Ice Age Fossils
Ancient Weather “Forecasters” of the Past
By Dr. Simon Jackson, Collections and Learning Curator, Ipswich Museums
New research is investigating and reconstructing the unknown climates and environments of the past. Today, we feature University of Helsinki mammal palaeontologist, Dr Juha Saarinen, who visited the Ipswich Museum collections this November, who is leading a new, pioneering, 5 year international project to use fossil mammal collections across Europe, Africa, and South America to peer back to the ice age and beyond.
Teeth, in addition to helping us to understand an animal’s diet, as we explored in September with Laura Hemmingham, a PhD student from Royal Holloway, can also be used as an indicator for reconstructing vegetation cover and past climates. For instance, high (crowned) teeth, with relatively flat surfaces, are specialised for chewing grass, which typically reflect drier environments¹. Such teeth can be found in horses. So, therefore, we can use the shape of teeth as a way of making inferences to how dry certain environments were (relating to the amount of rainfall or precipitation).
The dimensions of limb bones can also help us to estimate how much these fossil creatures weighed (their body mass); specifically, thicker bones indicating larger animals. By studying large collections of ice age mammals we can see how animal sizes changed through time and how this is related to the changing conditions of the ice age. Previous work by Juha has looked at the relationship between body size and vegetation openness, with the Ipswich collections helping to show that wild horses had smaller average body size in more open environments of the Pleistocene².
Juha’s eyes light up as I welcome him to a museum office. This is an office like no other. Sure, there are filing cabinets and a few computers, as you might expect, but there are boxes and boxes of ice age fossil mammals, more than 300 specimens, which we have brought out specially for Juha from the stores. Juha will be spending the next 2 days ‘wading’ through this selected collection, looking for the best specimens which might provide him with clues to investigating the past climates of the ice age. I stand by, eager to help, as a breath of “research-life” is breathed in to these collections…
Dr Juha Saarinen, University of Helsinki, sits amidst some 300 mammal specimens from the East Anglian crags and following ice age, which have been temporary relocated from the stores. There is much to look at over his next 2 days…
So why is Juha at Ipswich? Juha is drawn to the Ipswich collections for 2 reasons in his ground-breaking research. Ipswich has the pre-eminent geological collection for charting the cooling of ancient Britain into the ice age. This is the Plio-Pleistocene transition (2.5 million years ago), and in Britain, it is best exposed in Suffolk, through the deposits known as the East Anglian Red Crags. Ipswich has the most comprehensive collection of mammals from the Red Crag deposits and Juha’s work has the potential to reveal what this lost, cooling climate was like, and the animals which once roamed in Britain, at this time. Furthermore, Suffolk also charts the highly variable conditions of the ice age as Britain ‘roller-coasted’ between the more familiar cold, drier episodes (glacials) and warmer and wetter episodes (interglacials); so, therefore, we can understand what these climates and environments were like and how their mammalian inhabitants changed and adapted through time.
Furthermore, through understanding how these ancient mammals and their diets changed through past climate fluctuations, we can begin to understand how they might fare with our current global climate change, induced by human activity. For instance, what can we say about what may happen to living elephants, as temperatures possibly soar by 2°C or more by 2100? Will they increase or decrease in size (which will have a bearing on how much food they will need)? The Ipswich collections of extinct fossil elephant material, including for instance those of the straight-tusked elephant, have the power to answer this question.
Dr Juha Saarinen, using a digital angle meter to measure the grinding (occlusal) surface of a steppe mammoth (Mammuthus trogontherii) tooth from Brundon, which lived 210,000 years ago.
Juha carefully places the 210,000 year old steppe mammoth tooth on top of the desk, as it resumes the natural orientation it would have had in life. He then opens out a device, somewhat resembling a cross between a ruler and a spirit level, into a broad ‘v’ shape. With this device he can measure how prominent the ridges of the tooth are, and can therefore ascertain the amount of wear on the tooth and the type of vegetation the animal may have eaten (e.g. the amount of grass, and how dry the environment may have been). As he works his way through the other 299 specimens, he will be able to build up a picture of what these ancient climates may have been like. When combined with the data from other collections across the world, a strong picture will emerge to help us to understand global ancient mammal diets, and more importantly their long-lost environments of the past.
References
1. Fortelius, M., Eronen, J., Jernvall, J., Liu, L. P., Pushkina, D., Rinne, J., … & Fortelius, M. (2002). Fossil mammals resolve regional patterns of Eurasian climate change over 20 million years.
2. Saarinen, J., Eronen, J., Fortelius, M., Seppä, H., & Lister, A. M. (2016). Patterns of diet and body mass of large ungulates from the Pleistocene of Western Europe, and their relation to vegetation. Palaeontologia Electronica, 19(3), 1-58.
