In collaboration with an Italian colleague, a team of archaeologists, paleontologists, and researchers from China have identified a new species of theropod dinosaur distinguished by its peculiar hand characteristics. Their study, published in Cretaceous Research, provides insights into this recently unearthed dinosaur’s evolutionary placement within the broader family.

The fossilized specimen was discovered at the Pigeon Hill excavation site near Baoshan, Inner Mongolia, China. Embedded in a rock slab, the fossil could only be examined from a side view. Nonetheless, this limited perspective revealed a particular theropod fossil, representing a previously unknown species. Radiometric dating estimates its age to be approximately 121 million years, placing the dinosaur within the Early Cretaceous period.

The newly named dinosaur, Migmanychion laiyang, belongs to the Maniraptora group, a subset of coelurosaurian dinosaurs that includes some of the ancestors of modern birds. Examination of its bone structure confirms its classification within Maniraptora, a group encompassing famous dinosaurs like Tyrannosaurus rex and Allosaurus. Notably, Maniraptorans possess long arms and hands with three fingers, characterized by a unique crescent-shaped bone in the wrist. They are the only dinosaur group known to include flying species.

While the fossil remains incomplete, comprising a fully preserved hand, a few ribs, and a left forelimb, its hand structure distinguishes Migmanychion from all other known theropods. The hand exhibits similarities to oviraptorosaurs and therizinosaurs, with the latter represented by the well-known pot-bellied Therizinosaurus. Oviraptors are recognized for their feathered appearance, bird-like skulls, and omnivorous diet.

The researchers propose that M. laiyang likely evolved independently from lineages leading to modern birds, resembling the enigmatic Fukuivenator paradoxes discovered in Japan. Further exploration and discovery of additional specimens are essential for a more precise classification and deeper understanding of this new species.

At the same excavation site, fragmentary remains of limbs and a partial pelvis tentatively belong to a paravian maniraptoran. These findings contribute to our knowledge of the diverse array of theropod dinosaurs and their evolutionary relationships within the broader avian lineage.

References

• Wang, X., Cau, A., Wang, Z., Yu, K., Wu, W., Wang, Y., & Liu, Y. (2023). A new theropod dinosaur from the Lower Cretaceous Longjiang Formation of Inner Mongolia (China). Cretaceous Research, 105605. https://doi.org/10.1016/j.cretres.2023.105605
• Yirka, B. & Phys.org. (2023, June 22). Newly identified theropod dinosaur had strange hands. Phys.Org; Phys.org. https://phys.org/news/2023-06-newly-theropod-dinosaur-strange.html