INTRODUCTION

Unable to locate a good reference for Sharktooth Hill material, the two authors decided a webpage might prove helpful in gathering and sharing information on this site. We solicit suggestions, comments, criticism and new information to include in this page. The objective is to provide a list of the available shark and ray species, and provide illustrations or images that will assist in the identification of this material. We would like to thank the Buena Vista Museum of Natural History for much of the preliminary information included below.

STRATIGRAPHY AND DEPOSITIONAL ENVIRONMENT

The formation that includes "Sharktooth Hill" is locally refered to by geologists as the "Round Mountain Silt Formation". Located in Kern County, California, it was deposited by a river delta coming out of the mountains to the east of Bakersfield. At this time (Middle Miocene ) most of central California was covered by a small sea. As time progressed the central California region dried up exposing the Miocene and Early Pliocene deposits. The Southern Bakersfield region continued to exist as a swampy area well into the Pleistocene. At the same time the Miocene deposits eroded into a hilly area with many gullies exposing the so-called "Upper Layer of the Round Mountain Silt Formation". This is the layer containing most of the bone beds which have yielded the most diverse and best studied Tertiary fossil marine vetebrate assemblage yet known from anywhere within the Pacific Realm.

This fossil assemblage, called the Sharktooth Hill Local Fauna (Wood et al., 1941), is comprised of more than one hundered species of sharks, rays, bony fish, turtles, birds and mammals, including terrestrial species from the adjacent Miocene land mass (south of where Bakersfield currently is located). The "Round Mountain Silt Formation" covers approximately 110 square miles. The Sharktooth Hill Bonebed is a single, relatively thin, but widespread horizon -- this fossil producing layer is only 6-18" thick (with some exceptions). It has been correlated with the Barstovian North American Land Mammal Age, and is approximately 13 and 15 million years old.

CHONDRICHTHYAN FAUNA

The species list we obtained from the Buena Vista Museum (BVMNH) included certain species that were unfamiliar to us, and descriptions have not yet been located. Comments regarding these tentative identifications will be noted in the text of our cyber-list. If fossil teeth have been previously illustrated in other sections of the website, links will be directed to that material, otherwise, Sharktooth Hill material will be employed. The below shark faunal list incorporates the observations and help of Steve Alter, Bill Heim, Gordon Hubbell, Walter Hunt and Hideo Yabe.

