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USING MAMMALIAN ASSEMBLAGES TO RECONSTRUCT PAST CLIMATE: A STUDY OF FOUR LATE PLEISTOCENE SITES IN SUFFOLK ALEXANDER JACKSON This paper summarises an undergraduate dissertation undertaken in 2014 as part of a degree in Physical Geography at Royal Holloway, University of London. Large vertebrate remains are extremely useful in Quaternary studies. They can be found in many depositional environments, with fluvial deposits being some of the most common sites as they usually have excellent preservation. Due to the expansion of the northern ice fields towards the end of the Ipswichian interglacial (ca. 115,000 BP), the level of the sea receded causing rejuvenated rivers to cut down into their valleys. This river regime deposited gravels rich in mammalian remains, which now lie buried below the current floodplains in the valley bottoms. If it had not been for the commercial extraction of these gravels these faunas may have remained undiscovered (Spencer, 1970). The Ipswich Museum houses various collections of these Late Pleistocene remains, on which little recent research has been carried out. For this study, four sites were selected. Three originated within the present day Gipping valley: Bramford Road and Sproughton just west of Ipswich and Barham to the north. At Bramford Road, gravel was pumped up from a depth of 10–12 metres and appears to have being an infilling within a former meander of the River Gipping. A number of flint handaxes were also recovered from this site (Spencer, 1970). There had also been some prior work on the Late glacial assemblage at Sproughton (Wymer et al., 1975). Eastall’s Pit in Barham is a source of the largest collection of remains. The site is composed of gravels along with erratics derived from Gipping glacial outwash. The lower levels of the site were flooded, which made it difficult to determine if deposits originated from the same period (Spencer, 1970). In addition, the mammalian fauna of a fourth site from Weybread in the Waveney valley to the north of the county was also studied, for which there was no published information. The composition of each mammal assemblage was assessed and compared between each site. Table 1 shows a summary of the species at each site. In the Bramford Road assemblage, although bison and horse make up the highest percentages (19% and 21% respectively), the majority of these elements are teeth. Postcranial elements are relatively limited and the largest range of these come from woolly rhino. The only elements representing reindeer were antler fragments, but one was from a large individual and another was from a juvenile. There were nine woolly mammoth molars as well as a small sample of postcranial bones. In addition, two leg bone fragments from the genus Homo were found, but there was doubt as to whether they were part of the rest of the faunal assemblage. Although the flint handaxes also found here imply that Neanderthals were present in the landscape at the time, due to the unstratified nature of the excavation at this site there is uncertainty that the fragments of femur and tibia found alongside them derive from Homo neanderthalensis, as there is always the possibility that they are Homo sapiens from more recent deposits. Trans. Suffolk Nat. Soc. 50 (2014)
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Table 1 Species presence at each site.
Homindae Homo sp. Linné,1758, Hominin species Hyaenidae Crocuta crocata Erxieben, 1977, spotted hyaena
1a
4a 1j
2a
10
2
2
1
3
1a
1a
1a
1a
1a
Modified bone
Bramford Road Barham Sproughton Weybread NISP MNI NISP MNI NISP MNI NISP MNI 2
Modified bone Modified bone
42
1a
16
1a
1a 2
1
7a
3
1 12
2
46
2a 1a
Felidae Panthera spelaean Goldfuss,1810, cave lion Elephantidae Mammuthus primigenius Blumenbach, 1803, woolly mammoth
13
2a
6 3
2a 1j
1a 1j
Equidae Equus ferus Boddaert, 1785, horse
12
1a 1j
16
10
Rhinocerotidae Coelodonta antiquitatis Blumenbach, 1807 Woolly rhinoceros
4
2a
Cervidae Rangifer tarandus Linné,1758, reindeer Cervus elaphus Linné, 1758, red deer
20
Bovidae Bison Priscus Bojanus, 1827, bison
Numbers of Identified Specimens (NISP) and Minimum Numbers of Individuals (MNI) per taxon. The distribution of body part fragments per taxon is shown in bold type and the percentage of each element of the total for that taxon in italics. ‘a’ denotes an adult animal and ‘j’ a juvenile.
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At Barham the larger species predominate, with a minimum number of seven woolly rhinos (Figure 1) and five woolly mammoths identified, representing 40% and 37% of the assemblage respectively. Both species are represented by a large number of different bone elements. Bison is reasonably well represented with a minimum number of two adults and one juvenile. The identification of one bone element each indicates the presence of both horse and cave lion. The only representation of cave lion from the four sites is at Barham. Sproughton has a more restricted assemblage, with only three different species being identified. Two different sized tusks indicate that there were a minimum number of two woolly mammoths, with one being a juvenile. Elements from woolly rhino make up over half the assemblage but there is only a minimum of two individuals. Antler fragments indicate at least one reindeer. Weybread has the smallest number of specimens of all the sites, though still maintains a reasonable diversity of species. Elements from bison make up over half the assemblage. The low numbers of elements and the absence of any duplication mean that only a minimum of one individual of each species can be inferred. Altogether the sites are very similar to each other, with all of them sharing three common species of woolly rhino, woolly mammoth and reindeer. All apart from Sproughton also share the species horse, bison and spotted hyaena. Although the bones of spotted hyaena have not been found, their presence can be inferred by characteristic gnawing.
