Bengtson和Yue首次确定Olivooides和Markuelia为化石胚胎,建立了Olivooides的胚胎和胚后发育序列,并且提出Olivooides的亲缘关系是刺细胞类(Bengtson and Yue,1997;Yue and Bengtson,1999)。在过去的10年中,许多论述寒武纪化石胚胎的文...Bengtson和Yue首次确定Olivooides和Markuelia为化石胚胎,建立了Olivooides的胚胎和胚后发育序列,并且提出Olivooides的亲缘关系是刺细胞类(Bengtson and Yue,1997;Yue and Bengtson,1999)。在过去的10年中,许多论述寒武纪化石胚胎的文章问世,极大地提高了人们的认识。其中,Steiner等识别出Pseudooides为化石胚胎,并且推想了Pseudooides的发育序列(Steiner et al.,2004a,b)。基于在中国湖南西部中、上寒武统发现的许多精美保存的标本,对Markuelia进行了解剖学、亲缘关系和支序分析研究,限定Markuelia的亲缘关系为Scalidophora(动吻动物门、兜甲动物门和曳鳃动物门的统称)的干群。尝试性地建立了Markuelia的发育序列,特别是预孵化阶段的发育序列,即从吻刺形成的最早时期直至即将孵化的最后时期的发育序列。因为最近发现了保存完美的Olivooides预孵化阶段、孵化阶段以及未成年个体阶段(Olivooides和Punctatus之间的过渡类型)的标本,重新建立了Olivooides的胚胎和胚后发育序列。尽管Olivooides的亲缘关系仍然有争议,但多数作者支持其亲缘关系为刺细胞类。然而,迄今所描述的大多数寒武纪化石胚胎的亲缘关系,特别是谜一般的化石胚胎——Pseudooides的亲缘关系仍然不得而知。由于Markuelia孵化后的幼虫、未成年个体或成年个体的标本还未发现,其胚后发育序列则无从谈起,令人信服的原肠胚阶段的化石胚胎也未见报道。今后,可靠的原肠胚阶段的化石的发现很可能要借助于同步加速器辐射X射线层析显微技术。总之,寒武纪化石胚胎的研究还有很多悬而未决的问题。展开更多
Yue and Bengtson(1 997;1 998) make us to pay attention to the earliest Cambrian fossilized metazoan embryos.Based on recent observation of the fossils from Ningiang and Emei,Author came to the same conclusion that the...Yue and Bengtson(1 997;1 998) make us to pay attention to the earliest Cambrian fossilized metazoan embryos.Based on recent observation of the fossils from Ningiang and Emei,Author came to the same conclusion that they should represent various products from many taxa during differentstages oflife cycle.4 groups can be divided:1 . External structure or ornament of the oospheres(representing blastula) is various.2 . Oospheres(blastula) with lower tissue-differentiation.3 .Oospheres(blastula) with higher tissue-differentiation.4 .Pagoda-like larva(or polyp or transverse fission larva) .Many hypotheses concerning the biological entity of the spheres(fossils) , suchas Acritarch,algal,calcisphere,animal oosphere,sponge gemmule,and metazoan paleoembryo have been proposed.The idea that Olivooides-Punctatus developmentary succession is recognized by Yue and Bengston (1 997;1 998) ,has advanced the investigation of small shelly fossils to a new stage-researching the life展开更多
文摘Bengtson和Yue首次确定Olivooides和Markuelia为化石胚胎,建立了Olivooides的胚胎和胚后发育序列,并且提出Olivooides的亲缘关系是刺细胞类(Bengtson and Yue,1997;Yue and Bengtson,1999)。在过去的10年中,许多论述寒武纪化石胚胎的文章问世,极大地提高了人们的认识。其中,Steiner等识别出Pseudooides为化石胚胎,并且推想了Pseudooides的发育序列(Steiner et al.,2004a,b)。基于在中国湖南西部中、上寒武统发现的许多精美保存的标本,对Markuelia进行了解剖学、亲缘关系和支序分析研究,限定Markuelia的亲缘关系为Scalidophora(动吻动物门、兜甲动物门和曳鳃动物门的统称)的干群。尝试性地建立了Markuelia的发育序列,特别是预孵化阶段的发育序列,即从吻刺形成的最早时期直至即将孵化的最后时期的发育序列。因为最近发现了保存完美的Olivooides预孵化阶段、孵化阶段以及未成年个体阶段(Olivooides和Punctatus之间的过渡类型)的标本,重新建立了Olivooides的胚胎和胚后发育序列。尽管Olivooides的亲缘关系仍然有争议,但多数作者支持其亲缘关系为刺细胞类。然而,迄今所描述的大多数寒武纪化石胚胎的亲缘关系,特别是谜一般的化石胚胎——Pseudooides的亲缘关系仍然不得而知。由于Markuelia孵化后的幼虫、未成年个体或成年个体的标本还未发现,其胚后发育序列则无从谈起,令人信服的原肠胚阶段的化石胚胎也未见报道。今后,可靠的原肠胚阶段的化石的发现很可能要借助于同步加速器辐射X射线层析显微技术。总之,寒武纪化石胚胎的研究还有很多悬而未决的问题。
文摘Yue and Bengtson(1 997;1 998) make us to pay attention to the earliest Cambrian fossilized metazoan embryos.Based on recent observation of the fossils from Ningiang and Emei,Author came to the same conclusion that they should represent various products from many taxa during differentstages oflife cycle.4 groups can be divided:1 . External structure or ornament of the oospheres(representing blastula) is various.2 . Oospheres(blastula) with lower tissue-differentiation.3 .Oospheres(blastula) with higher tissue-differentiation.4 .Pagoda-like larva(or polyp or transverse fission larva) .Many hypotheses concerning the biological entity of the spheres(fossils) , suchas Acritarch,algal,calcisphere,animal oosphere,sponge gemmule,and metazoan paleoembryo have been proposed.The idea that Olivooides-Punctatus developmentary succession is recognized by Yue and Bengston (1 997;1 998) ,has advanced the investigation of small shelly fossils to a new stage-researching the life
