China is famous for its numerous feathered theropod discoveries. Some taxa that have been scientifically described for more than twenty years are still capable of providing palaeontologists with a new perspective on the evolution of feathered dinosaurs. Take for example Beipiaosaurus inexpectus, from the Lower Cretaceous Yixian Formation (Sihetun locality, near Beipiao), Liaoning, north-eastern China. It is a key taxon for understanding the early evolution of therizinosaurians and their close relatives.

However, since its initial scientific description back in 1999, only the cranial elements of this dinosaur have been described in any detail.

Beipiaosaurus scale drawing.
Therizinosaur drawing – Beipiaosaurus inexpectus. Despite having been scientifically described more than twenty years ago, only the skull material of this dinosaur has been studied in detail. A new scientific paper published recently has examined the postcranial fossil material associated with this taxon and provided palaeontologists with new insights into the evolution of this feathered theropod.

Writing in the peer-reviewed, open access journal “PLOS One”, scientists from the Chinese Academy of Sciences in collaboration with the North Carolina Museum of Natural Sciences (USA), present a detailed description of the postcranial skeletal anatomy of the holotype specimen of B. inexpectus.

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Beipiaosaurus inexpectus

The study incorporates two never before described dorsal vertebrae from the anterior half of the series. Based on these observations, and comparisons with the postcranial skeleton of therizinosaurian taxa named since this dinosaur was scientifically described, the scientists revise the diagnostic features for B. inexpectus adding three new possible, unique anatomical characteristics. The newly acquired data from the postcranial osteology of the holotype specimen sheds light on our understanding of postcranial skeletal evolution and identification of therizinosaurians.

When the paper came out, “Postcranial osteology of Beipiaosaurus inexpectus (Theropoda: Therizinosauria)” by Liao et al, Everything Dinosaur published a detailed blog post about this new research.

The earlier Everything Dinosaur blog post provides more information: Beipiaosaurus Revisited.

It seems our feathered dinosaur friends have a lot more to teach us and without giving too much away, readers can expect to see more posts about feathered dinosaurs on the Everything Dinosaur blog next year (2022).

To view figures of feathered dinosaurs including therizinosaurs, visit the models section of the Everything Dinosaur website: Feathered Dinosaurs and Prehistoric Animal Models.