Dromaeosauroides Bornholmensis
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''Dromaeosauroides'' is a
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
dromaeosaurid Dromaeosauridae () is a family of feathered theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek ('), meaning ...
theropod
dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
from the
Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145  Ma to 100.5 Ma. Geology Pro ...
of what is now
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
and possibly also
England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
. It was discovered in the
Jydegaard Formation The Jydegaard Formation (also spelled as 'Jydegård') is a geological formation dating to the Early Cretaceous, about 145-139 million years ago. It is on the island of Bornholm, Denmark. Vertebrate fossils have been found in the formation. Fossi ...
in the Robbedale valley, on the island of
Bornholm Bornholm () is a Danish island in the Baltic Sea, to the east of the rest of Denmark, south of Sweden, northeast of Germany and north of Poland. Strategically located, Bornholm has been fought over for centuries. It has usually been ruled by ...
in the
Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain. The sea stretches from 53°N to 66°N latitude and from ...
. This is the only likely place for dinosaur remains to be discovered on Danish territory, since the
Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...
deposits exposed in the rest of the country are marine. ''Dromaeosauroides'' is the first known dinosaur from this location, and the only one which has been scientifically named. It is one of the oldest known dromaeosaurs in the world, and the first known uncontested dromaeosaur from the Early Cretaceous of Europe. It is known from two teeth, the first of which was found in 2000 and the second in 2008. Based on the first tooth (the
holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
), the genus and species ''Dromaeosauroides bornholmensis'' was named in 2003. The genus name means "''
Dromaeosaurus ''Dromaeosaurus'' (, "running lizard") is a genus of dromaeosaurid theropod dinosaur which lived during the Late Cretaceous period (middle late Campanian and Maastrichtian), sometime between 80 and 69 million years ago, in Alberta, Canada and the ...
''-like", due to the similarity to the teeth of that genus, and the species name means "from Bornholm". After this discovery, remains and tracks of more dinosaurs were found in several formations on Bornholm. Some teeth from the United Kingdom that have been referred to the genus ''
Nuthetes ''Nuthetes'' is the name given to a genus of theropod dinosaur, likely a dromaeosaurid, known only from fossil teeth and jaw fragments found in rocks of the middle Berriasian (Early Cretaceous) age in the Cherty Freshwater Member of the Lulworth ...
'' may also belong to this animal. Coprolites containing fish remains found in the Jydegaard Formation may belong to ''Dromaeosauroides''. The holotype tooth is long, and the second tooth is . They are curved and finely serrated. In life, ''Dromaeosauroides'' would have been in length, and weighed about . As a dromaeosaur it would have been feathered, and had a large sickle claw on its feet like its relatives ''Dromaeosaurus'' and '' Deinonychus''. It lived in a coastal lagoon environment with sauropods, as evidenced by a possible
titanosaur Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still th ...
tooth.


