Comparing rock and fossil records in the deep sea
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Comparing rock and fossil records in the deep sea
- 1. Comparing rock and fossil records in the deep sea Graeme T. Lloyd, Andrew B. Smith and Jeremy R. Young
- 2. Fossil record is our only record of the diversification of life
- 3. Diversity correlates with rock record on land Peters and Foote 2001 Smith and McGowan 2007
- 4. An alternative record • Calcareous microfossils such as coccolithophores have land-based and deep sea records • i.e., two diversity records and two rock records • What is the relationship between these records? • How much does the rock record influence diversity patterns?
- 5. The database • Study groups are Coccolithophores and planktic Foraminifera • Novel compilation from North Atlantic • Compiled from 40 years ODP/DSDP data • 64,077+ occs from 20,723+ samples • High temporal resolution (biozones)
- 6. Deep sea species richness
- 7. Deep sea genus richness
- 8. Deep sea rock record
- 9. Correlation tests • First both time series were log-transformed • Long term test: – Simple correlation • Short term tests: – First differences (absolute) – Moving average differences (relative to long term trend) • Degree (rho) and significance (p) of correlations determined using Spearman rank
- 10. Deep sea long-term correlation
- 11. Deep sea short-term correlation I
- 12. Deep sea short-term correlation I
- 13. Deep sea short-term correlation II
- 14. Deep sea short-term correlation II
- 15. Modeling
- 16. Modeling results
- 17. Modeling results
- 18. Subsampling
- 20. Conclusions • Deep sea diversity curve largely explicable by sampling • Apparent rise in nannofossil diversity to present strongly associated with rise in sampling
- 21. The other side of the story • What about the land-based record for the same groups? • Sampling strategy based on distribution charts from primary literature • Rock record measure is number of localities
- 22. Two rock records
- 24. Summary • Both land and sea have measurable rock biases that follow different trajectories over geological time • Will allow a clear and explicit test of how important a role these play in shaping our fossil record
Hinweis der Redaktion
- The history of biodiversity –based on counts of fossils sampled from the rock record and for most groups biodiversity patterns have been based on the fossil record available from land-based outcrops.
- But there is a problem – a worrisome correlation exists between sampled diversity and the rock record driven by large transgression-regression cycles. As we have heard from Shanan this could be biological as much as sampling artefact - so what we need is another system where the rock record is very different so that we can resolve how important rock sampling is. Such a record exists! – in the deep-sea.
- For microfossils such as coccolithophorids we have access to both a deep-sea record and a land-based record which gives us two biodiversity estimates under two different rock records which allows us to explore the relationship between rock & fossil records and pinpoint how much the rock record influences biodiversity curves. Today I’m going to concentrate on the deep sea