Macrosemius rostratus Agassiz 1844

Taxonomy

Kingdom: Animalia
Phylum: Chordata Haeckel 1874
Class: Actinopteri Cope 1871
Order: Semionotiformes Arambourg and Bertin 1958
Family: Macrosemiidae Thiollière 1858
Genus: Macrosemius
Species: Macrosemius rostratus
Author Citation Agassiz 1844

Geological Time Scale

Eon: Phanerozoic
Era: Mesozoic
Period: Jurassic
Sub Period: None
Epoch: Late
International Age: Tithonian

Stratigraphy

Weissjura Group
Altmühltal Formation

Biostratigraphy

Hybonoticeras hybonotum Zone
Subplanites rueppelianus Subzone

Provenance

Acquired by: Purchase/Trade

Dimensions

Length: 11 cm

Location

Obere Haardt Quarry
Langenaltheim Village
Bavaria
Germany

• haardt
• jurassic
• macrosemius
• solnhofen
• tff-oilshale-ch13

Comments

Taxonomy according to fossilworks.org.

Diagnosis for the genus according to Bartram, 1977 (p. 140, excerpts): "Large, elongate macrosemiid fishes; skull roof free from ganoine; supratemporals  greatly reduced; cephalic division of main lateral line and supratemporal commisure exposed by fenestrae; vomers bearing a transverse row of stout pointed teeth and a pair of large blunt teeth; ventral parts of anterior three infraorbitals expanded and overlapping the maxilla; gape very small, the quadrate articulation lying in front of the orbit ... dorsal fin single, extending from the occiput to the base of caudal fin, with between 32 and 39 rays each bearing denticles, leading ray proceeded by two basal fulcra, fringing fulcra absent; region immediately on either side of dorsal fin devoid of scales; scales rhomboid, secondary transverse rows intervening between primary rows above the lateral line, scales below lateral line forming a pattern of rectangles."

Line drawing from Bartram, 1977, p. 141.

Identified by oilshale using Bartram, 1977. Macrosemius is easily recognized among the fishes of Solnhofen by the continuous dorsal fin.

References:
Agassiz, L. (1843): Recherches Sur Les Poissons Fossiles. Tome I (livr. 18). Imprimerie de Petitpierre, Neuchatel xxxii-188.

Bartram, A. W. H. (1977): The Macrosemiidae, a Mesozoic family of holostean fishes. Bulletin of the British Museum (Natural History), Geology Series 29:137–234.

Ebert, M., Lane, Jennifer A. & Kölbl-Ebert, Martina (2016): Palaeomacrosemius thiollieri, gen. et sp. nov., a new Macrosemiidae (Neopterygii) from the Upper Jurassic of the Solnhofen Archipelago (Germany) and Cerin (France), with a revision of the genus Macrosemius. Journal of Vertebrate Paleontology, DOI: 10.1080/02724634.2016.1196081.