P Formanoy and HJ Ahrens (The Netherlands)
De Kuilen is a moist sandpit forming a lake and leisure space situated close to the small village of Langenboom, about 15 miles south of Nijmegen, within the japanese a part of the Dutch province of Noord-Brabant (Fig. 1). Amongst fossil collectors, the positioning is famend for its wealth of animal stays courting from historic instances.
The locality (Fig. 2) is located on prime of an space (Peelhorst) that’s slowly being lifted by tectonic exercise, whereas the encompassing space is subsiding. Consequently, layers of commercially helpful sand and gravel, originally deposited in a temperate sea that covered the area between three and 20 milion years ago during the Miocene and Pliocene, are being pushed towards the surface and into the reach of commercial exploitation.
The sand and gravel are very suitable for road construction works and, over the past 30 years, have been dredged from the bottom of an artificial lake from a depth of about 7m to 25m below the water level by a stationary suction dredger (Fig. 3).
An underwater water jet, which is attached to the inlet of the suction mouth, is used to break up the sediment, after which the loose material is transported to a large nearby depot through floating pipes.
The fine-grained sand, with its favourable chemical qualities, guarantees wonderful fossil preservation and, therefore, is prized by amateur palaeontologists (Fig. 4).
In it can be found countless, well-preserved invertebrate remains (for example, fresh-looking mollusc shells, sometimes with surviving colour patterns) and vertebrate remains, especially sharks’ teeth. However, many vertebrate fossils also show signs of severe erosion. For instance, more often than not, whale vertebrae are broken and have worn edges from rolling. These are indications that they were reworked from older layers and have, for quite some time, been rolling in the storm wave base on the seabed or in the breakers along the shoreline.
At the site, several distinct layers, with a high fossil potential can be found. The most important of these is 12m to 15m below the present water level and produces the majority of the shells, teeth and bones. This layer is estimated to be of Middle Pliocene age and can be assigned to the Oosterhout Formation (early Zanclean to early Piacenzian). Below this layer (15m to 18m) are Miocene strata belonging to the Breda Formation (early-middle Tortonian). Perhaps further down lie Oligocene and Eocene strata, but they have not yet been reached by commercial exploitation.
The high resolution, taphonomical units can be regarded as ‘bone beds’ or even Lagerstätten, judging from their broad, paleoecological content. As one can find phosphorite attached to many bones, these layers are markers of transgressive conditions (that is, rising sea levels). As a result of the outwash of fossils from old deposits and their mixing up with animal remains of a later time, there are two or more faunal assemblages present in the same geological unit.
Therefore, determining the age of the remains and their ecological interrelationships poses a real problem. It follows that additional scientific investigation into the horizontal and vertical dispersal, concentration rates and relative abundance of fossil species within the Langenboom strata is now essential. Subaqueous, in situ, probing of remains in their original layers, which has recently started as a collaborative effort between amateur divers (Fig. 5) and scientists, is a welcome first step in the unravelling of the geological and taphonomical history of the Langenboom sequence. The resulting information will be a massive help in interpreting the wealth of ex-situ fossils that amateur palaeontologists have, and continue to, collect under the mud pipe.
This article focuses on the wealth of fossil remains of vertebrates found at this locality. So far, more than 30 species of shark, over 35 species of bony fish, about 20 whale and dolphin species, at least four seals (Fig. 6) , a walrus, over 30 species of bird and several land mammals have been identified, several of which are new to science.
Sharks
The De Kuilen locality is best known for its sharks’ teeth. On a good collecting day, hundreds of teeth, often perfectly preserved, can be found.
The most common sharks’ teeth at De Kuilen are those of Cosmopolitodus hastalis (formerly Isurus hastalis). The teeth of this species account for more than 80% of all sharks’ teeth found here. The triangular teeth of this animal, from the side, appear compressed and are not conical (that is, they are labio-distally compressed) and can reach sizes of over 8cm measured along the longest side of the teeth. Cosmopolitodus was a species of large lamniform shark, a species that most likely gave rise to the modern day great white shark, Carcharodon carcharias.
Another species of lamniform shark regularly found at De Kuilen is Isurus escheri. These teeth are more robust than those of C. hastalis and bear serrations, while teeth of C hastalis have smooth edges. I escheri is an evolutionary dead end and its position in shark taxonomy is not yet clear.
