Dromaeosauroides
Encyclopedia
Dromaeosauroides is a genus
of dromaeosaurid theropod dinosaur
from the Early Cretaceous
of Denmark
.
In the southwest of the island of Bornholm
, layers of the Early Cretaceous
Jydegaard Formation surface, dating to the late Berriasian
age, about 140 million years ago and consisting of marine sediments, deposited in a lagoon
. From the A/S Carl Nielsen site, a gravel and sand pit in the Robbedale valley, microfossils emerged since the 1980s. In the late 1990s an activation programme, "Project Fossil", was started for unemployed youth having to sieve the sand in search of bone fragments in exchange for a welfare benefit. In September 2000 palaeontologists Per Christiansen and Niels Bonde providing an excavation field course, visited the site with a group of students from Copenhagen
, accompanied by a camera team of the Danish television. On that occasion 18-year-old geology student Eliza Jarl Estrup found a theropod tooth, the first dinosaur find on Danish territory.
The type species, Dromaeosauroides bornholmensis, was named and described by Christiansen and Bonde in 2003, as the first Danish dinosaur. The generic name combines the name of Dromaeosaurus with Greek ~ides, "in the form of", referring to the resemblance between the taxa. The specific name refers to Bornholm.
The holotype
specimen, MGUH DK 315, was uncovered in a sand layer, three metres above the Neomiodon Bed of the Tornhøj Member of the Jydegaard Formation. It consists of a tooth crown; the shape and length of the tooth indicates that it was placed in the front part of the lower jaw.
The tooth crown is 21 millimetres long, about a quarter longer than equivalent teeth of Dromaeosaurus, from which a body length for Dromaeosauroides of three metres was estimated. The tooth is relatively elongated, slightly flattened with an oval cross-section, and recurved with a sudden backwards bend. The front and hindmost parts of the tooth, the cutting edges, are finely serrated, and the front part has been strongly worn; the tooth was probably shed when the animal was alive. The square shape of the denticles and the distance between the serrations of which about six are placed per millimetre, are only known from dromaeosaurids.
In August 2008 a second dromaeosaurid tooth was reported by ranger Jens Kofoed. "Project Fossil" had been terminated in 2004, but the site was subsequently used as a tourist attraction providing day trips to families digging up fossils. The second tooth, also from the anterior dentary, is fifteen millimetres long and has been provisionally referred to Dromaeosauroides by Bonde. The two dromaeosaurid teeth and a titanosaur
tooth found by a welfare recipient in 2002, were declared Danish national heritage, Danekræ, meaning they cannot be legally sold to a private collection or exported.
Dromaeosauroides was by the describers assigned to the Dromaeosaurinae
within the Dromaeosauridae
. It might be the only known true dromaeosaurid from the Lower Cretaceous of Europe, depending on the identity of Nuthetes
.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of dromaeosaurid theropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
from the Early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
of Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
.
In the southwest of the island of Bornholm
Bornholm
Bornholm is a Danish island in the Baltic Sea located to the east of the rest of Denmark, the south of Sweden, and the north of Poland. The main industries on the island include fishing, arts and crafts like glass making and pottery using locally worked clay, and dairy farming. Tourism is...
, layers of the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
Jydegaard Formation surface, dating to the late Berriasian
Berriasian
In the geological timescale, the Berriasian is an age or stage of the Early or Lower Creteceous. It is the oldest or lowest subdivision in the entire Cretaceous. It spanned between 145.5 ± 4.0 Ma and 140.2 ± 3.0 Ma...
age, about 140 million years ago and consisting of marine sediments, deposited in a lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
. From the A/S Carl Nielsen site, a gravel and sand pit in the Robbedale valley, microfossils emerged since the 1980s. In the late 1990s an activation programme, "Project Fossil", was started for unemployed youth having to sieve the sand in search of bone fragments in exchange for a welfare benefit. In September 2000 palaeontologists Per Christiansen and Niels Bonde providing an excavation field course, visited the site with a group of students from Copenhagen
Copenhagen
Copenhagen is the capital and largest city of Denmark, with an urban population of 1,199,224 and a metropolitan population of 1,930,260 . With the completion of the transnational Øresund Bridge in 2000, Copenhagen has become the centre of the increasingly integrating Øresund Region...
, accompanied by a camera team of the Danish television. On that occasion 18-year-old geology student Eliza Jarl Estrup found a theropod tooth, the first dinosaur find on Danish territory.
The type species, Dromaeosauroides bornholmensis, was named and described by Christiansen and Bonde in 2003, as the first Danish dinosaur. The generic name combines the name of Dromaeosaurus with Greek ~ides, "in the form of", referring to the resemblance between the taxa. The specific name refers to Bornholm.
The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
specimen, MGUH DK 315, was uncovered in a sand layer, three metres above the Neomiodon Bed of the Tornhøj Member of the Jydegaard Formation. It consists of a tooth crown; the shape and length of the tooth indicates that it was placed in the front part of the lower jaw.
The tooth crown is 21 millimetres long, about a quarter longer than equivalent teeth of Dromaeosaurus, from which a body length for Dromaeosauroides of three metres was estimated. The tooth is relatively elongated, slightly flattened with an oval cross-section, and recurved with a sudden backwards bend. The front and hindmost parts of the tooth, the cutting edges, are finely serrated, and the front part has been strongly worn; the tooth was probably shed when the animal was alive. The square shape of the denticles and the distance between the serrations of which about six are placed per millimetre, are only known from dromaeosaurids.
In August 2008 a second dromaeosaurid tooth was reported by ranger Jens Kofoed. "Project Fossil" had been terminated in 2004, but the site was subsequently used as a tourist attraction providing day trips to families digging up fossils. The second tooth, also from the anterior dentary, is fifteen millimetres long and has been provisionally referred to Dromaeosauroides by Bonde. The two dromaeosaurid teeth and a titanosaur
Titanosaur
Titanosaurs were a diverse group of sauropod dinosaurs, which included Saltasaurus and Isisaurus. It includes some of the heaviest creatures ever to walk the earth, such as Argentinosaurus and Paralititan — which some believe have weighed up to 100 tonnes...
tooth found by a welfare recipient in 2002, were declared Danish national heritage, Danekræ, meaning they cannot be legally sold to a private collection or exported.
Dromaeosauroides was by the describers assigned to the Dromaeosaurinae
Dromaeosaurinae
Dromaeosaurinae is a subfamily of Dromaeosauridae. Most dromaeosaurines lived in what is now the USA and Canada, , as well as Mongolia, , and possibly Denmark, , as well. Isolated teeth that may belong to African dromaeosaurines have also been discovered in Ethiopia...
within the Dromaeosauridae
Dromaeosauridae
Dromaeosauridae is a family of bird-like theropod dinosaurs. They were small- to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek dromeus meaning 'runner' and sauros meaning 'lizard'...
. It might be the only known true dromaeosaurid from the Lower Cretaceous of Europe, depending on the identity of Nuthetes
Nuthetes
Nuthetes is the name given to a dubious, possibly dromaeosaurid, genus of theropod dinosaur, known only from fossil teeth and jaw fragments found in rocks of the middle Berriasian age in the Cherty Freshwater Member of the Lulworth Formation in England...
.