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Genus of nyctosaurid pterosaur from the Late Cretaceous
Alamodactylus
is an
extinct
genus
of
nyctosaurid
pteranodontoid
pterosaur
known from the
Late Cretaceous
of
Texas
, southern United States. It contains a single species,
Alamodactylus byrdi
.
[1]
Discovery
[
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]
Alamodactylus
is known solely from its
holotype
,
SMU
76476, a partial left
wing
first described by Myers (2010).
[2]
This specimen is crushed and consists of a left
humerus
, the distal end of the fourth wing
metacarpal
and the proximal end of the first wing
phalanx
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
bones, an articular surface that appears to be the
mandible
articulation of the right quadrate as well as thin bones that do not taper and may be ossified
tendons
.
Alamodactylus
was first named by Brian Andres and Timothy S. Myers in
2013
and the
type species
is
Alamodactylus byrdi
. The
generic name
is derived from
Alamo
? symbol of Texas independence and
dactylos
, meaning "finger" in
Ancient Greek
which is a traditional suffix for
pterosaur
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
of Austin Group, north of
Dallas
in
Collin County
, dating to the lower
Coniacian
stage of the middle
Late Cretaceous
period
, about 89.8?88
million years ago
.
[1]
Description
[
edit
]
The holotype of
Alamodactylus
was originally referred to
Pteranodontidae
by Myers (2010) and tentatively identified as cf.
Pteranodon
. Myers (2010) noted that the humerus was superficially similar to that of
Pteranodon
while other similarities were noted with
Nyctosaurus
, 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
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.
[1]
Phylogeny
[
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]
As suggested in the original description by Myers (2010), the
phylogenetic
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
taxon. Although the clade name
Pteranodontia
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
and other taxa. Therefore,
A. byrdi
was classified as a non-pteranodontoid pteranodontian, and its
sister taxon
relationship with
Pteranodontoidea
warranted the erection of a new genus and species for this material. Below is a
cladogram
based on the study upheld by Andres and Myers in 2013, showing the phylogenetic placement of
A. byrdi
within the clade Pteranodontia.
[1]
In 2018, a phylogenetic analysis published by Nicholas Longrich and colleagues recovered
Alamodactylus
within the family
Nyctosauridae
, in the
basalmost
position, contrary to the analysis by Andres and Myers above.
[3]
[4]
See also
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]
References
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]