Marine Turtles

Marine turtles from the Western Interior Sea

Mike Everhart

Last updated 08/09/2014

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. RIGHT: Brachauchenius takes a turtle out for lunch. Paintings 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.

Did mosasaurs eat turtles?

Well, according to most authors, including me, "Yes, they did." Do we have proof of that? Well, maybe.... In 1887, Louis Dollo, a respected Belgian naturalist published a paper in which he wrote (page 520), "Quoi qu'il en soit, le Hainosaure se nourrissait assurément de tortues marines, car nous en avons trouvé des restes dans sa carcasse."

Translated, he said, "However, Hainosaurus undoubtedly fed upon marine tortoises, because their remains have been found in its carcass."

Unfortunately he did not identify which specimens or where they were housed. Since Dollo's work is certainly well respected, most of us simply took his word for it. Recently I began asking questions about the whereabouts of the specimens that he was describing. While none have been located as of today (January, 2011), the search is on.

This crushing injury on a turtle shell fragment in the Teylers Museum in Haarlem, The Netherlands appears to indicate that it was bitten by something very large and powerful. It is likely that turtles in the Western Interior Sea were also eaten by the larger mosasaurs, initially by Tylosaurus and then by Mosasaurus and Prognathodon nearer the end of the Cretaceous.

REFERENCE: Dollo, L. 1887. Le hainosaure et les nouveaux vertébrés fossiles du Musée de Bruxelles. Revue des Questions Scienfiques XXI 504-539. (April 1887)

Family Toxochelyidae

In 2010, I became interested in finding the correct source of the family name (Toxochelyidae) or this group of extinct marine turtles, which led me in circles for several hours fruitless searching the Internet. There are many hits for “Baur 1895, emended by Zangerl (1953)” .... which goes exactly nowhere, since few papers I found actually provide the full citation for Baur (1895).

However, my friend, the late Betsy Nicholls (1988) did cite “Baur, G. 1895. Ueber die Morphologie des Unterkiefers der Reptilien [On the morphology of the lower jaw of reptiles]. Anatomischer Anzeiger 11:410-415.” Unfortunately, that article by Baur turned out to be published in 1896, not 1895, and discusses the comparative anatomy of lower jaw of reptiles… and while Baur does illustrate a turtle dentary, he does not mention Toxochelyidae.

So far as I can determine, the family name Toxochelyidae was first used by Baur in another 1896 paper. The correct citation is:

Baur, G. 1896. Bemerkungen über die Phylogenie der Schildkröten [Remarks on the phylogeny of turtles]. Anatomischer Anzeiger 12:561-570. The term “Toxochelyidae” first occurs in print on page 564.

Note that Hay (1903) uses the term, but gives no citation:

Hay, O.P. 1903. A revision of the species of the family of fossil turtles called Toxochelyidae, with descriptions of two new species of Toxochelys and a new species of Porthochelys. Bulletin of the American Museum of Natural History 21(10):177-185.

However, Hay(1908, p. 164) credits Baur as the source of the name, but again, provides no citation:

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

Zangerl (1953), on the other hand, uses the term, but credits no one:

Zangerl, R. 1953. The vertebrate fauna of the Selma formation of Alabama, Part IV, The turtles of the family Toxochelyidae. Fieldiana, Geology Memoirs 3(4): 137-277.

In my opinion, “emended by Zangerl” gives credit where it is not due.

Baur (1896, p. 564) should be cited as the original source of the family name Toxochelyidae.

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 type specimen (AMNH 2362) was described by Cope(1873) and figured in his 1875 Vertebrata (Plate VIII). It consists of a partial lower jaw (1 and 1a) and a coracoid bone (2), and was most likely collected from the Pierre Shale, and not the Smoky Hill Chalk as originally reported (See Nicholls, 1988).

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. See Konuki 2008 for more information on this specimen. RIGHT: The left humerus of FHSM VP-700 in dorsal and ventral views. (Adapted from Konuki 2008)
	LEFT: The left side of the pelvis and left rear limb (minus foot) of FHSM VP-700. (Adapted from Konuki 2008) RIGHT: The pectoral girdle and left front limb of FHSM VP-700. (Adapted from Konuki 2008)

	*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: A fragmentary specimen of Toxochelys latiremis (UNSM 50040) collected by George Sternberg in 1955 (GFS 103-55) from the Smoky Hill Chalk of Gove County, southeast of Oakley, Kansas, between Hackberry Creek and the Smoky Hill River. The specimen was purchased by the University of Nebraska State Museum.

