Omnivoropterygidae is a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of primitive bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s known exclusively from the Jiufotang Formation

Jiufotang Formation

The Jiufotang Formation is an Early Cretaceous geological formation in Chaoyang, Liaoning which has yielded fossils of feathered dinosaurs, primitive birds, pterosaurs, and other organisms. . It is a member of the Jehol group. The exact age of the Jiufotang has been debated for years, with...

 of China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

. They had short skeletal tails and unusual skulls with teeth in the upper, but not lower, jaws. Their unique dentition has led some scientists to suggest an omnivorous

Omnivore

Omnivores are species that eat both plants and animals as their primary food source...

 diet for them. The family was named by Stephen A. Czerkas & Qiang Ji in 2002, though its junior synonym Sapeornithidae is often used instead, though it was named four years later in 2006. It is the only named family in the order Omnivoropterygiformes (=Sapeornithiformes).