Belonostomus (from , 'dart' and 'mouth') is a genus of prehistoric ray-finned fish that was described by Louis Agassiz in 1844. It is a member of the order Aspidorhynchiformes, a group of fish known for their distinctive elongated rostrums.
Fossils of Belonostomus have been found worldwide in marine deposits, although some species are known from freshwater habitats. The oldest known species are from the Upper Jurassic of Germany and England, with the youngest known species from the late Maastrichtian. One specimen has been recovered from the late Paleocene-aged Tongue River Member of North Dakota, which would suggest that this genus was the only aspidorhynchean to survive into the Cenozoic, although it is possible this fossil may have been reworked from earlier formations.
It likely consumed plankton or other small fish, though one specimen from the Late Jurassic of Germany was found with the rhynchocephalian Homoeosaurus as stomach contents.
Taxonomy
Known Belonostomus species are:
- B. aciculiferus <small>Nessov, 1985</small> - Turonian of Uzbekistan (Bissekty Formation)
- B. attentuatus <small>Dixon, 1850</small> - Cenomanian of England (English Chalk) (nomen dubium)
- B. cinctus <small>Agassiz, 1837</small> - Cenomanian of England (English Chalk) and Italy (Scaglia Rossa Formation)
- B. comenianus <small>(Kner, 1867)</small> - Cenomanian of Slovenia (Komen Limestone) (syn: Hemirhynchus comenianus <small>Kner, 1867</small>)
- B. crassirostris <small>Costa, 1853</small> - Cenomanian of Morocco (Jbel Tselfat) and Italy (Pietraroja Plattenkalk)
- B. dalmaticus <small>GorjanoviÃÂ-Kramberger, 1895</small> - Cenomanian of Croatia
- B. dorsetensis <small>Woodward, 1895</small> - Kimmeridgian of England (Kimmeridge Clay)
- B. helgolandicus <small>Taverne & Ross, 1973</small> - Aptian of Germany
- B. hooleyi <small>Woodward, 1916</small> - Barremian of England (Wealden Formation)
- B. genevensis <small>(Pictet, 1858)</small> - Early Cretaceous of Switzerland (Voirons Flysch) (syn: Aspidorhynchus genevensis <small>Pictet, 1858</small>) (nomen dubium)
- B. kochi <small>Agassiz, 1843</small> - Tithonian of Germany (Solnhofen Limestone) (syn: B. kocki <small>Agassiz, 1843</small>)
- B. lamarquensis <small>Bogan et al., 2011</small> - Campanian/Maastrichtian of Argentina (Allen Formation)
- B. leptosteus <small>Agassiz ex Egerton, 1836</small> - Bathonian of England (Stonesfield Slate) (nomen dubium)
- B. lesinaensis <small>Bassani, 1882</small> - Cenomanian of Croatia and Slovenia (Komen Limestone) (possibly synonymous with B. crassirostris) (syn: Hemirhynchus heckelii <small>Kner, 1867</small>)
- B. longirostris <small>Lambe, 1902</small> - Santonian to late Maastrichtian of the Americas, including Alberta & Saskatchewan, Canada (Milk River Formation, Belly River Group and Frenchman Formation), Montana, North Dakota & Wyoming, US (Mesaverde, Judith River, Lance, and Hell Creek Formations), Argentina (Allen Formation), and Chile (Quiriquina Formation)
- B. marquesbritoi <small>Taverne & Capasso, 2012</small> - Campanian/Maastrichtian of Italy (Calcare di Melissano Formation)
- B. matteuzi <small>GorjanoviÃÂ-Kramberger, 1895</small> - Cenomanian of Slovenia
- B. muensteri <small>Agassiz, 1844</small> - Tithonian of Germany (Solnhofen Limestone) (syn: B. speciosus <small>Wagner, 1863</small>)
- B. novaki <small>GorjanoviÃÂ-Kramberger, 1895</small> - Cenomanian of Croatia
- B. ornatus <small>Felix, 1891</small> - Berriasian of Mexico (Sabinal Formation) (nomen dubium)
- B. sphyraenoides <small>Agassiz, 1844</small> - Tithonian of Germany (Solnhofen Formation) (syn: B. brachysomus <small>Agassiz, 1837</small>, B. angustus <small>zu Münster ex von Leonhard & Bronn, 1842</small>)
- B. tenuirostris <small>(Agassiz, 1833)</small> - Tithonian of Germany (Solnhofen Formation) and France (paleontological site of Cerin) (type species) (syn: Aspidorhynchus tenuirostris <small>Agassiz, 1833</small>, B. subulatus <small>Agassiz, 1834</small>, B. ventralis <small>Agassiz, 1834</small>)
Indeterminate remains are known from worldwide, including the Gulf Coast of the United States (Alabama, Arkansas, and Texas), Australia, Belgium, Lebanon, and Russia.The former species B. acutus <small>Agassiz, 1844</small> (syn: B. tenellus <small>Agassiz ex Egerton 1841</small>) and B. anningiae <small>Agassiz, 1843</small> from the early-mid Jurassic of England are now thought to be species of the unrelated saurichthyiform Saurorhynchus. The former species B. carinatus <small>Mawson and Woodward, 1907</small> from the Hauterivian of Brazil is now thought to be a stem-gar in the family Obaichthyidae. The former species B. indicus <small>Woodward, 1890</small> is now thought to be a true gar, Lepisosteus indicus. The former species B. microcephalus <small>Winkler, 1862</small> from the Tithonian of Germany is now thought to be a junior synonym of Aspidorhynchus acustirostris, while B. flexuosus <small>Philips, 1871</small> is one of A. crassus. The former species B. sweeti <small>Etheridge & Woodward, 1892</small> is now placed in Richmondichthys. The former species B. pygmaeus <small>Winkler, 1874</small> from the Tithonian of Germany is thought to be an immature specimen of one of the other Solnhofen Belonostomus species.
References