Ischyodus bifurcatus Case, 1978

Remarks

• Ratfish are really strange looking!

• Tony Fabian provided us with an great assortment and quality of material from the Monmouth Group, Navesink Formation (Monmouth County, NJ) for photographing.  Many thanks Tony!

• The manibular tooth plates are made of these wing-like bones that have several crushing surfaces called Tritors.  The tritors are those white areas in the jaw, and you can see a closeup of one in the bottom photos.  In the middle photos, some of the tritors are missing, leaving those light-colored shallow cavities that you can see.

• One striking aspect of the "teeth" is that the crushing surfaces are all at different heights in the jaw, instead of in a row, as most teeth are.  Pretty cool!!

General Info

Synonyms

• Chimaera
• "Ratfish"
• 1978 Ischyodus bifurcatus Case
• 1979 Ischyodus bifurcatus Case; Case
• 1991 Ischyodus bifurcatus Case; Case
• 1992 Ischyodus bifurcatus Case; Case and Schwimmer
• 1995 Ischyodus bifurcatus Case; Case

Stratigraphic Occurrence

• Asuncion Group, Chico Formation of Northern California
• Monmouth Group, Navesink Formation of NJ and Delaware
• Monmouth Group, Mount Laurel Formation of New Jersey
• Montana Group, Judith River Formation of Montana
• Maastricht Fm, d'Obourg Chalk Mbr of Belgium
• Taylor Group, Marlbrook Marl of Arkansas
• Matawan Group, Woodbury Formation of New Jersey
• Matawan Group, Merchantville Formation of Delaware
• Selma Group, Blufftown Formation of Georgia

Age

• Ischyodus bifurcatus Case ranges from about latest Santonian time (assuming that I. bifurcatus Case ranges down to the base of the Merchantville Fm.) to at least middle Maastrichtian time, and may have survived right up to the K-T boundary (~84-68 mya)

Geographic Occurrence (not an all-inclusive list)

• Blaine County, MT

• Butte County, CA

• Clark County, AR

• Gloucester County, NJ

• Monmouth County, NJ

• New Castle County, DE

• Stewart County, GA

Remarks

       For more information, see:

• Case, G. R.  1978.  Ischyodus bifurcatus, A New Species of Chimaeroid Fish From the Upper Cretaceous of New Jersey.  Géobios 11 (1), 21–29.
• Case, G. R.  1979.  Additional Fish Records From the Judith River Formation (Campanian) of Montana.  Géobios 12 (2), 223–233.
• Case, G. R.; Schwimmer, D. R.  1992.  Occurrence of the Chimaeroid Ischyodus bifurcatus Case in the Cusseta Formation (Upper Cretaceous, Campanian) of Western Georgia and Its Distribution.  Journal of Paleontology 66 (2), 347–350.