Discovery and naming

Few
dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
remains have been found in
Scandinavia Scandinavia; Sámi languages: /. ( ) is a subregion#Europe, subregion in Northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. In English usage, ''Scandinavia'' most commonly refers to Denmark, ...
. The mainland of western Denmark is an unlikely region to find dinosaur remains, since the Mesozoic sediments there are marine
Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...
chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Chalk ...
. Fossils of non-dinosaurian marine animals, including
mosasaurs Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Greek ' meaning 'lizard') comprise a group of extinct, large marine reptiles from the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Maastricht on the ...
and plesiosaurs, have been found in these deposits. Mesozoic deposits in
Scania Scania, also known by its native name of Skåne (, ), is the southernmost of the historical provinces of Sweden, provinces (''landskap'') of Sweden. Located in the south tip of the geographical region of Götaland, the province is roughly conte ...
, Sweden, are much richer in fossils, including those of dinosaurs. The Danish island of
Bornholm Bornholm () is a Danish island in the Baltic Sea, to the east of the rest of Denmark, south of Sweden, northeast of Germany and north of Poland. Strategically located, Bornholm has been fought over for centuries. It has usually been ruled by ...
in the
Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain. The sea stretches from 53°N to 66°N latitude and from ...
was part of the same land mass as Scania (the Scandinavian-Russian continent), and has a similar geology. The southwestern part of the island is the only place in Denmark which has yielded dinosaur remains. During the 1990s, the Fossil Project (disbanded in 2005) was formed by a group of unemployed people who received funding from Denmark and the
EEC The European Economic Community (EEC) was a regional organization created by the Treaty of Rome of 1957,Today the largely rewritten treaty continues in force as the ''Treaty on the functioning of the European Union'', as renamed by the Lisb ...
to maintain geological sites on Bornholm. One of these, "Carl Nielsen's sandpit" in the Robbedale valley (not to be confused with the
Robbedale Formation The Robbedale Formation is a geological formation dating to the Berriasian stage of the Early Cretaceous, about 142 million years ago.Jydegaard Formation The Jydegaard Formation (also spelled as 'Jydegård') is a geological formation dating to the Early Cretaceous, about 145-139 million years ago. It is on the island of Bornholm, Denmark. Vertebrate fossils have been found in the formation. Fossi ...
. This formation is 140 million years old, dating to the
Late Berriasian In the geological timescale, the Berriasian is an age/ stage of the Early/Lower Cretaceous. It is the oldest subdivision in the entire Cretaceous. It has been taken to span the time between 145.0 ± 4.0 Ma and 139.8 ± 3.0 Ma (million years ago ...
(or Ryazanian) stage of the
Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145  Ma to 100.5 Ma. Geology Pro ...
period. The Fossil Project sifted sand at these sites in cooperation with the NaturBornholm
interpretation centre An interpretation centre, interpretive centre, or visitor interpretive centre is an institution for dissemination of knowledge of natural or cultural heritage. Interpretation centres are a kind of new-style museum, often associated with visitor ...
, which exhibited the fossils discovered. In September 2000, Danish
palaeontologists Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
Per Christiansen and
Niels Bonde Niels is a male given name, equivalent to Nicholas, which is common in Denmark, Belgium, Norway (formerly) and the Netherlands. The Norwegian and Swedish variant is Nils. The name is a developed short form of Nicholas or Greek Nicolaos after Saint ...
taught a field course at the site, "The Hunt for Danish Dinosaurs". During the course, geology student Eliza Jarl Estrup found a theropod tooth, the first dinosaur discovered on Danish territory, and the find was recorded by a local television station. The tooth was presented at the 45th annual meeting of the Palaeontological Association in 2001, and identified as a dromaeosaur. In 2003 the tooth (MGUH 27218/DK 315) was made the
holotype specimen A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
of ''Dromaeosauroides bornholmensis''—named and described by Christiansen and Bonde. The
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
name combines ''
Dromaeosaurus ''Dromaeosaurus'' (, "running lizard") is a genus of dromaeosaurid theropod dinosaur which lived during the Late Cretaceous period (middle late Campanian and Maastrichtian), sometime between 80 and 69 million years ago, in Alberta, Canada and the ...
