Thursday, 7 January 2021

NORTH SEA DOLPHIN VERT

Dolphin lumbar vertebrae, North Sea (12 cm)
A lovely 12 cm creamy orange Bottlenose Dolphin, Tursiops sp. lumbar vertebrae found in the Brown Bank area of the North Sea, one of the busiest seaways in the world.

Bottlenose dolphins first appeared during the Miocene and swam the shallow seas of this region. We still find them today in warm and temperate seas worldwide though unlike narwhal, beluga and bowhead whales, Bottlenose dolphins avoid the Arctic and Antarctic Circle regions. Their name derives from the Latin tursio (dolphin) and truncatus for their characteristic truncated teeth

We find their remains in the sediments of the North Sea. There are two known fossil species from Italy that include Tursiops osennae (late Miocene to early Pliocene) from the Piacenzian coastal mudstone, and Tursiops miocaenus (Miocene) from the Burdigalian marine sandstone.

Many waterworn vertebrae from the Harbour Porpoise Phocoena sp., (Cuvier, 1816), Bottlenose dolphin Tursiops sp. (Gervais, 1855), and Beluga Whale, Delphinapterus sp. (Lacépède‎, 1804‎) are found by fishermen as they dredge the bottom of the Brown Bank, one of the deepest sections of the North Sea.  

The North Sea is a sea of the Atlantic Ocean located between the United Kingdom, Denmark, Norway, Germany, the Netherlands, Belgium and France. An epeiric sea on the European continental shelf, it connects to the ocean through the English Channel in the south and the Norwegian Sea in the north.

The fishermen use small mesh trawl nets that tend to scoop up harder bits from the bottom. This technique is one of the only ways this Pleistocene and other more recent material is recovered from the seabed, making them relatively uncommon. The most profitable region for fossil mammal material is in the Brown Bank area of the North Sea. I've circled this area on the map below to give you an idea of the region.

Brown Bank, North Sea, Pleistocene Dredging Area
In May 2019, an 11-day expedition by European scientists from Belgium and the United Kingdom was undertaken to explore three sites of potential geologic and archaeologic interest in the southern North Sea. 

It has long been suspected that the southern North Sea plain may have been home to thousands of people, and chance finds by fishermen over many decades support this theory. 

A concentration of archaeological material, including worked bone, stone and human remains, has been found within the area around the Brown Bank, roughly 100 km due east from Great Yarmouth and 80 km west of the Dutch coast. The quantities of material strongly suggest the presence of a prehistoric settlement. As such the Brown Bank provides archaeologists with a unique opportunity to locate a prehistoric settlement in the deeper and more remote areas of the North Sea, known today as Doggerland.

Until sea levels rose at the end of the last Ice Age, between 8-10,000 years ago, an area of land connected Great Britain to Scandinavia and the continent.  It has long been suspected that the southern North Sea plain was home to thousands of people, and chance finds by fishermen over many decades support this theory. 

Over the past decades a concentration of archaeological material, including worked bone, stone and human remains, has been found within the area around the Brown Bank, roughly 100 km due east from Great Yarmouth and 80 km west of the Dutch coast. The quantities of material strongly suggest the presence of a prehistoric settlement. As such the Brown Bank provides archaeologists with a unique opportunity to locate a prehistoric settlement in the deeper and more remote areas of the North Sea, known today as Doggerland.

Prospecting for such a settlement within the North Sea is a challenging activity.  Multiple utilities cross the area, bad weather is frequent, and visibility underwater is often limited.  Given these challenging conditions, researchers on the Belgian vessel, RV Belgica, used acoustic techniques and physical sampling of the seabed to unravel the topography and history of 3 areas chosen for the survey.  

During the survey, the team used a novel parametric echosounder from the Flanders Marine Institute (VLIZ). This uses sonar technology to obtain images of the sub-bottom with the highest possible resolution and was combined with the more traditional “sparker” seismic source to explore deeper sediments.  On the Brown Bank, the Belgica also deployed a grab and a Gilson dredge for sampling near-surface stratigraphy. Video footage was collated using VLIZ’s dedicated video frame and a simpler GoPro mounted on the Gilson dredge. A video showing the equipment in operation on the expedition can be seen at https://youtu.be/sGKfyrDCtmw

Additional reading: http://www.vliz.be/en/press-release/update-research-prehistoric-settlements-North-Sea