Marine Turtles

Marine turtles from the Western Interior Sea

Mike Everhart

Last updated 05/02/2008

LEFT: A five-foot-long Hesperornis regalis swims over the top of a giant Protostega gigas turtle in the middle of the Western Interior Sea during the early Campanian. Painting copyright © 2005 by Dan Varner and may not be reproduced in any form without the express written permission of Dan Varner and Mike Everhart.

There were two major groups of marine turtles that lived in the Western Interior Sea during the Late Cretaceous; the Toxochelyids and the Protostegids. These turtles probably ate seaweed and jellyfish, or may have scavenged floating carcasses, much the same as modern turtles. Although their remains are found in the middle of the sea, the females must have periodically migrated hundreds of miles to the east or west to find sandy shorelines where they could lay their eggs above the high tide mark. Turtle bone found in the Smoky Hill Chalk is dense and very finely grained, and is readily differentiated from mosasaur or plesiosaur bone.

Toxochelys latiremis Cope is the most common species of marine turtle found in the Smoky Hill Chalk in western Kansas.

Toxochelyids - Toxochelys was a small to medium sized turtle (up to 2 m (6 ft) in length) that is found throughout the chalk. This turtle was similar in outward appearance to a modern leatherback turtle (i.e. the Green Turtle, Dermochelys coriacea) but is not closely related. Common fossils include shell, limb and skull material. Several species have been described from the chalk but T. latiremis is the most common.

LEFT: The first complete skull of Toxochelys latiremis, found by B. F. Mudge about 1876 (From Hay, 1908). It is interesting to note that skull and limb material is found far more often than the carapace and plastron that covered the turtle's body. Composed of thin bone under a leathery covering, it is likely that the bodies of these turtles were quite edible to sharks, large fish, and mosasaurs.

RIGHT: Drawing of the skull of Toxochelys latiremis Cope - Dorsal view, from Williston, 1901). Click to enlarge. This figure is drawn from KUVP 1203 and KUVP 1212. KUVP 1203 is currently on exhibit (and difficult to photograph!)

	LEFT and RIGHT: Dorsal and ventral views of a small Toxochelys latiremis skull (VP -13449) that I collected in Gove County, Kansas in 1988. The skull was found lying upside down on top of the chalk, where it had recently eroded out, in one piece, and with the lower jaw still in place. Click here for a ventral view of the skull without the lower jaw; and here for a view of lower jaw. Parts of the anterior portion of the turtle's shell, neck vertebrae and front limbs were also found. It appeared that the skull, neck and front part of the shell had been severed by the bite of something fairly large... perhaps a Ginsu shark (Cretoxyrhina mantelli).
	LEFT: Some of the limb bones of a medium sized Toxochelys latiremis (FHSM VP-700) in the collection of the Sternberg Museum of Natural History. The specimen was collected by M.C. Bonner in 1956 along Twin Butte Creek in eastern Logan County.

	*LEFT: The disarticulated shell and limb bones of a juvenile Toxochelys latiremis* (KUVP 1244) from the Smoky Hill Chalk. RIGHT: A dorsal view of the skull of Toxochelys "brachyrhina" (KUVP 1215). This specimen was collected by E. P. West in Gove County sometime before 1898. See type specimen below.**
	LEFT: Dorsal view of the type specimen of Toxochelys "brachyrhina" Williston (KUVP 1212). Discovered in 1891 by S.W. Williston in the Smoky Hill Chalk of Gove County, KS. Toxochelys "brachyrhina" is a junior synonym of T. latiremis Cope. *RIGHT: Ventral view of the type specimen of Toxochelys* "brachyrhina" Williston (KUVP 1212), including the lower jaw.**
	*LEFT: A well preserved skull of Toxochelys latiremis* in dorsal view... found as stomach contents of a shark (Squalicorax falcatus) in Logan County, Kansas (see Druckenmiller, et al., 1993) for more information. (University of Wisconsin-Madison, Museum of Geology)** RIGHT: Another view of the same specimen, showing other turtle bones and a fish vertebra (Ichthyodectes). The lower jaw had been separated from the skull and is shown here (upper right).

Three views of a large toxochelyid skull (CMC VP-6947) from the Pierre Shale of Logan Co., KS. Donated by Pete Bussen to the Cincinnati Museum Center.