'' with the Greek ("in the form of"), referring to the resemblance between the teeth of the two genera. The
specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...
refers to Bornholm. The name ''Dromaeosaurus'' itself has been translated as "swift" or "running reptile". Bonde and Christiansen had expected the first Danish dinosaur remains to be teeth of herbivorous dinosaurs such as hypsilophodonts or '' Iguanodon'', and were surprised to find a dromaeosaur tooth instead, since these are rare in Early Cretaceous formations; herbivores would have been more abundant than carnivores. Because the dromaeosaur seems to have been large, they expected that resilient bones, such as claws, might be found in the future. The palaeontologists did not expect bones of larger dinosaurs to be discovered in the formation (since these would most likely have been found when the sand was commercially exploited), but hoped the remains of a Mesozoic mammal would be found. The holotype tooth has been illustrated in several books and research articles. It was certified ''" Danekræ"'' ("Danish creature", according to a 1990 Danish museum law securing important fossils) when its scientific importance was evaluated by the
Geological Museum in Copenhagen The University of Copenhagen ( da, Københavns Universitet, KU) is a prestigious public research university in Copenhagen, Denmark. Founded in 1479, the University of Copenhagen is the second-oldest university in Scandinavia after Uppsala Unive ...
. In late summer 2008, ranger Jens Kofoed found a second dromaeosaurid tooth. This specimen (DK 559) was found in the same location, and later assigned to ''D. bornholmensis'' as well. Kofoed explained that the finds were surprising because people had been unsuccessfully searching for dinosaur remains in Denmark for years, and it was like finding a "needle in a haystack". In a press release, the second dromaeosaur tooth was also certified ''Danekræ'' by the
Natural History Museum of Denmark The Natural History Museum of Denmark ( da, Statens Naturhistoriske Museum) is a natural history museum located in Copenhagen, Denmark. It was created as a 1 January 2004 merger of Copenhagen's Zoological Museum, Geological Museum, Botanical Muse ...
, which compared the animal to the raptors in the film ''
Jurassic Park ''Jurassic Park'', later also referred to as ''Jurassic World'', is an American science fiction media franchise created by Michael Crichton and centered on a disastrous attempt to create a theme park of cloned dinosaurs. It began in 1990 when ...
'', noting that the animals, unlike the film's raptors, would have been feathered. Since the discovery of ''Dromaeosauroides'', evidence of more dinosaurs has been found on Bornholm. In 2002, a tooth thought to belong to a juvenile
titanosaurian Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thr ...
sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their bo ...
was found in the Jydegaard Formation. Footprints of a sauropod and a
thyreophoran Thyreophora ("shield bearers", often known simply as "armored dinosaurs") is a group of armored ornithischian dinosaurs that lived from the Early Jurassic until the end of the Cretaceous. Thyreophorans are characterized by the presence of body ...
were reported from the
Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...
Bagå Formation in 2005. Small dromaeosaur and indeterminate maniraptoran teeth from the Early Cretaceous
Rabekke Formation The Rabekke Formation is a geological formation dating to the latest Jurassic or earliest Cretaceous, around 146 to 145 million years ago. and sauropod tracks were also reported from the formation that year. In 2011, footprints of a sauropod, a thyreophoran and a theropod were reported from the Bagå Formation. Lower Jurassic tracks reported form the Rønne Formation on Bornholm in 2014 are the earliest evidence of dinosaur activity in Denmark. A tooth from the multituberculate ''
Sunnyodon ''Sunnyodon'' is a genus of tiny, extinct mammal, probably of the Lower Cretaceous. Found in what is now southern England and Denmark, it was a relatively early member of the extinct order of Multituberculata. It is part of the suborder Plagiau ...
'' was found in the Rabekke Formation in 2004, making it the first known Danish and Scandinavian Mesozoic mammal. In 2012, Jesper Milàn and colleagues described two
coprolite A coprolite (also known as a coprolith) is fossilized feces. Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour (in this case, diet) rather than morphology. The name is de ...
s (fossilised faeces) containing fish scales and bones. They were found in the Jydegaard Formation, the first such fossils found in Danish continental Mesozoic deposits. Although the producer of these faeces cannot be identified with certainty, marine turtles and dromaeosaurids such as ''Dromaeosauroides'' are the most likely candidates.


