Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Evening Poster

B (Biogeosciences) » B-PT Paleontology

[B-PT06] Biotic History

Sun. May 20, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Isao Motoyama(Department of Earth and Environmental Sciences, Yamagata University), Takao Ubukata(Division of Geology & Mineralogy, Department of Earth & Planetary Sciences, Kyoto University), Kazuyoshi Moriya(早稲田大学 教育・総合科学学術院 地球科学専修)

[BPT06-P01] Shelly fossils from the upper Ediacaran formation in southwestern Mongolia

*Kyoichiro Ishikawa1, Tatsuo Oji2 (1.Graduate School of Environmental Studies, Nagoya University, 2.Nagoya University Museum, Nagoya University)

Keywords:Ediacaran, Small Shelly Fossils

A rapid diversification event occurred in Cambrian is referred to as the “Cambrian Explosion”. The Cambrian Explosion is not only an extremely important event in animal history in that almost all the modern animal phyla have appeared, but also in that many lineages of animals have formed shells. The small remains of initial shell-bearing organisms are collectively called small shelly fossils (SSFs). SSFs are known from the late Ediacaran to early Cambrian, though the fossil record is not enough to reveal the evolution of the shell acquirements in animals.

Here we report a new possible SSFs assemblage which was found from the middle part of the late Ediacaran Zuun-Arts Formation in southwestern Mongolia. Several different types of fossils were found from the assemblage. One of which had the similar shape to Ceratoconus, one of the early Cambrian SSFs. However, none of them were comparable to the Ediacaran SSFs. Two different types of spicules, which probably belong to sponges, were also found from the middle part of the formation. One is tetractine structure with the processes in triangular section, and another is needle-like structure with several small spikes extending along the axis. None of them are yet to be identified as previously known SSFs species.

Algal fossils and Arenicolites, a U-shaped ichnofossil, have already been discovered from the base and middle part of the Zuun-Arts Formation, respectively (Dornbos et al., 2016; Oji et al., in press). The possible SSFs found from the Zuun-Arts Formation will be identified, and will be compared with the late Ediacaran to early Cambrian fossil assemblage from the other sections, such as China.