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Ptychodus mortoni

The earliest occurrence of a giant, shell-crushing
shark in the Fort Hays Limestone



Copyright © 2011-2013 by Mike Everhart

Page Created 02/27/2010 - Last updated 08/19/2013






LEFT: An artist's reconstruction of Ptychodus mortoni - Sternberg Museum of Natural History, Hays, Kansas. While this painting is based on the body form of Heterodontus, the Port Jackson shark, there is evidence to indicate that Ptychodus would have looked more like a typical lamniform.

The recent discovery of the remains of a giant shell-crushing shark near the Kansas-Nebraska border resulted in the publication of this paper:

Shimada, K., Everhart, M.J., Decker, R. and Decker P.D. 2010. A new skeletal remain of the durophagous shark, Ptychodus mortoni, from the Upper Cretaceous of North America: an indication of gigantic body size. Cretaceous Research 31(2):249-254.

This specimen represents the earliest known and documented occurrence of this species of Ptychodus. It was found just above the contact of the Fort Hays Limestone with the Codell Sandstone Member of the Carlile Shale and would be early Coniacian in age (~89 ma). 

The first Ptychodus mortoni tooth was collected Alabama in the 1830s. The genus was poorly known in the North America at the time and the tooth was initially mis-identified.

LEFT: The first illustration of a Ptychodus mortoni tooth was published by Morton (1834) but was not further identified than "The palate bones of a Fish?" 

The same specimen was later sent to Dr. Mantell in England for identification. According to Morton (1842), the first tooth of Ptychodus mortoni was found by "Mr. Conrad in the older cretaceous strata at Prairie Bluff, Alabama." Manning (Pers. comm, 2002) indicated that is more likely that the tooth was from the Mooreville Chalk near Erie, Alabama.

Although Morton was the first to publish the name, he did so without a description of the tooth, assuming that Mantell had already published it. The species was officially described and named P. mortoni by Agassiz in 1839 (Vol. 3, p. 158, pl. 25, fig. 1-3).

Dr. G. M. Sternberg   and Professor B. F. Mudge) were among the first to collect Ptychodus teeth from the Smoky Hill Chalk. Mudge's contribution was acknowledged by Cope (1874) while Sternberg was credited by Leidy (1873), including several specimens that he illustrated.  In regard to the Ptychodus mortoni teeth, Leidy noted that. "The Smithsonian Institution has submitted to my examination a collection of fourteen specimens of teeth obtained by Dr. George M. Sternberg, United States Army, from the banks of Chalk Bluff Creek, a branch of Smoky Hill River, about sixty miles east of Fort Wallace, Kansas. The specimens were found in two parcels, each together, as if pertaining to two individuals."

Ptychodus mortoni is one of five ptychodontid species documented from the Smoky Hill Chalk Member of the Niobrara Chalk Formation (P. anonymus, P. latissimus, P. polygyrus and P. martini are the other four). From the number of single teeth and other remains that have been found, P. mortoni apparently was the most common species at this time, and probably the last species of Ptychodus to be found in the Western Interior Sea.  P. mortoni became extinct in the Western Interior Sea about the 86 million years ago, near the boundary between the Coniacian and Santonian stages.  No one is quite sure what they looked like, but from the shark-like vertebrae associated with several specimens, it appears that they may have been more shark-like in body form than ray-like. Judging from the size of some isolated teeth and this specimen of 539 associated teeth (KUVP 55270) in the University of Kansas Museum of Natural History collection, these fish probably grew to lengths of more than 5 meters. Here are some representative (and very worn) teeth from a specimen in the Sternberg Museum of Natural History that includes over 870 teeth (FHSM VP-335).

FHSM VP-335a.jpg (20436 bytes) LEFT: Three of 876 Ptychodus mortoni teeth from a single specimen (FHSM VP-335). Collected from Hells Bar Canyon in southwest Gove County in 1952.   Note the wear facet on the large tooth at far left.

RIGHT: Three of 112 teeth of a single specimen of Ptychodus mortoni (FHSM VP-336) from the same locality as above. This locality represents the last (uppermost) occurrence of Ptychodus in the Smoky Hill Chalk (Just below Marker Unit 10, Middle Santonian).

FHSM VP-336a.jpg (22789 bytes)

Since that time, many other specimens of Ptychodus mortoni have been collected.  

