[dinosaur] Ancistronychus, new drepanosauromorph from Late Triassic Petrified Forest National Park, Arizona (free pdf)

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Ben [email protected]=0A=0AA new paper in open access:=0A=0A=
=0AAncistronychus paradoxus  gen. et sp. nov.=0A=0AGabriel S. Gon=C3=A7alve=
s & Christian A. Sidor (2019)=0AA new drepanosauromorph, Ancistronychus par=
adoxus n. gen. et sp., from the=0AChinle Formation of Petrified Forest Nati=
onal Park, Arizona, USA.=0APaleoBios 36: 1=E2=80=9310=0Ahttps://urldefense.=
proofpoint.com/v2/url?u=3Dhttps-3A__escholarship.org_uc_item_8x7767f8&d=3DD=
wIFaQ&c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=3DRy_mO4IFaUmGof_Yl=
9MyZgecRCKHn5g4z1CYJgFW9SI&m=3Dj3fXdONmm1DiTsKfqFhSmpHsRcwjvQGxzqwaEOX0kTg&=
s=3DiJE6hKIzbN9lfNg0uWCXHmH5rNOuZGN3gdkZy0oecWk&e=3D=20=0A=0A=0A=0ADrepanos=
auromorpha is an extinct group of reptiles known from the Middle=0ATriassic=
 to Late Triassic (237=E2=80=93212 Ma). The clade currently includes seven=
=0Agenera (Avicranium, Dolabrosaurus, Drepanosaurus, Hypuronector,=0AKyrgzs=
aurus, Megalancosaurus, and Vallesaurus) that are known from fossils=0Acoll=
ected in Europe, North America, and Asia. These discoveries have helped=0As=
hape our understanding of the biology and diversity of drepanosauromorphs.=
=0AHere we describe Ancistronychus paradoxus n. gen. et sp. from the Chinle=
=0AFormation in Petrified Forest National Park, Arizona based on the ungual=
=0Aphalanx of the second digit of the manus. A characteristic that this tax=
on=0Ashares with Drepanosaurus unguicaudatus is the pronounced size of the=
=0Aungual relative to the penultimate element. It differs significantly fro=
m=0AD. unguicaudatus and the Hayden Quarry Drepanosaurus in the shortened=
=0Aproximal dorsoventral height of the claw, its great transverse breath, t=
he=0Apresence of both a furrow on the midline of the extensor surface and a=
=0Acleft on the apex, and a broad and flattened terminus. We suggest that A=
.=0Aparadoxus is likely closely related to D. unguicaudatus and the Hayden=
=0AQuarry Drepanosaurus, but missing phylogenetic data precludes a more=0Ad=
efinitive assessment at this point. Ancistronychus paradoxus highlights=0Au=
nsuspected morphological variation within Drepanosauromorpha and suggests=
=0Athat different drepanosauromorphs used their enlarged second manual ungu=
als=0Afor distinct functions enabling them to fill different ecological nic=
hes.=0A=

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<div dir=3D"ltr"><div><br></div>Ben Creisler<div><a href=3D"mailto:bcreisle=
[email protected]">[email protected]</a></div><div><br></div><div>A new paper i=
n open access:<br><div><br></div><div><br></div><div>Ancistronychus paradox=
us=C2=A0 gen. et sp. nov.</div><div><br>Gabriel S. Gon=C3=A7alves &amp; Chr=
istian A. Sidor (2019) <br>A new drepanosauromorph, Ancistronychus paradoxu=
s n. gen. et sp., from the Chinle Formation of Petrified Forest National Pa=
rk, Arizona, USA.<br>PaleoBios 36: 1=E2=80=9310<br><a href=3D"https://urlde=
fense.proofpoint.com/v2/url?u=3Dhttps-3A__escholarship.org_uc_item_8x7767f8=
&amp;d=3DDwMFaQ&amp;c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&amp;r=
=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&amp;m=3Dj3fXdONmm1DiTsKfqFhS=
mpHsRcwjvQGxzqwaEOX0kTg&amp;s=3DiJE6hKIzbN9lfNg0uWCXHmH5rNOuZGN3gdkZy0oecWk=
&amp;e=3D">https://escholarship.org/uc/item/8x7767f8</a></div><div><br><br>=
<br>Drepanosauromorpha is an extinct group of reptiles known from the Middl=
e Triassic to Late Triassic (237=E2=80=93212 Ma). The clade currently inclu=
des seven genera (Avicranium, Dolabrosaurus, Drepanosaurus, Hypuronector, K=
yrgzsaurus, Megalancosaurus, and Vallesaurus) that are known from fossils c=
ollected in Europe, North America, and Asia. These discoveries have helped =
shape our understanding of the biology and diversity of drepanosauromorphs.=
 Here we describe Ancistronychus paradoxus n. gen. et sp. from the Chinle F=
ormation in Petrified Forest National Park, Arizona based on the ungual pha=
lanx of the second digit of the manus. A characteristic that this taxon sha=
res with Drepanosaurus unguicaudatus is the pronounced size of the ungual r=
elative to the penultimate element. It differs significantly from D. unguic=
audatus and the Hayden Quarry Drepanosaurus in the shortened proximal dorso=
ventral height of the claw, its great transverse breath, the presence of bo=
th a furrow on the midline of the extensor surface and a cleft on the apex,=
 and a broad and flattened terminus. We suggest that A. paradoxus is likely=
 closely related to D. unguicaudatus and the Hayden Quarry Drepanosaurus, b=
ut missing phylogenetic data precludes a more definitive assessment at this=
 point. Ancistronychus paradoxus highlights unsuspected morphological varia=
tion within Drepanosauromorpha and suggests that different drepanosauromorp=
hs used their enlarged second manual unguals for distinct functions enablin=
g them to fill different ecological niches.<br><br></div></div></div>=0A=

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