Herasmius

Herasmius Temporal range: Devonian, 422.9–385.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N
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
Herasmius granulatus Orvig, 1969 (Type) Herasmius dayi Schultze & Cumbaa, 2017

Herasmius is an extinct genus of heterosteid placoderm from the Devonian period. Fossils have been discovered freshwater deposits in Norway and Canada.

Description

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]

References

1. Zhu, You-An; Zhu, Min; Wang, Jun-Qing (1 April 2016). "Redescription of Yinostius major (Arthrodira: Heterostiidae) from the Lower Devonian of China, and the interrelationships of Brachythoraci". Zoological Journal of the Linnean Society. 176 (4): 806–834. doi:10.1111/zoj.12356. ISSN 0024-4082.
2. Denison, Robert (1978). Placodermi Volume 2 of Handbook of Paleoichthyology. Stuttgart New York: Gustav Fischer Verlag. p. 66. ISBN 978-0-89574-027-4.
3. Schultze, Hans-Peter; Cumbaa, Stephen L. (26 April 2017). "A new Early Devonian (Emsian) arthrodire from the Northwest Territories, Canada, and its significance for paleogeographic reconstruction". Canadian Journal of Earth Sciences. 54 (5): 461–476. Bibcode:2017CaJES..54..461S. doi:10.1139/cjes-2017-0013. hdl:1807/76893.