LEFT: Dorsal and ventral views of a smaller Toxochelyid skull (CMC VP-6948) from the Sharon Springs Member of the Pierre Shale of Logan Co., KS. Donated by Pete Bussen to the Cincinnati Museum Center. Note poor preservation due to the intrusion of calcite crystals into the bone. This a common problem in all vertebrate remains from the Pierre Shale in Kansas. It is of some interest to note that the type specimen of Toxochelys latiremis (AMNH 2362) was actually collected from the Pierre Shale by B. F. Mudge near McAllaster Butte in Logan County, and not in the Smoky Hill Chalk as is often assumed (see Cope 1875; Nicholls, 1988).

LEFT: PR 123 - Right and left humeri of Toxochelys latiremis collected by George F. Sternberg from Logan County in the collection of the Field Museum, Chicago, IL.

RIGHT: PR 123 - Cervical vertebrae from the same specimen (Toxochelys latiremis).

LEFT: (FHSM VP-17018) A shell fragment from a large turtle, probably Toxochelys, found in Gove County (Late Coniacian). Note the bite marks from a large shark (Cretoxyrhina) on the right side of the fragment in the lower frame. This piece was the only part found of the turtle. The thin shells of even the largest turtles were no match for the strong jaws and sharp teeth of predators. Go here for a photo of a modern Loggerhead turtle bitten by a large shark, most likely a Great White. (Photo by Adam Mckinnon, used with permission).

RIGHT: (FHSM VP-1344_) The anterior portion of a lower jaw (right and left dentarys) of a large Toxochelys turtle found in the upper chalk (MU 17) of Logan County.

LEFT: Clockwise, dorso left-lateral view, ventral right-lateral view and dorsal view of a slightly crushed cervical (?) vertebra from a recently discovered Toxochelys latiremis specimen.

RIGHT: The partial carapace of a very small toxochelyid turtle that I found in 1996. The shell would have been about 3 inches wide and less than 6 inches long. The Western Interior Sea would not have been a good place to be for a turtle this size! The remains indicate that it was probably bitten in two by a larger predator, probably a shark.

LEFT: A cast of a small but complete specimen of Toxochelys latiremis in dorsal view. Another view is HERE. The upper shell is called the carapace.

RIGHT: The same cast of a small but complete specimen of Toxochelys latiremis in ventral view. The lower shell is called the plastron. Cast by Triebold Paleontology, Inc.

Note that Gudger (1949) reported the remains of marine turtles in the stomachs of 5 out of 5 Tiger sharks (Galeocerdo tigrinus) that were caught near Key West, Florida. It appears that things haven't improved much for turtles in 85 million years.

Ctenochelys stenopora

LEFT: The carapace and lower jaw of a small Ctenochelys stenopora turtle in the collection of the Keystone Gallery. The carapace is about 8 inches long. See Sternberg (1907) for a brief description of this turtle.

RIGHT: A detail from a mural painted by Charles Bonner (Keystone Gallery) showing what these small turtles might have looked like when they were living in the Western Interior Sea.

BELOW: Ctenochelys stenopora (originally Toxochelys bauri Wieland 1905) was discovered by C. H. Sternberg on December 14, 1904, near Monument Rocks in Gove Co., KS. (Yale Peabody Museum collection; YPM-1786)

EXTREME LEFT: Dorsal view of the carapace of Toxochelys bauri.

FAR LEFT: Left lateral view of same specimen.

LEFT: Ventral view of same specimen, showing the hyoplastron and hypoplastron.

RIGHT: a nearly complete carapace and plastron of Ctenochelys stenopora in the University of Wisconsin-Madison collection.

Cyanocercus incisus - The second turtle to be described from the Smoky Hill Chalk.

While Cope was collecting fossils in western Kansas in 1871, one of the Army personnel (Sgt. William Gardner) assigned to escort him found the tail vertebrae of a small turtle "two or three hundred yards" from the type locality of Protostega gigas, southeast of Fort Wallace. Although the remains were fragmentary, Cope (1872) described and named the species Cyanocercus incisus in an article read before the American Philosophical Society on January 19, 1872. Lane (1946) considered them to be very similar to Toxochelys, and if so, the name would have precedence by date.

LEFT: The caudal vertebrae of Cyanocercus incisus, republished by Williston (1898) from Cope (1875, Plate VIII).

