Despite the mental image of Kansas as a vast, flat landscape, rivers such as the Smoky Hill cut deeply through the sediments laid down by a once vibrant marine environment. The Western Interior Seaway (Inland Sea) covered much of North America for millions of years, until finally retreating for good, near the end of the Cretaceous, 65 million years ago.

The Smoky Hill Chalk of western Kansas provides well preserved reminders of the area's past. The disassociated material so common on the East Coast is present, but articulated material is also common. Whether it's a "fish-in-a-fish", slain mosasaur or the crumpled remains of what was once a graceful pteranodon, the chalk provides much more than an isolated tooth.

STRATIGRAPHY AND DEPOSITIONAL ENVIRONMENT

The width and depth of the inland seaway changed relatively frequently, responding to plate tectonics and fluctuating sea levels. The depositional environment also changed in response to the distance to shorelines, climate changes (increased rainfall, etc) and the influx of erosional sediments. Water circulation in the central and northern portions of the seaway was generally poor and the water may have been stratified from time to time, leading to anoxic bottom conditions. These changing conditions certainly affected the distribution of many species of marine life. The number of shark species, in particular, seems somewhat limited when compared to the Cretaceous marine exposures of Texas and the East Coast.

Cretaceous marine deposits in Kansas overlie the Late Jurassic Morrison formation. The Kiowa Formation is the lowest member of the group, consisting of shales, mudstones and sandstones deposited during the Kiowa-Skull Creek cyclothem. (A cyclothem is a geologic term for periods when alternating layers of marine and terrestrial sediments were laid down as the seas retreated and advanced) According to Stewart (1990b), sharks include: Hybodus sp., Scapanorhynchus sp., Lamna sp., and Scyliorhinus sp. The Dakota formation (Middle Cenomanian, 15+ meters thick) is found in the central portion of the state and consists of sandstones, siltstones, mudstones and shales from non-marine and marginal marine sediments deposited in the early portion of the Greenhorn cyclothem.

The Graneros Shale (late Middle Cenomanian, about 9 meters thick) consists of shales, sandstones and limestones deposited as marine sediments in deeper water during the early part of the Greenhorn cyclothem. Ptychodus occidentalis is found in this formation. The Greenhorn Limestone (Upper Cenomanian through lower Turonian, about 30 meters thick) consists of shaley chalks and chalky limestones deposited during the maximum transgression of the Greenhorn cyclothem.

The Carlile Shale (Middle Turonian, about 84 meters thick) is made up of shales, shaley chalks and chalky limestones deposited during the regression of the Greenhorn cyclothem. Stewart (1990b) reported Cretalamna appendiculata, Cretodus crassidens, Cretoxyrhina mantelli, Squalicorax falcatus and Ptychodus whipplei from this formation. Russell (1993) does not include P. whipplei, however, and adds Ptychodus mammilaris to Stewart's list.

The Niobrara consists of chalky limestones (Fort Hays Limestone, Lower through middle Coniacian, about 20 meters thick) and chalks (Smoky Hill Chalk, upper Coniacian through lower Campanian, about 180 meters thick) deposited in the middle of the seaway during the maximum transgression (advance) of the Niobrara cyclothem.

Shark teeth and other vertebrate fossils are rare in the Fort Hays Limestone. Shimada (1996) lists Scapanorhynchus sp., Cretalamna appendiculata, Paranomotodon sp., Squalicorax falcatus, Cretoxyrhina mantelli and Ptychodus mortoni.

The Smoky Hill chalk represents a completely different depositional environment and sharks' teeth are more commonly found. Stewart (1990) lists the following species from the Smoky Hill chalk: Squalicorax falcatus, Squalicorax sp. aff. kaupi, Scapanorhynchus raphiodon, Psuedocorax laevis, Cretoxyrhina mantelli, Cretalamna appendiculata, Rhinobatos incertus, Ptychodus mortoni, P. martini and P. anonymous. Stewart (1990) also suggests that small enterospirae (coprolites) found only in the lower chalk suggest that an unknown species of shark was also present. In 1998, the teeth of an undescribed species of paleoanacoracid shark were was discovered in the lower chalk (Mikael Siverson, personal communication) and will be published in the near future.

