The Cenozoic fossil record of the teleost order Siluriformes (catfishes) is reviewed. Fossils from freshwater deposits

ranging from the late Paleocene through the Pleistocene represent two modern families: Ariidae and Ictaluridae.

The Eocene ariid genus Rhineastes, consisting of R. peltatus and R. smithi, has an uncertain relationship to modern

lineages. Rhineastes constitutes an exceptional freshwater record for its primarily marine family. Rhineastes radulus is a

nomen dubium. Bagre marinus and Arius felis, two living Atlantic and Gulf coast ariids, are known from late Pleistocene

deposits. The Miocene Arius stauroforus is close to A. felis.

Astephus and Hypsidoris are extinct early Cenozoic genera of the Ictaluridae. Astephus (Paleocene-Oligocene) consists

of three formally recognized species: A. antiquus (new combination), A. calvus, and A. resimus (described as new).

Rhineastes arcuatus andAmeiurusprimaevus are synonymized with A. antiquus. Much unnamed material is described

which points to a greater diversity of the genus. Hypsidoris from the Eocene is currently monotypic but a few poorly

preserved specimens may represent as yet unrecognized species.

Astephus and Hypsidoris share specializations of the pelvic fin and girdle with modern ictalurids. However, the extinct

genera are strikingly more primitive in their possession of vomerine teeth, constant development of a rib on the fifth

vertebra, and the absence of jaw muscle origin on the skull roof. Hypsidoris apparently has maxillary teeth, which

indicates that this dentition was retained beyond the "Diplomysres-grade" of catfish evolution. Astephus is probably

closer by common ancestry to modern ictalurids than is Hypsidoris.

The living ictalurids form a monophyletic group that is especially well characterized by extensive jaw muscle origin on

the skull roof. Seven major lineages of modern ictalurids are recognized: the subgenera Ictalurus and Amiurus of Ictalurns,

and the genera No turns, Pylodictis, Prietella, Satan, and Trogloglanis. The last three are rare troglody tes, none of

which is known as fossil.

The earliest known occurrence of the subgenus Ictalurus is with I. rhaeas (new combination) of the Oligocene Cypress

Hills Formation. Ameiurus cancellatus and Ameiurus maconnellii are synonymized with I. rhaeas. An unnamed Oligocene

fossil from South Dakota may also be an early representative of this lineage. Beyond these forms, the subgenus has

left an excellent record which documents a marked evolutionary conservatism. The distinctive Mio-Pliocene I. echinatus

(described as new) is one of two hewn extinct species of the subgenusIctalurus. Icr~liriiisl ambda, from the Pliocene,

is very similar to the living I. furcatus. The living channel catfish, I. punctatus, is known from well-preserved fossils

throughout the late Cenozoic, beginning in the middle Miocene. Ictalurus decorus from the Miocene is placed in synonymy

with I. punctatus. The Mexican I. dugesi has been recorded from lake deposits of late Pleistocene age.

The earliest known member of the subgenus Amiurus (bullheads) is the Oligocene Ictalurus pectinatus (new combination)

from the Florissant lake beds. Three of the four members of the I. catus species group (I. catus, I. serracanthus,

and I. brunneus) have left late Pleistocene remains in Atlantic and Gulf coast drainages. No known extinct species pertain

to this group.

The most diverse fossil record of any ictalurid group has been left by the I. natalis species group of Amiurus. The

three living species are known from the Pleistocene: I. natalis (Wisconsinan), I. nebulosus (Wisconsinan), and I. melas

(Kansan). There are six extinct species. Ictalurus macgrewi, described as new, is the oldest, coming from middle Miocene

deposits. Ictalurus lavetti, described as new, from the lower Pliocene is close to the lineage leading to I. natalis. The Mio-

Pliocene I. leidyi is described as a new species, lying close to the I. nebulosus-I. melas lineage. Ictalurus sawrockensis is a

Rio-Pleistocene form closely related to I. melas. Ictalunts benderensis has been placed in synonymy with I. sawrockensis.

Ictalurus peregrinus is described as new from the Pliocene of Oregon. This species, and the closely related I. vespertinus

from the Plio-Pleistocene of Idaho and Oregon, occur well outside of the geographical range of living ictalurids.

Noturus, the most species rich subgroup of the Ictaluridae, has left a meager Pleistocene fossil record.

The monotypic Pylodictis has a history that parallels that of Ictalurus punctatus. Pylodictis olivaris is known from

middle Miocene and younger deposits, and over this period it has undergone no detectable osteological change.

University of Michigan Deep Blue - digital version

Publisher: University of Michigan

Year of Publication: 1975

Location: Ann Arbor, MI

Volume Number: 11

# of Pages: 60