Figure 1 Woolly rhino cranium
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An analysis of the past habitats and palaeobiologies of each species was carried out and using this, the environmental conditions could be inferred. All the species found fit within what is termed the Mammuthus–Coelodonta Faunal Complex (Kahlke, 1999) and were capable of surviving in the cold, dry environment of what is described as ‘the mammoth steppe’ (Guthrie, 1990). The main evidence to support this comes from the presence of woolly mammoth, woolly rhino and reindeer at all four of the sites. These, combined with the other species that were found (spotted hyaena, cave lion, bison, horse and red deer) are all components of this faunal complex. The mammalian biostratigraphy of the Late Pleistocene was then examined in detail and based on the composition of the assemblages these four Suffolk sites were each found to correspond with the Pin Hole (Creswell Crags, Nottinghamshire) Mammal Assemblage Zone (MAZ), which dates to the period of the Middle Devensian known as Marine Isotope Stage 3 (MIS 3). The Pin Hole MAZ, dating between 60,000 and 26,000 BP is one of the best representation of the faunas of this time. The assemblage consists of woolly mammoth, woolly rhino, reindeer and bison, along with lion and spotted hyaena (Jacobi et al, 1998). The Pin Hole fauna can be viewed as a western extension of a Central Asian assemblage characteristic in the Late Quaternary. It indicates that extreme continental conditions of the ‘mammoth steppe’ reached Britain and the Atlantic seaboard. This cold, arid combination of steppe and tundra conditions was maintained by this distinctive community of species and has no modern analogue (Zimov et al., 2012). Upton Warren, in Worcestershire, also exhibits faunal remains contemporary with a Pin Hole assemblage. Lack of any trees such as birch Betula sps, pine Pinus spp and willow Salix spp in the pollen records here indicates an open, tundra environment and the presence of insects restricted to northern Russia and Scandinavia in the present day (Amara interstitialis, Dej. and Amara torrida, Ill.) infer colder climate conditions (Coope, 1962). MIS 3 represents the warmest part of the Last Glacial, though there were dramatic fluctuations in climate which occurred often at a decadal scale (Currant and Jacobi, 2011). However, modelled temperatures show that a typical ‘warm’ event would not have been warm relative to today: summer temperatures would have rarely exceeded 8–12°C, with winter temperatures falling to -8°C. Atmospheric circulation models over Europe project strong westerlies and the subsequent wind chill factor would have lowered temperatures further (Barron et al., 2003). Based on coleopteran assemblages, coldest months during MIS 3 could have plummeted to -27°C (Coope, 2002). These are therefore the conditions which are likely to have existed across Suffolk when the animals which are the focus of this study – the real counterparts of the famous woolly mammoth re-created in the Suffolk Wildlife Gallery of the Ipswich Museum – were alive and competing for survival.
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Acknowledgements I thank Professor Danielle Schreve for her supervision and guidance throughout the project and Ann Ainsworth and the staff of Ipswich Museum for their time and resources during the collection of data. References Barron, E., van Andel, T. & Pollard, D. (2003). Glacial environments II: Reconstructing the climate of Europe in the last glaciation, in van Andel, T. & Davies S. W. G. (eds.) Neanderthals and modern humans in the European landscape during the last glaciation: Archaeological results of the stage 3 project. Cambridge: McDonald Institute: 57–78. Coope, G. R. (1962). A Pleistocene Coleopterous fauna with arctic affinities from Fladbury, Worcestershire. Quarterly Journal of the Geological Society of London, 118: 103–123. Coope, G. R. (2002). Changes in the thermal climate in Northwestern Europe during Marine Oxygen Isotope Stage 3, estimated from fossil insect assemblages. Quaternary Research, 57: 401–408. Currant, A. P. & Jacobi, R. (2011). The Mammal Faunas of the British Late Pleistocene, In Ashton, N., Lewis, S. & Stringer, C. (eds.) The Ancient Human Occupation of Britain. Developments in Quaternary Science. Amsterdam: Elsevier, 14: 165–180. Guthrie, R. D. (1990). Frozen fauna of the mammoth steppe. Chicago: Chicago University Press. Jacobi, R. M., Rowe, P. J., Gilmour, M. A., Grün, R. & Atkinson, T. C. (1998). Radiometric dating of the Middle Palaeolithic tool industry and associated fauna of Pin Hole Cave, Creswell Crags, England. Journal of Quaternary Science, 13: 29–42. Kahlke R-D., (1999). The history of the origin, evolution and dispersal of the late Pleistocene Mammuthus-Coelodonta faunal complex in Eurasia (large mammal). Rapid City: Fenske Companies. Spencer, H. E. P. (1970). A contribution to the geological history of Suffolk, part 4. Trans. Suffolk Nat. Soc., 15: 148–196. Wymer J. J., Jacobi R. M. & Rose J. (1975). Late Devensian and early Flandrian barbed points from Sproughton Suffolk. Proc. Prehist. Soc., 41: 235–241 Zimov, S. A., Zimov, N. S., Tikhonov, A. N. & Chapin III, F. S. (2012.) Mammoth steppe: a high-productivity phenomenon. Quaternary Science Reviews, 57: 26–45. Alexander Jackson The Old School Church Lane Brantham Suffolk CO11 1QA alex.jackson@uwclub.net
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