''Minjinia turgenensis'' is a species of

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 ...

from the

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

Mongolia Mongolia is a landlocked country in East Asia, bordered by Russia to the north and China to the south and southeast. It covers an area of , with a population of 3.5 million, making it the world's List of countries and dependencies by po ...

. It is known from a single specimen preserving part of the skull, including remains of

endochondral bone Endochondral ossification is one of the two essential pathways by which bone tissue is produced during fetal development and bone repair of the mammalian skeletal system, the other pathway being intramembranous ossification. Both endochondral an ...

, which indicates that a mineralised endoskeleton evolved before the split between bony and

cartilaginous fish Chondrichthyes (; ) is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which have skeleto ...

, and that it was lost in the latter group. ''Minjinia'', an ancient armored fish from the Devonian period, helps scientists understand how the shoulder bones of vertebrates first developed. Researchers found evidence that its skull was connected to the shoulder in a way that suggests the shoulder bones may have evolved from parts of the gill skeleton, supporting one of the main ideas about how fish fins and shoulders first appeared.Brazeau, M. D., Castiello, M., El Fassi El Fehri, A., Hamilton, L., Ivanov, A. O., Johanson, Z., & Friedman, M. (2023, November 1). Fossil evidence for a pharyngeal origin of the vertebrate pectoral girdle. Nature News. https://www.nature.com/articles/s41586-023-06702-4

Classification

In the

phylogenetic analysis In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

ran by Brazeau ''et al.'', ''M. turgenensis'' was found as the sister taxon of a clade formed by '' Entelognathus'', '' Ramirosuarezia'', '' Janusiscus'' and the crown gnathostomes. A

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

simplified from their analysis is shown below:

References

Placoderm genera Fossil taxa described in 2020 Placoderms {{Placoderm-stub