Early evolutionary history of belemnites, revisited: Importance of East Asian fossil records

2015 Fiscal Year Final Research Report

• Project/Area Number: 25800285
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Stratigraphy/Paleontology
• Research Institution: Hokkaido University
• Principal Investigator: Iba Yasuhiro 北海道大学, 理学(系)研究科(研究院), 助教 (80610451)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 古生物学 / 頭足類 / ベレムナイト / 進化 / 中生代 / 東アジア

Outline of Final Research Achievements

Belemnites (Belemnitida), a very successful group of Mesozoic cephalopods, provide an important clue for understanding Mesozoic marine ecosystems. Following current hypotheses, belemnites originated in the earliest Jurassic (201 to 197 Ma) with very small forms without prominent groove. According to this view their paleobiogeographic distribution was restricted to northern Europe until the Toarcian (183 to176 Ma). The fossil record is, however, biased by the fact that all the previous studies on belemnites so far focused on Europe. This study on fossil records conclude that the late Triassic to earliest Jurassic Belemnitida had a much higher diversity, and wider distribution than previously thought. It is postulated here that the belemnites did not originate in the earliest Jurassic in northern Europe, but in the Late Triassic in eastern Tethys (S.China). The fossil record of the Order Belemnitida is therefore extended by ~33 m.y. before the Triassic-Jurassic extinction event.

Free Research Field

古生物学