''Alamodactylus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of nyctosaurid pteranodontoid

pterosaur Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the Order (biology), order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cre ...

known 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'', ...

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

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

Discovery

''Alamodactylus'' is known solely from its

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 seve ...

, SMU 76476, a partial left

wing A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is exp ...

first described by Myers (2010).Myers, T.S., 2010, "Earliest occurrence of the Pteranodontidae (Archosauria: Pterosauria) in North America: New material from the Austin Group of Texas", ''Journal of Paleontology'' 84(6): 1071–1081 This specimen is crushed and consists of a left

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 ...

, the distal end of the fourth wing

metacarpal In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ...

and the proximal end of the first wing

phalanx The phalanx ( grc, φάλαγξ; plural phalanxes or phalanges, , ) was a rectangular mass military formation, usually composed entirely of heavy infantry armed with spears, pikes, sarissas, or similar pole weapons. The term is particular ...

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 is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, t ...

bones, an articular surface that appears to be 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 teeth in place. The mandible sits beneath the maxilla. It is the only movable bon ...

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, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

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

2013 File:2013 Events Collage V2.png, From left, clockwise: Edward Snowden becomes internationally famous for leaking classified NSA wiretapping information; Typhoon Haiyan kills over 6,000 in the Philippines and Southeast Asia; The Dhaka garment ...

and 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 ''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 ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...

which is a traditional suffix for

genera in reference to their elongate wing digits. The specific name, ''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 A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, sh ...

of Austin Group, north of

Dallas Dallas () is the List of municipalities in Texas, third largest city in Texas and the largest city in the Dallas–Fort Worth metroplex, the List of metropolitan statistical areas, fourth-largest metropolitan area in the United States at 7.5 ...

Collin County Collin County is located in the U.S. state of Texas. It is part of the Dallas- Fort Worth- Arlington metropolitan statistical area, and a small portion of the city of Dallas is in the county. At the 2020 United States census, the county's popula ...

, 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 b ...

stage of the middle

period, about 89.8–88

million years ago The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). ...

Description

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

Pteranodontidae The Pteranodontidae are a family of large pterosaurs of the Cretaceous Period of North America and Africa. The family was named in 1876 by Othniel Charles Marsh. Pteranodontids had a distinctive, elongated crest jutting from the rear of the head ...

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

Pteranodon ''Pteranodon'' (); from Ancient Greek (''pteron'', "wing") and (''anodon'', "toothless") is a genus of pterosaur that included some of the largest known flying reptiles, with ''P. longiceps'' having a wingspan of . They lived during the late C ...

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

Nyctosaurus ''Nyctosaurus'' (meaning "night lizard" or "bat 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 aliv ...

'', 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 (;Entry "foramen"
in

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

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis performed by Andres & Myers (2013) recovered ''A. byrdi'' as closely related to ''Pteranodon'' and the Nyctosauridae. ''A. byrdi'' and nyctosaurids were recovered as successive sister groups to the Pteranodontoidea, of which ''Pteranodon'' is defined to be the most

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

taxon. Although the clade name

Pteranodontia Pteranodontia is an extinct group of ornithocheiroid pterodactyloid pterosaurs that lived during the Late Cretaceous period (Coniacian to Maastrichtian stages) of North America and Africa. They were some of the most advanced pterosaurs, and poss ...

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 Ornithocheirae is an extinct clade of pteranodontoid pterosaurs from the Early Cretaceous to the Late Cretaceous (Valanginian to Turonian stages) of Asia, Europe, North America and South America. It was named by Harry Seeley in 1870 as a family ...

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

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

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, 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 ...

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.

References

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

Discovery

Description

Phylogeny

See also

References