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Copyright © 2010-2011  by Mike Everhart


Page created  02/24/2010 - Updated 08/23/2011





LEFT: DMNS 57159 - A large and nearly complete Pentanogmius evolutus (Cope) discovered by Chuck Bonner in the Smoky Hill Chalk of western Kansas. The tail is reconstructed.

Class Osteichthyes (Bony Fish)

    Subclass Actinopterygii

        Subdivision Teleostei (teleost fish)

            Order Tselfatiiformes

                Family Plethodidae




The plethodids are a fairly common but relatively primitive group of fish that had skeletons composed of varying amounts of cartilage. In most cases only a small portion of the skull of the fish is preserved.  The Family Plethodidae includes the genera: Niobrara, Zanclites, Luxilites, Syntegmodus, Bananogmius, Pentanogmius ("Anogmius" evolutus), Martinichthys, Thryptodus, and Plethodus (a European genus).


Pentanogmius evolutus (Cope)


(This species was recently removed from the genus Bananogmius and renamed Pentanogmius evolutus by Taverne): A medium sized fish (4 to 6 feet) with a narrow, but deep body (like an Angel Fish) and jaws that had small, comb-like teeth. Most of the skeleton was bone and preserved well. A commonly found fossil is the palatine bone from the roof of the mouth. These have a pebbled surface that served as the base for hundreds of small, sharp teeth.


DMNS 57159-01a.jpg (28934 bytes) LEFT: DMNS 57159 is probably the best preserved, most complete example known of Pentanogmius evolutus. Shown here in right lateral view.  See more photos on the Keystone Gallery site

RIGHT: The skull of DMNS 57159 in right lateral view.

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LEFT: A close up of the dorsal fin (sail) of DMNS 57159, showing some of the scales preserved with the specimen.

RIGHT: A close-up of the jaws of DMNS 57159 showing the hundreds of tiny teeth that covered the jaw plates.

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Other specimens:

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LEFT: The exhibit specimen of Bananogmius (Pentanogmius) evolutus (FHSM VP-2182) in the collection of the Sternberg Museum. Although not fully displayed in this photograph of the reconstruction, the fish had a large, sail-like dorsal fin.

LEFT: Pentanogmius evolutus (FHSM VP-2117) in the collection of the Sternberg Museum of Natural History. The caudal fin (tail) is reconstructed. A close up view of the skull is HERE. A view of the teeth on the lower jaw of another specimen is HERE.

VP-2117Ga.jpg (19324 bytes) LEFT: The oddly crushed skull of FHSM VP-2117.

RIGHT: Close-up of one of the tooth bearing elements (left lower jaw?) of FHSM VP-2117 (note that teeth are missing).

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KUVP27815a.jpg (20632 bytes) LEFT: The skull of a large Bananogmius (Pentanogmius) evolutus - KUVP 27815 in left lateral view collected from the Pierre Shale in 1971 by the Orville Bonner party.  

RIGHT: The type specimen of Bananogmius ellisensis, preserved uncrushed in a concretion from the Blue Hill Shale Member of the Carlile Shale, Ellis County, Kansas (Middle Turonian in age).

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KUVP 445Ca.jpg (39104 bytes) LEFT: KUVP 445 - Right lateral view of a large Bananogmius (Pentanogmius?) specimen collected from a concretion in the Fairport Chalk Member (Middle Turonian) of the Carlile Shale, Russell County, KS. A detailed view of the skull is here.



Complete skulls of this strange, "battering-ram" fish are found rarely in the chalk, but mostly, only the rostrum at the tip of the skull survives. Unfortunately, the type specimen from the Kansas Chalk was destroyed in Germany during World War II.


LEFT: The skull of Thryptodus was heavily built, with a rostrum (the ethmoid bone) that is very massive.  Another unusual feature is the flat surface at the anterior end. How was this fish using its head?   Click HERE for a drawing of the skull of Thryptodus zitteli (from Loomis 1900). 

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LEFT: Complete skulls of Thryptodus have been found rarely in the chalk. The type specimen of Thryptodus zitteli (from Kansas and described by Loomis, 1900) was in a museum in Germany that was destroyed by Allied bombs during World War II.  In Kansas, these fish are only found in the lower 1/4 of the Smoky Hill Chalk and apparently become extinct by the end of Coniacian time (about 86 mya).  

