Paleontology and Mineral History
- Haruyoshi Maeda, Professor
- Our laboratory aims at frontier researches on paleontology and mineral history. In paleontology laboratory, our current goal is settled to elucidate fossilization mechanism in geologic time scale, i.e., taphonomy. Our research starts from a very primitive question “How and why were fossils made?” But it provides an essential bridgehead for all fields of paleontology, and gives rise to innovation in sciences about the history of life. From this unique viewpoint, our laboratory leads this field in Japan, and the chief is now active as the president of the Palaeontological Society of Japan.
Besides, detailed analyses on meteorites have been carried out in the mineral history laboratory, while it is temporary closed because of retirement of the faculty.
By field-oriented research, we have collected several tons of fossil materials not only from Japan but also from various areas in the world.
1. Extraordinarily preserved fossils
Discovery of phosphatized minute ostracod-like animals showing 3D soft-part preservation in fecal pellets from the Cambrian Orsten deposits substantiated our new hypothesis of preservation of animal soft-tissues about 500 million years ago (Fig. 1). Our laboratory acts as a research center of extraordinarily preserved fossils (=fossil Lagerstätten) in Japan.
2. Revision and updating ammonoid taxonomy:
Another emphasis of our laboratory is on ammonoid paleoecology and systematics. Close investigation revealed the existence of a dimorphic pair within a single species (e.g., male and female; Fig. 2). Such dimorphs are quite different in appearance, and have been designated to different taxa. This results cast doubts on traditional scheme of typological taxonomy, and triggered off revision of the systematics.
3. Ammonoid taphonomy:
To reconstruct paleoecology of extinct animals like ammonoids, detailed observation about modes of fossil occurrence is essential. Bed-by-bed observation on the Cretaceous strata inspires us an new idea that an empty large ammonoid shell triggers off accumulations of small ammonoid carcasses, shell fragments and plant remains like a “trap” on the sea floor. Abundant examples showing similar occurrence in outcrops support this view.