What we can learn from duck fossils | Martijn van der Meer | TEDxJvL Youth

Key Concepts

• Doggerland: The landmass that connected Great Britain to mainland Europe during the late Pleistocene, now submerged under the North Sea.
• Taphonomic Bias: The process by which certain organisms are more likely to be preserved in the fossil record due to physical characteristics (e.g., bone density).
• Vagrant (Dwaalgast): A species found outside its normal range or migration path.
• Late Pleistocene: The geological epoch ending approximately 10,000 years ago, characterized by glacial cycles.
• Osteological Identification: The process of identifying bird species based on isolated, often damaged, skeletal elements (humerus, coracoid, carpometacarpus).

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1. The North Sea Fossil Record and Doggerland

The North Sea is a rich source of fossils, but the presence of species like the common moorhen (freshwater) and the snowy owl (Arctic) in a marine environment is explained by Doggerland. During the last Ice Age, this area was a dry, terrestrial landscape. As the climate warmed and glaciers melted, the area was inundated by rising sea levels. Fossils from this period are now frequently recovered from the seabed, particularly at sites like Maasvlakte 2.

2. Methodological Challenges: The "Duck" Study

Martine’s research focused on duck fossils, which are abundant in the North Sea record.

• The Bias Problem: There is a significant discrepancy between modern bird populations and the fossil record. For example, crows are common today but absent in the fossil record, while long-tailed ducks are rare today but abundant as fossils. This is attributed to taphonomic bias: ducks have denser, more robust bones that survive fossilization better than the fragile bones of smaller birds like crows.
• Identification Framework: Identifying isolated, damaged duck bones is difficult due to the high similarity between the 24 European species. The study analyzed three specific bones:
  • Humerus: The upper arm bone.
  • Coracoid: Part of the shoulder girdle (absent in humans).
  • Carpometacarpus: The middle hand bone.

3. Key Findings and Ecological Shifts

• Long-tailed Duck (Clangula hyemalis): The abundance of these fossils in the North Sea, compared to their current concentration in the Baltic Sea, suggests a range shift. During the late Pleistocene, the Baltic was covered by glaciers, forcing the population into the North Sea. As the climate warmed, the species migrated north to the Baltic.
• Harlequin Duck (Histrionicus histrionicus): The discovery of this species—which typically stays in Atlantic waters near Iceland—indicates it was a vagrant in the North Sea during the Pleistocene, mirroring modern occurrences where birds occasionally get lost outside their natural range.
• The "Common Eider" Mystery: Despite being the second most common duck in the North Sea today, the Common Eider is entirely absent from the fossil sample, a phenomenon that remains a subject of ongoing research and hypothesis testing.

4. Birds of Prey and Rare Records

The research also examined claw bones and phalanges (toe bones) of raptors, which serve as "killing devices."

• Northern Hawk Owl: A 2mm bone fragment confirmed the presence of this species, which is currently restricted to Scandinavia.
• Golden Eagle (Aquila chrysaetos): The identification of a golden eagle phalanx marked the first-ever fossil record of this species in the Netherlands, a finding that received significant media attention.

5. Synthesis and Future Implications

The study of North Sea bird fossils provides a "deep time" perspective on species distribution. By understanding how bird populations shifted in response to the warming climate at the end of the Ice Age, researchers can better predict how modern species—such as the long-tailed duck—might respond to contemporary climate change.

Notable Quote:

"Studying the past may help us understand the present and thus predict the future." — Martine

Conclusion: The fossil record of the North Sea is not merely a collection of bones but a dynamic map of past ecological shifts. The research highlights that current species distributions are not static; they are the result of long-term environmental adaptations. Future work aims to investigate other species, such as the extinct Great Auk, to further refine our understanding of historical biodiversity.