Monday, May 7, 2012
Geological and Planetary Sciences Seminar
Exceptional fossils and new technologies: revealing the big steps in our early evolution
John Long, Vice President, Research and Collections , Natural History Museum of Los Angeles County
The 380 million year old Gogo Formation of north Western Australia preserves a unique Late Devonian fish fauna. The exceptional three-dimensional preservation of uncompressed macrofossils combined with unprecedented soft-tissue preservation (by bacterial permineralisation), including muscle bundles, nerves cells and umbilical structures, is represented by a particularly rich assemblage with almost 50 species of fishes now described. The most significant discoveries have contributed to better understanding the origins of internal fertilization, including data on the oldest known vertebrate embryos and male reproductive organs in placoderm fishes; the anatomy and relationships of primitive bony fishes (osteichthyans); the histology and radiation and plasticity of dipnoan dental and cranial structures; the anatomy and functional morphology of sarcopterygians (onychodonts, lungfishes); the origins of air-breathing in sarcopterygian fishes, and to elucidating the anatomy of the fish-tetrapod transition through remarkable new finds of the stem tetrapod Gogonasus. Much has been revealed using a newly developed high resolution microCT with in-house imaging software (Drishti) at the Australian National University Dept of Applied Mathematics, and using the European synchrotron facility to study tissue microstructure.