The most recent specimen is currently being collected from the middle of the Smoky Hill Chalk in Logan County, Kansas.

In November, 2008, Ramo and Pam Decker were prospecting along a newly exposed roadcut in Jewell County. What they found turned out to be the earliest documented example of Ptychodus mortoni.

Decker2008-01a.jpg (18306 bytes) LEFT: The preserved cartilage of the upper right jaw (palatoquadrate) of a large Ptychodus mortoni, complete with associated teeth was visible on the near vertical limestone wall.

RIGHT: They were able to establish the stratigraphic position of the specimen when they discovered the Codell Sandstone and Blue Hill Shale at the base of the limestone wall. Although the Codell Sandstone can be nearly 10 m (30 ft) thick in western Kansas, here it has been reduced to a thickness of about 10 inches.

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Decker2008-03a.jpg (17017 bytes) LEFT: Several Ptychodus mortoni teeth were discovered on the surface of the limestone and removed (U.S. quarter for scale = 1 inch or 2.54 cm in diameter).

RIGHT: Another view of the teeth.

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In April, 2009, Kenshu Shimada and I arranged to meet the Deckers, and then spent most the rest of the day recovering the specimen.

FtHaysPtychodus01a.jpg (21666 bytes) LEFT: Our first look at the roadcut on a bright, sunny. but relatively cold day in early April, 2009. Ramo and Pam Decker had discovered the specimen the previous year, after the highway had been widened and a fresh surface of nearly vertical limestone had been exposed. Unfortunately, it appeared that much of the specimen had been destroyed by the heavy equipment used to widen the road.

RIGHT: Ramo Decker points out the location of the specimen relative to the exposure of the basal Fort Hays Limestone. The specimen occurred about 1.7 meters above the contact of the Fort Hays with the underlying formation, the Codell Sandstone Member of the Carlile Shale.

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FtHaysPtychodus02a.jpg (15139 bytes) LEFT: Kenshu Shimada and Ramo Decker consider how best to remove the remains. The Fort Hays Limestone is much harder than the Smoky Hill Chalk, and has generally been avoided by collectors. The Deckers, however, have had good success in the Fort Hays, collecting only the second plesiosaur ever found there. (SEE Fort Hays Plesiosaur web page HERE)

RIGHT: We started out using hammer and chisel, and realized very quickly that it was going to be a long day. Ramo remembered that he had a portable drill in his truck and we decided to give it a try. Photo by Kenshu Shimada.

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FtHaysPtychodus04a.jpg (22063 bytes) LEFT: Using a half inch drill bit, we were able to drill a series of holes above and below the shark remains. We allowed enough space around the fossil to insure that we weren't damaging it, and were mostly successful in that regard.  The drill cut through the limestone fairly easily, but we used up three fully charged batteries in the process.

RIGHT: At this point we had removed quite a bit of matrix from under the calcified cartilage and encountered a number of teeth in the process (circled). It was slow going most of the day. Photo by Kenshu Shimada.

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FtHaysPtychodus05a.jpg (21867 bytes) LEFT: Here Kenshu Shimada is working with hammer and chisel to chip away at the limestone.

RIGHT: Ramo Decker examines the limited progress were had made. At this point, we had been working on the limestone for about 3 hours. The temperature had come up and there was no wind, so it was a very pleasant place to work. 

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FtHaysPtychodus06a.jpg (16790 bytes) LEFT: Still pounding rocks early in the afternoon. We continued to drill and chisel around the specimen, removing about a dozen teeth in the process, but were not making a lot of progress.  The limestone was a lot tougher than we had imagined.

RIGHT: Finally, about 3 PM, we managed to free the fragment of the right upper jaw and associated teeth from the limestone wall.  The photo shows the underside of the remains.

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FtHaysPtychodus08a.jpg (14259 bytes) LEFT: Here is a field phone of one of the teeth recovered with the specimen. (Scale = mm)

RIGHT: The sad news was that a small, anterior portion of the jaw (palatoquadrate) remained in the excavation. We coated it with preservative and covered it back up for a possible future dig, but it is really in a tough spot to work. We were also a little concerned with the possibility of falling rocks as we pounded on the limestone. A few years of natural weathering may help solve the problem.

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July, 2010

LEFT: The prepared portion of the upper jaw (palatoquadrate) of FHSM VP-17415, with four associated teeth.

