''Montanazhdarcho'' 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
azhdarchoid
Azhdarchoidea (or azhdarchoids) is a group of pterosaurs within the suborder Pterodactyloidea, more specifically within the group Ornithocheiroidea. Pterosaurs belonging to this group lived throughout the Early and Late Cretaceous periods, with ...
pterosaur
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 ...
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'', the ...
period (
Campanian
The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian s ...
stage) of what is now the state of
Montana
Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbi ...
,
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
. ''Montanazhdarcho'' is known from only one species, ''M. minor''.
Discovery
![Montanazhdarcho forelimb](https://upload.wikimedia.org/wikipedia/commons/d/d3/Montanazhdarcho_forelimb.png)
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 ...
specimen, MOR 691 (
Museum of the Rockies
Museum of the Rockies is a museum in Bozeman, Montana. Originally affiliated with Montana State University in Bozeman, and now also, the Smithsonian Institution, the museum is largely known for its paleontological collections. The Museum houses ...
), was found by
Robert W. Harmon in
Glacier County, in the territory of the
Blackfoot
The Blackfoot Confederacy, ''Niitsitapi'' or ''Siksikaitsitapi'' (ᖹᐟᒧᐧᒣᑯ, meaning "the people" or " Blackfoot-speaking real people"), is a historic collective name for linguistically related groups that make up the Blackfoot or Bla ...
, in sandstone of the Upper
Two Medicine Formation
The Two Medicine Formation is a geological formation, or rock body, in northwestern Montana and southern Alberta that was deposited between and (million years ago), during Campanian (Late Cretaceous) time. It crops out to the east of the Rocky M ...
, a layer about 74 million years old. The genus name ''Montanazhdarcho'' was first given informally in 1993 by
Kevin Padian
Kevin Padian (born 1951) is a Professor of Integrative Biology at the University of California, Berkeley, Curator of Paleontology, University of California Museum of Paleontology and was President of the National Center for Science Education fro ...
,
Armand de Ricqlès, and
Jack Horner.
It was then named formally in 1995 by the same researchers,
and was fully described in 2002.
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 ...
is ''Montanazhdarcho minor''. The
generic name refers to the state of
Montana
Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbi ...
and to the related species ''
Azhdarcho
''Azhdarcho'' is a genus of azhdarchid pterosaur from the late Cretaceous Period of the Bissekty Formation (middle Turonian stage, about 92 million years ago) of Uzbekistan, as well as the Zhirkindek Formation of Kazakhstan. It is known from ...
''. The
specific name means "the smaller one" in
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
, a reference to the relatively small size in comparison to closely related forms.
Description
''Montanazhdarcho'' was a relatively small pterosaur, reaching in wingspan.
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
A symphysis (, pl. symphyses) is a fibrocartilaginous fusion between two bones. It is a type of cartilaginous joint, specifically a secondary cartilaginous joint.
# A symphysis is an amphiarthrosis, a slightly movable joint.
# A growing together ...
of the
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 ...
. The jaws were edentulous, i.e. they lacked teeth.
Classification
![Significant pterosaur discoveries in western North America](https://upload.wikimedia.org/wikipedia/commons/3/3d/Significant_pterosaur_discoveries_in_western_North_America.png)
''Montanazhdarcho'' was by the authors assigned to the
Azhdarchidae
Azhdarchidae (from the Persian word , , a dragon-like creature in Persian mythology) is a family of pterosaurs known primarily from the Late Cretaceous Period, though an isolated vertebra apparently from an azhdarchid is known from the Early Cret ...
, mainly based on the elongated form of the neck vertebra. Compared to other azhdarchids however, it was small; the fragments of
humerus
The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...
,
radius
In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...
, and
carpal
The carpal bones are the eight small bones that make up the wrist (or carpus) that connects the hand to the forearm. The term "carpus" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, th ...
suggest an animal with a wingspan. Its
ulna
The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...
was longer than the wing metacarpal, which is atypical for azhdarchids. In addition to this, a phylogenetic study in 2015 has disagreed to its phylogenetic position, and reassigned ''Montanazhdarcho'' as a non-azhdarchid azhdarchoid.
However, in 2018, Nicholas Longrich and colleagues had recovered ''Montanazhdarcho'' within the Azhdarchidae again, though placed in the
basalmost
In phylogenetics, basal is the direction of the ''base'' (or root) of a rooted phylogenetic tree or cladogram. The term may be more strictly applied only to nodes adjacent to the root, or more loosely applied to nodes regarded as being close to th ...
position.
Their phylogenetic analysis is shown below:
See also
*
List of pterosaur genera
This list of pterosaurs is a comprehensive listing of all genera that have ever been included in the order Pterosauria, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now considered inval ...
*
Timeline of pterosaur research
This timeline of pterosaur research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, and taxonomic revisions of pterosaurs, the famed flying reptiles of the Mesozoic era. Although pterosaurs w ...
References
{{Portal bar, Paleontology, Cretaceous, United States
Late Cretaceous pterosaurs of North America
Azhdarchoids
Fossil taxa described in 1995
Taxa named by Kevin Padian
Taxa named by Armand de Ricqlès
Taxa named by Jack Horner