1. Different records give different curves:
comparing deep sea and land-based
palaeobiodiversity
Graeme T. Lloyd, Andrew B. Smith and Jeremy R. Young
Department of Palaeontology,The Natural History Museum, London, UK

2. Macrostratigraphic record Raw palaeodiversity
Sampling
opportunity
Sedimentary Habitat
record availability
Rock record Biological driver
driver
Geotectonic history

3. Macrostratigraphic record Raw palaeodiversity
Sampling
opportunity
Rock bias hypothesis
Sedimentary Habitat
record availability
Rock record Biological driver
driver
Geotectonic history

4. Macrostratigraphic record Raw palaeodiversity
Sampling
opportunity
Common cause hypothesis
Sedimentary Habitat
record availability
Rock record Biological driver
driver
Geotectonic history

5. Macrostratigraphic record Raw palaeodiversity
Which pathway drives the fossil record?
Problem so far is that we have been looking at how different
taxonomic groups are affected in the same rock record -
where both rock and fossil records are created by the same
set of drivers

6. coccolithophorids
To understand which pathway drives the
fossil record
We need to look how the evolutionary history of a single
widespread marine group (coccolithophorids)
is recorded by 2 contrasting rock records
(deep sea v. land based)
Deep sea Land

7. coccolithophorids
Predictions
Common cause - correlation between sampled
diversity and rock record in only one
of the environments (land)
Rock record bias - both environments will show
strong link between sampled diversity
and rock record
Deep sea Land

8. Databases
Deep sea Land
205 sites, 14405 samples, 462 sections, 5563+ samples,
46538 occurrence records 22745 occurrence records

9. Rock records
Deep sea Land
Rock record
Number of cores recovering Number of localities with
rock of given age published nannofossil
taxonomic lists
Time (Ma) Time (Ma)

10. Species diversity in fossil records
Deep sea Land
Raw species diversity
Number of species Number of species
Time (Ma) Time (Ma)

11. Species diversity versus rock record (1): raw data
Deep sea Land
Log (Nsites) Log (Nsites)
Log (species richness) Log (species richness)

12. Species diversity versus rock record (1): first differences
Deep sea Land
Log (Nsites) Log (Nsites)
Log (species richness) Log (species richness)

13. Estimating True Diversity
Deep sea Land
Two diversity curves - so which (if either) is correct?
Use 4 techniques to try to find the true underlying diversity:
• Rarefaction
• Modeling
• Alpha diversity estimates
• Shareholder quorum
With two rock records can cross-validate methods!

14. Estimating True Diversity: 1, Rarefaction
Deep sea Land
109 samples per bin 106 samples per bin
Species diversity (max) Species diversity (max)
Time (Ma) Time (Ma)
Blue = empirical pattern
Black = diversity at equal subsampling

15. Estimating True Diversity: 2, Modeling
Deep sea Land
Diversity modeled as invariant
Species diversity Species diversity
Time (Ma) Time (Ma)
Blue = empirical pattern
Red = model prediction assuming diversity is invariant
and shaped by rock abundance

16. Estimating True Diversity: 2, Modeling
Deep sea Land
Residuals from modeled diversity
Time (Ma) Time (Ma)

17. Estimating True Diversity: 3, Alpha Diversity
Deep sea Land
Mean number of species
recorded per site
Species Species
Time (Ma)
Time (Ma) Time (Ma)

18. Estimating True Diversity: 4, Shareholder Quorum
Deep sea Land
Shareholder quorum
richness at q = .40
Species Species
Time (Ma) Time (Ma)

19. Summary
Deep sea Land
• The recorded history of coccolithophorid diversity over last 150
Ma changes dramatically according to whether data is drawn
from land-based or deep-sea rock records
• Coccolithophorid diversity correlates strongly to the shape of
the rock record it is recovered from
• Subsampling, modeling and estimates of mean alpha diversity
all point to a third, much more uniform, diversity over time
irrespective of which record is used

20. coccolithophorids
Predictions
Common cause - little or no correlation between
diversity and rock record in the deep
sea
Rock record bias - both environments will show
strong link between diversity and
rock record
Deep sea Land

21. Macrostratigraphic record Palaeodiversity
Sampling
opportunity
Rock bias dominates
Sedimentary Habitat
record availability
Rock record Biological driver
driver
Geotectonic history