Elopteryx
Encyclopedia
Elopteryx is a genus
of troodontid maniraptora
n theropod dinosaur
based on fragmentary fossil
s found in late Cretaceous
Period rocks of Romania
. These fossils date from the early-mid Maastrichtian
(Begudian) faunal stage
, c.71-68 million years ago. The single species
, Elopteryx nopcsai, is known only from very incomplete material, and therefore is considered a nomen dubium
("dubious name") by most paleontologists. The genus name Elopteryx is from Ancient Greek
elos (έλος) "marsh" + pteryx (πτερυξ) "wing". The specific name honors the famous Hungarian
paleontologist Franz Nopcsa von Felső-Szilvás
.
(specimen BMNH
A1234). A distal tibiotarsus
was also tentatively assigned to this taxon
; it was initially classified with the same specimen number and was found in close proximity, but may not be from the same individual (see below). This has since been relabeled and is now specimen BMNH A4359. The animal was at first believed to be a pelecaniform seabird
.
The supposed family Elopterygidae was initially placed in the suborder Sulae – then still in the polyphyletic "Pelecaniformes
" – by Pierce Brodkorb
in his fossil bird catalogue, and the Cenozoic
genera Argillornis and Eostega were moved to it. These two are unequivocal modern birds and the latter indeed seems to be an ancient sulid
, whereas Argillornis has turned out to be referrable to the giant pseudotooth bird Dasornis
which was almost certainly not very closely related to the Sulae. Reconstruction attempts of E. nopcsai like this are based on this presumed affiliation with gannet
s and cormorant
s. But more recent studies have indicated radically different results.
Other material had been assigned to E. nopcsai, including the proximal femur BMNH A1235 and the distal tibiotarsi BMNH A1528 and BMNH A1588. These two together with A4359 were eventually removed from Elopteryx, redescribed as Bradycneme draculae and Heptasteornis andrewsi, and used to establish a supposed family of gigantic owl
s. Today however, they are generally accepted as non-avian
dinosaur
s, at least one of which seems to be an alvarezsaurid. Brodkorb had changed his opinion after the supposed Elopteryx material was divided among three species in total, and was actually the first scholar in modern times to suggest that the Mesozoic
bones were not of birds.
Later, a supposed distal femur (FGGUB R.351) was for some years added to the proximal parts of that bone which remained assigned to Elopteryx, but was eventually identified as a hadrosaurid
distal metatarsal. Likewise a skull (FGGUB 1007) supposedly belonging to Elopteryx turned out to be from a sauropod.
In 1992, it was proposed that Bradycneme and Heptasteornis should be synonymized with E. nopcsai again, and a femur (MDE-D203), an anterior dorsal
vertebra (MDE-D01), a posterior sacral vertebra (MDE collection, unnumbered) and some dorsal rib
fragments from the Jurassic
Grès à Reptiles Formation of France
were described as indeterminate species of Elopteryx; that study placed all this material in the Dromaeosauridae
or a family or subfamily (Elopteryginae) very close to these. The vertebrae were eventually separated again and assigned to a new dromaeosaurid, Variraptor mechinorum.
The new femur does not appear to belong to Elopteryx either; while similar in general appearance it differs in details. And neither the ribs nor the tibiotarsi can be compared to the type specimen. In recent years, yet another (distal) femur piece, FGGUB R.1957, has been placed with Elopteryx, and although this cannot be compared directly either, it does not appear as if any other known animal had a femur that was proximally like A1234 and distally like FGGUB R.1957.
Bradycneme
and Heptasteornis
have meanwhile been synonymized and split from each other and Elopteryx many times, and various solutions were proposed for this dilemma. Among more recent studies, Elopteryx was considered an eumaniraptoran incertae sedis
, possibly either a non-ornithuran "pygostylia
n" bird or a troodontid. Thus E. nopcsai seems to be some sort of birdlike eumaniraptoran, but not related to modern birds. While little can be said about BMNH A1588 - the Bradycneme specimen - Heptasteornis does indeed seem to belong to a more ancient lineage of theropods, which is interesting given that its holotype
bone BMNH A4359 was believed to be from the very same individual as the Elopteryx holotype when they were dug up (see also Rahonavis
and Vorona
).