LEFT: The lower jaw of a Toxochelys turtle (FHSM VP-2006) collected by George Sternberg in 1949 from Gove County.

RIGHT: (FHSM VP-1344) The anterior portion of a lower jaw (right and left dentarys) of a large Toxochelys turtle collected from the upper Smoky Hill 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 Toxochelys latiremis (FHSM VP-17432) specimen discovered in 2005. RIGHT: We finally were able to recover the turtle remains in 2009 (The original site had been "lost" after a heavy rain in the summer of 2005)... Here are additional photos of the vertebrae from the neck, body and tail. (scale = cm)
	LEFT: The hyoplastron, hypoplastron and xiphiplastron of the FHSM VP-17432, bones making up the left half of the turtle's lower shell (plastron). See drawing below. RIGHT: The broken right humerus of FHSM VP-17432. Based on a comparison with the humerus of FHSM VP-13449 (see skull above), these two specimens would have been about the same size.
	LEFT: Field shot of the hyoplastron of FHSM VP-17432. RIGHT: The dig site where FHSM VP-17432 was discovered. Hattin's marker unit 7 was about 5 cm below the turtle bones...

LEFT: The fragmentary remains of a small toxochelyid (?) turtle (FHSM VP-17464) that I collected in 1991 from southeastern Gove County. Pieces of the carapace / plastron had eroded out earlier and were scattered over a wide area.

RIGHT: (FHSM VP-17018) A fragment (peripheral or marginal bone) from the carapace of 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).

LEFT: Keith Ewell and I collected fragments of an even smaller individual (FHSM VP-17572) in July, 2009....Probably newly hatched, this little one didn't live very long. Shell was less than 4 inches long.

RIGHT: The remains of a very small (hatchling) turtle (FHSM VP-17466) discovered by Keith Ewell in the lower chalk of western Trego County in July, 2009. Although the remains are too fragmentary for a positive identification, they are most likely from a baby Toxochelys latiremis.

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.

The type specimen of Toxochelys bauri (YPM 1786) was collected by Charles H. Sternberg about 1904 from the Smoky Hill Chalk in western Gove County, Kansas. It was subsequently described by Wieland in 1905, who published these figures and a photograph of the reconstructed carapace. The actual bones present are shown here. The carapace is a 39 cm (15 in) by 23 cm (14 in). It was named in honor of Georg Baur (1859-1898).

FAR LEFT: Reconstructed dorsal view of the carapace of Toxochelys bauri (neurals, ribs and marginals / peripherals).

LEFT: Left lateral view of same specimen.

RIGHT: Ventral view of same specimen, showing the components of the plastron. (Abbreviations: en - entoplastron; h - hyoplastron; hp - hypoplastron; x - xiphiplastron.

Chelospargis advena - The type specimen of Protostega advena (KUVP 1219) was described by Hay (1908). It was collected by S.W. Williston in 1891, probably from Gove County. While showing some protostegid characters, it is a relatively small individual with only a little cranial or limb material present in the specimen. The genus name was changed to Chelosphargis by Zangerl in 1953.

LEFT: The type specimen of Chelospargis advena in the collection at the University of Kansas.

RIGHT: Figures 256-259 from Hay (1908) of the type specimen. Zangerl (1953, fig. 21) figured the skull, mandible and hyoid.

LEFT: The peripherals (marginals) of a partial carapace of a very small Chelospargis advena turtle that I discovered in 1996 in Gove County, between MU 6 and MU7. 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.

RIGHT: A similar sized specimen of Chelospargis advena (KUVP 1258) showing the distinctive shape of the peripheral bones that make up the rim of the carapace. Another specimen in the Yale Peabody collection (YPM 3601) is shown here.

LEFT: The remains of another small Chelospargis turtle (FHSM VP-17463) collected in 1989 (EPC 1989-31) from the Smoky Hill Chalk in southern Gove County. The remains show evidence of scavenging (serrated bite marks) by Squalicorax and it appears that both front paddles had been bitten off.

