Quasipetalichthyidae is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of primitive petalichthyid

placoderm Placoderms (from Ancient Greek πλάξ 'plax'', ''plakos'''Plate (animal anatomy), plate' and δέρμα 'derma'''skin') are vertebrate animals of the class (biology), class Placodermi, an extinct group of prehistoric fish known from Pal ...

s from

Givetian The Givetian is one of two faunal stages in the Middle Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Eifelian Stage and followed by the Frasnian Stage. It is named after the town of Givet in ...

-aged marine strata of

Yunnan Yunnan; is an inland Provinces of China, province in Southwestern China. The province spans approximately and has a population of 47.2 million (as of 2020). The capital of the province is Kunming. The province borders the Chinese provinces ...

, China, and possibly

Vietnam Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of mainland Southeast Asia, with an area of about and a population of over 100 million, making it the world's List of countries and depende ...

Anatomy

The family differ from the more advanced macropetalichthyids by having more squared skulls that have the eye sockets placed on the side of their skulls, rather than nearer to the center. More basal petalichthyids, such as ''

Diandongpetalichthys ''Diandongpetalichthys liaojiaoshanensis'' is an extinct petalichthyid placoderm from the Early Devonian of China. Fossils Several specimens, in the forms of one complete and several incomplete skull roofs, disarticulated portions of the trunk s ...

'' and ''

Neopetalichthys ''Neopetalichthys yenmenpaensis'' is an extinct petalichthid placoderm from the Early Devonian of China. Fossils The holotype and only known specimen is a poorly preserved partial, and elongated skull from Emsian-aged strata in Sichuan. The s ...

'', differ from the Quasipetalichthyidae by having comparatively elongated skulls.

Synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to ...

of the family include the presence of a posterior descending

lamina Lamina may refer to: People * Saa Emerson Lamina, Sierra Leonean politician * Tamba Lamina, Sierra Leonean politician and diplomat Science and technology * Planar lamina, a two-dimensional planar closed surface with mass and density, in mathem ...

, the absence of a

supraorbital Supraorbital refers to the region immediately above the eye sockets, where in humans the eyebrows are located. It denotes several anatomical features, such as: *Supraorbital artery *Supraorbital foramen *Supraorbital gland *Supraorbital nerve *Sup ...

process, the posterior position of the

ossification Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in t ...

center of the nuchal plate, and the roundness of the preorbital plate.

References

Placoderms of Asia Placoderm families Petalichthyida Middle Devonian extinctions Middle Devonian first appearances {{Placoderm-stub