With the exception of Heptasteornis, which seems quite robustly identified as an alvarezsaurid of subfamily Parvicursorinae, these taxa will be subject to continuing debate.
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 troodontid maniraptora
Maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. Ornitholestes and the Alvarezsauroidea...
n 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...
based on fragmentary fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s found in late 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...
Period rocks of Romania
Romania
Romania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...
. These fossils date from the early-mid Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
(Begudian) faunal stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
, c.71-68 million years ago. The single species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, Elopteryx nopcsai, is known only from very incomplete material, and therefore is considered a nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
("dubious name") by most paleontologists. The genus name Elopteryx is from Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
elos (έλος) "marsh" + pteryx (πτερυξ) "wing". The specific name honors the famous Hungarian
Hungary
Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...
paleontologist Franz Nopcsa von Felső-Szilvás
Franz Nopcsa von Felso-Szilvás
Baron Franz Nopcsa von Felső-Szilvás was a Hungarian-born aristocrat, adventurer, scholar, and paleontologist...
.
History
Initially, Elopteryx was described from a proximal femurFemur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
(specimen BMNH
BMNH
BMNH may refer to:*British Museum of Natural History, commonly known as Natural History Museum, in London, the United Kingdom*Beijing Museum of Natural History, in Beijing, China...
A1234). A distal tibiotarsus
Tibiotarsus
The tibiotarsus is the large bone between the femur and the tarsometatarsus in the leg of a bird. It is the fusion of the proximal part of the tarsus with the tibia.A similar structure also occurred in the Mesozoic Heterodontosauridae...
was also tentatively assigned to this taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
; it was initially classified with the same specimen number and was found in close proximity, but may not be from the same individual (see below). This has since been relabeled and is now specimen BMNH A4359. The animal was at first believed to be a pelecaniform seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
.
The supposed family Elopterygidae was initially placed in the suborder Sulae – then still in the polyphyletic "Pelecaniformes
Pelecaniformes
The Pelecaniformes is a order of medium-sized and large waterbirds found worldwide. As traditionally—but erroneously—defined, they encompass all birds that have feet with all four toes webbed. Hence, they were formerly also known by such names as totipalmates or steganopodes...
" – by Pierce Brodkorb
Pierce Brodkorb
Pierce Brodkorb , also stated as William Pierce Brodkorb, was an American ornithologist and paleontologist....
in his fossil bird catalogue, and the Cenozoic
Cenozoic
The Cenozoic era is the current and most recent of the three Phanerozoic geological eras and covers the period from 65.5 mya to the present. The era began in the wake of the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and...
genera Argillornis and Eostega were moved to it. These two are unequivocal modern birds and the latter indeed seems to be an ancient sulid
Sulidae
The bird family Sulidae comprises the gannets and boobies. Collectively called sulidas, they are medium-large coastal seabirds that plunge-dive for fish and similar prey. The ten species in this family are often considered congeneric in older sources, placing all in the genus Sula...
, whereas Argillornis has turned out to be referrable to the giant pseudotooth bird Dasornis
Dasornis
Dasornis is a genus of the prehistoric pseudotooth birds. These were probably rather close relatives of either pelicans and storks, or of waterfowl, and are here placed in the order Odontopterygiformes to account for this uncertainty....
which was almost certainly not very closely related to the Sulae. Reconstruction attempts of E. nopcsai like this are based on this presumed affiliation with gannet
Gannet
Gannets are seabirds comprising the genus Morus, in the family Sulidae, closely related to the boobies.The gannets are large black and white birds with yellow heads. They have long pointed wings and long bills. Northern gannets are the largest seabirds in the North Atlantic, with a wingspan of up...
s and cormorant
Cormorant
The bird family Phalacrocoracidae is represented by some 40 species of cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed.- Names :...
s. But more recent studies have indicated radically different results.