If one is persistent, teeth from other shark species can be found, for example, Carcharias taurus (sand tiger shark) and the rare Galeocerdo aduncus (tiger shark). Teeth of C taurus are slender and have side cusps, while teeth of G aduncus are of a very different design, being asymmetrical and showing a somewhat elevated crown with serrated edges.
The teeth of cow sharks are always a pleasure to find, especially the multi-cusped lower teeth. Two species occur at this locality: Notorhynchus cepedianus and Hexanchus gigas, the latter being much rarer. Notorhynchus teeth are smaller than those of Hexanchus and the lower teeth have fewer cusps (up to seven) than Hexanchus (8 to 12).
If one is very lucky, even teeth of Megaselachus megalodon, the largest shark that ever lived, can be found, although they are very rare at this locality. Even rarer are teeth of the enigmatic Parotodus benedeni, a lamniform shark whose taxonomical position is not yet clear, and Somniosus microcephalus, the Greenland shark.
There are also a number of small shark species present. Among these are Squalus sp. (spiny dogshark), Cetorhinus sp.(basking shark), Scyliorhinus sp. (catshark) and Galeorhinus sp. (tope shark). The best way to find these small teeth, and also ray oral teeth (like Raja sp.) and the teeth and otoliths of bony fish, is to sieve material, take the residue home and sort it under a microscope. Then, your need to sieve the material with a mesh of 0.5cm or 1cm to get rid of the larger particles and sieve what is left through a sieve with a mesh of 1mm or less to get rid of the sand. This is best done in water.
Several of the fossil shark species, found at this locality, still live in the North Sea and waters around Britain. These include basking sharks, spiny dogsharks and catsharks (Fig.. 7).
Bony fish
A lot of bony fish material can be found at De Kuilen. Numerous small teeth, vertebrae and otoliths (‘ear stones’; Fig. 8) can be found, if one takes the time to sort the sieve residue under a microscope.
While small vertebrae and loose teeth are hard, if not impossible, to identify, most otoliths can be identified at least to family level. Over 35 species of fish have been identified from this locality from otoliths alone. The most common are those of Gadidae, a family of fish that includes cod, haddock, whiting and pollack.
Remains of larger fish can also be found. Particularly noteworthy are the scales of the large tuna, Miothunnus deldenius (named after Delden, another locality in The Netherlands), and the dermal scutes of sturgeons (Acipenser sp.; Fig. 9). Complete dermal scutes are rare, but fragments can regularly be found.
Marine mammals
De Kuilen really is an Eldorado for marine mammal material, especially Cetaceans – whales, dolphins (Fig. 10) and porpoises. Next to Cetaceans, remains of seals and walruses are the most common.
Cetacea. The Cetacea is an order of aquatic mammals, which is divided into two sub-orders: Mysticeti (baleen whales) and Odontoceti (toothed whales and dolphins). Vertebrae are the most common finds, but other bones and teeth also occur. These, especially the periotic bones (‘ear bones’; Fig. 11), are very useful in identifying the different types of dolphins and whales that inhabited this area in Miocene and Pliocene times. While most bones, like vertebrae, mostly lack features that are specific for a certain species or family, periotic bones are different in each family and, therefore, can be assigned to a particular family of dolphins. So far, research has shown that at least seven families of toothed whales were also present.
Based solely on periotic bones, we can give an overview of the Odontocetes that lived in the Langenboom area. The most common dolphins were several species of Delphinids and Kentriodonts. The Delphinids, or pelagic (that is, from a deep water environment) dolphins, are the most diverse family of Cetaceans nowadays, while the Kentriodontidae is an extinct, primitive family that emerged during the Oligocene epoch and went extinct during the early Pliocene. Kentriodonts are considered a stem group of delphinoids, which gave rise to several modern day dolphin families (Fig. 12), like Delphinidae, Monodontidae and Phocoenidae. The Monodontidae, or white dolphins, includes the modern day belugas and narwhals, and are known from De Kuilen from just one species. Porpoises (family Phocoenidae) were also present in the fauna, but were not abundant, unlike today, when the harbour porpoise (Phocoena phocoena) is the most common odontocete in the North Sea.
Other dolphins that can be found as fossils are the beaked dolphins (Family Ziphiidae). These are relatively large Odontocetes (4m to 12m in length) that live in the deep waters off the edges of the continental shelves. They primarily prey on squid, but also on fish and crustaceans. At least two species of Ziphiids have been found at The Kuilen.