RIGHT: The severed humeri of FHSM VP-17463, possibly evidence of predation / scavenging by a larger shark like Cretoxyrhina.

Prionochelys galeotergum

LEFT: The type specimen of Prionochelys galeotergum (CMNH PR125) from the Smoky Hill Chalk of Gove County, Kansas, collected by G.F. Sternberg in 1931 and sold to the Chicago Museum of Natural History (Specimen is now in the Field Museum). The genus and species were described by Zangerl (1953).

RIGHT: Figure 114 from Zangerl (1953) showing a comparison of the "saw-back" dorsal keel of Prionochelys in lateral view among the three known species. Prionochelys nauta and P. matulino are found in Late Cretaceous Gulf Coast deposits.

HERE is a model of Prionochelys nauta reconstructed by the Rocky Mountain Dinosaur Resource Center (Triebold Paleontology, Inc.)

Ctenochelys stenoporus

Order TESTUDINES
Suborder CRYPTODIRA
    Superfamily CHELONOIDEA
      Family CHELONIIDAE Gray, 1825
       Genus CTENOCHELYS Zangerl, 1953
          Ctenochelys stenoporus (Hay, 1905)

BELOW: Note that, contrary to some Internet web pages that credit the name to Sternberg (1904), this species was actually named by two other authors in 1905. Charles Sternberg never named a species of anything that he collected and in 1907 credits Wieland with the name.

Ctenochelys stenopora (Yale Peabody Museum collection; YPM-1786) was collected by C. H. Sternberg on December 14, 1904, near Monument Rocks in western Gove County, Kansas. It was originally named Toxochelys bauri Wieland (1905), AND Toxochelys stenoporus by Hay (1905). Apparently Hay's name had precedence and Hay (1908) changed the species name to stenopora. Zangerl (1953, p. 227) assigned the species to a new genus (Ctenochelys) and used Hays 1908 revision of the species name. Matzke (2007) referred back to Hay's original species name.

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

LEFT: The skull of Ctenochelys stenoporus in dorsal and ventral views as figured originally by Case (1898).

RIGHT: A partial carapace of the type specimen of Ctenochelys stenoporus as figured by Case (1898).

Originally described as Toxochelys stenoporus by E.C. Case in 1898, it was recognized as a new genus by Hay (1905)

LEFT: Skull of the type specimen at the University of Kansas Museum of Natural History as figured by Hay (1905).

RIGHT: Lower jaw of the type specimen at the University of Kansas Museum of Natural History as figured by Hay (1905).

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. See Matzke 2007 for comments on nearly complete specimen (USNM 357166).

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.

Cynocercus 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 two caudal 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 very limited, Cope (1872) described and named the species Cynocercus 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: Two caudal vertebrae of Cynocercus incisus (AMNH FR1583), in left lateral, ventral, anterior and posterior views; republished by Williston (1898) from Cope (1875, Plate VIII). A metapodial (3.4 cm in length) is also included with the specimen.

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 distinctive skull and lower jaw of Porthochelys laticeps as published in Williston, 1901. More of 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).

Based on the rareness of Porthochelys remains in the Western Interior Sea, it seems likely that this species lived somewhere else (possibly near shore / fresh water).

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.

NEW - See the dig of the first Desmatochelysskull found in Kansas.... September, 2008

	LEFT: A right lateral view of the skull of Desmatochelys lowii. RIGHT: A dorsal view of the skull of Desmatochelys lowii
	LEFT: A ventral view of the skull of Desmatochelys lowii. 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 lowii* adapted from Hay, 1908. ALSO, see a drawing of the skull, carapace (ventral, dorsal), humerus and limb bones of a South Dakota specimen from Zangerl and Sloan (1960)**
	*LEFT: A new specimen of Desmatochelys lowii* (FHSM VP-17470) from the Smoky Hill Chalk of Mitchell County, KS. The specimen was discovered in 2008 by Gail Pearson. RIGHT: The left front paddle of the new turtle specimen.**
	LEFT: (May, 2010) - Here is the ventral side of the skull and lower jaws after additional preparation and cleaning by Dennis Roth at the Sternberg Museum of Natural History. (Photo by Dennis Roth) The specimen was discovered in 2008 by Gail Pearson. RIGHT: (May, 2010) - This is the first view of the dorsal side of the skull (FHSM VP-17470) since we put the plaster and burlap jacket on it in September, 2008 (Additional preparation and photograph by Dennis Roth, Sternberg Museum of Natural History, Hays, Kansas). Note that while this skull is badly crushed and not as photogenic as KUVP 1200, it is more complete, and is certainly the best (and only) skull of Desmatochelys lowii ever collected in Kansas.