More recently, Shimada and Schumacher (2003) described what is probably the oldest specimen of Thryptodus (FHSM VP-13996) from the Lincoln Limestone (Middle Cenomanian) Member of the Greenhorn Limestone Formation in Russell County, KS.  

thrypt1a.jpg (3173 bytes) A dorsal view of two 'noses' of Thryptodus zitteli  (FHSM VP-15571 / EPC 1995-34 and FHSM VP 15572 / EPC 1999-01), The anterior end is at the bottom of the scan. The size of the two fish must have been about the same.
thrypt2a.jpg (2797 bytes) A ventral view of the same two specimens.   Both of these specimens had other skull material and vertebrae associated with them, including a large, flat parasphenoid bone that covered the roof of the mouth.
thrypt3a.jpg (4018 bytes) The 'business end' of the two specimens showing the flat surface of the 'nose'.  What were these 'battering ram' like adaptations used for? Three views of a recently discovered Texas specimen are shown HERE, HERE, and HERE. Based on specimens I have seen recently from Texas, the species seems to be more common there.



These fish are somewhat mysterious in that they are only known to occur in Kansas, and only in a relatively narrow section (less than 20 ft in thickness) of the chalk. There are only two partial skulls of these fish known and few vertebrae. One of them (KUVP 497) is shown here.


Additional web page:

Martinichthys, mystery fish from the chalk


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LEFT: Martinichthys "noses" or "snouts" are usually the only part of the fish that is preserved. This is a drawing the type specimen (AMNH FF_2131) in the American Museum of Natural History (adapted from O.P. Hay, 1903). Note that both Cope and Hay described / figured this specimen "upside-down."


The specimen was collected by Charles H. Sternberg in June, 1877 and  described by Cope:   Cope, E. D., 1877. On the genus Erisichthe. Bull. U. S. Geol. and Geog. Surv. iii, article xx. pp. 821-823.

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These fish are usually represented in the fossil record only by a hard, blunt nose or rostrum. These rostra are often worn off at an angle as if the fish was using it to hammer at a hard substrate such as shells. The teeth are very small and comb-like in appearance. These fish only occur in a narrow zone in the lower 1/3 of the chalk. They are relatively rare (found only in Kansas) and there are less than 85 examples in collections. Most of the specimens are in the collections of the Sternberg Museum and the Museum of Natural History at the University of Kansas.


LEFT: FHSM VP-15567 - A recently discovered (2003), well-preserved Martinichthys brevis rostrum from the lower Smoky Hill Chalk of Gove County, KS.


Plethodid fossils: The most common plethodid fossils collected in the Smoky Hill Chalk are the parasphenoid bones... a flat, roughly rectangular bone on the roof of the mouth that is has hundreds of small pits.... These pits held small teeth when the fish was alive.


LEFT: The parasphenoid of a large plethodid fish in ventral (top) and dorsal views.  In life, each of the tiny pits would have held a small tooth that helped keep small prey from escaping from the fish's mouth.

RIGHT: Fragments of a plethodid parasphenoid bone.

LEFT: A fragment of a plethodid parasphenoid bone showing the distinctive pitted oral (occlusal) surface.

RIGHT: The fragmented skull of a plethodid - Pentanogmius evolutus. Note that the jaw fragments show the same pitted texture as the parasphenoid...and in fact have the same kind of villiform teeth....


Other Plethodids:


Relatively rare and unknown.  These specimens are in the KU Museum of Natural History:


KUVP 296a.jpg (19292 bytes) LEFT: The skull of Ferrifrons rugosus Jordan 1924 (KUVP 296), the anterior portion of a complete specimen (damaged). It was almost 75 years later that this species was determined to be a plethodid (see Arratia and Chorn. 1998. Journal of Vertebrate Paleontology, 18(2): 301-314. The original specimen is 24.5 inches long and was collected by H.T. Martin about 4 miles northeast of Gove, in Gove County, KS.

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LEFT: Niobrara encarsia Jordon 1924 - This specimen was collected by H.T. Martin in Trego County. Another view of the type specimen (KUVP 179).

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LEFT: Zanclites xenurus Jordon 1924 - This specimen was collected by H.T. Martin about 1/2 mile northeast of Gove, Gove County, KS.  Another view  of the type specimen (KUVP 52)

Other Oceans of Kansas webpages on Late Cretaceous fish:


Field Guide to Sharks and Bony Fish of the Smoky Hill Chalk



Kansas Shark Teeth

Cretoxyrhina and Squalicorax




Bony Fish


Pycnodonts and Hadrodus












Saurodon and Saurocephalus




Cope, E. D., 1877. On some new or little known reptiles and fishes of the Cretaceous No. 3 of Kansas. Proceedings of the American Philosophical Society 17(100):176-181. (Anogmius and Stratodus)

Cope, E. D., 1877. On the genus Erisichthe. Bulletin U. S. Geological and Geographical. Survey iii, article xx. pp. 821-823. (first description of Martinichthys)

Everhart, M. J. and P. A. Everhart, 1992. Oyster-shell concentrations; a stratigraphic marker in the Smoky Hill Chalk (upper Cretaceous) of western Kansas. Kansas Academy of Science, Transactions, 11(Abstracts):12.

