Yunnanolepididae is an extinct

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

of primitive

Antiarch Antiarchi ("opposite anus") is an order of heavily armored placoderms. The antiarchs form the second-most successful group of placoderms after the arthrodires in terms of numbers of species and range of environments. The order's name was coi ...

placoderms characterized by having short, broad skull roofs, and by having a feature on the visceral side of the posterior medial dorsal plate, the ''crista transversalis interna posterior'', which is diagnostic of antiarchs, turning forward, and lying in front of the posterior ventral process and pit (with this position being diagnostic of yunnanolepids in particular). At least three genera, ''Yunnanolepis'', ''Phymolepis'', and ''

Vukhuclepis ''Vukhuclepis lyhoaensis'' is an extinct, primitive antiarch placoderm. Specimens are of mostly complete thoracic armor from the Early Devonian Ly Hoa Formation in Vietnam. The armor is very similar to that of ''Yunnanolepis ''Yunnanolepis'' ...

'' are confirmed to have a unique organ called the "Chang's Apparatus," named in honor of Professor

Meemann Chang Meemann Chang (; born 17 April 1936) also known as Zhang Miman, is a Chinese paleontologist at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP). She completed her undergraduate studies at Moscow University and completed her ...

, which is an internal cavity with an external opening within the suture of the anterior dorsal lateral plate and the anterior ventral lateral plate. The other genera in Yunnanolepidae that are not confirmed to have the Chang's Apparatus are included in the family because of anatomical similarities to ''Yunnanolepis''. The fossils of the various genera are found in Early to Middle

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

strata in Southern

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

and Middle

strata in

Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...

References

Prehistoric fish of Asia Antiarchi Fossils of China Fossils of Vietnam Placoderm families Early Devonian first appearances Middle Devonian extinctions {{placoderm-stub