Description

Fossil theropod teeth are typically identified according to features including size, proportion, curvature of the crown and the
morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...
and number of denticles (serrations). The holotype of ''D. bornholmensis'' is a
tooth crown In dentistry, crown refers to the anatomical area of teeth, usually covered by tooth enamel, enamel. The crown is usually visible in the mouth after tooth development, developing below the gingiva and then tooth eruption, erupting into place. ...
long, from front to back and wide at the base. The front part of the tooth was worn, indicating that it was shed when the animal was alive. It was further affected by
taphonomic Taphonomy is the study of how organisms decay and become fossilized or preserved in the paleontological record. The term ''taphonomy'' (from Greek , 'burial' and , 'law') was introduced to paleontology in 1940 by Soviet scientist Ivan Efremov t ...
wear; the base of the tooth is irregular, so it may have been slightly longer in life. The curvature and length of the holotype tooth and the length of its hindmost cutting edge (carina) indicates it was in the front of the jaw. The tooth is recurved with a backward bend, and is oval in cross-section. Its front and back cutting edges are finely serrated, extending two-thirds down each edge. There are six denticles per millimeter (0.04 in), and each denticle is square and chiseled. The overall form of the tooth, its width and shape in cross-section and its curvature resemble those in the
maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...
(upper jawbone) and
mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
of the species ''Dromaeosaurus albertensis'' from
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
. Blood grooves are indistinct or absent, also similar to ''Dromaeosaurus'', and differing from members of the Velociraptorinae subfamily. ''Dromaeosauroides'' differs from ''Dromaeosaurus'' in that the cutting edge at the front side is further from the middle of the tooth. Although the tooth is larger and the denticles similar, each denticle was smaller than those of ''Dromaeosaurus'', which had only 13–20 denticles per , instead of ''Dromaeosauroides 30. The second known tooth is smaller——with the same features as the holotype. The holotype tooth is roughly 25 percent larger than equivalent ''Dromaeosaurus'' teeth, from which a body length of or more was estimated for ''Dromaeosauroides''; it may have been as long as . In an interview, Christiansen estimated its skull to be long and the animal's weight ; a
Bengal tiger The Bengal tiger is a population of the ''Panthera tigris tigris'' subspecies. It ranks among the biggest wild cats alive today. It is considered to belong to the world's charismatic megafauna. The tiger is estimated to have been present in ...
of the same length would weigh by comparison. As a dromaeosaur, ''Dromaeosauroides'' would have had a large sickle claw on its highly mobile second toe, like its relatives ''Dromaeosaurus'', ''
Velociraptor ''Velociraptor'' (; ) is a genus of small dromaeosaurid dinosaur that lived in Asia during the Late Cretaceous epoch, about 75 million to 71 million years ago. Two species are currently recognized, although others have been assigned in the pa ...
'' and '' Deinonychus''. That group is closely related to
birds Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...
, and the NaturBornholm interpretive centre houses a roughly life-sized sculpture of ''Dromaeosauroides'' covered in feathers. Later Chinese finds of well-preserved feathered dromaeosaurs indicate that the sculpture should have more and longer feathers to be accurate. Although some smaller dromaeosaurs may have been able to fly, flight was unlikely for an animal the size of ''Dromaeosauroides''.


Classification

Several features of the tooth are only known from members of the family Dromaeosauridae of theropod dinosaurs. ''Dromaeosauroides'' was classified as a member of the Dromaeosaurinae
subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...
within the Dromaeosauridae, due to its similarity to ''Dromaeosaurus''. Despite the resemblance, ''Dromaeosauroides'' is not considered part of that genus. It is unlikely that a genus would survive for 60 million years; ''Dromaeosauroides'' lived during the Early Cretaceous, and ''Dromaeosaurus'' during the
Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
. The differences between their denticles also indicate they should be kept separate. According to Bonde, ''Dromaeosauroides'' is one of the oldest known dromaeosaurs in the world; older remains, for the most part, have only tentatively been referred to Dromaeosauridae. ''Dromaeosauroides'' was the first definite dromaeosaurid known from the Early Cretaceous of Europe, depending on the identity of ''
Nuthetes ''Nuthetes'' is the name given to a genus of theropod dinosaur, likely a dromaeosaurid, known only from fossil teeth and jaw fragments found in rocks of the middle Berriasian (Early Cretaceous) age in the Cherty Freshwater Member of the Lulworth ...
'' from the
Middle Purbeck The Purbeck Group is an Upper Jurassic to Lower Cretaceous lithostratigraphic group (a sequence of rock strata) in south-east England. The name is derived from the district known as the Isle of Purbeck in Dorset where the strata are exposed in ...
formation of the United Kingdom (which may slightly predate the Jydegaard Formation). It is uncertain whether the juvenile holotype specimen of ''Nuthetes'' has dromaeosaurid characteristics. Large specimens referred to ''Nuthetes'' appear to belong to true dromaeosaurs, and may belong to ''Dromaeosauroides'' rather than ''Nuthetes''. These specimens measure . ''Dromaeosauroides'' has been considered an indeterminate dromaeosaur by some scientists. Bonde responded that since the teeth differ from those of other dromaeosaurs from the Early Cretaceous (and later members of the group, including ''Dromaeosaurus''), it should be considered valid. He also said that these scientists had provided incorrect information about the location, strata and age of the specimen, and that the circumstances of its naming were no different from those of other tooth-based taxa. The German palaeontologist Oliver W. M. Rauhut and colleagues cautioned in 2010 that theropod teeth from the Late Jurassic/Early Cretaceous similar to those of dromaeosaurids may instead have belonged to the small
tyrannosauroid Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent b ...
''
Proceratosaurus ''Proceratosaurus'' is a genus of carnivore, carnivorous theropod dinosaur from the Middle Jurassic (Bathonian) of England. ''Proceratosaurus'' was a small dinosaur, measuring in length and in body mass.Holtz, Thomas R. Jr. (2008) ''Dinosaurs: ...
'' or related taxa.


