Examinarion of DOXAM hypothesis that links Neoproterozoic animal evolution with climate changes

2014 Fiscal Year Final Research Report

• Project/Area Number: 23403014
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 海外学術
• Research Field: Geology
• Research Institution: Kyushu University
• Principal Investigator: KANO Akihiro 九州大学, 比較社会文化研究科(研究院), 教授 (60231263)
• Co-Investigator(Kenkyū-buntansha): HASEGAWA Takashi 金沢大学, 自然システム学系, 教授 (50272943) ; TAKASHIMA Chiduru 佐賀大学, 文化教育学部, 准教授 (10568348)
• Project Period (FY): 2011-04-01 – 2015-03-31
• Keywords: 動物進化 / 新原生代 / 安定同位体 / 海綿動物 / 炭素循環

Outline of Final Research Achievements

Ediacaran sedimentary sequences in China, Brazil, and Spain were examined in order to understand the linkage between the Neoproterozoic animal evolution and drastic climate changes. We newly found sponge spicules from Guizhou province in China, and sponge-like fossils of digitate forms from central Bahia in Brazil. The latter is associated with spheroidal structures of ~4 mm in diameter, which was likely eggs of the digitate fossils. Chemostratigraphy based on inorganic carbon isotope indecates that these fossils were early Ediacaran when the ocean and atmosphere were poor in oxygen. Because the degradation of organic matter was somehow limited, a huge amount of organic matter were suspended in the anoxic oceanic water column. Sponges evolved as the first multicellular animals for adapting these oceanographic conditions. Their sessile and filter feeding habitats were the consequences of this scenario.

Free Research Field

地質学