Porthochelys laticeps Williston 1901 - Holotype

Porthochelys laticeps (KUVP 1204) is a one-of-a-kind specimen... the only one collected so far.

LEFT: The reconstructed carapace, skull and right humerus of the holotype specimen of Porthochelys laticeps (KUVP 1204). The specimen was collected by E. H. Sellards and J. T. Shearer from the Smoky Hill Chalk near the Saline River in Trego County, KS. The shell is about 60% complete and is 30 in. long by 29 in wide. It is unusual for a Late Cretaceous marine turtle because of its solid construction (most modern marine turtles, however, have solid shells). The specimen was described and named by Williston in 1900 and is on exhibit at the University of Kansas Museum of Natural History.

RIGHT: A left oblique view of Porthochelys laticeps (KUVP 1204). Small bone at lower right is the right humerus, in ventral view.

LEFT: The skull of KUVP 1204 measures 4.5 in (11 cm ) long by 4.5 in (11cm) wide across the quadrates.

RIGHT: Drawings of the skull of Porthochelys laticeps as published in Hay, 1908. Williston's original illustrations are here: Plate XIX, Figure 1 (Lower jaw, dorsal view); Plate XIX, Figure 2 (Skull, dorsal view) Williston provided figure showing the skull of Toxochelys latiremis for comparison.; Plate XX (Skull, ventral view); Plate XXI (Carapace, dorsal view); Plate XXII (Humerus and plastron, dorsal view).

Desmatochelys lowi Williston 1894

Desmatochelys lowi Williston 1894 (KUVP 1200) is probably the oldest marine turtle yet described from the Midwest. Fragmentary turtle remains have been reported by Beamon, 1999, from the Kiowa Shale (Early Cretaceous, Albian) of McPherson County, KS, but they are otherwise unidentifiable. The fairly complete specimen of Desmatochelys lowi was collected from the "Benton Cretaceous" near the town of Fairbury in Jefferson County, Nebraska in 1893. This locality is just north of the Kansas-Nebraska state line and other remains (KUVP 32401 and 32405) of this species have been found in Kansas. From the excellent, 3-dimensional preservation of the skull (below), it is likely the remains came from the Fairport Chalk Member of the Carlile Shale and are Middle Turonian in age. Right lateral, dorsal and ventral views of the skull of the type specimen (KUVP 1200) are shown below. A photograph of the lower jaw is HERE. The photographs were taken in January, 2004.

	LEFT: A right lateral view of the skull of Desmatochelys lowi. RIGHT: A dorsal view of the skull of Desmatochelys lowi
	*LEFT: A ventral view of the skull of Desmatochelys lowi.* Note that the round hole visible at the back of the palate was drilled there for mounting purposes when it was originally on exhibit. RIGHT: Drawings of the skull of Desmatochelys lowi adapted from Hay, 1908.**

The endocast of a possible marine turtle from the Dakota Sandstone of Republic County, Kansas

LEFT: Dorsal view of the endocast (from the inside the shell) of a possible marine turtle from the Middle Cenomanian Dakota Sandstone of Republic County, Kansas. The specimen is housed in the Republic County Historical Society Museum, Belleville, KS.

RIGHT: Ventral view of the endocast (from the inside the shell) of a possible marine turtle from the Middle Cenomanian Dakota Sandstone of Republic County, Kansas. A side view is HERE.

A marine (?) turtle from the Kiowa Shale (Albian, Early Cretaceous)

LEFT: The carapace (upper shell) of a medium sized turtle (KUVP 16370) found in the Kiowa Shale of Kiowa County, Kansas. The specimen was discovered by Orville Bonner in June, 1969 and was tentatively identified as Glyptops sp. It is possible that Glyptops was not a fully marine species. However, the specimen was found in off-shore marine sediments. Anterior is to the left.

RIGHT: The plastron (lower shell) of the same specimen. This is probably one of the oldest turtle specimens known from Kansas, but it is as yet unreported. Anterior is to the left in both photos.

LEFT: Dorsal and ventral views of a large turtle shell fragment (FHSM VP-13551) from the Kiowa Shale (Albian, Early Cretaceous) of McPherson County, KS. The same deposit also includes crocodile remains and it is possible that these crocodiles fed upon the turtles, and/or that their shells were simply battered apart by waves in the high-energy, near shore environment.

