Beipiaosaurus - "The Lizard of Beipia"

Beipiaosaurus received its species name inexpectus because it had some surprising features.

While late therizinosaurs had all four toes well developed and thus in contact with the ground, Beipiaosaurus had the inner toes underdeveloped.

The most outstanding feature, however, was the presence of two different types of feathers. First, it possessed a dense layer of down that probably covered the entire body and probably served as thermal insulation.

A second type of feathers, larger and longer, protruded upward through this down layer. These feathers were between 10 and 15 cm long and were not suitable for flying. Their quills resembled those of a porcupine.

Prehistoric EraLower Cretaceous 125 million years ago
SpeciesBeipiaosaurus inexpectus
Height0.9 meter
Length2.2 meter
Weight45 to 90 kg
TerritoryYixian Formation , Liaoning Provinz, China


These feathers are known as EBFF in professional circles.

  • elongated broad filamentous feathers = elongated broad filamentous feathers.

These long feathers probably did not have a practical purpose. They served more for display purposes, such as courtship. Much like peacocks today.

EBFFs are concentrated on the head, neck, and tail of Beipiaosaurus.

Areas where modern birds are more likely to show flight feathers.

Beipiaosaurus Größenvergleich
Beipiaosaurus Size Comparison

Beipiaosaurus held the title of the largest known dinosaur with feathers for many years. It had a length of 2.2 m. However, he lost this title when Yutyrannus was excavated and described in 2012.

Beipiaosaurus Skelett
Beipiaosaurus Skelett

In 1996 the first remains of Beipiaosaurus were found and formally described in 1999. From these three specimens it is known that numerous impressions of feather structures are present. From these impressions, scientists are even able to determine the colors of the feathers. This turned out to be brownish.

Image Source: PaleoNeolitic, CC BY 4.0, via Wikimedia Commons

Jaime A. Headden (User:Qilong), CC BY 3.0, via Wikimedia Commons

PaleoNeolitic, CC0, via Wikimedia Commons

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