Montanazhdarcho
Encyclopedia
Montanazhdarcho is a genus
of azhdarchid
pterosaur
from the late Cretaceous
Period (Campanian
stage) of North America, known from only one species, M. minor.
The genus was named in 1993 by Kevin Padian
, Armand de Ricqlès, and Jack Horner
, again published by the same authors in 1995 and fully described in 2002.
The type species
is Montanazhdarcho minor. The genus name refers to Montana
and to the related species Azhdarcho
. The specific name means "the smaller one" in Latin
, a reference to the relatively small size in comparison to closely related forms.
The holotype
, MOR 691 (Museum of the Rockies
), was found by Robert W. Harmon in Glacier County, in the territory of the Blackfoot
, in sandstone of the Upper Two Medicine Formation
, a layer about 74 million years old. The fossil is largely uncompressed and that of an adult exemplar, as established by a study of the bone by de Ricqlès. It consists of a partial left wing, lacking the outer three wing finger phalanges, a complete shoulder girdle, a crushed cervical vertebra and two fragments of the symphysis
of the mandible
. The jaws were edentulous, i.e.: they lacked teeth.
Montanazhdarcho was by the authors assigned to the Azhdarchidae, mainly based on the elongated form of the neck vertebra. Compared to other azhdarchids, it was small; the fragments of humerus
, radius
, and carpal
suggest an animal with a 2.5 meter wingspan (eight feet). Its ulna
was longer than the wing metacarpal, which is atypical for azhdarchids.
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 azhdarchid
Azhdarchidae
Azhdarchidae is a family of pterosaurs known primarily from the late Cretaceous Period, though an isolated vertebrae apparently from an azhdarchid is known from the early Cretaceous as well...
pterosaur
Pterosaur
Pterosaurs were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period . Pterosaurs are the earliest vertebrates known to have evolved powered flight...
from the 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 (Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
stage) of North America, known from only one species, M. minor.
The genus was named in 1993 by Kevin Padian
Kevin Padian
Kevin Padian is a Professor of Integrative Biology at the University of California, Berkeley, Curator of Paleontology, University of California Museum of Paleontology and President of the National Center for Science Education. Padian's area of interest is in vertebrate evolution, especially the...
, Armand de Ricqlès, and Jack Horner
Jack Horner (paleontologist)
John "Jack" R. Horner is an American paleontologist who discovered and named Maiasaura, providing the first clear evidence that some dinosaurs cared for their young. He is one of the best-known paleontologists in the United States...
, again published by the same authors in 1995 and fully described in 2002.
The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
is Montanazhdarcho minor. The genus name refers to Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
and to the related species Azhdarcho
Azhdarcho
Azhdarcho is a genus of pterodactyloid pterosaur from the late Cretaceous Period of the Bissekty Formation of Uzbekistan. It is known from fragmentary remains including the distinctive, elongated neck vertebrae that characterizes members of the family Azhdarchidae, which also includes such giant...
. The specific name means "the smaller one" in Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
, a reference to the relatively small size in comparison to closely related forms.
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...
, MOR 691 (Museum of the Rockies
Museum of the Rockies
The Museum of the Rockies, is located in Bozeman, Montana. The museum, originally affiliated with Montana State University in Bozeman, and now, also the Smithsonian Institution, is known for its paleontological collections, although these are not its sole focus...
), was found by Robert W. Harmon in Glacier County, in the territory of the Blackfoot
Blackfoot
The Blackfoot Confederacy or Niitsítapi is the collective name of three First Nations in Alberta and one Native American tribe in Montana....
, in sandstone of the Upper Two Medicine Formation
Two Medicine Formation
The Two Medicine Formation is a geologic formation, or rock body, that was deposited between 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma , during Campanian time, and is located in northwestern Montana...
, a layer about 74 million years old. The fossil is largely uncompressed and that of an adult exemplar, as established by a study of the bone by de Ricqlès. It consists of a partial left wing, lacking the outer three wing finger phalanges, a complete shoulder girdle, a crushed cervical vertebra and two fragments of the symphysis
Symphysis
A symphysis is a fibrocartilaginous fusion between two bones. It is a type of cartilaginous joint, specifically a secondary cartilaginous joint.1.A symphysis is an amphiarthrosis, a slightly movable joint.2.A growing together of parts or structures...
of the mandible
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
. The jaws were edentulous, i.e.: they lacked teeth.
Montanazhdarcho was by the authors assigned to the Azhdarchidae, mainly based on the elongated form of the neck vertebra. Compared to other azhdarchids, it was small; the fragments of humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
, radius
Radius (bone)
The radius is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna, which exceeds it in length and size. It is a long bone, prism-shaped and slightly curved longitudinally...
, and carpal
Carpus
In tetrapods, the carpus is the sole cluster of bones in the wrist between the radius and ulna and the metacarpus. The bones of the carpus do not belong to individual fingers , whereas those of the metacarpus do. The corresponding part of the foot is the tarsus...
suggest an animal with a 2.5 meter wingspan (eight feet). Its ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
was longer than the wing metacarpal, which is atypical for azhdarchids.