RIGHT: A collection of turtle shell fragments from large, early Cretaceous turtles in the Kiowa Shale of McPherson County, KS.

Protostega gigas and Archelon ischyros were giant (Volkswagen-sized!) sea turtles that are found in Cretaceous deposits.

LEFT: Protostega gigas - a detail from a mural painted by Charles Bonner in the Keystone Gallery (© Charles Bonner, Keystone Gallery)

RIGHT: Archelon ischyros (adapted from Berry, 1929). Of the two, only Protostega is found in the chalk and generally only in the upper chalk. Somewhat like modern leather back sea turtles in overall appearance, they still retain a portion of their original bony shell. The protostegids may have migrated in and out of the Western Interior Sea. Fossilized remains are relatively rare, but nearly complete skeletons from the Kansas chalk are found in many museums.

LEFT: Four views of the upper (proximal) end of a small protostegid humerus, probably severed and partially digested by a large shark, found in the Late Coniacian chalk of Gove County by Pam Everhart in 1990. This may be an unusually early occurrence of this genus.

BELOW: Left: Pam Everhart works on the partial remains of a Protostega gigas that she discovered in July, 1994 in Logan County, Kansas. Center - Most of the left half of the turtle's plastron (lower shell) is exposed here in dorsal view. Right: Removed from the chalk, the 'spiky' look of the plastron (ventral view) is very apparent. We donated this specimen to the Sternberg Museum in 1997 where it is curated as FHSM VP-13448 (Our EPC 1994-42). About 30 inches in maximum length, anterior to the left. See a photo of a composite Protostega plastron here.

RIGHT and FAR RIGHT: Close up views of damaged areas that are visible on the anterior and posterior lobes of this plastron (More recent photo here) in ventral view. These appear to abrasions that might have resulted as a large, heavy female turtle dragged herself across a sand beach to lay her eggs. (added October 28, 2006)

The photo at right is of the left plastron from the type specimen of Protostega gigas Cope 1872 as published on Plate IV by Hay, 1895. It measures 1.2 m (almost 4 ft) from left to right and came from a turtle that measured about 3.0 m (10 ft) long (from nose the end of the tail). The specimen is curated in the American Museum of Natural History as FR 1503. (Anterior to the left)

"This plate represents the hyoplastron and hypoplastron of the left side of Protostega gigas seen from below. A view is also given of the nuchal bone." (Hay, 1895) (Click to enlarge)

E. D. Cope found and collected the type specimen of Protostega gigas during his only trip to the Kansas chalk in 1871. He wrote about his experiences, including the discovery of Protostega, in a letter dated October 9, 1871 to Professor Lesley of the American Philosophical Society:

"On another occasion, we detected unusually attenuated bones projecting from the side of a low bluff of yellow chalk, and some pains were taken to uncover them. They were found to belong to a singular reptile, of affinities probably to the Testudinata, this point remaining uncertain. Instead of being expanded into a carapace, the ribs are slender and flat. The tubercular portion is expanded into a transverse shield to beyond the capitular articulation, which thus projects as it were in the midst of a flat plate. These plates have radiating lines of growth to the circumference, which is dentate. Above each rib was a large flat ossification of much tenuity, and digitate on the margins, which appears to represent the dermo-ossification of the Tortoises. Two of these bones were recovered, each two feet across. The femur resembles in some measure that ascribed by Leidy to Platecarpus tympaniticus, while the phalanges are of great size. Those of one series measured eight inches and a half in length, and are very stout, indicating a length of limb of seven feet at least. The whole expanse would thus be twenty feet if estimated on a Chelonian basis. The proper reference of this species cannot now be made, but both it and the genus are clearly new to science, and its affinities not very near to those known. Not the least of its peculiarities is the great tenuity of all the bones. It may be called Protostega gigas." E. D. Cope, 1871

LEFT: A reconstruction of the skeleton of Protostega gigas in the exhibit at the Smithsonian Institution (USNM), Washington, D.C. This reconstruction is based on several specimens purchased from G.F. Sternberg.

LEFT: The partial carapace and plastron on a large Protostega gigas collected and prepared by George F. Sternberg (4886-A) and later acquired by the United States National Museum (Smithsonian). Sternberg noted that the specimen was found without limbs or skull. It is likely that this specimen served as the basis for the reconstruction above.

