The Bony Fish Fossils of the Western Limfjord – Evolution and Climate Adaptation in the Earliest Eocene

Why this place matters

UNESCO’s assessment of its heritage significance, adapted in formatting from the source dataset.

Brief synthesis

The Bony Fish Fossils of the Western Limfjord – Evolution and Climate Adaptation in the Earliest Eocene represent the world’s single best fossil site to illustrate the evolution of the earliest modern fishes of the Eocene epoch that followed shortly after the mass extinction at the end of the Cretaceous. Located in the Western Limfjord sea of northern Jutland, Denmark, the serial property comprises the two largest and best coastal cliffs that contain some of the best-preserved fossil fishes in the world and that represent the only known fish-bearing succession that covers the very warm climatic conditions of the Paleocene–Eocene Thermal Maximum (PETM) and the immediately succeeding cooler period. The property comprising the coastal cliffs of Hanklit and Knudeklint, located on the islands of Mors and Fur, respectively, is protected as a pristine reference for fossils in their characteristic source of diatomite-rich Fur Formation and Stolleklint Clay with volcanic ash layers. The ash layers and glaciotectonic structures are important supporting features for correlation, dating and interpretation.

Fossil discoveries continue to be made in open excavations and in cliff debris as well as in nearby mo-clay pits with which the museums have close collaboration. Exceptional fossils include marine organisms such as fishes, sea-turtles, diatoms, silicoflagellates and dinoflagellates, together with several invertebrate groups, and terrestrial organisms such as nearly complete bird skeletons, abundant insects, spores and pollen, together with rarer leaves and petrified tree trunks.

Criterion (viii):

The property constitutes the world’s oldest and single best site for the study of the early evolution of modern bony fish lineages (teleosts), shortly after the fifth and last mass extinction of life at the end of the Cretaceous. Overall, it offers a supreme insight in the earliest Eocene biosphere because it contains abundant and diverse, extremely well-preserved fossils from both oceanic and continental environments, and because it is the only known substantial teleost-bearing site which documents the biotic response to one of the most significant temperature fluctuations in the Earth’s history – the Paleocene–Eocene Thermal Maximum (PETM). The attributes of Outstanding Universal Value comprise the fish fossils documenting early ‘modern’ fish evolution and diversification; the biotic and geochemical record across the PETM and the succeeding recovery phase expressed in the Stolleklint Clay and lower Fur Formation; and the diverse marine and terrestrial fossil assemblages that provide an exceptional insight into the earliest Eocene biosphere. Abundant, diverse, and outstandingly well-preserved fossils provide an unparalleled insight into the origin of the earliest ancestors of many modern organisms, together with their early evolution.

This is the oldest known (c. 56 to 54.6 Ma), exceptionally well-preserved occurrence of ray-finned fish lineages that emerged succeeding the Cretaceous-Paleogene mass extinction. The property presents between 25 and 29 fish orders and more than 80 species that underwent significant changes in response to rapid climate change.

Integrity

The property is the largest, most intact, and accessible, fossil site that is fully representative of the Western Limfjord deposits. It encompasses all palaeontological and palaeoclimate change-related attributes within a natural environment integrated into a protected area network. There are no adverse effects of development and/or neglect, and the property is not under threat. Some impact through natural cliff erosion may be accelerated by climate change in the long-term, although no major conservation challenges are envisaged for the foreseeable future.

Fossil discoveries continue to be made in mo-clay pits in the wider setting. This is seen as an advantage since palaeontology is an extractive science that involves the removal of fossils for research. The two regional museums have close collaboration with industry in terms of access for research, and popular fossil collecting, without impacting the property.

Protection and management requirements

The principal protection and management requirement is to ensure that the cliff exposures, fossil recovery, collection protocols and regulation of visitor access enable the long-term conservation of the attributes of Outstanding Universal Value over time. Site management needs to ensure coordinated cliff-exposure stewardship, clear protocols for fossil discovery, reporting and curation as well as research access, monitoring of coastal processes and site condition, and practical provisions for safe visitor access within carrying capacities, interpretation and education. Adaptive approaches are maintained in response to any future increases in visitation or climate-related coastal change. The property, acknowledged for its significant national and international geological value, is afforded the highest level of protection under Danish law through a robust and comprehensive legal framework, giving the two component parts top priority in the planning procedures of local governments.

Key legislation includes the Nature Protection Act, the Shore Protection Zone provisions, the Planning Act, the Museum Act, and the Danekræ system. Danekræ is defined as earth-found, nature-made objects of exceptional or unique natural scientific and/or exhibition value. Other applicable national instruments include the Raw Materials Act and apply to both component parts. No commercial extraction of mo-clay is possible in the property.

A collaborative management organisation is anchored at the local level on the two municipalities and their respective museums, supported by landowners, local communities, and state authorities. The management plan defines the management system of the property. Overall, the protection context is strengthened by the long-standing involvement of museums and research institutions that curate collections, support documentation, and provide an institutional pathway for reporting, safeguarding and scientific use of specimens.