Thursday 16 September 2021

NORTH SEA DOLPHIN VERTEBRAE: HATSAWE'

A lovely 17 cm deep chocolate brown fossil Bottlenose Dolphin, Tursiops sp. 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. In the Kwak̓wala language of the Kwakiutl or Kwakwaka'wakw, speakers of Kwak'wala, of the Pacific Northwest — and part of my heritage — dolphin are hatsawe'. 

On the north end of Vancouver Island, we have pods of 50-100 Pacific White-Sided dolphins, cousins of the Bottlenose, who frolic and jump alongside your boat if you are out on the water. Similar to their southern cousins, Pacific White-Sided dolphins feed on salmon, herring, pilchards, anchovies, needlefish, squid, shrimp, pollock, sablefish, rock cod and other small fish — a tasty menu that reflects my own. 

Bottlenose dolphins are the most common dolphin species in the Pacific Northwest but do not often venture farther north than Oregon. We have two populations of bottlenose dolphins here, the California coastal population and those that prefer to live offshore. It is as exciting to see them playing in our oceans today as it is to see the fossil remains of their ancestors from the Brown Bank sediments of the North Sea. 

Brown Bank, North Sea, Pleistocene Dredging Area
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 have circled this area on the map below to give you an idea of the region.

Found by Fishermen in the North Sea. Using a small mesh trawl net is often the only time these come up from the seabed, hence they are uncommon. ​Size: 17.0cm. Age: 30-40,000 Years old.