Periotic bones and skull fragments found in Langenboom and the Antwerp area in Belgium seem to show that two species of river dolphins (Pontoporiidae) lived here during the Miocene epoch. Nowadays, no Pontoporiidae are present in the North Sea and northern Atlantic Ocean, and the only surviving member of this family is the La Plata dolphin (Pontoporia blainvillei), which lives in coastal Atlantic waters, in the south-eastern part of South America. However, the finds of several skull fragments of Pontoporiid dolphins have recentlymade headlines. Before 2001, this family of dolphins was thought to have originated in South America and spread from there. Now, De Kuilen has yielded over ten partial skulls of this animal.
The remains of several different Physeteridae, or sperm whales, have also been found in Langenboom, while today, only one sperm whale occurs in the waters around Britain: Physeter macrocephalus (11m to 18m in length). These are the largest Odontocetes.
As well as Odontocetes, the remains of Mysticetes (Fig. 13) can also be found. During Miocene and Early Pliocene times, a number of small baleen whale species inhabited the North Atlantic region. Among them were the ancestors of the present day rorquals, right whales, bowhead, humpback and gray whales. The most commonly found fossils are vertebrae, and fragments of ribs and skull bones. Larger bones are not found complete because of the way the material is collected. They are simply too large to fit through the narrow pipe that are used to bring the dredged material ashore.
Pinnipedia. Another group of marine mammals, fossils of which can be found at The Kuilen, are Pinnipeds. The Pinnipedia are a superfamily of marine animals in the mammal order Carnivora. The most commonly found pinnipeds found here are seals. These are all placed in one family, referred to as Phocidae. Studies on phocid material from The Kuilen show a fauna that compares very well to the modern day North Atlantic fauna. At least six different taxa of Miocene and Pliocene seals are present at this locality, like Callophoca and the relatively small and recently described Batavipusa neerlandica.
Recent studies by Noud Peters (from the Oertijdmuseum de Groene Poort, Boxtel, The Netherlands) and others suggest that the phocidae present in the Miocene and Pliocene of the Netherlands are the same as those from Belgium. Most of the material also compares very well to fossils from the east coast of North America. Some species even show affinity with material from South Africa.
Other pinnipeds that have been found include walruses (Family Odobenidae).
Birds
Bird remains are considered to be rare in the fossil record. Because most birds have to fly, their skeletons have adapted in several ways to be as light as possible. Many of the bones of a bird are hollow with internal, criss-crossing struts and trusses for strength to reduce weight, and some bones are even fused together, which reduces the total number of bones in the skeleton. The most commonly encountered bones are humeri, ulnae and coracoids. These bones are among the heaviest and densest of a bird’s bones and, therefore, have the best chances to become fossils.
Despite this, bird remains are relatively common at De Kuilen. Hundreds of bones have been found and a study of bird remains originating from this locality has been performed by Erik Wijnker of Wageningen University in The Netherlands. This study resulted in a faunal list of seven Miocene and 26 Pliocene birds. While the entire Miocene avifauna was made up of pelagic birds like auks, gannets and a tropicbird, the Pliocene avifauna shows that land was probably nearby. This Pliocene avifauna also consists of mostly pelagic birds like auks (Fig. 14), gannets, shearwaters and albatrosses, but also includes land-bound birds like geese, ducks and a thrush. The most common bones found are those of auks, a family of birds that includes puffins and razorbills.
The fossil bird remains from De Kuilen have given us a lot of new knowledge about bird diversity during the Miocene and Pliocene epochs. The locality has turned out to be one of the most productive places for fossil bird material in the northern hemisphere. Of all the birds found, 19 were not previously known from the Miocene and Pliocene of Europe and several, yet undescribed, species have been found.
Reptiles
Reptile remains are rare at De Kuilen and are restricted to turtle material. These remains consist mostly of carapace fragments of at least four species. Most common are fragments of sea turtles (Cheloniidae), but also fragments of leatherback turtles (Dermochelyidae) can be found. Next to these, fragments of land tortoises (Testudinidae; Fig. 15) and soft-shelled turtles (Trionychidae) have occasionally been found.
Terrestrial mammals
Occasionally, remains of land mammals can be found at The Kuilen. Although very rare, a number of different species have been found. Among these are a mastodon elephant (Anancus arvernensis), a bear (Ursus cf. etruscus), a pig (Sus strozzii), a horse (possibly Hipparion sp.), a deer (?Cervus rhenanus) and a tapir. Most of the remains seem to be of Late Pliocene and/or Early Pleistocene age.
