A monodactyl nonavian dinosaur and the complex evolution of the alvarezsauroid hand

Xu, Xing; Sullivan, Corwin; Pittman, Michael; Choiniere, Jonah N.; Hone, David W. E.; Upchurch, Paul; Tan, Qi; Xiao, Dong; Tan, Lin; Han, Fenglu

doi:10.1073/pnas.1011052108

Cited by 51 publications

(91 citation statements)

References 36 publications

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“…However, the manual morphology of those nonavian theropods differs substantially from the avian hands and did not function in flight. For instance, the unique manus in alvarezsauroids has been regarded as adaptation for digging (23). We performed a parsimony-based ancestral state reconstruction for the alula-major metacarpals and pelvis fusions across the phylogeny of Paraves.…”

Section: Discussionmentioning

confidence: 99%

Insight into the growth pattern and bone fusion of basal birds from an Early Cretaceous enantiornithine bird

Wang

Zhou

2017

Proc. Natl. Acad. Sci. U.S.A.

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Bird skeletons exhibit remarkable modifications that allow for flight. The most distinguishable features are the fusion of the bones in the hand, feet, and pelvis into composite rigid and bony structures. However, the historical origins of these avian bone fusions remain elusive because of the rarity of transitional fossils and developmental studies on modern birds. Here, we describe an Early Cretaceous bird (120 Mya) that has fully fused alular-major metacarpals and pelvis. We discuss the manus and pelvis fusions across Paravian phylogeny and demonstrate that these features evolved independently across nonavian theropods, Enantiornithes, and Ornithuromorpha. The fusions of these bones are rare in known nonavian theropods and Early Cretaceous birds but are well established among Late Cretaceous and modern birds, revealing a complicated evolution pattern unrecognized previously. We posit that the developments of bone fusion were polymorphic close to the origin of birds, resulting in the varying degrees of fusion in Paraves. However, that development polymorphism appears to be fundamentally restricted along the line to modern birds by the Late Cretaceous, where all birds have a completely fused manus and pelvis. Such changes likely correspond to a refinement of flight capability. Alternatively, the degree of bone fusion in this primitive bird may have been related to modifications in genes or developmental paths. Future studies and fossil discoveries are required to clarify these hypotheses and pinpoint the developmental pathways involving the bone fusions in early avian evolution through to their modern pattern.

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Section: Discussionmentioning

confidence: 99%

Insight into the growth pattern and bone fusion of basal birds from an Early Cretaceous enantiornithine bird

Wang

Zhou

2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Currently, only one parvicursorine— Linhenykus monodactylus Xu et al 2011—is known from the same locality and formation as IVPP V20341 (Bayan Mandahu, Inner Mongolia, China; the Upper Cretaceous—possibly Campanian—Wulansuhai Formation (Xu et al, 2010b; Eberth, 1993; Jerzykiewicz et al, 1993)). However, six other parvicursorines are known from more northerly localities within the Santonian to Maastrichtian-aged Upper Cretaceous rocks (Alifanov & Barsbold, 2009; Karhu & Rautian, 1996; Eberth et al, 2009; Gao & Norell, 2000; Jerzykiewicz & Russell, 1991; Lillegraven & McKenna, 1986) of the Mongolian Gobi Basin: Albinykus (Nesbitt et al, 2011), Ceratonykus (Alifanov & Barsbold, 2009), Mononykus (Perle et al, 1994), Parvicursor (Karhu & Rautian, 1996), Shuvuuia (Chiappe, Norell & Clark, 1998) and Kol (Turner, Nesbitt & Norell, 2009) (Table S1).…”

Section: Discussionmentioning

confidence: 99%

The taxonomy of a new parvicursorine alvarezsauroid specimen IVPP V20341 (Dinosauria: Theropoda) from the Upper Cretaceous Wulansuhai Formation of Bayan Mandahu, Inner Mongolia, China

Pittman

Stiegler

2015

PeerJ

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A new parvicursorine alvarezsauroid theropod specimen IVPP V20341 from the Upper Cretaceous Wulansuhai Formation of Bayan Mandahu, Inner Mongolia, China is described. IVPP V20341 appears to be distinguishable amongst alvarezsauroids by possible cervical procoely and relatively larger semi-circular caudal neural canals, but these features are not proposed as autapomorphies because current knowledge of alvarezsauroid necks and tails remains sparse. IVPP V20341 is distinguishable from Linhenykus—the sole parvicursorine at Bayan Mandahu—by the location of the origination points of the anterior caudal transverse processes; in IVPP V20341 this is the anterodorsal corner of the centra, whereas in Linhenykus it is the posterior end of the prezygapophyses. A number of additional tentative differences between IVPP V20341 and Linhenykus are also identified, but cannot be confirmed until further details of anatomical variation along the neck and tail are revealed by future finds. Thus, following the study of IVPP V20341 there are still seven parvicursorine species from the Upper Cretaceous Gobi Basin, but future finds could increase this to eight species.

