寸和在枝动物中获得触角之前演变.
- 坎布里亚中期出现了肠和枝,这表明在坎布里亚爆发开始时的起源是半弦状的.
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