臺灣博碩士論文加值系統

陡山沱地層富含大量的多細胞動物, 包括海綿、 腔腸動物及兩側對稱動物的胚胎, 其中有一群大小介於250-500μm的動物具有大量的微絨毛結構分佈在體表, 藉著掃描式電子顯微鏡的觀察發現現生海葵的觸手表面結構與此種動物的表面結構類似, 另外在光學顯微鏡下觀察到的化石磨片, 似腔腸動物口及柄的構造也有被發現, 因此此種動物可能屬於腔腸動物的珊瑚綱。
另外在大約百分之一的化石胚胎中可以發現許多管狀的構造, 這些管狀構造的大小範圍與線蟲的大小範圍符合, 藉由X-ray顯微鏡所觀察到的胚胎內部管狀構造的型態及掃描式電子顯微鏡觀察到的管道表面及截面結構, 我們可以將此管狀結構推斷為寄生性線蟲的動物胚胎化石。

The Doushantuo Formation contains fossils of animal embryos in various stage of development and they were the earliest convincing evidence for animal existence. Other than these unrecognizable cleavaging embryos are fossils of algae, sponges, putative cnidarian and bilaterian embryos. The new animal bearing cnidarian affinity sized in 250-500μm of the Doushantuo Formation has been studied with transmitted light in thin sections. The key feature of this animal is the conical projections that cover all over the surface. These conical projections are 7.5μm in height and 5.5μm in width, which are comparable to the sensory projections found in living sea anemone. The putative stalk and the mouth also exhibite anthozoan affinity. Lack of similarity in cnidoblasts and tentacles between living anthozoan and this animal, indicates that the animal described here might be stem group cnidarian. About one percent of animal embryos in the Doushantuo Formation have microtunnels inside. These microtunnels were interpreted as trails made by moving pyrite grain. With the application of X-ray microscopy, the three dimensional structure of the microtunnels were observed. The well-preserved surface ornament and the morphology of the microtunnels found in embryos indicate that these microtunnels might be body fossils of parasitic nematodes.

中文摘要..1
Abstract..3
Introduction..4
Materials and Methods..7
Results..9
Discussion..13
Reference..15
Tables..16
Figures..18
Figure Legends..36

1. Bengtson, S. (1994) Early life on earth (Columbia University Press New York)
2. Bentoni, M. J. and Ayala, F. J. (2003) Science 300, 1698-1700.
3. Wray, G. A., Levinton, J. S., Shapiro, L.H. (1996) Science 274, 568-573.
4. Ayala, F.J, Rzhetsky, A. and Ayala, F.J. (1998) Proc. Natl. Acad. Sci. USA 95, 606-611
5. Vermeij, G. J. (1996) Sceince 274, 525-526.
6. Rasmussen, B., Bengtson, S., Fletcher, J. R., McNaughton, N. J. (2002) Sceince 296, 1112-1114.
7. Sceince 298, 57-58.
8. Seilacher, A,.Bose, P. K., Pflu¨ger, F. (1998) Sceince 282,80-83.
9. Rajita, V. Gautam, R. (1999) Science 284, 1235
10. Li,C. W., Chen,J.Y., Hua, T. E. (1998) Sceince 279, 879-882.
11. Xiao, S. and Knoll, A. K. (2000) Journal of Paleontology 74, 767-788.
12. Chen, J-Y,.Oliveri, P,. Gao,F., Dornbos, S. Q., Li, C-W.,Bottjer, D. J. and Davidson, E. H. (2002) Developmental Biology 248, 182-196.
13. Chen, J-Y., Oliveri, P., Li, C-W., Zhou, G.Q., Gao, F., Hagadorn, J.W., Peterson, J. K.and Davidson, E. H.Special (2000) Proc. Natl. Acad. Sci.97, 4457-4462
14. Fisher, M. K. (1952) Invertebrate Fossil. (University of Kansas)
15. Fedonkin, M. A., and Waggoner, B. M. (1997) Nature 388, 868-872.
16. Xiao, S and Knoll, A. K. (1999) Lethaia 32, 219-240.
17. Gibbons, L. M. (1986) SEM Guide to the Morphology of Nematode Parasites of Vertebrates (C.A.B. International)