Sunday, 28 August 2016

Analysing the distribution of Pleistocene Terrestrial Vertebrate Fossils from the North Sea.

Today the UK is an island separated from the European mainland by the North Sea and English Channel, but for much of the Pleistocene the UK was attached to the rest of Europe, with large areas of land that were occupied by early Humans and other terrestrial animals. Over the past two centuries a very large number of Pleistocene Terrestrial Vertebrate Fossils have been recovered from the North Sea. Some of this has some from sites which have been the site of organised archaeological and palaeontological investigations, such as Bouldnor Cliff in the Solent (not strictly part of the North Sea), Area 240 off the north coast of Norfolk and Brown Bank and Eurogeul off the coast of the Netherlands, but the largest proportion of the material has been brought up by fishing trawlers and dredgers from areas never directly accessed by archaeologists or palaeontologists. In recent years some effort has been made to analyse North Sea material in Dutch collections in order to build up a picture of the age of the specimens, and understand the environments in which they were living.

In a paper published in the journal Antiquity on 28 June 2016, Rachel Bynoe of the Department of Archaeology at the University of Southampton, Justin Dix of the National Oceanography Centre Southampton, also at the University of Southampton, and Fraser Sturt, again of the Department of Archaeology at the University of Southampton describe the results of a study of 1120 specimens collected from the North Sea and currently in the collections of museums in the east of England.

Bynoe et al. identified three main areas targeted by large fishing fleets from the East of England in the nineteenth and twentieth centuries. The area from the Dogger Bank, northward to the Skagerrak and towards the Shetland Islands, Greenland and the Barents Sea was targeted by fleets from the ports of Grimsby and Hull, the area from Dogger Bank south to the Leman and Ower Banks was exploited by the Yarmouth Fleet and the area south of the Leman and Ower Banks, east to the Dutch coast and south to the Gabbards was utilised by the fleet from Lowestoft. In addition numerous smaller coastal fleets targeted inshore areas close to their home ports.

All locations and sites mentioned in the text, with contours showing current offshore bathymetry. Bynoe et al. (2016).

The accessible fossil record of the North Sea is known to be skewed; only the largest and most robust specimens are likely to have survived on the sea floor for thousands of years, become entangled in fishing nets then spotted by Human observers not specifically looking for fossil remains. Nevertheless even with such a bias towards large specimens some biostratigraphical and environmental reconstruction is possible; in particular considerable faunal turnover is associated with the Anglian Glaciation (roughly 478 000–424 000 years ago), when the glaciers reached as far south as London, and most specimens can be confidently described as belonging to pre- or post-Anglian Glaciation species. Likewise some species present were clearly not adapted to colder conditions (such as the Straight-tusked Elephant, Palaeoloxodon antiquus, or Narrow-nosed Rhinoceros, Stephanorhinus hemitoechus) and therefore must have lived during warm, interglacial periods.

Of the examined specimens 71% were found to have sufficient information to tie them to an approximate location. The information recorded at the time when the fossils were collected is often somewhat vague, such as 'East Coast' or 'Suffolk'; however this can be further refines, for example a specimen labelled 'Suffolk' is likely to have been collected by a fishing vessel from Lowestoft, and therefore can be assigned to the area targeted by the Lowestoft fleet. The identity of the collectors that amassed the material and donated it to the museums was also useful, for example the antiquarian John Owles is known to have collected material brought ashore by the Great Yarmouth fleet in the mid nineteenth century, so fossils collected by him and labelled 'East Coast' can be assigned to the area targeted by the Great Yarmouth fleet.

Cervus sp. skull showing Owles’s Great Yarmouth stamp. Bynoe et al. (2016).

Of the Great Yarmouth specimens 85% are considered to be post-Anglian species, with 9% pre-Anglican and 6% species present both before and after the Anglian glaciation. 68% of the post-Anglian specimens are assigned to a single species, the Woolly Mammoth, Mammuthus primigenius, with the Woolly Rhinoceros, Coelodonta antiquitatis, and the Aurochs, Bos primigenius, each making up 6% of the specimens, Reindeer, Rangifer tarandus, made up 3% of these specimens, and Walrus, Trichechus rosmarus, and Giant Deer, Megaloceros giganteus, each making up less than one percent of the specimens. The warm-climate Straight-tusked Elephant, Palaeoloxodon antiquus, was also present, albeit at a very low level.

Post-Anglian species also dominated the Lowestoft specimens, comprising 72% of the total, though here pre-Anglican specimens made up 19% of the total and species present both before and after the Anglian glaciation made up 9% of the total. Again the most abundant species in the post-Anglican set was the Woolly Mammoth, Mammuthus primigenius, though here it only made up 51% of the total, with the Aurochs, Bos primigenius, making up 9% of the specimens, and the Woolly Rhinoceros, Coelodonta antiquitatis, making up 8%.

The inshore specimens shore a more detailed picture, with the northern coast of East Anglia having an assemblage dominated by pre-Anglian specimens, with the proportion of post-Anglian specimens rising further south along the coast, with a distinct pocket of warm-climate species including Straight-tusked Elephant, Palaeoloxodon antiquus, or Narrow-nosed Rhinoceros, Stephanorhinus hemitoechus and Hippopotamus sp. found around the Tendring Peninsula, interpreted as having been deposited late in the last interglacial period; a hypothesis supported by a sediment core taken from nearby deposits that yielded an optically stimulated luminescence date of about 116 000 years ago.

(a) Changing proportions along the coastal locations; (b) changing proportions from Great Yarmouth and Lowestoft fleets, plus inset chart showing the coastal species from locations with larger sample sizes. Bynoe et al. (2016).

This data ties in well from that from the Dutch coastal sites, which are likely to overlap with the Lowestoft data, which yielded radiocarbon dates of 60 000–15 000 years ago and an environmental reconstruction that suggests the area was dominated be Mammoth Steppe; a cold grassland environment most associated with the last glaciation, appearing slightly over 100 000 years ago and disappearing about 12 000 years ago. These Dutch deposits have also produced the only known Pleistocene Human remains from the North Sea, a Neanderthal brow ridge from the Zeeland Ridges.

See also...

http://sciencythoughts.blogspot.co.uk/2016/07/evidence-of-cannibalism-in-neanderthal.htmlEvidence of cannibalism in a Neanderthal population from the Late Pleistocene of Belgium.                                                        
http://sciencythoughts.blogspot.co.uk/2016/04/mitochondrial-genomes-of-pleistocene.htmlMitochondrial genomes of Pleistocene Europeans provide insight into early migrations to the continent.                      Recent studies of the genomes of ancient and modern peoples have provided considerable insight into the migration of modern...
http://sciencythoughts.blogspot.co.uk/2014/10/human-remains-from-middle-pleistocene.htmlHuman remains from the Middle Pleistocene of Normandy.                                                             Early and Middle Pleistocene Human remains are extremely rare in northern Europe, having to date...
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