The only turtle remains known from the Greenhorn Limestone in Kansas

Turtle remains are very rare in the Greenhorn Formation.

LEFT: A single turtle caudal vertebra (FHSM VP-17571) from the basal Lincoln Limestone Member of the Greenhorn Formation in Russell County, Kansas.

RIGHT: The edge of the plastron (marginal or peripheral), the proximal end of a rib and a part of the skull of a toxochelyid turtle from the basal Greenhorn of Lincoln County, KS. Collected by Keith Ewell in June, 2005.

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.

Note that the first known Protostega specimen (YPM 1408) was collected on July 4 by the 1871 Yale College Scientific Expedition, eight miles east of Fort Wallace, almost 5 months before Cope arrived in Kansas. However, it has never been described.

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 (USNM 11651) in the exhibit at the Smithsonian Institution, Washington, D.C. This reconstruction is based on a specimen purchased from G.F. Sternberg.

Cope (1872, p. 433) described the discovery and recovery of the type specimen:

Distribution. This fossil was found near Ft. Wallace, W. Kansas. It was entirely recovered by excavating. The edges of one of the large bony shields were seen projecting from a bluff near Butte Creek, and was followed into the chalk rock with pick-axe and shovel with the result already indicated. The large bones were exposed in an entire condition, but were much fractured in the attempt to lift them from their bed. Though carefully packed, the transport of 1500 miles still further injured them, and the portions described were reconstructed of over 800 pieces by myself. One of the bony plates was broken into 108 pieces, the ribs into 183, the marginals into 146, etc.

LEFT: Cope (1875, Plate XIII) – “Two dermal bones of Protostega gigas” - Portions of the plastron of the type specimen of Protostega gigas (AMNH FR 1503) mis-identified by Cope as part of the carapace. They were later correctly identified by Baur (1886) and Hay (1895). Baur (1886, p. 688) wrote: "Was Cope für Platten des Carapace hält, gehört zum Plastron," which translated means: "What Cope considers as plates of the carapace, belong to the plastron."

RIGHT: The left humerus of the type specimen of Protostega gigas (Cope, 1875, Plate XII). Cope (1872) noted that it was one foot (0.3 m) in length.

Cope (1872) estimated the head to tail length of the animal at 12.8 feet; Hay (1895) disagreed with Cope's assumptions, but arrived at the same overall length:-3.9 m

Hay (1908, p. 191) wrote: "The specimen of this species which Cope originally described was found by him in 1871, in Niobrara deposits, near Butte Creek, south of Wallace, Kansas. This is now in the American Museum of Natural History and has the number 1503. At the time of its discovery the bones were much distorted and comprest [sic]; and most of them were much fractured in collecting them. Cope states that the portions described by him were reconstructed out of over 800 pieces. One of the large bony plates, described as overlying the ribs, had been broken into 108 pieces. Most of the bones are yet in the condition in which Cope left them; the large plates are, to a great extent, again broken up.
As stated by Cope, the remains preserved include many parts of the skull; 5 vertebræ, more or less incomplete; the scapular arches of both sides, with the coracoids; both humeri perfect, and some phalanges; 10 ribs; 1 doubtful neural bone; 10 peripherals; parts of 4 large plates, described as overlying the ribs; and some undetermined bones.
From his study of his materials Cope arrived at the conclusion that Protostegawas a large marine-turtle closely allied to Dermochelys, and had a total length of about 12 feet. The first author who added to the knowledge of the species was Dr. George Baur, who (Zool. Anzeiger, IX, 1886, p. 688), regarding the genus as Atlantochelys, stated that the plates assigned by Cope to the dorsal region were really portions of the plastron. This determination was undoubtedly made from the bones collected by Cope. Hay, as cited, gave, in 1897, a description, with figures, of the hyoplastra and hypoplastra of a specimen that had been collected for him near Butte Creek, Kansas. Case (1897, as cited) described portions of the skull and a more complete plastron than had previously been secured, materials now in the University of Kansas; and made correction of Hay's restoration of the xiphiplastra. More recently Wieland has described excellent materials which belong to the Carnegie Museum, at Pittsburg."

