Blochius is an extinct genus of billfish from the Eocene. It is only known from the Monte Bolca deposits in Italy, and was likely restricted to shallow, tropical waters of the Tethys Ocean.[1][2]
Discovery
The existence of Blochius was known as early as 1709, where it is mentioned in a written account by Johann Jakob Scheuchzer, who identified a fragment of a Blochius skeleton and identified it as being either related to the Xiphias (swordfish) or Siluro (catfish). It was not until the advent of Linnean taxonomy that it properly received a scientific name by Giovanni Serafino Volta, who named Blochius in 1796 after pioneering ichthyologist Marcus Elieser Bloch.[3]
Taxonomy
It is one of two known definite genera in the family Blochiidae, alongside Loancorhynchus from earlier in the Eocene of Chile.[4] The indeterminate remains of a Blochius-like fish are known from the Late Paleocene of Peru.[5] Indeterminate blochiid remains are also known from the middle Eocene of Uzbekistan, and from the latest Paleocene/earliest Eocene Danata Formation of Turkmenistan.[6][7] Other potential blochiids such as Acestrus, Aglyptorhynchus, Hemirhabdorhynchus, Cylindracanthus and Congorhynchus are based on highly fragmentary remains and it is thus uncertain if they are blochiids, or even billfish for the last two.[2][8][3] Some authorities have found the Blochiidae to be basal billfish not closely related to any extant groups, whereas others find them to be more closely related to swordfish (Xiphiidae) than to marlins & sailfish (Istiophoridae).[9]
Blochius had a very slender elongated body, a narrow head with elongated upper and lower jaws and large eyes. Much like its modern relatives such as swordfish, it had an elongated rostrum.[2][10] Although generally small in size at around 2 feet in length, it could reach a maximum length of 2.155 metres (7.07 ft). The rostrum generally comprised 40% of the body length.[3][11] It likely hunted in a manner similar to modern needlefish.[3][11]
Bibliography
G. S. Volta, Ittiolitologia Veronese del museo Bozziano ora annesso a quello del conte Giovambattista Gazola e di altri gabinetti fossili veronesi con la versione latina, Stamperia Guiliari, Verona, 1796–1808, 323 pp.
C. R. Eastman, Catalog of fishes in the Carnegie Museum. Part 1. Fishes from the Upper Eocene of monte Bolca. Mem. Carnegie Mus., Pittsburgh 4, 1911. pp. 349–391.
W. Landini e L. Sorbini. 1996. Ecological and trophic relationships of Eocene monte Bolca (Pesciara) fish fauna, pp 105–112 in A. Cherchi, ed. Autoecology of selected fossil organisms: achievements and problems. Boll. soc. Paleo. Italiana spec 3.
H. L. Fierstine e K. A. Monsch. 2002. Redescription and phylogenetic relationships of the Family Blochiidae (Perciformes: Scombroidei), middle Eocene, monte Bolca, Italy. Miscellanea Paleontologica, studi e ricerche sui giacimenti terziari di Bolca, mus. civico storia nat. Verona 9: 121–163.
H. L. Fierstine, 2006. Fossil history of billfishes (Xiphioidei). Bull. Mar. Sci., 79(3): 433–453.
Harry L. Fierstine: Fossil History of Billfishes (Xiphioidei). Bulletin of Marine Science, Volume 79, Issue 3, January 2006, Seiten 433-453 AbstractArchived 2019-02-07 at the Wayback Machine
Karl Albert Frickhinger: Fossilien Atlas Fische, Mergus-Verlag, Melle, 1999, ISBN3-88244-018-X
