Janiosteus Temporal range:
Middle Devonian:
Givetian,
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Scientific classification
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Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | † Placodermi |
Order: | † Arthrodira |
Suborder: | † Brachythoraci |
Family: | † Panxiosteidae |
Genus: | †
Janiosteus Ivanov, 1988 |
Type species | |
Janiosteus timanicus Ivanov, 1989
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Janiosteus is an extinct monospecific genus of placoderm arthrodire from the Middle Devonian: Late Givetian stage found in Timan, Russia.
Janiosteus is a member of Panxiosteidae. In the 2010 Carr & Hlavin phylogenetic study, Panxiosteidae was recognized as the sister taxon to the family Dunkleosteidae, which together comprised the superfamily Dunkleosteoidea (one of the three major clades of Eubrachythoraci). [1] The phylogeny of Janiosteus within Panxiosteidae is shown in the cladogram below from the 2013 Zhu & Zhu study: [2]
Eubrachythoraci |
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Pachyosteomorphi | |||||||||||||||||||||||||||||||||
However, the subsequent 2016 Zhu et al. study using a larger morphological dataset recovered Panxiosteidae well outside of Dunkleosteoidea, instead within Coccosteomorphi and then Coccosteoidea as the sister group of Coccosteidae, as shown in the cladogram below: [3]
Eubrachythoraci | |