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Science Bulletin

, Volume 60, Issue 22, pp 1947–1953 | Cite as

The oldest known larva and its implications for the plesiomorphy of metazoan development

  • Huaqiao Zhang
  • Xi-Ping Dong
Article Earth Sciences

Abstract

There has been a century-long debate in evolutionary developmental biology about whether the ancestral metazoan was a larva or an adult. Two competing hypotheses have been proposed: the “terminal addition” theory, which assumes the primitiveness of larvae, and the “intercalation” theory, which assumes the primitiveness of adults. A consensus has not yet been reached, but the “terminal addition” theory appears to be more widely accepted. However, in contrast to the majority of larvae among living metazoans, all currently known fossil invertebrate embryos such as Markuelia and Olivooides are direct developers. Here, we describe Eolarva kuanchuanpuensis gen. et sp. nov., the oldest known larva, from the early Cambrian (~535 Ma) of South China. Eolarva kuanchuanpuensis lacks a mouth or any other type of feeding apparatus, which is non-feeding or lecithotrophic. It possesses a distinct body plan and might represent a cnidarian-grade animal. This is the first fossil evidence indicating that indirect development is the plesiomorphy of metazoan development.

Keywords

Oldest known larva Indirect development Plesiomorphy of metazoan development Cambrian South China 

已知最古老的幼虫以及它们对后生动物发育祖征的启示

摘要

绝大多数现生海洋无脊椎动物的个体发育都有幼虫阶段,因而,生物学家认为间接发育是后生动物发育的原始特征。然而,由于已知的化石胚胎都是直接发育的,古生物学家认为直接发育才是后生动物发育的原始特征。本文报道了距今5.35亿年的化石幼虫——宽川铺始祖幼虫。此幼虫缺乏摄食器官,是不摄食或蛋黄营养型的。它展示了独特的体构,可能代表刺胞级的动物。据此,本文首次提供了间接发育是后生动物发育原始特征的化石证据。

关键词

已知最古老的幼虫 间接发育 后生动物发育祖征 

Notes

Acknowledgements

This work was supported by the National Natural Science Foundation of China (41372015, 41102003, J1210006), the State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (103102, 20132107), and the Research Fund for the Doctoral Program of High Education (20060001059). We thank Shuhai Xiao for discussion and suggestions, Dinghua Yang for technical help, and two anonymous reviewers for their constructive comments.

Conflict of interest

The authors declare that they have no conflicts of interest.

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Copyright information

© Science China Press and Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  1. 1.Key Laboratory of Economic Stratigraphy and PalaeogeographyChinese Academy of Sciences (Nanjing Institute of Geology and Palaeontology)NanjingChina
  2. 2.School of Earth and Space SciencesPeking UniversityBeijingChina

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