Drag to rotate the Beipiaosaurus, scroll or pinch to zoom, and click a body part - the head, an arm, or the tail - to read what fossils tell us about it. The panel beside the model carries the real figures.
Beipiaosaurus was a small, early therizinosaur - turn on the human figure to see how a roughly 2.2 m animal compares to a person, and note the somewhat elongated arms it kept from earlier in its family's evolution.
The colors and skin here are an artistic reconstruction; fossils preserve bone (and, for this species, feather filaments), not soft-tissue color. This model is not a fossil-accurate skeleton, and the filament feathers themselves are not rendered as geometry - the info panel and facts below say so directly. The measurements in the panel follow published estimates, with ranges shown where sources disagree.
Beipiaosaurus 3D Viewer
This page renders a Beipiaosaurus as a 3D model you can spin in the browser - drag to rotate, scroll or pinch to zoom, toggle a 1.8 m person beside it for scale, and click the head, an arm, or the tail to read a fact about that part.
Beipiaosaurus lived in the Early Cretaceous, roughly 125 million years ago, in what is now the Yixian Formation of Liaoning Province, China - the same fossil-rich beds that preserved many other feathered dinosaurs. Published length estimates run about 1.8 to 2.6 m, and it is one of the smallest and most basal known members of the therizinosaur family, a group of theropods that mostly grew into large, slow-moving herbivores such as Therizinosaurus. What makes Beipiaosaurus scientifically important is that it is the species that gave the first direct fossil evidence of feathers anywhere in the therizinosaur family: long, simple, unbranched filamentous proto-feathers were preserved alongside the skeleton, so feathering on the larger and later Therizinosaurus is inferred from this smaller relative rather than observed directly.
Beipiaosaurus was named by Xu, Tang and Wang in 1999, from a holotype (specimen IVPP V11559) found in the Yixian Formation. Published mass estimates vary widely by method, from about 27 kg in one study up to roughly 85-135 kg in others; this page uses 85 kg as a commonly cited mid-range figure. Unlike the huge, sickle-like claws of later therizinosaurs, its forelimbs were elongated but modestly clawed, a trait it retained from earlier, non-herbivorous theropod ancestors.
| Measure | Figure |
|---|---|
| Length | about 1.8-2.6 m (this page uses 2.2 m) |
| Weight | about 27-135 kg depending on method (this page uses 85 kg) |
| When it lived | about 125 million years ago (Early Cretaceous) |
| Group | Basal therizinosauroid (feathered theropod) |
| Diet | Herbivore (probable) |
Everything runs on your device with WebGL, so the model works without an account and without sending anything to a server. The skin tone and pattern are an artistic reconstruction, because fossils do not preserve color or soft tissue; the filament feathers themselves are not rendered as geometry on the model. The numbers above are real published values, with a range given where sources disagree.
Frequently Asked Questions
Why is Beipiaosaurus important to paleontologists?
It is the species that gave the first direct fossil evidence of feathers anywhere in the therizinosaur family - long, simple, unbranched filaments preserved alongside its skeleton. Larger, later therizinosaurs such as Therizinosaurus have no feathers directly preserved on their own fossils, so their feathering is inferred from this smaller relative.
How big was Beipiaosaurus?
Published estimates put it at roughly 1.8 to 2.6 m long, with this page using 2.2 m. Weight is much less certain - estimates range from about 27 kg up to roughly 135 kg depending on the method used, so this page cites 85 kg as a commonly used mid-range figure. Turn on the human figure in the viewer to see the scale against a 1.8 m person.
Was Beipiaosaurus a plant eater?
Probably, yes. It belongs to the therizinosaurs, a group of theropod dinosaurs that mostly evolved toward slow-moving, herbivorous lifestyles despite descending from meat-eating ancestors. Beipiaosaurus is one of the earliest and smallest known members of that group.
Did Beipiaosaurus have big claws like Therizinosaurus?
No - its forelimbs were elongated but only modestly clawed, closer to earlier theropod ancestors than to the huge, sickle-shaped claws later therizinosaurs such as Therizinosaurus evolved. The enlarged claws seen in that later relative developed further along the family's evolution.
When and where did Beipiaosaurus live?
In the Early Cretaceous, roughly 125 million years ago, in what is now the Yixian Formation of Liaoning Province, China - one of the most productive fossil beds for feathered dinosaurs. It was named by Xu, Tang and Wang in 1999 from a holotype specimen (IVPP V11559).
Is the model scientifically accurate?
The body proportions follow published length and mass figures for this species, but the skin color and pattern are an artistic reconstruction - fossils preserve bone and, for this species, feather filaments, but not soft-tissue color. This model is not a fossil-accurate skeleton, and the filament feathers themselves are not rendered as geometry. The length, weight, and age figures shown are real published values, with ranges cited because sources vary.