Orthomerus
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''Orthomerus'' (meaning "straight
femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...
") is a
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...
of
dubious Doubt is a mental state in which the mind remains suspended between two or more contradictory propositions, unable to be certain of any of them. Doubt on an emotional level is indecision between belief and disbelief. It may involve uncertainty ...
hadrosaurid Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which incl ...
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
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'', ...
of the
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
. It is today an obscure genus, but in the past was conflated with the much better known ''
Telmatosaurus ''Telmatosaurus'' (meaning "marsh lizard") is a genus of basal hadrosauromorph dinosaur from the Late Cretaceous of Romania. It was a relatively small hadrosaur, measuring approximately in length and in body mass, which has been explained as an ...
''.


Discovery and history

The
type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...
''Orthomerus dolloi'' was in 1883 named by the well-known
British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies. ** Britishness, the British identity and common culture * British English ...
paleontologist 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 foss ...
Harry Govier Seeley Harry Govier Seeley (18 February 1839 – 8 January 1909) was a British paleontologist. Early life Seeley was born in London on 18 February 1839, the second son of Richard Hovill Seeley, a goldsmith, and his second wife Mary Govier. When his fat ...
. The genus name is derived from the Greek ὀρθός (''orthos''), "straight", and μηρός (''meros''), "thigh". The specific name honours the French/Belgian paleontologist
Louis Dollo Louis Antoine Marie Joseph Dollo ( Lille, 7 December 1857 – Brussels, 19 April 1931) was a Belgian palaeontologist, known for his work on dinosaurs. He also posited that evolution is not reversible, known as Dollo's law. Together with the Aust ...
, who had identified the bones in August 1882, during a visit to London. The
type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes the ...
, formed by the
syntype In biological nomenclature, a syntype is any one of two or more biological types that is listed in a description of a taxon where no holotype was designated. Precise definitions of this and related terms for types have been established as part of ...
s BMNH 42954-57, was probably found in the chalkstone quarries of the
Sint-Pietersberg Mount Saint Peter (French: ''Montagne Saint-Pierre''; Dutch: ''Sint-Pietersberg''), also referred to as Caestert Plateau, is the northern part of a plateau running north to south between the valleys of the river Geer to the west, and the Meuse to ...
near the city of
Maastricht Maastricht ( , , ; li, Mestreech ; french: Maestricht ; es, Mastrique ) is a city and a municipality in the southeastern Netherlands. It is the capital and largest city of the province of Limburg. Maastricht is located on both sides of the ...
, The Netherlands. It mainly consists of partial juvenile skeletal elements. These remains are from the
Maastricht Formation The Maastricht Formation ( Dutch: ''Formatie van Maastricht''; abbreviation: MMa), named after the city of Maastricht in the Netherlands, is a geological formation in the Netherlands and Belgium whose strata date back to the Late Cretaceous, wi ...
of the late
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 interv ...
stage of 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'', ...
, about 66 million years old. The type bones include the straight left and right femora that moved Seeley to give it its name. A left tibia and a metatarsal also discovered in the collection of
Jacob Gijsbertus Samuël van Breda Jacob Gijsbertus Samuël van Breda (24 October 1788, in Delft – 2 September 1867, in Haarlem) was a Dutch biologist and geologist. Jacob was the son of Jacob van Breda, a Dutch physician, physicist and politician, and Anna Elsenera van Camp ...
acquired by the
British Museum of Natural History The Natural History Museum in London is a museum that exhibits a vast range of specimens from various segments of natural history. It is one of three major museums on Exhibition Road in South Kensington, the others being the Science Museu ...
in 1871, were referred by him to the species. The leg bones are only about half the size of those belonging to the then largely unknown North American and
Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an ...
n duckbills, with the femur long. Other more fragmentary hadrosaurid remains have been found, some of them in The Netherlands, where the species is sometimes presented as a rare "Dutch dinosaur", others perhaps in Belgium where in 1882 Dollo acquired two hadrosaurid tail vertebrae near Zichen, a Belgian border village in
Belgian Limburg Limburg ( nl, Limburg, ; li, Limburg or ''Wes-Limburg'' ; french: Limbourg, ) is a province in Belgium. It is the easternmost of the five Dutch-speaking provinces that together form the Region of Flanders, one of the three main political and ...
. It is hard to establish whether such finds belonged to the same species and not all of them have been explicitly referred to ''Orthomerus dolloi''. Later Belgian finds included a left third metatarsal, NHMM 1996001 discovered by J.H. Kuypers near
Eben Emael Fort Eben-Emael (french: Fort d'Ében-Émael, ) is an inactive Belgian fortress located between Liège and Maastricht, on the Belgian-Dutch border, near the Albert Canal, outside the village of Ében-Émael. It was designed to defend Belg ...
, where a larger right third metatarsal was also collected, NHMM RD 241, and a right maxillary tooth, NHMM 1999012, found by E. Croimans. Some phalanges and a left ulna have been reported from private collections, lacking an inventory number. The Dutch finds include two tail vertebrae collected in the nineteenth century. A second individual dating from just below the
Cretaceous–Paleogene boundary The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K–T) boundary, is a geological signature, usually a thin band of rock containing much more iridium than other bands. The K–Pg boundary marks the end ...
was in September 1967 discovered in a quarry near Geulhem by L. de Heer; it consists of a fragmentary left femur (MND K 21.04.003), left tibia (MND K 21.04.004) and left fibula (MND K21.04.005). Later found limb bone fragments are OGP 0196 and OGP 2111. NHMM 2002067, a partial tibia, seems not to be cospecific with the other finds, suggesting two hadrosaurid species were present in the formation. In a quarry near
Bemelen Bemelen (; li, Bieëmele ) is a village in the Dutch province of Limburg. It is part of the municipality of Eijsden-Margraten, and lies about 5 km east of Maastricht. The village was first mentioned in 1096 as Bemele. The etymology is unk ...
a partial right dentary was found, specimen NHMM 198027, that however lacked any teeth. However, isolated teeth have been found: NHMM 1997274 by J. Vollers near Sibbe and left dentary tooth NHMM RD 214 from
Berg en Terblijt Berg en Terblijt (; li, Berg or ) is the official Dutch name of a village in the municipality of Valkenburg aan de Geul in the province of Limburg in the Southern part of the Netherlands. History The area now known as Berg en Terblijt has ...
, were also dentary tooth NHMM RN 28 was discovered. Finally the collection of the
Teylers Museum Teylers Museum () is an art, natural history, and science museum in Haarlem, Netherlands. Established in 1778, Teylers Museum was founded as a centre for contemporary art and science. The historic centre of the museum is the neoclassical Oval ...
at Haarlem features a partial right humerus, TM 11253. A second species, ''Orthomerus weberi'', was first described by
Anatoly Nikolaevich Riabinin {{Short pages monitor