LEFT: 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). Hay stated that the combined length of the hyoplastron and hypoplastron (at left) was 1.2 m (4 ft)

RIGHT: Plate V from Hay 1895: “A partial restoration of the plastron of Protostega, to show the relative positions of the bones and the size of the fontanelle. Only the bases of the epiplastra and of the xiphiplastra are shown.”

LEFT: The skull of the type specimen of Protostega gigas (AMNH 1503) in left lateral view from Hay, 1908, fig. 247. Hay (1908) noted that : "Cope had considerable portions of the skull and most of these he figured. The writer has studied these bones and has found that in most cases Cope's determinations were incorrect. Baur had also examined these cranial bones and accepted Cope's determinations (American Naturalist, xxiv, 1890, p. 532). Fig. 247 represents these bones, each having its name indicated. Cope's determinations are indicated in parentheses."

RIGHT: The carapace of CMNH 1421 in ventral view from Wieland (1906, fig. 2), showing the dorsal vertebrae and the very limited extent of the costal plates (less than 1/3 the length of the ribs).

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. (FHSM VP-17557)

RIGHT: Figure 3 from Wieland (1906) showing the right humerus of Protostega gigas (CMNH 1421) in dorsal view. The bone is 34 cm (13.4 in) long.

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.

LEFT and 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)

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 (GFS 103-31)

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 (GFS 10145) from Logan County.

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

In 1897, E.C. Case described two Protostega specimens in an article in the Journal of Morphology. Although Case does not identify the specimens by number, it is likely they were in the collection of the Field Museum in Chicago, IL.

LEFT: A medial view of the mandible of Protostega gigas.

RIGHT: Plate V from Case, 1897: Fig. 1. Supraoccipital. The badly crushed petrosal and paroccipital are not shown; Fig. 2. Exoccipital. Right side; Fig. 3. Basioccipital. a, from above; b, from below; Fig. 4. Petrosal. a, from within; b, from without; Fig. 5. Paroccipital. Right side; Fig. 6. Quadrate, pterygoid, and palatine. Right side; Fig. 7. Quadrate-jugal. Right side; Fig. 8. Lower jaw. [Dorsal view]; Fig. 9. Xiphiplastron. Left side, showing attachment with hypoplastron and xiphiplastron of right side; Fig. 10. Nuchal plate; Fig. 11. Fifth and sixth peripherals. Left side.

LEFT: Plate IV from Case, 1897. Photograph of plastron with nuchal plate and peripherals. (Dorsal view)

RIGHT: Plate VI from Case 181917. Fig. 12. Humerus. Right side; Fig. 13. Scapula. (See PR127); Right side; Fig. 14. Coracoid. Right side. Fig. 15. Pubis. Right side; Fig. 16. Ischium. Right side; Fig. 17. Ilium. Right side (taken from smaller specimen); Fig. 18. Femur. Left side; Fig. 19. Rib head. (Taken from smaller specimen).

	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). RIGHT: The proximal end of a large Protostega gigas humerus (UW-M VP1503-57) from the upper chalk of western Logan County with deep gouges from the teeth of a large shark.**

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).

LEFT: The skull and right front limb of the Carnegie Museum No. 1421 Protostega gigas, collected by Charles H. Sternberg from the Smoky Hill Chalk along Hackberry Creek in Gove County, Kansas (Adapted from Wieland 1906, Figure 1).

RIGHT: The right front limb of No. 1421 reconstructed by Wieland (1906, fig. 4)

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 36 cm (14 in) long. The entire limb would have been about 4 feet long.

RIGHT: The right hind limb of Protostega gigas as reconstructed by Wieland (1906, fig.5).

