Eastmanosteus
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Eastmanosteus Temporal range: Middle to Late Devonian |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Placodermi |
| Order: | Arthrodira |
| Suborder: | Dunkleosteoidea |
| Family: | Dunkleosteidae |
| Genus: | Eastmanosteus |
| Type species | |
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Eastmanosteus pustulosus (Eastman 1897) |
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Eastmanosteus ("Eastman's bone") is a fossil genus of dunkleosteid placoderms. It was closely related to the giant Dunkleosteus, but differed from that genus in size, in possessing a distinctive tuberculated bone ornament, a differently shaped nuchal plate and a more zig-zagging course of the sutures of the skull roof.
Species of Eastmanosteus had powerful jaws with sharp cutting edges and were likely active predators. Fossils have been found in many parts of the world in marine sediments dating from the Middle to Late Devonian. They were medium-to-large fish, with specimens E. pustulosus and E. licharevi approaching a total length of 3 metres. Complete exoskeletons with soft-tissue traces of E. calliaspis from Australia make this one of the best known dunkleosteids.
From the Frasnian Gogo Formation of northwestern Western Australia. This is the best known member of the genus with many articulated skulls and trunk armours in museum collections. Evidence of muscle fibres, circulatory structures and nerve tissue have been preserved representing some of the oldest known gnathostome soft tissue. The largest known skull is 272mm in length suggesting a total body length of roughly 1.5m. It was one of the largest fish in the Gogo assemblage. A reexamination of the family Dunkleosteidae posits the Late Emsian Xiangshuiosteus as E. calliaspis' sister taxon, and further implicates that E. calliaspis differs enough from other members of this genus to merit placement with its own genus.
A poorly known species from Russia, originally described from an isolated nuchal plate from the Frasnian of Timman with additional material from the Famennian of Lipetsk.
A medium-sized species from the Eifelian of south-central Manitoba, Canada. One of the earliest and most completely known members of the genus.
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