This document summarizes a study on the paleoecology of bivalves from the Lower Miocene of Kutch, India. The study aimed to characterize the bivalve taxonomy, diversity, and morphology over time and evaluate the possible effects of climatic change. Bivalve shells were collected from two formations - the older Khari Nadi formation and younger Chhasra formation. Results showed higher taxonomic diversity, γ diversity, and larger average body sizes in the older formation. Isotopic analysis also indicated warmer temperatures in the younger formation. This supports the hypothesis that increased temperature leads to increased diversity but decreased body size, demonstrating the impact of climatic change on bivalve paleoecology.

1. Paleoecology of Bivalves from Lower Miocene of Kutch, India
Shibajyoti Das
5th
Year BS-MS
DES, IISER Kolkata

2. Outline
• Introduction
• Previous work
• Theme
• Bivalve
• Miocene global climatic scenario
• Kutch
• Objectives
• Material Methods
• Results
• Taxonomic diversity
• Rarefaction
• γ diversity
• Morphological diversity
• Discussion and Conclusion
• References
• Acknowledgement
http://www.fossilmall.com/Pangaea/pfossils/pf115/pfo433bb.JPG

3. Previous work
• Physical triggers affect the biodiversity of organisms.
• Climate change – major driving force (Matthew, 1915).
• Increase in temperature – Increase in biodiversity (Mayhew et al. 2012).
• Evolutionary trend of Cenozoic Mollusc as a result of climatic shifts –
• North American (Roy et al., 2001)
• Antarctic (Ivany et al., 2000, 2003, 2004, 2008)
• European assemblages (Lockwood, 2005 )
• Decrease in Bivalve body size with an increase in temperature (Belanger, 2012).

4. Theme
• Possible effect of the physical trigger (climatic fluctuation) on
• Bivalve diversity and community structure
• Bivalve morphology (body size) from the Miocene of Kutch

5. Bivalves
• Good fossilization potential
• Common in the fossil record
• Accretionary growth recording events
happening during life
• δ18
O and δ13
C isotopic signature preserved
• Accretion: Adding discrete growth layers to
skeletons as they get larger.
http://paleoecology.syr.edu/research-pages/growth.html

6. Geologic time scale
Khari Nadi formation
Chhasra formation
Stratigraphy of Kutch after Biswas (1992)

7. Climatic fluctuations over the Tertiary Period
• Through the Tertiary climate varied from colder to warmer in
regular cycles.
• Average global temperature was warmer during the Tertiary
Period so that continental glaciations did not take place.
• Geochemical data demonstrate that the Miocene represents a
time of rapid palaeoclimatic change (Zachos et al. 2001).

8. Fluctuations during Miocene
Sea level estimates derived from New Jersey (Miller et al., 2005;
Kominz et al., 2008) that provide a testable record of global sea-
level. Also shown is the oxygen isotopic synthesis of Cramer et al.
(2009). NHIS = northern hemisphere ice sheets.

9. Kutch, India
• The Early Miocene succession of Kutch represents a mixed carbonate-siliciclastic
depositional system (Kumar et al., 2009).
• The carbonate succession had abundant shallow marine benthic fauna consisting of shelled
organisms in large concentration.
• The carbonate-siliciclastic depoitional environment helps in good preservation of the
mollusc shell because:
• Carbonate shell
• Contrasting depositional environment
• Difference in texture of fossil and surrounding rocks

10. Objectives
• Characterization of Bivalves from Early Miocene of Kutch.
• Characterizing the nature of taxonomic and morphological diversity and
community structure of the bivalve community.
• Evaluating the possible effect of climatic change on the bivalve community.

11. Field area

12. Bio-assemblage

13. Field protocol
• Selection of locality (ridge or river bed section).
• Identification of lithological units.
• Making brief lithologs.
• Collection of bulk lithological samples and fossils.

14. Methods used

15. Methods used

16. Identification protocol
• Paleodb database
•Treaties of
Invertebrate
Paleontology
•Borkar et al. 2004

17. Bivalve Taxonomy
Ostreidae
Veneridae
TellinidaePectinidae
GlycymeridaeCardiidae
Plicatulidae

18. Results
• Total Specimen Identified: 1479
• Khari Nadi formation : 902
• Chhasra formation: 577
• Number of identified Families:9
Family Khari Nadi Chassra
Arcidae 9 6
Cardiidae 38 6
Glycymeridae 10 2
Lucinidae 8 2
Plicatulidae 0 5
Pectenidae 234 50
Ostreidae 439 482
Tellinidae 56 8
Veneroidae 108 16
902 577
1. Taxonomic diversity

19. Abundance distribution
Family Khari Nadi (%) Chassra (%)
Ostreidae 48.6 83.5
Pectinidae 25.9 8.6
Veneridae 11.9 2.7
Tellinidae 6.2 1.3
Arcidae 0.9 1.0
Glycymeridae 1.1 0.3
Lucininidae 0.8 0.3
Cardiidae 4.2 1.0
Plicatulidae 0 0.8

20. Rarefaction
• This curve is a plot of the number of taxa as a
function of the number of samples.
• Estimates the number of taxa that would have
been found if a smaller number of individuals
had been sampled.
A
B
Number of Individuals
NumberofTaxa

21. γ diversity
• Total taxonomic diversity in a landscape (Formation).
Mann-Whitney Test: p<<0.05

22. Most abundant families
• Ostreidae
• Pectinidae
• Veneridae
• Tellinidae

23. Abundance in each locality
Khari nadi
Dominance = 0.47
Chassra
Dominance = 0.8
p = 0.0018

24. Results
• Body size measurement
• Length
• Height
• Total specimen measured: 373
• Khari Nadi formation : 281
• Chhasra formation: 92
• Number of Families whose specimens were measured: 4
Family Khari Nadi Chassra
Pectenidae 54 18
Ostreidae 125 65
Veneridae 69 6
Tellinidae 33 3
281 92
2. Morphological diversity

25. Body-Size plots
Percentage decrease: 49.35
p << 0.05
Percentage decrease: 73.17
p << 0.05
Percentage decrease: 30.63
p << 0.05

26. Comparison of percentage shrink

27. Paleoclimate
• δ18
O values for two cross sectional
samples of Ostrea angulata
• Paleotemperature reconstruction from
the δ18
O values.
Khari Nadi
Chhasra
Khari Nadi
Chhasra
Khari Nadi

28. Discussion and Conclusion
• A significant increase in temperature from the older to the younger formation.
• Difference in abundance of families between the two formations.
• Significant difference in the γ diversity in the two formations.