RIGHT: A close-up of the same fragment. Click here for a picture of the other teeth.

LEFT: This is my initial arrangement the teeth in the upper jaw of another Ptychodus specimen collected in 2010 from the Smoky Hill Chalk. There are about 390 teeth in the arranged portion with two groups of 50 posterior laterals on each side. In life, there would be no spaces between the teeth in the jaw plate... and the little mesial teeth in the center row would not be visible (buried in gum tissue between the two rows of larger teeth. The reconstruction is 20 inches wide by 22 inches in length.

RIGHT: My reconstruction of the upper jaw (palatoquadrate) with an articulated  jaw plate, in ventral view, and it's relationship to a model of Ptychodus mortoni, based on: Shimada, K., Everhart, M.J., Decker, R. and Decker P.D. 2010. 

Suggested references on Ptychodus in Kansas and around the world:

Agassiz, J. L. R. 1833-1844. Recherches sur les Poissons Fossiles. 3: pp. vii + 390 + 32, Neuchàtel and Soleure.

Applegate, S. P. 1970. The vertebrate fauna of the Selma Formation of Alabama; Part VIII, The Fishes. Fieldiana Geology Memoirs 3(8):383-433, text figs. 174-204.

Cappetta, H. 1973.   Selachians from the Carlile Shale (Turonian) of South Dakota. Journal of Paleontology 47(3):504-514.

Cappetta, H. 1987. Chondrichthyes II - Mesozoic and Cenozoic Elasmobranchii. Gustav Fischer Verlag, Stuttgart and New York. 193 p., 148 fig.

Case, G. R. and D. R. Schwimmer. 1988. Late Cretaceous fish from the Blufftown Formation (Campanian) in western Georgia. Journal of Paleontology 62(2):290-301.

Case, G. R., T. T. Tokaryk and D. Baird.  1990.  Selachians from the Niobrara Formation of the Upper Cretaceous (Coniacian) of Carrot River, Saskatchewan, Canada. Canadian Journal of Earth Sciences 27:1084-1094.

ON LINE: Cicimurri, D. 2001. Cretaceous elasmobranchs of the Greenhorn Formation (Middle Cenomanian-Middle Turonian), western South Dakota. p. 27-43 in V. L. Santucci and L. McClelland (eds.), Proceedings of the Sixth Fossil Resource Conference, Geologic Resources Division Technical Report, NPS/NRGRD/GRDTR-01/01.

Cicimurri, D. J. 2004. Late Cretaceous chondrichthyans from the Carlile Shale (Middle Turonian to Early Coniacian) of the Black Hills region, South Dakota and Wyoming. The Mountain Geologist 41(1):1-16.

Cope, E. D. 1874.  Review of the Vertebrata of the Cretaceous period found west of the Mississippi River. U. S. Geological and Geographical Survey of the Territories, Bulletin 1(2):3-48.

Cope, E. D. 1875.  The Vertebrata of the Cretaceous formations of the West. Report of the U. S. Geological Survey of the Territories (Hayden). 2:302 pp., 57 pls.

Dibley, G. E.  1911.  On the teeth of Ptychodus and their distribution the English Chalk. Quarterly Journal of the Geological Society of London 67:263-277, pls. 17-22.

Everhart, M. J. 2003. First records of plesiosaurs from the lower Smoky Hill Chalk Member (Upper Coniacian) of the Niobrara Formation of western Kansas. Kansas Academy of Science, Transactions 106(3-4):139-148.

Everhart, M.J. 2013.The Palate Bones of a Fish?” – The First Specimen of Ptychodus mortoni (Chondrichthyes; Elasmobranchii) from Alabama. Bulletin of the Alabama Museum of Natural History 31(1):98-104.

Everhart, M. J. and Caggiano, T.   2004.  An associated dentition and calcified vertebral centra of the Late Cretaceous elasmobranch, Ptychodus anonymus Williston 1900. Paludicola 4(4),  p. 125-136.

Everhart, M. J., T. Caggiano, and K. Shimada. 2003.  Note on the occurrence of five species of ptychodontid sharks from a single locality in the Smoky Hill Chalk (Late Cretaceous) of western Kansas. (Abstract) Kansas Academy of Science, Transactions 22:29.

Evetts, M. J. 1979. Upper Cretaceous sharks from the Black Hills region, Wyoming and South Dakota. The Mountain Geologist, 16(2):59-66.

