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| Dolphin Fossil Vertebrae |
Today, the North Sea is shallow, busy, and heavily worked by trawlers, dredges, and offshore infrastructure. Beneath that modern churn lies a remarkable archive of Cenozoic life, quietly releasing its fossils when nets and dredges scrape sediments that have not seen daylight for millions of years.
Fossil cetacean bones—vertebrae, ribs, mandibles, and the occasional ear bone—are among the most evocative finds recovered from the seafloor.
Dolphin vertebrae are especially common compared to skulls, as their dense, spool-shaped centra survive transport and burial better than more delicate skeletal elements.
These fossils are typically dark brown to black, stained by long exposure to iron-rich sediments and phosphates, and often bear the polished surfaces and rounded edges that speak to a history of reworking by currents before final burial.
The North Sea is famous for yielding a mixed assemblage of fossils spanning multiple ice ages and interglacial periods, but many marine mammal remains originate from Miocene deposits, roughly 23 to 5 million years old. During the Miocene, this region was not the marginal, shallow sea we know today. It formed part of a broad, warm to temperate epicontinental sea connected to the Atlantic, rich in plankton, fish, sharks, and early whales and dolphins.
This was a critical chapter in cetacean evolution, when modern groups of toothed whales, including early delphinids and their close relatives, were diversifying and refining the echolocation-based hunting strategies that define dolphins today.
Most North Sea cetacean fossils are found accidentally rather than through targeted excavation. Commercial fishing trawls, aggregate dredging for sand and gravel, and construction linked to wind farms and pipelines routinely disturb Miocene and Pliocene sediments.
Fossils are hauled up tangled in nets or mixed with shell hash and glacial debris, often far from their original point of burial. As a result, precise stratigraphic context is usually lost, and age estimates rely on sediment still adhering to the bone, associated microfossils, or comparison with well-dated onshore Miocene marine deposits in the Netherlands, Belgium, Germany, and eastern England.
A dolphin vertebra from this setting tells a story of both life and loss. In life, it was part of a flexible, powerful spine built for speed and agility, driving rapid tail beats through warm Miocene waters.
After death, the carcass likely sank to the seafloor, where scavengers stripped it and currents scattered the bones. Over time, burial in sand and silt allowed mineral-rich waters to replace organic material with stone, locking the bone into the geological record.
Much later, Ice Age glaciers reshaped the seafloor, reworking older sediments and concentrating fossils into lag deposits that modern dredges now disturb.
Though often found in isolation, these vertebrae are scientifically valuable. They confirm the long presence of dolphins in northern European seas and help refine our understanding of Miocene marine ecosystems, biogeography, and climate.