Among the more recent discoveries that are currently being described is the molar of a European jaguar, Panthera gombaszoegensis (Fig. 16). This has been studied extensively by a team of palaeontologists, among whom are Dick Mol, Wilrie van Logchem and John de Vos. A comparative study has been made using the collections of vertebrate remains of other European Early Pleistocene sites such as Untermassfeld (Thuringia, Germany) and Tegelen, (Limburg, the Netherlands).
The molar was collected by Jan Boes from Emmeloord in The Netherlands, and brought to the attention of Dick Mol (a regular contributor and supporter of Deposits), who recognised it as something special. This is an excellent example of how amateur fossil collectors can cooperate with scientists and contribute to our scientific knowledge.
Other fossils
Of course, other fossils can also be found at De Kuilen, the most common of which are molluscs. Over 200 species of bivalves and gastropods have been recorded. Sometimes, their shells have been preserved so well that they show their original colour patterns. Next to bivalves and gastropods, remains of a number of other invertebrates, like echinoids, crustaceans, corals, bryozoans and others, can be found.
Over the years, a large amount of fossil vertebrate remains have been uncovered from the De Kuilen locality in The Netherlands. Although we find the remains of a number of different animals, this does not mean that all these animals lived together, at this locality, at the same time. The presence of some species may have been seasonal or occasional occurrences of animals whose geographical range was not naturally in this area. In addition, we have to bear in mind that the material is found ex-situ and both Miocene and Pliocene material can be found. This is a time span of roughly 8myrs, from 11 to 2.5 milion years ago.
Acknowledgements
We must mention Rene van der Vliet (Uden; Fig. 17) and Erik Meeuwsen (Nijmegen), two Dutch shark tooth collectors, who also have a very keen eye for other fossils and have donated many of their finds. Without these and numerous other fossil collectors, named and not named in this article, willing to cooperate with scientists and other people doing research, writing this article would not have been possible. Also Dick Mol and Klaas Post are thanked for their assistance, Marjolein Heurman for reviewing the text of the manuscript and Rob Buiter for allowing us to use some of his photographs of fossil collectors in action at the locality.
Suggested further reading
Ahrens, H., 2005 – Weer een schedel van Protophocaena minima erbij! – Cranium 22: 41-44.
Hamilton, H., Caballero, S., Colins, A. and Brownell Jr., R. L., 2001 – Evolution of river dolphins; Proceedings of the Royal Society of London, B. Biological Sciences 268: 549-556.
Koretsky, I.A. & Peters, A.M.M., 2008 – Batavipusa (Carnivora, Phocidae, Phocinae): a new genus from the eastern shore of the North Atlantic Ocean (Miocene seals of the Netherlands, part II); DEINSEA 12: 53-62 [ISSN 0923-9308]
Lambert, O. & Put up, Ok., 2005 – First European pontoporiid dolphins (Mammalia: Cetacea, Odontoceti) from the Miocene of Belgium and the Netherlands. – Deinsea 11: 7-20.
Mol, D., Logchem, W. van, Vos, J. de, in prep – A Pliocene, Early/Center Pleistocene European jaguar, Panthera onca gombaszoegensis (Kretzoi, 1938), from Langenboom (Noord-Brabant, the Netherlands)
Peters, N., 2009 – Brabant tussen walvissen en mastodonten; 110 pp., Nationaal Beiaard- en Natuurmuseum Asten and Oertijdmuseum de Groene Poort, Boxtel [ISBN 978 90 807642 2 4]
Reumer, J., 2008 – Opgeraapt, Opgevist, Uitgehakt; 287 pp., Uitgeverij Contact [ISBN 9789025426286]
Vos, J. de & Wijnker, E., 2006 – A deer (Cervus rhenanus) from the Early Pliocene of Langenboom, Noord-Brabant (The Netherlands); Cainozoic Analysis, 5(1-2): 107-110.
Wijnker, E., Bor, T.J., Wesselingh, F.P., Munstermann, D.Ok., Brinkhuis, H., Burger, A.W., Vonhof, H.B., Put up, Ok., Hoedemakers, C., Janse, A.C. & Taverne, N., 2008 – Neogene stratigraphy of the Langenboom locality (Noord-Brabant, the Netherlands); Netherlands Journal of Geosciences, 87: 165-180.
http://www.geologievannederland.nl/fossielen/vindplaatsen/langenboom
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