''Protitanichthys'' 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 ...

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 comparatively large

coccosteid 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 ...

arthrodire placoderms 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, whe ...

of the eastern

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. Fossils are found primarily in the Eifelian-epoch aged

Delaware Limestone The Delaware Limestone is a geologic formation in Ohio. It dates back to the 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 ( ...

Ohio Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...

, and the Lower Givetian-aged Rockport Quarry Limestone of

Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and the ...

Description

''Protitanichthys'' is very similar to other coccosteids, though the skull is proportionally narrower, and the orbits are comparatively smaller. As mentioned earlier, species are quite large for coccosteids, surpassed only in size by the

Old World The "Old World" is a term for Afro-Eurasia that originated in Europe , after Europeans became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia, which were previously thought of by the ...

genus, '' Livosteus''.

Phylogeny

''Protitanichthys'' is a member of the

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 ...

Coccosteidae, which belongs to the

clade 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, ...

Coccosteomorphi, one of the two major clades within Eubrachythoraci. The cladogram below shows 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 ''Protitanichthys'':

Species

''P. fossatus''

The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

of the genus. The description of ''P. fossatus'' is based on a cranial roof, possibly long, found in the Eifelian-aged

''P. rockportensis''

As the specific name suggests, numerous scrappy remains of this species are found in the Lower- Givetian Rockport Quarry Limestone in

. Denison (1978) questions the status of ''P. rockportensis'' being distinct from ''P. fossatus'', as there are very few differences between the two, aside from chronological and geographical differences.

References

{{Taxonbar, from=Q16992251, from2=Q112327191 Coccosteidae Placoderms of North America Paleontology in Ohio Paleontology in Michigan Eifelian life Givetian life