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

作　　者：Huaqiao Zhang Xi-Ping Dong 

机构地区：[1]Key Laboratory of Economic Stratigraphy and Palaeogeography,Chinese Academy of Sciences (Nanjing Institute of Geology and Palaeontology) [2]School of Earth and Space Sciences, Peking University

出　　处：《Science Bulletin》2015年第22期1947-1953,共7页科学通报（英文版）

基　　金：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);the Research Fund for the Doctoral Program of High Education(20060001059)

摘　　要：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.There has been a century-long debate in evo- lutionary 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 inver- tebrate embryos such as Markuelia and Olivooides are direct developers. Here, we describe Eolarva kuanchuan- puensis 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.

关 键 词：Oldest known larva Indirectdevelopment Plesiomorphy of metazoandevelopment CAMBRIAN South China 

分 类 号：Q915[天文地球—古生物学与地层学]