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THE CENOZOIC DEEP SEA MICROFOSSIL RECORD: EXPLORATIONS OF THE DSDP/ODP SAMPLE SET USING THE NEPTUNE DATABASE

PLAIN LANGUAGE SUMMARY:

Marine sediments contain the most complete record of the evolution of life on Earth. After the mass extinction event of the Cretaceous/Tertiary boundary, 65 million years' worth of sediments have accumulated on the sea floor. The Deep Sea Drilling Project and its successor, the Ocean Drilling Program, have drilled, retrieved and analysed kilometers of cores, as well as described their paleontological content. The Neptune database was established to compile the most valuable and significant data, and to use them to study the evolution of marine plankton. The global geographic coverage (165 holes), the high number of species described (1400+) from four marine plankton groups, the improved age control on the sediments, and the relatively high sample resolution (a few hundred thousand years) make this relational database the most complete paleontological data set currently available.

The analysis of these data has shown different evolutionary patterns in different plankton groups. On average a plankton species ‘survives’ 7 to 10 millions of years. Siliceous plankton (diatoms and radiolarians) tend to speciate and become extinct at distinct climatic and oceanographic boundaries independently from their nutritional habits (photosynthetic algae or plankton feeders). On the other hand, calcareous plankton seems to be more independent from these conditions. The results also show that the total number of species preserved in the sediments as fossils (a subset of the total number of species that existed at each given time and location) has gradually increased through time, but has also fluctuated strongly in the last 65 million years perhaps in response to climatic changes. This database has the potential to allow paleontologists to study the complex interactions between marine life and environment at a geological scale.

Cinzia Spencer-Cervato, Eidgenössische Technische Hochschule, Geologisches Institut, ETH Zentrum, 8092 Zurich, Switzerland
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