The evolutionary origin of the mammalian diaphragm: an integrative approach studying genes, cells and Permo-Triassic fossils

2014 Fiscal Year Final Research Report

• Project/Area Number: 25610152
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Stratigraphy/Paleontology
• Research Institution: The Institute of Physical and Chemical Research
• Principal Investigator: HIRASAWA Tatsuya 独立行政法人理化学研究所, 倉谷形態進化研究室, 研究員 (60585793)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: 進化 / 発生 / 化石 / 横隔膜 / 哺乳類 / 前肢筋 / 肩帯 / 羊膜類

Outline of Final Research Achievements

The diaphragm is a mammalian-specific evolutionary novelty, whose origin and early evolution has remained unclear. In this study, through investigations on the fossil record, in particular skeletons of basal synapsids, and on Hox gene expression patterns, I obtained evidence that the diaphragm evolved from a shoulder muscle of the ancestors. In addition, analyses on transformations of lateral body walls during embryonic development demonstrated that the lateral body wall at cervical levels later extends into the thorax along with the caudal transposition of the heart, and suggest that this infolding of the lateral body wall in the embryonic body provided the basis for the diaphragm separating the thoracic cavity from the abdominal cavity.

Free Research Field

古生物学