''Mesadactylus'' ('mesa finger') is an extinct

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 ...

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

Kimmeridgian In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxfordian ...

Tithonian In the geological timescale, the Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series. It spans the time between 152.1 ± 4 Ma and 145.0 ± 4 Ma (million years ago). It is preceded by the K ...

-age

Upper Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

Morrison Formation The Morrison Formation is a distinctive sequence of Late Jurassic, Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandsto ...

Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...

, United States. The genus was named in 1989 by James Jensen and

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 ...

. 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 ''Mesadactylus ornithosphyos''.

Classification

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 ...

BYU Brigham Young University (BYU, sometimes referred to colloquially as The Y) is a private research university in Provo, Utah. It was founded in 1875 by religious leader Brigham Young and is sponsored by the Church of Jesus Christ of Latter-day S ...

2024, a

synsacrum The synsacrum is a skeletal structure of birds and other dinosaurs, in which the sacrum is extended by incorporation of additional fused or partially fused caudal or lumbar vertebrae and it can only be seen in birds. Some posterior thoracic vert ...

of seven sacral vertebrae, featuring a unique—for a pterosaur—complete fusion of the spinae into a supraneural blade, a character, as the

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

indicates more typical for birds, at first leading Jensen to assign the fossil to a bird, '' Palaeopteryx''. Further referred associated remains include arms bones,

pectoral girdle The shoulder girdle or pectoral girdle is the set of bones in the appendicular skeleton which connects to the arm on each side. In humans it consists of the clavicle and scapula; in those species with three bones in the shoulder, it consists of t ...

bones,

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

e (including

cervix The cervix or cervix uteri (Latin, 'neck of the uterus') is the lower part of the uterus (womb) in the human female reproductive system. The cervix is usually 2 to 3 cm long (~1 inch) and roughly cylindrical in shape, which changes during ...

and

sacral Sacral may refer to: *Sacred, associated with divinity and considered worthy of spiritual respect or devotion *Of the sacrum The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spi ...

), and

femora 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 with t ...

.Jensen, J. A., and Padian, K. (1989) Small pterosaurs and dinosaurs from the Uncompahgre fauna (Brushy Basin Member, Morrison Formation: ?Tithonian), late Jurassic, western Colorado. ''Journal of Paleontology'' 63:363–374. Additional material was described in 2004 (including a partial

braincase In human anatomy, the neurocranium, also known as the braincase, brainpan, or brain-pan is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the calvaria or skul ...

)Smith, D.K., Sanders, R.K., and Stadtman, K.L. (2004). New material of ''Mesadactylus ornithosphyos'', a primitive pterodactyloid pterosaur from the Upper Jurassic of Colorado. ''Journal of Vertebrate Paleontology'' 24(4):850-856. and 2006; in the latter publication, the authors suggested that its larger contemporary ''

Kepodactylus ''Kepodactylus'' is an extinct genus of ctenochasmatid pterodactyloid pterosaur from the Kimmeridgian- Tithonian-age Upper Jurassic Morrison Formation of Colorado, United States. In 1992, a team from the Denver Museum of Natural History dug ...

'' could be the same animal, although there are minor differences.King, L.R., Foster, J.R., and Scheetz, R.D. (2006). New pterosaur specimens from the Morrison Formation and a summary of the Late Jurassic pterosaur record of the Rocky Mountain region. In: Foster, J.R., and Lucas, S.G. (eds.). ''Paleontology and Geology of the Upper Morrison Formation''. New Mexico Museum of Natural History and Science Bulletin 36:109-113. ISSN 1524-4156.Harris, J.D., and Carpenter, K. (1996). A large pterodactyloid from the Morrison Formation (Late Jurassic) of Garden Park, Colorado. ''Neues Jahrbuch für Geologie und Paläontologie - Monatshefte'' 1996(8):473-484. Jensen and Padian classified ''Mesadactylus'' as a pterodactyloid. In 2007 S. Christopher Bennett claimed that the holotype and the referred material came from different forms and that, while the last was indeed of a pterodactyloid nature, the synsacrum belonged to a member of the

Anurognathidae Anurognathidae is a family (biology), family of small, short-tailed pterosaurs that lived in Europe, Asia, and possibly North America during the Jurassic and Cretaceous periods. Five genera are known: ''Anurognathus'', from the Late Jurassic of G ...

.Bennett, S. C. (2007). "Reassessment of ''Utahdactylus'' from the Jurassic Morrison Formation of Utah". ''Journal of Vertebrate Paleontology'' 27(1): 257–260

References

{{Portal bar, Paleontology, United States Monofenestratans Late Jurassic pterosaurs of North America Morrison fauna Taxa named by James A. Jensen Taxa named by Kevin Padian Fossil taxa described in 1989

Classification

See also

References