Other material had been assigned to E. nopcsai, including the proximal femur BMNH A1235 and the distal tibiotarsi BMNH A1528 and BMNH A1588. These two together with A4359 were eventually removed from Elopteryx, redescribed as Bradycneme draculae and Heptasteornis andrewsi, and used to establish a supposed family of gigantic owl
Owl
Owls are a group of birds that belong to the order Strigiformes, constituting 200 bird of prey species. Most are solitary and nocturnal, with some exceptions . Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish...
s. Today however, they are generally accepted as non-avian
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
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...
s, at least one of which seems to be an alvarezsaurid. Brodkorb had changed his opinion after the supposed Elopteryx material was divided among three species in total, and was actually the first scholar in modern times to suggest that the Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
bones were not of birds.
Later, a supposed distal femur (FGGUB R.351) was for some years added to the proximal parts of that bone which remained assigned to Elopteryx, but was eventually identified as a hadrosaurid
Hadrosaurid
Hadrosaurids or duck-billed dinosaurs are members of the family Hadrosauridae, and include ornithopods such as Edmontosaurus and Parasaurolophus. They were common herbivores in the Upper Cretaceous Period of what are now Asia, Europe and North America. They are descendants of the Upper...
distal metatarsal. Likewise a skull (FGGUB 1007) supposedly belonging to Elopteryx turned out to be from a sauropod.
In 1992, it was proposed that Bradycneme and Heptasteornis should be synonymized with E. nopcsai again, and a femur (MDE-D203), an anterior dorsal
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...
vertebra (MDE-D01), a posterior sacral vertebra (MDE collection, unnumbered) and some dorsal rib
Rib
In vertebrate anatomy, ribs are the long curved bones which form the rib cage. In most vertebrates, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax...
fragments from the Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
Grès à Reptiles Formation of France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
were described as indeterminate species of Elopteryx; that study placed all this material in 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'...
or a family or subfamily (Elopteryginae) very close to these. The vertebrae were eventually separated again and assigned to a new dromaeosaurid, Variraptor mechinorum.
The new femur does not appear to belong to Elopteryx either; while similar in general appearance it differs in details. And neither the ribs nor the tibiotarsi can be compared to the type specimen. In recent years, yet another (distal) femur piece, FGGUB R.1957, has been placed with Elopteryx, and although this cannot be compared directly either, it does not appear as if any other known animal had a femur that was proximally like A1234 and distally like FGGUB R.1957.
Bradycneme
Bradycneme
Bradycneme is a genus of theropod dinosaur from the early Maastrichtian-age Upper Cretaceous Sânpetru Formation of the Haţeg Basin, Transylvania, Romania. It is known only from a partial right lower leg , which its describers believed came from a giant owl.-History:Harrison and Walker described...
and Heptasteornis
Heptasteornis
Heptasteornis is the name given to a dubious genus of small dinosaur from the Late Cretaceous. The type species is Heptasteornis andrewsi, described as a presumed gigantic prehistoric owl in 1975...
have meanwhile been synonymized and split from each other and Elopteryx many times, and various solutions were proposed for this dilemma. Among more recent studies, Elopteryx was considered an eumaniraptoran incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
, possibly either a non-ornithuran "pygostylia
Pygostylia
Pygostylia is a group of birds which includes Confuciusornis and all of the more derived birds; the Ornithothoraces. Chiappe defined the Pygostylia as "the common ancestor of the Confuciusornithidae and Neornithes plus all its descendants". This is a node-based definition.Chiappe united the...
n" bird or a troodontid. Thus E. nopcsai seems to be some sort of birdlike eumaniraptoran, but not related to modern birds. While little can be said about BMNH A1588 - the Bradycneme specimen - Heptasteornis does indeed seem to belong to a more ancient lineage of theropods, which is interesting given that its 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...
bone BMNH A4359 was believed to be from the very same individual as the Elopteryx holotype when they were dug up (see also Rahonavis
Rahonavis
Rahonavis is a genus of bird-like dinosaur from the Late Cretaceous of what is now northwestern Madagascar. It is known from a partial skeleton found in Maevarano Formation rocks at a quarry near Berivotra, Mahajanga Province...
and Vorona
Vorona
Vorona is a monotypic genus of prehistoric birds. It was described from fossils found in a Maevarano Formation quarry near the village of Berivotra, Mahajanga Province, Madagascar. The age is Late Cretaceous, probably Campanian . V...
).
With the exception of Heptasteornis, which seems quite robustly identified as an alvarezsaurid of subfamily Parvicursorinae, these taxa will be subject to continuing debate.