Gibbes, R. W., 1848. Monograph of the fossil Squalidae of the United States.  Jour. Acad. Nat. Sci. Phila. Vol. 1, 2nd Ser., pt. 2, art. 12:139-147. pls. 18-21 (Ptychodus polygyrus).

Hamm , S.A. 2010. The Late Cretaceous shark, Ptychodus rugosus, (Ptychodontidae) in the Western Interior Sea . Kansas Academy of Science, Transactions 113(1-2):44-55.

Hamm , S.A. 2010. The Late Cretaceous shark Ptychodus marginalis in the Western Interior Seaway , USA . Journal of Paleontology 84(3):538-554

Hamm, S. A. and M. J. Everhart.  1999.  The occurrence of a rare ptychodid shark from the Smoky Hill Chalk (Upper Cretaceous) of western Kansas. Kansas Academy of Science, Transactions (Abstracts) 18:34.

Hamm, S. A. and K. Shimada.  2002. Associated tooth set of the Late Cretaceous lamniform shark, Scapanorhynchus raphiodon (Mitsukurinidae), from the Niobrara Chalk of western Kansas. Kansas Academy of Science, Transactions 105(1-2):18-26. Hattin, D. E.  1982.  Stratigraphy and depositional environment of the Smoky Hill Chalk Member, Niobrara Chalk (Upper Cretaceous) of the type area, western Kansas. Kansas Geological Survey Bulletin 225:108 pp.

Herman, J.  1977.  Les sélaciens des terrains néocrétacés et paléocenes de Belgique et des contrées limitrophes. Eléments d’une biostratigraphique inter-continentale. Mémoires pour sérvir a l'explication des Cartes géologiques et miniéres de la Belgique. Service Géoligique de Belgique, Mémoire 15, 401 pp.

Kauffman, E. G.   1972.  Ptychodus predation upon a Cretaceous Inoceramus. Journal of Paleontology 15(3):439-444.

Leidy, J. 1868. Notice of American species of Ptychodus. Proceedings of the Academy of Natural Sciences of Philadelphia 20:205-208.

Leidy, J. 1873. Contributions to the extinct vertebrate fauna of the western territories. Report of the U.S. Geological Survey of the Territories (Hayden), 1:358 pp., 37 pls.

Lucas, S. G., B. S. Kues, S. N. Hayden, B. D. Allen, K. K. Kietzke, T. E. Williamson, P. Sealy, and R. Pence. 1988. Cretaceous stratigraphy and biostratigraphy, Cookes Range, Luna County, New Mexico. New Mexico Geological Society Guidebook, 39th Field Conference 143-167.

MacLeod, N. and B. H. Slaughter.  1980.  A new ptychodontid shark from the Upper Cretaceous of northeast Texas.  The Texas Journal of Science 32(4):333-335.

MacLeod, N. 1982. The first North American occurrence of the Late Cretaceous elasmobranch Ptychodus rugosus Dixon with comments on the functional morphology of the dentition and dermal denticles. Journal of Paleontology 56(2): 520-524.

Manning, E. M. and D. T. Dockery III. 1992. A guide to the Frankstown vertebrate fossil locality (Upper Cretaceous), Prentiss County, Mississippi. Mississippi Department Environmental Quality, Office of Geology Circular 4:43 pp., 2 pl.

Meyer, R. L.  1974.  Late Cretaceous elasmobranchs from the Mississippi and east Texas embayments of the Gulf Coastal Plain. Unpublished doctoral dissertation, Southern Methodist University, Dallas, 400pp.

Morton, S. G., 1834. Synopsis of the organic remains of the Cretaceous group of the United States. Key and Biddle, Philadelphia, 88 pp., 19 pl.

Morton, S. G. 1842. Description of some new species of organic remains of the Cretaceous group of the United States; with a tabular view of the fossils hitherto discovered in this formation. Journal of the Academy of Natural Sciences of Philadelphia. 8:207-227, 2 pl.

Mudge, B. F. 1876. Notes on the Tertiary and Cretaceous periods of Kansas. Bulletin of the U. S. Geological Survey of the Territories (Hayden), 2(3):211-221.

Nicholls, E. L.  1988.   New material of Toxochelys latiremis Cope, and a revision of the genus Toxochelys (Testudines, Chelonoidea). Journal of Vertebrate Paleontology 8(2):181-187.