RIGHT: The skull, lower jaw and other fragments from another Protostega specimen that was collected by George Sternberg in the 1920s and sent to the University of Nebraska State Museum. It is probably the same specimen as shown below. Both photos from Sternberg archives, Forsyth Library, Fort Hays State University.

LEFT: A wall-mounted reconstruction of the partial remains of a Protostega gigas turtle in ventral view at the University of Nebraska State Museum. Collected by George F. Sternberg.

RIGHT: The skull of the turtle shown at left in right lateral view. Note that Protostega lacks the large bony extension of the beak (premaxilla) found in Archelon.

LEFT: The exhibit specimen of Protostega gigas in the Denver Museum of Nature and Science. This specimen was collected by George F. Sternberg in late 1945.

RIGHT: Left lateral view of the skull of the exhibit specimen in the Denver Museum of Science and Nature. Click here for an original photo of the skull.

LEFT: Photograph (circa 1945) by George F. Sternberg of the above Denver Museum Protostega gigas in dorsal view. As described by Sternberg, this was probably a juvenile turtle with a shell that is about 3'8" wide... and a length of about 5 feet from tip of beak to the back edge of the carapace

RIGHT: Right lateral view of the same specimen as prepared and photographed by G.F. Sternberg about 1945. Sternberg's field number on this specimen was 10145 (the 101st specimen he collected in 1945). The specimen is about 5 feet in length, with a maximum shell width of 44 inches. Sternberg also noted that the skull was 16 inches long.

LEFT: An early photo by C.H. Sternberg of Protostega gigas from the chalk of western Kansas. The specimen is actually a composite of two specimens (CMNH #1420 and #1421), both discovered by Sternberg about "three miles northwest of Monument Rock" in western Gove County in 1903 and acquired by the Carnegie Museum of Natural History in Pittsburgh, PA in 1904. Sternberg (1906) noted that this specimen measured 10 feet (3 m) across the front paddles. A more recent picture is HERE.

RIGHT: A dorsal view of a Protostega gigas (FHSM VP-79) carapace and plastron on exhibit at the Sternberg Museum of Natural History. This specimen was collected by George Sternberg. (about 4 ft x 4 ft). Side view

	LEFT: UR 79 - A nearly complete left half of the plastron of a large Protostega gigas in the collection of the Field Museum, Chicago, IL. This specimen was described and figured by O.P. Hay (1895). RIGHT: UR 90 - The anterior portion of the left plastron of a large Protostega gigas in the collection of the Field Museum, Chicago, IL. Note the bite marks at the upper right. These were probably the result of scavenging by a large shark (Cretoxyrhina mantelli). Click HERE for a closer view.
	*LEFT: A fragment of a Protostega* plastron collected from Graham County that preserves large and deep bite marks, probably from a Ginsu shark (Cretoxyrhina mantelli).**

LEFT: The right hind limb of a large Protostega gigas turtle (KUVP 1201) in the University of Kansas Museum of Natural History. It was collected by Charles Sternberg in 1900 somewhere west of Russell Springs in Logan County. This specimen was one of the first examples of the rear limb of this giant turtle ever found, and was the subject of a paper by S. W. Williston in 1902. See a colorized version of his Text-Figure 1 here. The femur (upper leg bone) is 360 cm (14 in) long. The entire limb would have been about 4 feet long.

LEFT: The right front limb and shoulder of Protostega gigas, adapted from Hay (1908).

RIGHT: The right half of the pelvis and right hind limb of Protostega gigas, adapted from Hay (1908).

The following information was provided by Dr. Kraig Derstler of the University of New Orleans. Kraig is one of the few people currently studying protostegid turtles.

"Very little is written about Protostegids, other than the descriptive stuff by Wieland and his colleagues in the 1890's and earliest 1900's. Protostega is a huge-headed sea turtle. The species are pretty poorly defined at present. Specimens come from the Niobrara of Kansas, the Pierre of Kansas, Colorado, Wyoming, and South Dakota, the Mooreville, Demopolis, and Eutaw formations of Alabama and Mississippi, and the Campanian - Santonian marls of Texas. Possible scraps also come from other Santonian-lowermost Maastrichtian deposits around the world. Other Protostegids (Calcarichelys, Chelosphargis, and a couple of unnamed things) range from the Albian through the latest Maastrichtian worldwide.

