''Panxiosteus'' is an
extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
monospecific
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
placoderm arthrodire
Arthrodira (Greek for "jointed neck") is an Order (biology), order of extinct armored, jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetratin ...
from the
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, wher ...
:
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 Fra ...
stage of
Yunnan
Yunnan , () is a landlocked Provinces of China, province in Southwest China, the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is ...
province,
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 ...
.
Phylogeny
''Panxiosteus'' is a member of
Panxiosteidae
Panxiosteidae is an extinct family of arthrodire placoderms that lived during the Devonian period.
Phylogeny
The family Panxiosteidae was erected by Wang in 1979. Members of the family are noted for showing morphologically intermediate traits ...
. In the 2010 Carr & Hlavin
phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
study,
Panxiosteidae
Panxiosteidae is an extinct family of arthrodire placoderms that lived during the Devonian period.
Phylogeny
The family Panxiosteidae was erected by Wang in 1979. Members of the family are noted for showing morphologically intermediate traits ...
was recognized as the
sister taxon
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and t ...
to the family
Dunkleosteidae
Dunkleosteidae is an extinct family of arthrodire placoderms that lived during the Devonian period. The gigantic apex predator ''Dunkleosteus terrelli'' is the best known member of this group.
Phylogeny
While members of Dunkleosteidae were prev ...
, which together comprised the
superfamily
SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...
Dunkleosteoidea
Dunkleosteoidea is an extinct superfamily of arthrodire placoderms that lived during the Devonian period. The gigantic apex predator ''Dunkleosteus terrelli'' is the best known member of this group.
Phylogeny
Eubrachythoraci is divided into the ...
(one of the three major
clades
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, t ...
of
Eubrachythoraci
Eubrachythoraci is an extinct clade of arthrodire placoderms within the suborder Brachythoraci, armored fish most diverse during the Devonian. Most are considered to be pelagic (open ocean) long-distance swimmers, leading to their widespread dis ...
).
The
phylogeny
A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...
of ''Panxiosteus'' within
Panxiosteidae
Panxiosteidae is an extinct family of arthrodire placoderms that lived during the Devonian period.
Phylogeny
The family Panxiosteidae was erected by Wang in 1979. Members of the family are noted for showing morphologically intermediate traits ...
is shown in the
cladogram
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...
below from the 2013 Zhu & Zhu study:
However, the subsequent 2016 Zhu ''et al.'' study using a larger
morphological dataset recovered
Panxiosteidae
Panxiosteidae is an extinct family of arthrodire placoderms that lived during the Devonian period.
Phylogeny
The family Panxiosteidae was erected by Wang in 1979. Members of the family are noted for showing morphologically intermediate traits ...
well outside of
Dunkleosteoidea
Dunkleosteoidea is an extinct superfamily of arthrodire placoderms that lived during the Devonian period. The gigantic apex predator ''Dunkleosteus terrelli'' is the best known member of this group.
Phylogeny
Eubrachythoraci is divided into the ...
, instead within
Coccosteomorphi
Coccosteomorphi is an extinct clade of arthrodire placoderms within the Eubrachythoraci (of the suborder Brachythoraci), armored fish most diverse during the Devonian. Most are considered to be pelagic (open ocean) long-distance swimmers, leadin ...
and then
Coccosteoidea
Coccosteoidea is an extinct superfamily of arthrodire placoderms that lived during the Devonian period.
Phylogeny
Eubrachythoraci is divided into the sister clades Pachyosteomorphi and Coccosteomorphi, the latter of which can be further sub-di ...
as the
sister group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and t ...
of
Coccosteidae
Coccosteidae is a family of arthrodire placoderms from the Early to Late Devonian. Fossils appear in various strata in Europe, North America and China.
Phylogeny
Coccosteidae belongs to the larger clade Coccosteomorphi, which together with its ...
, as shown in the cladogram below:
References
Arthrodires
Arthrodire genera
{{Placoderm-stub