Parkin, J. A., K. Shimada, and B. A. Schumacher.  2002.  Fossil fishes from the lowermost Greenhorn Limestone (Upper Cretaceous: Middle Cenomanian) in southeastern Colorado. Paper No. 187-15, Geological Society of American Annual Meeting.

Schwimmer, D. R., J. D. Stewart and G. D. Williams.  1997.  Scavenging by sharks of the genus Squalicorax in the Late Cretaceous of North America. Palaios 12:71-83.

Shimada, K. 1993. Upper Cretaceous elasmobranchs from the Blue Hill Shale Member of the Carlile Shale, Western Kansas. Kansas Academy of Science, Transactions 12(78).

Shimada, K. 1996. Selachians from the Fort Hays Limestone Member of the Niobrara Chalk (Upper Cretaceous), Ellis County, Kansas. Kansas Academy of Science, Transactions 99(1-2):1-15.

Shimada, K. and Everhart, M.J. 2003. Ptychodus mammillaris (Elasmobranchii) and Enchodus cf. shumardi (Teleostei) from the Fort Hays Limestone Member of the Niobrara Chalk (Upper Cretaceous) in Ellis County, Kansas. Kansas Academy of Science, Transactions 106(3-4):171-176.

Shimada, K., Everhart, M.J., Decker, R. and Decker P.D. 2010. A new skeletal remain of the durophagous shark, Ptychodus mortoni, from the Upper Cretaceous of North America: an indication of gigantic body size. Cretaceous Research 31(2):249-254.

Shimada, K. and D. J. Martin. 1993. Upper Cretaceous selachians from the basal Greenhorn Limestone in Russell Co., Kansas. Kansas Academy of Science, Transactions 12:78.

Skelton, L. H. 1996. A brief history of the Kansas Academy of Science. Kansas Academy of Science, Transactions 101(3-4):140-145.

Stewart, J. D. 1980. Reevaluation of the phylogenetic position of the Ptychodontidae. Abstracts of Papers, Kansas Academy of Science, Transactions 83(3):154.

Stewart, J. D.  1988.  Paleoecology and the first North American west coast record of the shark genus Ptychodus. Journal of Vertebrate Paleontology, 8:27A.

Stewart, J. D.  1990.  Niobrara Formation vertebrate stratigraphy. Pages 19-30, in S. C. Bennett, (ed.), Niobrara Chalk Excursion Guidebook. University of Kansas Museum of Natural History and Kansas Geological Survey.

Welton, B. J. and R. F. Farish.   1993.  The collectors guide to fossil sharks and rays from the Cretaceous of Texas. Horton Printing Company, Dallas, 204 pp.

Williamson, T. E., J. I. Kirkland and S. G. Lucas. 1993. Selachians from the Greenhorn cyclothem ("Middle" Cretaceous: Cenomanian-Turonian), Black Mesa, Arizona, and the paleogeographic distribution of Late Cretaceous selachians. Journal of Paleontology 67(3):447-474.

Williamson, T. E., S. G. Lucas and J. I. Kirkland. 1990. The Cretaceous elasmobranch Ptychodus decurrens Agassiz from North America. Geobios 24(5):595-599.

Williston, S. W. 1900. Cretaceous fishes [of Kansas]. Selachians and Pycnodonts. University Geological Survey Kansas VI pp. 237-256, with pls.

Woodward, A. S.  1887. On the dentition and affinities of the selachian genus Ptychodus Agassiz. Quarterly Journal of the Geological Society 43:121-131, 1 pl.

Woodward, A.S. 1904. On the jaws of Ptychodus from the chalk. Quarterly Journal Geological Society London 60:133-136, 1 fig., pl. XV.

LINKS:  Ptychodus mortoni - A shell-crushing shark from the Late Cretaceous of western Kansas

                Sharks teeth by the hundreds - A nearly complete specimen of Ptychodus anonymus from Kansas

               Ptychodus sharks teeth from around the world    including Ptychodus teeth from the English chalk.

              Jim Bourdon's Ptychodus pages -  The Life and Times of Long Dead Sharks

              Kansas Sharks - Kansas shark teeth from the Lower Permian through the Upper Cretaceous.

             More here on Ptychodus from the English Chalk  - Robert Randall's British Chalk Fossils web site