ONTOGENY AND TAPHONOMY: AN EXPERIMENTAL TAPHONOMY STUDY OF THE DEVELOPMENT OF THE BRINE SHRIMP ARTEMIA SALINA
ONTOGENY AND TAPHONOMY: AN EXPERIMENTAL TAPHONOMY STUDY OF THE DEVELOPMENT OF THE BRINE SHRIMP ARTEMIA SALINA
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DOI：
10.1111/j.1475-4983.2008.00834.x
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发表时间：
2009-01-01
期刊：
影响因子：
2.6
通讯作者：
Donoghue, Philip C. J.
中科院分区：
文献类型：
--
作者：
Gostling, Neil J.;Dong, Xiping;Donoghue, Philip C. J.
虽然古生物学家对个体发育和生殖发育之间的关系一直很感兴趣，但化石记录对长期灭绝的生物的发展几乎没有提供任何见解。这已经改变了许多组合的无脊椎动物胚胎和幼虫的发现，但认识到他们的进化意义是阻碍了缺乏数据之间的关系，个体发育和埋藏。我们描述的anostracan卤虫的发展，这表明，在水的好氧和厌氧自溶和微生物腐烂的条件下，发育阶段表现出不同的保存潜力的实验埋藏学研究的结果。最耐腐烂的发育阶段是滞育包囊，使原肠胚破裂，其中胚胎的总体形态可以在简单的厌氧条件下维持18个月或更长时间。否则，胚胎在囊肿内收缩，细胞和组织细节随着脂滴的合并而分解。胚后脱囊的幼虫腐烂得更快。除L-4幼虫外，所有幼虫阶段的腐烂率相似，其抵抗角质层失效的时间长于后期发育阶段。幼虫腐烂导致肌肉和内脏液化，留下一个完整但空的，逐渐萎缩和扭曲的角质层，最终失去结构完整性和崩溃。我们的实验结果提供了一个解释模式的现象丰富的假定滞育阶段的胚胎，在没有胚后阶段，看到在埃迪卡拉纪陡山沱组的中国南方和不完整的胚胎和幼虫的发育序列更普遍。它还警告说，在没有额外证据的情况下，不要将化石沉积物中的发育阶段联系起来。最后，在幼虫中看到的腐烂模式为奥斯滕型LagerstAtten的保存风格提供了一个解释，其中表皮细节的保存可以非常精细，但内部延伸到肌肉和内脏的情况很少。
Although the relationship between ontogeny and phylogeny has been of long-standing interest to palaeontologists, the fossil record has provided little insight into the development of long extinct organisms. This has changed with the discovery of numerous assemblages of fossilized invertebrate embryos and larvae, but realising their evolutionary significance is hampered by a paucity of data on the relationship between ontogeny and taphonomy. We describe the results of an experimental taphonomy study of the development of the anostracan brine shrimp Artemia salina, which show that in conditions of aqueous aerobic and anaerobic autolysis and microbial decay, the developmental stages exhibit differential preservation potential. The most decay resistant developmental stage is the diapause cyst, encapulsating the gastrula, in which the gross morphology of the embryo can be maintained for 18 months or more in simple anaerobic conditions. Otherwise, the embryo shrinks within the cyst and cellular and tissue detail of breaks down as lipid droplets coalesce. Postembryonic excysted larvae decay more rapidly. The rate of decay is similar among all larval stages with the exception of the L-4 larva, which resists cuticle failure for longer than later developmental stages. The larvae decay leading to liquefaction of the muscles and viscera, leaving an intact but empty and progressively shrunken and distorted cuticle that eventually loses structural integrity and collapses. Our experimental results provide an explanatory model for the phenomenal abundance of putative diapause stage embryos, in the absence of postembryonic stages, as seen in the Ediacaran Doushantuo Formation of South China and the incompleteness of fossilized developmental sequences of embryos and larvae more generally. It also cautions against the association of developmental stages in fossil deposits without additional evidence. Finally, the pattern of decay seen in larvae provides an explanation for the preservation style of Orsten-type LagerstAtten where preservation of cuticular detail can be astonishingly fine, but extends internally to muscles and viscera only rarely.