Hypsidoris farsonensis Lundberg & Case, 1970

Taxonomy

Catfish

Kingdom: Animalia
Phylum: Chordata
Class: Actinopteri Cope 1871
Order: SILURIFORMES (sensu Chardon, 1968)
Family: Hypsidoridae Grande 1987
Genus: Hypsidoris
Species: Hypsidoris farsonensis
Author Citation Lundberg & Case, 1970

Geological Time Scale

Eon: Phanerozoic
Era: Cenozoic
Period: Paleogene
Sub Period: None
Epoch: Eocene
International Age: Ypresian

Stratigraphy

Green River Formation
Laney Member

Provenance

Acquired by: Purchase/Trade

Location

Farson fish beds
Farson
Wyoming
United States

• catfish
• farson
• green river
• hypsidoris
• tff-oilshale-ch1054

Comments

 

Astephus and Hypsidoris are both members of the Family Ictaluridae, native to North America. Green River catfish are easily recognized by their stout dorsal and pectoral spines, scale less bodies and broad skull. Ictalurid species have four pairs of barbels (or whiskers).  Like modern catfish, they possessed a vibration sensitive organ called the Weberian apparatus. The Weberian apparatus consists out of specialized vertebrae at the front of the spinal column which passed vibrations to the inner ear using the swim bladder as a resonance chamber. The structure essentially acts as an amplifier of sound waves that would otherwise be only slightly perceivable by the inner ear structure alone. Normal size of Astephus is around 15cm and rarely exceeds 18cm, maximum total length is about 30cm. Hypsidoris seems to be in the same size range. The easiest way to distinguish Hypsidoris from Astephus is by counting anal fin rays; H. farsonensis has about 15 to 17 whereas A. antiquus has about 26.

The diet of Green River catfish was probably similar to existing ictalurids consisting of plants, small fish, crayfish and mollusks. Astephus and Hypsidoris were probably bottom feeders. Astephus antiquus is unknown as a body fossil in the middle unit of Fossil Butte Member, and only one specimen has been found in all of Fossil Lake, although it is abundant in Lake Gosiute strata. The discovery of numerous and widespread fossil catfish in oil shale units of the Laney Member of the Eocene Green River Formation is evidence of aerobic conditions in the hypolimnic waters of ancient Lake Gosiute. Hypsidoris farsonensis has only been found in Lake Gosiute deposits of the Green River Formation, east of Fossil Lake.

Taxonomy from Grande 1987.

Family Diagnosis from Grande 1987, p. 28: "A family of catfishes that differs from all other known catfishes by the following combination of characters. Unlike all families (at least primitively) but Diplomystidae, †hypsidorids have a maxilla that bears many close-set conical teeth (the teeth are essentially the same shape and size as those observed here in Diplomystes; a relatively large maxilla that is expanded distally and has a long mesially directed ventral palatine condyle (maxilla not reduced in size or thin and rod-like as in most living catfishes); and a palatine that is flattened anteriorly, where it is greatly expanded to form two condyles for the maxilla (vs. a relatively simple rod-like shape without a broad anterior end as in most other catfishes). Unlike Diplomystidae, †Hypsidoridae have a single suprapreopercle (Diplomystes has 2); six infraorbital bones (Diplomystes has at least 9); a principal caudal fin-ray count of 8/9 (Diplomystes has 9/9); and a posterior extension of lamellar bone over the ventral surface of the fifth and sixth centra from more anterior vertebrae (Diplomystes has no such bone). The shape of the lower jaw in †H. farsonensis appears to be unique among Siluriformes. It has an extremely high coronoid process that is higher than in any other catfish observed here that also has a long dentary (Trogloglanis also has an extremely high coronoid process, but the dentary is very short: see Fig. 8)."

Emended Species Diagnosis from Grande 1987, p. 28: "Same as for family (monotypic). The original description included a particular range of pectoral and dorsal spine length measurements as a diagnostic character, but based on additional material this is more variable within the species than previously recorded by Lundberg and Case (1970:452) and Grande (1984:116). See text for further explanation."

Line drawing from Grande 1987, p. 29:

Identified by oilshale.

References:
Grande, L. and J. G. Lundberg. 1988. Revision and redescription of the genus Astephus (Siluriformes: Ictaluridae) with a discussion of its phylogenetic relationships. J. Vert. Paleont 8:139–171.
Grande, L. 1987. Redescription of Hypsidoris farsonensis (Teleostei: Siluriformes), with a reassessment of its phylogenetic relationships. Journal of Vertebrate Paleontology 7:24–54.
Grande, L. and M. C. C. de Pinna. 1998. Description of a second species of the catfish Hypsidoris and a reevaluation of the genus and the family Hypsidoridae. Journal of Vertebrate Paleontology 18:451–474.