''Alamodactylus'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

pteranodontia Pteranodontia is an extinct group of ornithocheiroid pterodactyloid pterosaurs. It lived during the Late Cretaceous (Turonian to Maastrichtian stages) of North America, South America, Europe and Africa. They were some of the most advanced pterosa ...

pterosaur Pterosaurs are 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 million to 66 million years ago). Pterosaurs are the earli ...

known from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent 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 ''cre ...

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

, southern United States. It contains a single species, ''Alamodactylus byrdi''.

Discovery

''Alamodactylus'' is known solely from its

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

, SMU 76476, a partial left

wing A wing is a type of fin that produces both Lift (force), lift and drag while moving through air. Wings are defined by two shape characteristics, an airfoil section and a planform (aeronautics), planform. Wing efficiency is expressed as lift-to-d ...

first described by Myers (2010). This specimen is crushed and consists of a left

humerus The humerus (; : humeri) 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 (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

, the distal end of the fourth wing

metacarpal In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones ( wrist bones), which articulate ...

and the proximal end of the first wing

phalanx The phalanx (: phalanxes or phalanges) was a rectangular mass military formation, usually composed entirely of heavy infantry armed with spears, pikes, sarissas, or similar polearms tightly packed together. The term is particularly used t ...

of fourth digit. Other elements of the holotype first reported by Andres and Myers (2013) include a left proximal syncarpal, manual phalanx, and some fragments including four tapering processes that may represent

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

bones, an articular surface that appears to be the

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

articulation of the right quadrate as well as thin bones that do not taper and may be ossified

tendon A tendon or sinew is a tough band of fibrous connective tissue, dense fibrous connective tissue that connects skeletal muscle, muscle to bone. It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tensi ...

s. ''Alamodactylus'' was first named by Brian Andres and Timothy S. Myers in

2013 2013 was the first year since 1987 to contain four unique digits (a span of 26 years). 2013 was designated as: *International Year of Water Cooperation *International Year of Quinoa Events January * January 5 – 2013 Craig, Alask ...

and the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

is ''Alamodactylus byrdi''. The generic name is derived from ''Alamo'' – symbol of Texas independence and ''dactylos'', meaning "finger" in

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

which is a traditional suffix for

genera in reference to their elongate wing digits. 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 ...

, ''byrdi'', honors Gary Byrd for discovering the holotype. The holotype was collected from the

Atco Formation The Atco Formation is a geologic formation in Texas. It preserves fossils dating back to the Cretaceous period. See also * List of fossiliferous stratigraphic units in Texas * Paleontology in Texas Paleontology in Texas refers to paleontolog ...

of Austin Group, north of

Dallas Dallas () is a city in the U.S. state of Texas and the most populous city in the Dallas–Fort Worth metroplex, the List of Texas metropolitan areas, most populous metropolitan area in Texas and the Metropolitan statistical area, fourth-most ...

in Collin County, dating to the lower

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by ...

stage of the middle

period Period may refer to: Common uses * Period (punctuation) * Era, a length or span of time *Menstruation, commonly referred to as a "period" Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (o ...

, about 89.8–88

million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...

Description

The holotype of ''Alamodactylus'' was originally referred to

Pteranodontidae The Pteranodontidae are a Family (biology), family of large pterosaurs from the Late Cretaceous of North America and possibly other continents including Europe and Africa. The family was named in 1876 by Othniel Charles Marsh. Pteranodontids had a ...

by Myers (2010) and tentatively identified as cf. ''

Pteranodon ''Pteranodon'' (; from and ) is a genus of pterosaur that included some of the largest known flying reptiles, with ''P. longiceps'' having a wingspan of over . They lived during the late Cretaceous geological period of North America in presen ...

''. Myers (2010) noted that the humerus was superficially similar to that of ''Pteranodon'' while other similarities were noted with ''

Nyctosaurus ''Nyctosaurus'' (meaning "night lizard") is a genus of nyctosaurid pterosaur from the Late Cretaceous period of what is now the Niobrara Formation of the mid-western United States, which, during the time ''Nyctosaurus'' was alive, was covered in ...

'', but the holotype being crushed rendered comparison difficult. Andres and Myers (2013) diagnosed ''Alamodactylus'' on the basis of unique combination of constricted humerus mid-shaft and D-shaped distal humerus cross-section. This medium-sized pterosaur also has autapomorphic small pneumatic

foramen In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, artery, ...

on ventral surface of humerus proximal end, and dorsal nutrient foramen positioned on midline of humerus shaft level with the middle of deltopectoral crest. Additionally, its warped humerus deltopectoral crest thickens proximally.

Phylogeny

As suggested in the original description by Myers (2010), the

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

analysis performed by Andres & Myers (2013) recovered ''A. byrdi'' as closely related to ''Pteranodon'' and the Nyctosauridae. ''A. byrdi'' and

nyctosaurid Nyctosauridae (meaning "night lizards" or "bat lizards") is a family of specialized soaring pterosaurs of the late Cretaceous Period of North America, Africa, and possibly other continents including South America. It was named in 1889 by Henry A ...

s were recovered as successive sister groups to the

Pteranodontoidea Pteranodontoidea (or pteranodontoids, from Greek meaning "toothless wings") is an extinct clade of ornithocheiroid pterosaurs from the Early to Late Cretaceous (early Valanginian to late Maastrichtian stages) of Asia, Africa, Europe, North Amer ...

, of which ''Pteranodon'' is defined to be the most basal taxon. Although the clade name

Pteranodontia Pteranodontia is an extinct group of ornithocheiroid pterodactyloid pterosaurs. It lived during the Late Cretaceous (Turonian to Maastrichtian stages) of North America, South America, Europe and Africa. They were some of the most advanced pterosa ...

usually applies to the clade exclusively formed by pteranodontids and nyctosaurids, it was originally converted by Unwin (2003) to include ''Pteranodon'' and ''Nyctosaurus'' so under their phylogeny it contains also the

Ornithocheirae Ornithocheiromorpha (from Ancient Greek, meaning "bird hand form") is a group of pterosaurs within the suborder Pterodactyloidea. Fossil remains of this group date back from the Early Cretaceous, Early to Late Cretaceous Period (geology), period ...

and other taxa. Therefore, ''A. byrdi'' was classified as a non-pteranodontoid pteranodontian, and its

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

relationship with

warranted the erection of a new genus and species for this material. Below is a

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

based on the study upheld by Andres and Myers in 2013, showing the phylogenetic placement of ''A. byrdi'' within the clade Pteranodontia. In 2018, a phylogenetic analysis published by Nicholas Longrich and colleagues recovered ''Alamodactylus'' within the family

Nyctosauridae Nyctosauridae (meaning "night lizards" or "bat lizards") is a family of specialized soaring pterosaurs of the late Cretaceous Period of North America, Africa, and possibly other continents including South America. It was named in 1889 by Henry ...

, in the basalmost position, contrary to the analysis by Andres and Myers above.Nicholas R. Longrich; David M. Martill; Brian Andres (2018). "Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary". PLOS Biology. 16 (3): e2001663. . PMC 5849296 Freely accessible. However, subsequent phylogenetic analyses placed ''Alamodactylus'' as a pteranodontian outside

References

{{Taxonbar, from=Q14944712 Late Cretaceous pterosaurs of North America Fossil taxa described in 2013 Pteranodontia Paleontology in Texas