29. Climate change and biodiversity
• Beyond small geographical scales, biodiversity consistently decreases with latitude (Willig et
al. 2003; Hillebrand, 2004; Krug et al., 2009).
• Strong causal association between warmer climates and standing richness in marine realms
(Rombouts, 2009; Tittensor et al., 2010).
• Increase in temperature – Increase in biodiversity (Mayhew et al. 2012).
Temperature Diversity

30. Discussion and Conclusion
• A significant change in the body size with body shrinkage in the
younger formation.
• Shrinkage percentage varies within families.
• Highest for epifaunal mobile (free swimmers)
• Low for epifaunal stationary (bysally attached)
• Lowest for infaunal

31. Temperature and body size
Figure: Working hypothesis of the major processes of climate change
effects on organism size.
(1) Increased metabolic rate is
likely to reduce body size
unless organisms can consume
enough additional resources to
meet their increased demands.
(2) Decreased amounts of
dissolved oxygen in warmer
waters will make it difficult to
meet increased metabolic
needs.
(Sheridan and Bickford, 2001, Nature climate)

32. References
• Belanger, C. L. (2012). Individual to community-level faunal responses to environmental change from a marine fossil record of Early Miocene global warming. PloS one, 7(4), e36290.
• Biswas, S. K. (1992). Tertiary stratigraphy of Kutch. Journal of the Palaeontological Society of India, 37(1-29).
• Cramer, B. S., Toggweiler, J. R., Wright, J. D., Katz, M. E., & Miller, K. G. (2009). Ocean overturning since the Late Cretaceous: Inferences from a new benthic foraminiferal isotope
compilation. Paleoceanography, 24(4).
• Hillebrand H (2004) On the generality of the latitudinal diversity gradient. Am Nat 163:192–211.
• Ivany, L. C., K. C. Lohmann, and W. P. Patterson, 2003, From Greenhouse to Ice-house: The Marine Eocene-Oligocene Transition, pp. 232–251, Columbia Univ. Press, New York
• Ivany, L. C., W. P. Patterson, and K. C. Lohmann, 2000, Nature, 407: 887–890
• Ivany, L.C., Lohmann, K.C, Blake, D.B., 2008, GSA Bulletin, 120: 659-678.
• Ivany, Linda C., Wilkinson, Bruce W., Lohmann, Kyger C, 2004, J. Sed.Res., 74: 7-19.
• Kominz, M. A., Browning, J. V., Miller, K. G., Sugarman, P. J., Mizintseva, S., & Scotese, C. R. (2008). Late Cretaceous to Miocene sea level estimates from the New Jersey and Delaware‐
coastal plain coreholes: An error analysis. Basin Research, 20(2), 211-226.
• Krug AZ, Jablonski D, Valentine JW, Roy K (2009) Generation of Earth’s first order biodiversity pattern. Astrobiology 9:113–124
• Kumar, P., Saraswati, P. K., & Banerjee, S. (2009). Early Miocene shell concentration in the mixed carbonate-siliciclastic system of Kutch and their distribution in sequence stratigraphic
framework. Journal of the Geological Society of India, 74(4), 432-444.
• Matthew WD. 1915. Ann. NY Acad. Sc., 24:171-318
• Mayhew, P. J., Bell, M. A., Benton, T. G., & McGowan, A. J. (2012). Biodiversity tracks temperature over time. Proceedings of the National Academy of Sciences, 109(38), 15141-15145.
• Miller, K. G., Kominz, M. A., Browning, J. V., Wright, J. D., Mountain, G. S., Katz, M. E., & Pekar, S. F. (2005). The Phanerozoic record of global sea-level change. science, 310(5752),
1293-1298.
• Rombouts I, et al. (2009) Global latitudinal variations in marine copepod diversity and environmental factors. Proc Biol Sci 276:3053–3062.
• Roy, K., Jablonski, D., Valentine, J. W., 2001, Ecol. Letters, 4: 366-370
• Sheridan, J. A., & Bickford, D. (2011). Shrinking body size as an ecological response to climate change. Nature climate change, 1(8), 401-406.
• Tittensor DP, et al. (2010) Global patterns and predictors of marine biodiversity across taxa. Nature 466:1098–1101.
• Willig MR, Kaufman DM, Stevens RD (2003) Latitudinal gradients of biodiversity: Pattern, process, scale and synthesis. Annu Rev Ecol Evol Syst 34:273–309
• Zachos, J.C., Pagani, M., Sloan, L., 2001, Science, 292:686-693

33. Acknowledgements
• Dr. Devapriya Chattopadhyay
• Saurav Dutta, Debarati Chattopadhyay, Mansi Jain,
Mrinmoy Pal, Rohini Das, Neeti Mandal, Ravi
Kiran, Debanjan Chandra, Jayjit Das and Dipanjana
Dalui.
• Paleo lab members
• All members of the Department of Earth Sciences,
IISER Kolkata
• Friends and family

34. Thank you