CLICK ON IMAGES FOR ADDITIONAL DETAILS unless accompanied by "not linked" icon.
HEXANCHIFORMES
	Hexanchus andersoni JORDAN, 1907 Extinct Sixgilled shark.
	Notorynchus sp - Sevengill shark. Unlike the Lee Creek fauna, Notorynchus is the "tough" cow shark in Bakersfield.
SQUALIFORMES
	Enchinorhinus blakei AGASSIZ, 1856 Bramble shark A scarce species from Bakersfield, CA, The accommpanying tooth is only 1.5 cm wide x 1cm high
	Squalus serriculus JORDAN & HANNIBAL 1923 Dogshark
SQUATINFORMES
	Squatina lericheii JORDAN & BEAL, 1913 Angel shark
HETERODONTIFORMES
	Heterodontus -- Bullhead shark The illustrated tooth is 3.0 mm in height. Based on studied material, these teeth are relatively common and are easily confused with male dasyatid teeth or are thought to be from skates, unless observed under magnification.
LAMNIFORMES
	Carcharias cuspidata (AGASSIZ, 1843) extinct Sand Tiger shark. (Image of a Lee Creek specimen)
	?Megachasma sp - Megamouth shark. Known from Pyramid Hill with reports of Sharktooth Hill. West coast teeth ascribed to this genus are significantly different from Lee Creek specimens and the extant species. Likely a different genus.
	Alopias ?latidens (LERICHE 1909) extinct Thresher shark
	Cetorhinus cf maximus (GUNNER 1765) Basking shark This particular tooth, provided by Steve Alter is 7,0 mm in height. Another of his specimens was only 4.5 mm in height.
	Carcharocles chubutensis (AMEGHINO, 1906) extinct Mega-toothed shark from Early Miocene exposures.
	Carcharocles megalodon (AGASSIZ, 1837) extinct Mega-toothed shark. The largest and best known fossil shark teeth come from this huge predator. Jordan (1907) deemed the California teeth to be different from their right coast counterparts, and ascribed them to a new species -- Carcharodon branneri. In 1913, Jordan reassigned these teeth to Carcharodon megalodon.
	Cosmopolitodus (Isurus) planus (AGASSIZ, 1856) extinct Great White shark
	Cosmopolitodus (Isurus) hastalis (AGASSIZ, 1843) extinct Great White shark Teeth from this species often characterized by the broad flat labial root face.
	Cosmopolitodus (Isurus) sp extinct Great White shark Teeth similar to C. escheri and serrate Peruvian teeth.
	Carcharodon sp - Great White shark It is commonly assumed that the serrate lamnid teeth from Sharktooth Hill came from Carcharodon carcharias (LINNAEUS, 1758). Jordan saw more than one species in the fauna. He assigned teeth to C. rectus Agassiz ["perhaps nearer than any others here named to the living man-eating shark, C. carcharias"] but later (1913) noting that they might be C. megalodon with a lateral denticles. (Sounds like juvenile Carcharocles megalodon.). Another, he named C. arnoldi [noting, "serrae rather smaller and more numerous" than C. riversi] then resisted Leriche's attempt to shoe-horn this tooth into C. carcharias. (Sounds like the serrate Cosmopolitodus hastalis). A third he named C. riversi ["denticles fewer and coarser than in any other species".]; Sounds like Carcharodon carcharias. there are other opinions. . . . .
	Isurus oxyrinchus RAFINESQUE, 1809 aka I. desori (SISMONDA, 1849) Shortfin Mako shark
	Isurus retroflexus (AGASSIZ, 1843) aka I. paucus GUITART MANDAY, 1966 Longfin Mako shark
	Parotodus benedeni (LeHON, 1871) extinct False Mako shark. Teeth from this species are very uncommon.
CARCHARHINIFORMES
SPECIMEN REQUIRED	Cephaloscyllium -- Swellshark. This catshark is listed by the BVMNH as present in the fauna. An illustration or representive example of this tooth design has not been seen.
	cf Scyliorhinus -- Catshark. This specimen, from the collection of Gordon Hubbel, is the only catshark tooth-design seen from Sharktooth Hill, and it is very similar to Scyliorhinus teeth from Lee Creek. This may be the design that served as the basis of the Cephaloscyllium identification above. It should be noted that C. ventriosum (GARMAN, 1880), the extant catshark species of California waters, has a less robust tooth design, however, this tooth does compare rather well with an illustration of C. sufflans (REGAN, 1921), an extant Red Sea species.
	Galeorhinus sp - Tope shark. Not included in the BVMNH faunal list. Jordan & Beal (1913) describe a new species, G. hannibaldi from the Miocene and Pliocene. Illustrated specimen from Lee Creek.
	Triakis beali JORDAN, 1919. This species was included in the BVMNH faunal list but illustrations have not been seen. The depicted (Gordon Hubbel) specimen initially struck me as being catshark-like, but it is more similar to the extant species Triakis scyllium MÜLLER & HENLE, 1839
SPECIMEN REQUIRED	Mustelus -- Smooth-hound shark BVMNH faunal list, illustration not seen.
	Hemipristis serra AGASSIZ, 1843 Snaggletooth shark. Snaggletooth teeth from this site were originally assigned to H. heteropleurus Agassiz and H. chiconis Jordan (1907).
GOOD LUCK	Carcharhinus antiquus (AGASSIZ, 1856) This species was included in the BVMNH faunal list, but the illustration in Jordan (1907) was of poor quality and the tooth damaged. Jordan (1907) had originally identified this tooth as Agassiz's Prionodon antiquus but placed it in the genus Carcharias and in 1913, moved it to Carcharhinus but speculated it might be Carcharodon, possibly C. rectus.
	Carcharhinus cf egertoni (AGASSIZ, 1843) extinct requiem shark. BVMNH faunal list, illustration not seen.
	Carcharhinus cf limbatus (VALENCIENNES, 1839) Blacktip shark
	Carcharhinus obscurus (LeSUEUR, 1818) Dusky shark
	Galeocerdo aduncus (AGASSIZ, 1843) extinct Tiger shark Jordan (1907) followed Agassiz and attributed these teeth to G. productus AGASSIZ, 1853. Leriche subsequently indicated that they were identical to G. aduncas but Jordan (1913) rejected this notion based on geographic considerations.
	Galeocerdo contortus GIBBES, 1849 extinct Tiger shark. The illustrated specimen measures 15.0 mm in height.
	Sphyrna cf zygaena (LINNAEUS, 1758) — Hammerhead shark These teeth have been reported as Sphyrna ?laevissima
RAJIFORMES
SPECIMEN REQUIRED	Rhinobatos sp - Guitarfish. Reported from the fauna, no example available to authors.		see: the genus Rhinobatos
SPECIMEN REQUIRED	Raja sp - Skate. If skate teeth are in this fauna, they must be pretty rare. I've viewed a couple thousand Sharktooth Hill batoid teeth and haven't seen a skate tooth yet.
MYLIOBATIFORMES
TO BE DRAWN	Dasyatis spp - Stingray. There appears to be three common stingrays in this fauna.		see: the genus Dasyatis
EXAMPLE REQUIRED	Gymnura sp - Butterfly Rays. I haven't seen any teeth which I'd ascribe to this genus. The fauna does yield male devil ray teeth which are similar to the gymnurid tooth-design.
	Mobula loupianensis CAPPETTA, 1970 -- extinct devil ray. The illustrated male tooth is 2 mm high. These teeth are only 1/10th as common as those from stingrays, but are still common within the fauna.
EXAMPLE REQUIRED	Myliobatis merriami JORDAN & BEAL, 1913. Looking over myliobatid material, there appears to be at least one Myliobatis species, and another genus more reminiscent of Aetomylaeus. A third myliobatid may also be present. Refering to the 1913 illustration, this tooth-design may be the one that is reminiscent of the Aetomylaeus design.
EXAMPLE REQUIRED	Myliobatis smithii (JORDAN & BEAL, 1913) These teeth were originally placed in Rhinoptera by Jordan and Beal; who reassigned them is currently unknown. I've seen hundreds of myliobatid teeth from this location, and none conform with the rhinopterid design. Illustrations from the original publication were unable to provide sufficient detail for a better identification.