Everhart, M. J. and P. A. Everhart, 1993. Notes on the biostratigraphy of the plethodid Martinichthys in the Smoky Hill Chalk (upper Cretaceous) of western Kansas. Kansas Academy of Science, Transactions, 12(Abstracts):36.

Everhart, M. J. and P. A. Everhart, 1994. Evidence of predation on the rare plethodid Martinichthys in the Smoky Hill Chalk (upper Cretaceous) of western Kansas. Kansas Academy of Science, Transactions, 13(Abstracts):36.

Fielitz, C. and K. Shimada, 1999. A new species of Bananogmius (Teleostei; Tselfatiformes) from the Upper Cretaceous Carlile Shale of western Kansas. Journal of Paleontology 73(3):504-511

Jordon, D.S. 1924. A collection of fossil fishes in the University of Kansas from the Niobrara Formation of the Cretaceous. University Kansas Science Bulletin, 15(2): 219-245.

Loomis, F. B. 1900. Die anatomie und die verwandtschaft der Ganoid- und Knochen-fische aus der Kreide-Formation von Kansas, U.S.A. Palaeontographica, 46: 213-283.

McClung, C. E. 1926. Martinichthys, a new genus of Cretaceous fish from Kansas, with descriptions of six new species. Proceedings of the American Philosophical Society 65 no. 5, (suppl.) 20-26, 2 pls.

Shimada, K. and B. A. Schumacher, 2003. The earliest record of the Late Cretaceous fish, Thryptodus (Teleostei: Tselfatiiformes), from central Kansas. Kansas Academy of Science, Transactions 106(1-2):54-58.

Taverne, L., 1999. Révision du genre Martinichythys, poisson marin (Teleostei, Tselfatiirormes) du Crétecé supérior du Kansas (États-Unis). Geobios 33(2):211-222. (Revision of the genus Martinichthys, marine fish (Teleostei, Tselfatiiformes) from the Late Cretaceous of Kansas (United States))

Taverne, L., 1999. Revision de Zanclites xenurus, Teleosteen (Pisces, Tselfatiiformes) marin du Santonian (Cretace superior) du Kansas (Etas-Unis). Belg. Journal Zool. 129(2):421-438. (in French)

Taverne, L., 2000. Tselfatia formosa, teleosteen marin du Cretace (Pisces, Actinopertygii), et la position systematique des Tselfatiiformes ou Bananogmiiformes. Geodiversitas 22(1):5-22. (in French)

Taverne, L. 2000. Osteology et position systematique du genre Plethodus, et des nouveaux genres Dixonangomius et Pentanogmius, poissons du Crétacé (Telostei, Tselfatiiformes). Biologisch Jaarboek Dodonaea 67(1):94-123. (in French)

Taverne, L. 2001. Révision de Niobrara encarsia téléostéen (Osteichthyes,Tselfatiiformes) du Crétacé supérieur marin du Kansas (Etats-Unis). Belg. Journal Zool., 131(1):3-16. (in French)

Taverne, L., 2001. Révision de Syntegmodus altus (Teleostei, Tselfathformes), poisson marin du Crétacé supérieur du Kansas (Etats-Unis). Cybium 25(3):251-260. (in French)

Taverne, L., 2001. Révision du genre Bananogmius (Teleostei, Tselfatiiformes), poisson marin du Crétecé supérior d'Amérique du Nord et d'Europe. Geodiversitas 23(1):17-40. (Revision of the genus Bananogmius (Teleostei, Tselfatiiformes), marine fish from the Upper Cretaceous of North America and Europe).

Taverne, L., 2002. Révision de Luxilites striolatus poisson marin (Teleostei, Tselfatiiformes) du Crétacé supérieur du Kansas (États-Unis). Belg. Journal Zool. 132(1):25-34.

Taverne, L., 2002. Étude de Pseudanogmius maiseyi gen. et. sp. nov., poisson marin (Teleostei, Tselfatiiformes) du Crétacé supérieur du Kansas (États-Unis). Geobios 35:605-614. (Study of Pseudanogmius maiseyi gen. and sp. nov., marine fish (Teleostei, Tselfatiiformes) from the Late Cretaceous of Kansas (United States) - Holotype is AMNH 8129.

Taverne, L. 2003. Redescription critique des genres Thryptodus, Pseudothryptodus et Paranogmius, poissons marins (Telostei, Tselfatiiformes) du Crétecé supériorr des Etats-Unis d’ Egypte et de Libye. Belgian Journal of Zoology 133(2):163-173.

Taverne, L. 2004. Ostéologie de Pentanogmius evolutus (Cope, 1877) n. comb. (Teleostei, Tselfatiiformes) du Crétacé supérieur marin des États-Unis. Remarques sur la systématique du genre Pentanogmius Taverne 2000. Geodiversitas 26(1):89-113. <LT>