Archelon ischyros has a normal-sized skull, proportionally much smaller than Protostega. However, it has that distinctive hooked snout. It is so far confirmed only from the upper half Pierre in South Dakota. (Reports from Colorado and elsewhere are pretty unbelievable.)

Concerning size, the largest Protostega is a 3.4 m beast in the Dallas Museum of Natural History. I was consultant for this exhibit and I'm pretty confident of the identification as well as the size. The Yale Archelon is 3.0-3.1 m, but another I've studied is 4.6 m long! It is virtually perfect and articulated. As a result, the size and the identification are both solid.

I've never seen any Niobrara Protostega material from an animal that was more than about 2-2.5 m long. Niobrara giants may have existed, but I haven't seen any evidence. And, I've never seen any signs of Archelon in the Niobrara. However, there are lots of small to medium-size Chelosphargis specimens and possibly some pieces of the "thorny Protostegid" Calcarichelys". ( Dr. Kraig Derstler )

LEFT: A cast of the Dallas Protostega gigas in the McWane Center, Birmingham, AL. (Cast by Triebold Paleontology). A view of the underside of the skull is HERE

Archelon ischyros (Go here for another website about Archelon)

Williston made an interesting comment regarding the stratigraphic occurrence of various Late Cretaceous genera that is worth repeating here. He (1902, p. 270) noted that “the characters separating Archelon Wieland from Protostega Cope, while not very important, would seem sufficient. Nevertheless, one can derive little justification from the different geological horizons in which the forms are found. The relations between the Niobrara and Fort Pierre vertebrates are for the most part very close. I have recognized in both horizons Tylosaurus, Platecarpus and Mosasaurus (Clidastes), as well as Pteranodon and Hesperornis, all very typical of the Niobrara deposits, and the existence of Claosaurus [Marsh’s dinosaur discovery in Kansas] has been recently affirmed in the Fort Pierre. On lithological grounds, there is nothing separating the two groups of deposits and I protest against the names Colorado and Montana, as perpetuating a wrong impression. On paleontological and lithological grounds, there would be much better reasons for uniting the Niobrara with the Fort Pierre than with the Fort Benton.”

LEFT: Two views of "Archelon ischyros, a gigantic sea-turtle from the Upper Cretaceous of South Dakota" by S. W. Williston, 1914 (Fig. 126).

LEFT: A right lateral view of the skull of Archelon ischyros, adapted from Hay (1908) from the original in Wieland (1900). Note the distinctive hooked premaxilla which was covered with a horny beak in life, similar to what is seen in modern snapping turtles.

RIGHT: The cast of a very large Archelon ischyros skull from South Dakota. Scale is 10 cm (about 4 inches). A dorsal view of the skull is HERE

LEFT (Dorsal) AND RIGHT (Ventral): Old pictures of the type specimen of the protostegid Archelon ischyros (YPM-3000) in the Yale Peabody Museum. It was collected from the upper Pierre Formation of South Dakota in 1895 by Dr. G. R. Wieland, and described by him in 1896. While very similar to Protostega, it is much larger and lived several million years after the Smoky Hill Chalk species. (Click on LEFT photo to enlarge) .... A larger view is HERE

BELOW, left to right -- Drawings from Wieland (1909) of the same skeleton of Archelon: 1) From above; 2) From below without plastron; and, 3) From below, with plastron. Note the missing right rear limb.

Archelon ischyros, adapted from Wieland, 1909. (CLICK TO ENLARGE)

FAR LEFT: Dorsal view

LEFT: Ventral view

RIGHT: Ventral view, plastron removed.

RIGHT: The carapace and ribs of Archelon ischyros (adapted from Wieland, 1896)

LEFT: The plastron (lower shell) of Archelon ischyros (adapted from Hay (1908), originally from Wieland (1898)). Note that Wieland was unsure that Archelon was a separate genus in the Protostegidae, and briefly renamed his A. ischyros as Protostega ischyra in order to include it within that genus. The revision was brief and was not accepted. (head is to the top)

LARGE MARINE TURTLES FROM EUROPE - THE NETHERLANDS (Maastrichtian Age)