In the summer of 1903, Charles Sternberg collected a fairly complete specimen of a turtle that he identified as Protostega gigas. Later that year he noted that it would take another year to finish the preparation of this remains. His oral report at the annual meeting of the Kansas Academy of Science wasn't published until 1905. The paper included two photographs of the specimen during preparation. The specimen was sold to the Carnegie Museum of Natural History and is designated as #1420.

Sternberg, C. H. 1905. Protostega gigas and other Cretaceous reptiles and fishes from the Kansas chalk. Kansas Academy Science, Transactions 19:123-128.

LEFT: Plate XVIII shows the vertebral column from neck to tail, including the ribs.

RIGHT: Plate XIX shows the pelvis and hind limb, part of the shoulder and one front limb.

As described by H.F. Osborn (1904) in Science: "The [#1420] skeleton lay on its dorsal surface with the fore limbs stretched out at right angles to the median line of the carapace, measuring six feet between the ungual phalanges; the hind limbs were parallel with the neural arch, and stretched out behind.

LEFT: Plate 31 from Wieland (1906): a) Right and left shoulder girdles, with right front flipper and the proximal half of the left humerus; b) Pelvic girdle with both hind flippers; c) The accompanying hyoids.

RIGHT: Plate 32 from Wieland (1906): Enlarged views of the forearm and hand (right photograph) and the foot (left photograph).

Click here for the dig of the newest (2011) Protostega gigas specimen from the Smoky Hill Chalk.

LEFT: The cast of FHSM VP-17979, courtesy of Anthony Maltese, Triebold Paleontology, Inc.

Microstega (Protostega) Copei - The type specimen of Protostega copei (YPM VP 1787) was collected by Charles Sternberg from along Hackberry Creek in Gove County, Kansas. It was named and first described by Wieland in 1909. Later, Zangerl (1953) changed the genus name to Archelon, and Hooks (1998) redescribed it again as Microstega.

	LEFT: The reconstructed skull of Protostega copei (YPM VP 1787) in right lateral view as figured by Wieland in 1909. The specimen was collected in the summer of 1905 by Charles H. Sternberg from the Smoky Hill Chalk along Hackberry Creek in southern Gove County, KS. The specimen was subsequently referred to the genus Archelon by Zangerl (1953) and later described as a new genus (Microstega) by Hooks (1998) *RIGHT: The pectoral and pelvic girdles of Protostega copei* in dorsal view as figured by Wieland in 1909.**
	LEFT: The carapace of Protostega copei (YPM VP 1787) in dorsal view as figured by Wieland in 1909. Wieland reported that the carapace was on exhibit in the Yale Peabody Museum in 1909, but I did not see it in 2010. *RIGHT: The plastron of Protostega copei* in dorsal view as figured by Wieland in 1909.**

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. Protostegais 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.)

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 )

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.

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

RIGHT: The right front limb of a Protostega gigas turtle discovered in the Cretaceous of Greene County, Alabama in 1933 (from Renger 1935). The humerus is 42 cm long and came from an animal with a shell length of 150 cm (5 ft). Renger estimated that the animal when alive would have weighed 2.5 to 3 tons.

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 (Vienna specimen- below). Scale is 10 cm (about 4 inches). A dorsal view of the skull is HERE

LEFT: A cast of the "Vienna Archelon" recently on display at the Sternberg Museum of Natural History, Hays, KS. The original specimen was found in 1976 in the upper Pierre Shale of South Dakota and is on exhibit in the National Natural History Museum in Vienna, Austria. It measures about 15 feet from the tip of the beak to the tip of the tail... and about 16.5 feet across the outstretched front paddles. More information 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

LEFT and RIGHT: Large photos of the type specimen of Archelon ischyros published Wieland in 1909. I hadn't seen these photos before... not sure if they have ever been reproduced or not.

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. Wieland (1909) explained that the right tibia and fibula had been "cleanly severed" at sometime before the turtle died. The right femur is intact.

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

FAR LEFT: Dorsal view

LEFT: Ventral view

RIGHT: Ventral view, plastron removed.

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

RIGHT: 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.*

LARGE MARINE TURTLE FROM MOROCCO (Upper Campanian - Maastrichtian AGE)

LEFT: A large marine turtle from the phosphates of Morocco (Currently undescribed).

RIGHT: A dorsal view of the shell of a large marine turtle from the phosphates of Morocco.

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:

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