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“…Dyke and Naish (1) draw attention to three points that they consider to be "serious shortcomings" of our recent paper on a monodactyl nonavian dinosaur (2). Here, we respond to each point in turn.…”

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confidence: 99%

“…However, we did include this taxon in a section of our paper (albeit in the SI Appendix) dealing with the biogeography of the Alvarezsauroidea, and even discussed its possible systematic position (2). Because it is probably a derived alvarezsauroid deeply nested within an Asian clade (2), it will not affect our biogeographic hypothesis (at best adding another dispersal event from Asia to Europe after the three dispersal events we proposed).…”

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confidence: 99%

“…However, Linhenykus and other recently reported parvicursorines, such as Albertonykus (5) and Xixianykus (6), are so morphologically similar to members of this nodebased Parvicursorinae that we believe the most informative option is to treat Parvicursorinae as a stem-based taxon as proposed in our paper, allowing for the inclusion of this genus and other taxa. Finally, our previous study indicates that Linhenykus is clearly different from Parvicursor in a number of features (2,3). Large pneumatic foramina are present in the middorsal vertebrae of Linhenykus, whereas the dorsal vertebrae lack pleurocoels in Parvicursor; Linhenykus possesses biconvex dorsal vertebrae, whereas all the preserved dorsal vertebrae are opisthocoelous in Parvicursor; the anterior caudal vertebrae are amphicoelous in Linhenykus but procoelous in Parvicursor; and the supracetabular crest is prominent anteriorly and convex in dorsal view in Linhenykus but appears to be concave in dorsal view in Parvicursor.…”

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confidence: 99%

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Reply to Dyke and Naish: European alvarezsauroids do not change the picture

Xu¹,

Sullivan²,

Pittman³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Dyke and Naish (1) draw attention to three points that they consider to be "serious shortcomings" of our recent paper on a monodactyl nonavian dinosaur (2). Here, we respond to each point in turn.Our paleobiogeographic hypothesis was based strictly on the phylogenetic tree we recovered (2), which did not include the European alvarezsauroid Heptasteornis because of the extremely fragmentary nature of the known material (3). However, we did include this taxon in a section of our paper (albeit in the SI Appendix) dealing with the biogeography of the Alvarezsauroidea, and even discussed its possible systematic position (2). Because it is probably a derived alvarezsauroid deeply nested within an Asian clade (2), it will not affect our biogeographic hypothesis (at best adding another dispersal event from Asia to Europe after the three dispersal events we proposed). Second, we acknowledge that a node-based definition of Parvicursorinae that would exclude Linhenykus has previously been proposed (4). However, Linhenykus and other recently reported parvicursorines, such as Albertonykus (5) and Xixianykus (6), are so morphologically similar to members of this nodebased Parvicursorinae that we believe the most informative option is to treat Parvicursorinae as a stem-based taxon as proposed in our paper, allowing for the inclusion of this genus and other taxa. Finally, our previous study indicates that Linhenykus is clearly different from Parvicursor in a number of features (2, 3). Large pneumatic foramina are present in the middorsal vertebrae of Linhenykus, whereas the dorsal vertebrae lack pleurocoels in Parvicursor; Linhenykus possesses biconvex dorsal vertebrae, whereas all the preserved dorsal vertebrae are opisthocoelous in Parvicursor; the anterior caudal vertebrae are amphicoelous in Linhenykus but procoelous in Parvicursor; and the supracetabular crest is prominent anteriorly and convex in dorsal view in Linhenykus but appears to be concave in dorsal view in Parvicursor. The two taxa also show some proportional differences, such as a much longer metatarsal III in Linhenykus than in Parvicursor. Furthermore, Parvicursor has only been briefly described and a detailed comparison between the known specimens of the two taxa would be likely to reveal even more differences.

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A monodactyl nonavian dinosaur and the complex evolution of the alvarezsauroid hand

Cited by 51 publications

References 36 publications

Insight into the growth pattern and bone fusion of basal birds from an Early Cretaceous enantiornithine bird

Insight into the growth pattern and bone fusion of basal birds from an Early Cretaceous enantiornithine bird

The taxonomy of a new parvicursorine alvarezsauroid specimen IVPP V20341 (Dinosauria: Theropoda) from the Upper Cretaceous Wulansuhai Formation of Bayan Mandahu, Inner Mongolia, China

Reply to Dyke and Naish: European alvarezsauroids do not change the picture

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