New Species of Theropod Dinosaur Identified in China

A new genus and species of maniraptoran dinosaur has been
described from the fossilized skeletal material found in Inner Mongolia,
China.

Reconstruction of the small-bodied theropod dinosaur Fukuivenator paradoxus, a sister taxon of Migmanychion laiyang. Image credit: Piotr Menshikov / Sci.News. The newly-identified dinosaur species roamed our planet during the Early Cretaceous epoch, some 121 million years ago.

Named Migmanychion laiyang, it was a type of maniraptorian, a group of coelurosaurian dinosaurs that includes birds and some non-avian lineages.

Maniraptorans first appear in the fossil record during the Jurassic period, and survive today as living birds. They are characterized by long arms and three-fingered hands as well as a half-moon shaped (semi-lunate) bone in the wrist. Maniraptora is the only dinosaur group known to include flying
members, though how far back in this lineage flight extends is still
controversial. The fossilized remains of Migmanychion laiyang were found at the Pigeon Hill locality of the Longjiang Formation near Baoshan town in Inner Mongolia, China.

“In the last decade, a new Lower Cretaceous freshwater fossil
locality — the Pigeon Hill — has drawn extensive attention for yielding
exceptionally preserved fossils of the Jehol Biota,” said China
University of Geosciences researcher Yichuan Liu and colleagues.

“Although this new locality is far from the famous core area
containing the Jehol Biota in western Liaoning, the uncovered fossils
are similar and closely related in the two areas.”

Holotype of Migmanychion laiyang: (A) counterslab; (B) slab. Scale bar – 2 cm. Image credit: Wang et al., doi: 10.1016/j.cretres.2023.105605. Migmanychion laiyang is represented by an incompletely preserved skeleton including a partial left forelimb with complete hand.

“The new theropod material collected at Pigeon Hill differs from all
the previously named taxa from this locality, and supports the presence
of at least one new dinosaurian species in the Longjiang Formation,” the
paleontologists said.

“The holotype material includes fragments of ribs, the distal end of
one forearm, and a complete hand. Some dorsal ribs are preserved as
middle shaft portions.”

“It shows a peculiar hand morphology different from all known theropods, supporting the erection of a new taxon.”

The team’s phylogenetic analysis supports the closest affinity of Migmanychion laiyang with the enigmatic Fukuivenator paradoxus from Japan.

“Migmanychion laiyang possesses a peculiar combination of features in the hand, which is different from all other known theropods,” the authors said.

“Most of the derived features in Migmanychion laiyang hand
are variably widespread among non-paravian maniraptorans (in particular,
among early diverging oviraptorosaurs and therizinosauroids),
suggesting that this theropod belongs to this grade and it is not
particularly closer to the bird lineage.”

“Our phylogenetic analysis supports Migmanychion laiyang as closely related to the bizarre Fukuivenator paradoxus and places them closer to pennaraptorans than therizinosauroids.”

The discovery of Migmanychion laiyang is described in a paper published this month in the journal Cretaceous Research.

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Xuri Wang et al. A new theropod dinosaur from the Lower Cretaceous Longjiang Formation of Inner Mongolia (China). Cretaceous Research, published online June 5, 2023; doi: 10.1016/j.cretres.2023.105605