	LEFT: The very well preserved skull of Allopleuron hoffmanni, associated with a large part of the skeleton in exhibits of the Maastricht Museum of Natural History, Maastricht, The Netherlands. *RIGHT:The crushed skull of Allopleuron hoffmanni* in the exhibits of the Teylers Museum, Haarlem, The Netherlands.**
	LEFT: A fragment of turtle bone showing bite marks in the exhibits of the Teylers Museum, Haarlem, The Netherlands. *RIGHT: A fragment of a turtle carapace showing the results of a crushing bite by a large mosasaur, probably Prognathodon, in the exhibits of the Teylers Museum, Haarlem, The Netherlands.*

This Oceans of Kansas Paleontology web page has been selected as a resource by the Encyclopedia Britannica (October 2006). Click here to search for more information on prehistoric and modern marine turtles:

Suggested references:

Agassiz, Louis. 1849. [Remarks on crocodiles of the Green sand of New Jersey and on Atlantochelys]. Proceedings of the Academy of Natural Sciences of Philadelphia. 4:169.

Beamon, J. C. 1999. Depositional environment and fossil biota of a thin clastic unit of the Kiowa Formation, Lower Cretaceous (Albian), McPherson County, Kansas. Unpublished MS Thesis, Fort Hays State University, Hays, KS, 97 p. (oldest reported Cretaceous turtle remains in Kansas)

Case, E. C. 1898. Toxochelys. The University Geological Survey of Kansas, Part VI. 4:370-385. pls. 79-84.

Cope, E. D. 1870. Observations on the Reptilia of the Triassic formations of the Atlantic regions of the United States. Proceedings of the American Philosophical Society 11(84):444-446. (includes the description of Pneumatoarthrus peloreus, senior synonym of Archelon, Wieland 1896)

Cope, E. D. 1872. [Sketch of an expedition in the valley of the Smoky Hill River in Kansas]. Proceedings of the American Philosophical Society 12(87):174-176. (meeting of October 20, 1871)

Cope, E. D. 1872. On a new Testudinate from the chalk of Kansas. Proceedings of the American Philosophical Society 12(88):308-310. (Cyanocercus incisus )

Cope, E. D. 1872. A description of the genus Protostega, a form of extinct Testudinata. Proceedings of the American Philosophical Society 12(88):422-433. (March 1, 1872)

Cope, E. D. 1872. On the geology and paleontology of the Cretaceous strata of Kansas. Annual Report of the U. S. Geological Survey of the Territories 5:318-349 (Report for 1871).

Cope, E. D. 1873. [On Toxochelys latiremis]. Proceedings of the Academy of Natural Sciences of Philadelphia 25:10.

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

Cope, E. D. 1877. On some new or little known reptiles and fishes of the Cretaceous of Kansas. Proceedings of the American Philosophical Society 17(100):176-181. (Toxochelys latiremis Cope: issue of May-Dec., 1877, printed Nov. 20, 1877)

Druckenmiller, P. S., A. J. Daun, J. L. Skulan and J. C. Pladziewicz. 1993. Stomach contents in the upper Cretaceous shark Squalicorax falcatus. Journal of Vertebrate Paleontology. 13(supplement. to no. 3):33A.

Gudger, E.W. 1949. Natural history notes on tiger sharks, Galeocerdo tigrinis, caught in Key West, Florida with emphasis on food and feeding habits. Copeia 1949: 39-47, pl. 1-2.

Hay, O. P. 1895. On certain portions of the skeleton of Protostega gigas. Publ. Field Columbian Museum, Zoological Ser. (later Fieldiana: Zoology), 1(2):57-62, pls. 4 & 5.

Hay, O. P. 1896. On the skeleton of Toxochelys latiremis. Publ. Field Columbian Museum, Zoological Ser. (later Fieldiana: Zoology), 1(5):101-106, pls. 14 &15.

Hay, O. P. 1908. The fossil turtles of North America. Carnegie Institution of Washington, Publication No. 75, 568 pp, 113 pl.

Hooks, G. E., III. 1998. Systematic revision of the Protostegidae, with a redescription of Carcarichelys gemma Zangerl, 1957. Journal of Vertebrate Paleontology, 18(1):85-98.

Lane, H. H. 1946, A survey of the fossil vertebrates of Kansas, Part III, The Reptiles, Kansas Academy Science, Transactions 49(3):289-332, 7 figs.

Leidy, J. 1865. Cretaceous reptiles of the United States. Smithsonian Contributions to Knowledge 14(192):1-135, pls. 1-20.

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