Palaeoenvironment

Only a corner of the Jydegaard Formation is exposed today; the remainder is overgrown. Jydegaard is part of the
Nyker Group The Nyker Group is a group of geological formations from the Early Cretaceous, about 146 to 140 million years ago. It is on the island of Bornholm, Denmark. It includes the Rabekke, Robbedale and Jydegaard Formations. Rabekke Formation The ...
, which includes three formations (Rabekke, Robbedale and Jydegaard) ranging from the Berriasian to the
Valanginian In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 139.8 ± 3.0 Ma and 132.9 ± 2.0 Ma (million years ago). The Valanginian Stage succeeds the Berriasian Stage of the Lower Cretaceou ...
ages of the Early Cretaceous. Jydegaard consists of sediments deposited in a fresh-to-brackish
lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...
facing a coastal strip. In addition to ''Dromaeosauroides'' and a possible titanosaur, remains of
hybodont sharks Hybodontidae is an extinct family of sharks that first appeared in the Mississippian subperiod of the Carboniferous and disappeared at the end of the Late Cretaceous.
, fish such as '' Lepidotes'' and ''
Pleuropholis ''Pleuropholis'' is an extinct genus of prehistoric ray-finned fish. See also * List of prehistoric bony fish genera This list of prehistoric bony fish is an attempt to create a comprehensive listing of all genera from the fossil record that ...
'', turtles, lizards, the
crocodile Crocodiles (family (biology), family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to inclu ...
'' Pholidosaurus'' and thin bone fragments from birds or
pterosaurs Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 to ...
have been found in the deposit. The bivalve '' Neomiodon'' is found in abundance in the sediments below (the ''Neomiodon'' Bed), indicating mass mortality, perhaps due to
dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...
toxins. The fish and bivalves were found in clay which was probably a lagoon, and the dinosaurs and lizards in sand which probably was land, perhaps a beach; turtles and crocodiles were found in both. Freshwater snails were found in clay that may have been shallow, drying lakes behind a sandy barrier between lagoon and sea, in a setting perhaps similar to the
Florida Keys The Florida Keys are a coral cay archipelago located off the southern coast of Florida, forming the southernmost part of the continental United States. They begin at the southeastern coast of the Florida peninsula, about south of Miami, and e ...
or the southwestern coast of
Jutland Jutland ( da, Jylland ; german: Jütland ; ang, Ēota land ), known anciently as the Cimbric or Cimbrian Peninsula ( la, Cimbricus Chersonesus; da, den Kimbriske Halvø, links=no or ; german: Kimbrische Halbinsel, links=no), is a peninsula of ...
. Dinosaurs may have fed there, based on the remains of plants and small land animals, and theropods may have hunted along the shore. Bornholm and Scania appear to be the only places were remains of the Scandinavian-Russian fauna of the Early Cretaceous can be found. Further investigations there may show whether this fauna has European or Asian affinities. Based on possible dromaeosaur coprolites from the Jydegaard Formation, which contained scales of the fish ''Lepidotes'', Milàn and colleagues speculated that some dromaeosaurids were able to catch fish with the enlarged sickle claw on the second digit of the foot, similar to the "spear fishing" that has been proposed for the theropod '' Baryonyx'' and its enlarged thumb claw. The larger of the two coprolites has evidence of coprophagous organisms.


See also

* Timeline of dromaeosaurid research


References


External links


"Danish Dinosaurs" site by Geocenter Møns Klint
{{Taxonbar, from=Q1933219 Eudromaeosaurs Early Cretaceous dinosaurs of Europe Fossil taxa described in 2003 2003 in Denmark Bornholm