Individual shark teeth are a fairly common find in the Smoky Hill chalk. When they weather out of the softer chalk, most sharks teeth are in pristine condition and require little or no preparation besides washing in plain water. They do, however, deteriorate rapidly when exposed to weathering. Finding a large, nearly perfect sharks tooth with its shiny, brownish-grey enamel weathered to a pasty white, brittle layer is really disappointing.

Compete and articulated dentitions have been found for Squalicorax, Cretoxyrhina and three species of Ptychodus. Isolated vertebrae and calcified fin elements are also found occasionally in the Smoky Hill chalk. Evidence of predation / scavenging by sharks (bite marks, severed bones and embedded teeth) has been found on nearly all species of marine reptiles and the remains of most large fish.

The Pierre Shale (Middle through Upper Campanian, about 100 meters thick) consists of dark gray shales deposited during the regression (retreat) of the Niobrara cyclothem. The lowest (Sharon Springs) member of the Pierre Shale lie conformably on the top of the Smoky Hill chalk. While this member is quite fossiliferous, sharks are poorly represented. Teeth and vertebrae of Squalicorax sp. are known from the Pierre Shale.

CHONDRICHTHYAN FAUNA

CLICK ON IMAGES FOR ADDITIONAL DETAILS
HYBODONTIFORMES
IMAGE REQUIRED	Ptychodus whipplei MARCOU, 1858 - extinct family This species has bee reported from the Carlile Shale (Middle Turonian)
	Ptychodus mortoni AGASSIZ, 1839 - extinct family The high crowned teeth of P. mortoni is by far the most common Kansas ptychodid. It is known from Fort Hays Limestone (lower through middle Coniacian) and in the lower 1/3 of the Smoky Hill Chalk (latest Coniacian).
	Ptychodus martini WILLISTON, 1898 - extinct family Although the teeth of this species are rare, two dentitions have been found. The low-cusped teeth of P. martini appear to be relegated to lower 1/4 of the Smoky Hill Chalk (Coniacian).
	Ptychodus anonymus WILLISTON, 1900 - extinct family The teeth of this species are less common than those of P. mortoni and are known from lower Smoky Hill Chalk (Coniacian) exposures. The crown of these teeth are moderately inflated.
LAMNIFORMES
	Scapanorhynchus raphiodon (AGASSIZ, 1844) - goblin shark Scapanorhynchus. sp. has been reported from the Fort Hays Limestone and S. raphiodon from the Smoky Hill Chalk (upper Coniacian through lower Campanian).
	Cretodus crassidens (DIXON, 1850) - extinct lamnoid In Kansas, Cretodus teeth have only been reported from the Carlile Shale (Middle Turonian
	Cretoxyrhina mantelli (AGASSIZ, 1843) - extinct mako-like shark Found in Carlile Shale, Fort Hays Limestone and Smoky Hill Chalk, (upper Coniacian through lower Campanian) sediments, the teeth of C. mantelli reached it's greatest size and abundance in the lower one third (late Coniacian) of the chalk.
	Cretalamna appendiculata (AGASSIZ, 1843) - extinct makeral shark This species is represented in faunas from the Carlile Shale, Fort Hays Limestone and Smoky Hill Chalk, where they are a relatively rare find.
	Squalicorax cf falcatus (AGASSIZ, 1843) - crow shark Teeth of this species have been ascribed to the Carlile Shale, Fort Hays Limestone and through out the Smoky Hill Chalk.They tend to increase in size from the bottom to the top in the chalk.
	Squalicorax kaupi (AGASSIZ, 1843) - crow shark Larger than those of Squalicorax falcatus those of S. sp. aff. kaupi are found only in the upper quarter of the Smoky Hill Chalk, (early Campanian).
	Pseudocorax aff. granti CAPPETTA & CASE 1975 - extinct lamnoid shark These teeth are rare and known from Santonian sediments. P. laevis (LERICHE, 1906) has also been reported as present in upper Coniacian through lower Campanian sediments.
	Paranomotodon sp - extinct thresher shark Teeth from this species have been reported from the Fort Hays Limestone (lower through middle Coniacian) only.
RAJIFORMES
IMAGE REQUIRED	Rhinobatos incertus - guitarfish Rhinobatos teeth have been reported from the Smoky Hill Chalk