| Herasmius Temporal range: Devonian, | |
|---|---|
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| Life reconstruction of Herasmius granulatus | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | † Placodermi |
| Order: | † Arthrodira |
| Suborder: | † Brachythoraci |
| Family: | † Heterosteidae |
| Genus: | † Herasmius Ørvig, 1969 |
| Species | |
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Herasmius is an extinct genus of heterosteid placoderm from the Devonian period. Fossils have been discovered freshwater deposits in Norway and Canada.
The type species Herasmius granulatus was discovered in early Eifelian-aged freshwater deposits from the Wood Bay Group on the island of Spitsbergen in the Svalbard archipelago of Norway, and was described in 1966 by Ørvig based on an incomplete skull. [1] It was placed in the family Heterostiidae along with the genus Heterosteus . Herasmius is smaller than Heterosteus, and also differs by having a comparatively broader, shorter skull. [2] [1]
A second species, Herasmius dayi, was described in 2017 by Schultze & Cumbaa, found in Lower Devonian marine deposits of the Bear Rock Formation along the Anderson River of Northwest Territories, Canada. [3]
Dunkleosteus is an extinct genus of large arthrodire ("jointed-neck") fish that existed during the Late Devonian period, about 382–358 million years ago. It was a pelagic fish inhabiting open waters, and one of the first apex predators of any ecosystem.
Coccosteus is an extinct genus of arthrodire placoderm from the Devonian period. Its fossils have been found throughout Europe and North America. The majority of these have been found in freshwater sediments, though such a large range suggests that they may have been able to enter saltwater. It was a small placoderm, with Coccosteus cuspidatus measuring 29.6–39.4 cm (11.7–15.5 in) long.
Dinichthys is an extinct monospecific genus of large marine arthrodire placoderm from the Late Devonian measuring around 3 metres (9.8 ft) long. Fossils were recovered from the Ohio Shale Formation along the Olentangy River in Delaware County, Ohio.
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.
Rolfosteus is an extinct monospecific genus of arthrodire placoderm from the Early Frasnian stage of the Late Devonian period, found at the Gogo Formation of Western Australia.
Dicksonosteus is an extinct genus of basal arthrodire placoderm fish which lived during the Early Devonian period of Spitsbergen, Norway.
Eastmanosteus 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.
Bruntonichthys is an extinct monospecific genus of arthrodire placoderm from the Early Frasnian stage of the Late Devonian period. Fossils are found in the Gogo Formation of the Kimberley region of Australia. The skull is about 139 millimetres long, and had disproportionally large eye sockets. Researchers suggest it may have preyed on small mollusks.
Hadrosteus is an extinct monospecific genus of large arthrodire placoderm from the Late Frasnian Kellwasserkalk facies of Bad Wildungen, Germany. It had large, double-pronged inferognathals, and serrated edges along its mandible, strongly suggesting that it was a fish-eating predator. The head had a triangular snout, and the trunkshield was short, but high, with a median dorsal plate that was broader than wide. The average skull length is about 16 centimeters.
Stenosteus is an extinct monospecific genus of medium-sized selenosteid arthrodire placoderms of the Late Devonian period known from the Upper Famennian Cleveland Shale of Ohio. Estimated skull lengths range from 6 to 9 centimeters Most fossils of Stenosteus have been scraps of armor and portions of tooth-plates suggestive of Selenosteus. In 1996, enough material of a new species, S. angustopectus, was recovered to allow a reconstruction of armor that resembles that of Selenosteus.
Pachyosteus is an extinct monospecific genus of medium-sized selenosteid arthrodire placoderm known from the Upper Frasnian Kellwasserkalk facies of Late Devonian Bad Wildungen, Germany and from the Famennian portions of the Holy Cross Mountains of Poland. The type species Pachyosteus bulla has a broad skull about 7 to 10 centimetres long, a comparatively long median dorsal plate, and a short rostral plate that meets the pineal plate.
Xiangshuiosteus wui is an extinct monospecific genus of brachythoracid arthrodire placoderm from the Late Emsian stage of the Early Devonian epoch, discovered in Wuding County of Yunnan province, China. It has recently been reassessed as a dunkleosteid.
Protitanichthys is an extinct genus of comparatively large coccosteid arthrodire placoderms from the Middle Devonian of the eastern United States. Fossils are found primarily in the Eifelian-epoch aged Delaware Limestone of Ohio, and the Lower Givetian-aged Rockport Quarry Limestone of Michigan
Homostiidae is a family of flattened arthrodire placoderms from the Early to Middle Devonian. Fossils appear in various strata in Europe, Russia, Morocco, Australia, Canada and Greenland.
Heterosteidae is an extinct family of moderately large to giant, flattened, benthic arthrodire placoderms with distinctive, flattened, triangular skulls that are extremely broad posteriorly, but become very narrow anteriorly.
Coccosteidae is a family of arthrodire placoderms from the Early to Late Devonian. Fossils appear in various strata in Europe, North America and China.
Heterosteus is an extinct genus of heterosteid placoderm of the Middle Devonian known from remains discovered in Europe and Greenland. According to Denison, 1978, Heterosteus might have been planktivorous, along with Homosteus, and Titanichthys.
Golshanichthys is an extinct monospecific genus of dunkleosteid from the Late Devonian: Frasnian stage from Kerman, Iran.
Panxiosteus is an extinct monospecific genus of placoderm arthrodire from the Middle Devonian: Givetian stage of Yunnan province, China.
Torosteus is an extinct genus of arthrodire placoderm from the Early Frasnian stage of the Late Devonian period. Fossils are found in the Kimberley region of Australia.
