Bryozoans are colonial invertebrates, commonly found attached to hard surfaces from the shallow subtidal zone to the deep sea. Bryozoan colonies increase in size by the budding of the numerous individuals (zooids) that make up the colony.
A collaborative team, including Professor Beth Okamura, Dr Tanya Knowles and Dr Paul Taylor from the NHM, explored how the size of zooids in fossil bryozoans varied as temperature changed. This enabled them to use bryozoans to deduce the annual ranges of temperature during the Early Pliocene (around 4 million to 5.5 million years ago) in the Weddell Sea off the coast of Antarctica.
Their results show that during this period the climate was warmer than that of the present day, suggesting an ice-free environment in that part of Antarctica.
The research shows the value of fossil bryozoans from shallow seas as a tool for reconstructing seasonal variation in climate in near-polar latitudes in past periods of the Earth's history. This helps to understand how climates have changed naturally in the past - knowledge that in turn enables present-day changes in climate to be understood and predicted.
Clark, N., Williams, M., Okamura, B., Smellie, J., Nelson, A., Knowles, T., Taylor, P., Leng, M., Zalasiewicz, J. & Hayward, A. 2010. Early Pliocene Weddell Sea seasonality determined from bryozoans. Stratigraphy 7: 199-206.