Other Times Other Sharks
This book is generally focused on a small (geologically speaking), five-million-year window of time during the Late Cretaceous when the Smoky Hill Chalk was deposited on the bottom of the Western Interior Sea. The fauna from that interval (8 7-8 2 mya) is the most widely collected and the most thoroughly studied of any period from the Cretaceous of Kansas. The chalk is accessible in
many localities, preservation is excellent and the chalk matrix is relatively easy to remove. It is also my favorite because of the occurrence of mosasaurs and the large number of their remains that have been found in the chalk since the late 1860s. But many other productive Cretaceous rocks are largely unstudied, and thus Kansas lags far behind other places in the Midwest such as Texas and South Dakota in the number of shark species that have been documented from the state.
Since I began writing this book, however, I have had a number of opportunities for further study of Kansas sharks. The discovery of the huge Cretoxyrhina mantelli in 2 0 02 that is mentioned above was the beginning of a series of discoveries and studies on Kansas sharks. The opportunities even extended outside of the Cretaceous with the collection of the first known ctenacanth shark (Ctenacan-thus amblyxiphias) remains from Kansas (Everhart and Everhart, 2003) in August 2002 from the early Permian rocks near Herington, Kansas, and the subsequent discovery in 2 0 03 by my friend Keith Ewell of numerous Permian shark teeth and dorsal fin spines from three sites near Manhattan, Kansas. However, our work in the Cretaceous is still the focus of our research efforts.
In October 2 0 02, my wife and I began working with a "fish tooth conglomerate" from the Blue Hill Member (Turonian) of the Carlile Shale in Jewell County, Kansas, that had been discovered in 19 5 8 by Donald Hattin (19 6 2). Unlike our usual field trips, however, all of our collecting was done in our fossil lab. The conglomerate dissolved very slowly and the teeth had to be collected and sorted while we peered through a microscope. While the matrix was mostly composed of thousands of tiny teleost teeth (generally Enchodus), over a period of several months it produced a fair number of selachian species that had never been reported from Kansas (among them, Lonchidion sp., Chiloscyllium greeni, Ischyrhiza mira, and Pty-chotrygon triangularis). Many of the shark teeth were so small (1 mm or less) that they had to be picked and sorted using forceps and a binocular microscope. Imagine 5 00 or more Rhinobatos (a gui-tarfish) teeth in a volume about the size of an aspirin tablet! After Rhinobatos, Scapanorhynchus raphiodon, and Squalicorax falcatus were the most common species collected. The study generated an abstract/poster for the 2 003 Society of Vertebrate Paleontology meeting (Everhart et al., 2 0 03) and will result in a future paper.
In the late spring of 2 003, I began looking at the Kiowa Shale in McPherson County with Shawn Hamm, a student at Wichita State University. Except for a thin layer of sand called the Cheyenne Sandstone in southern Kansas, the Kiowa is the oldest Cretaceous formation (Albian) exposed in Kansas. It was deposited at a time when the Western Interior Sea was advancing from the south and had not yet covered the entire state. Unlike the deeper, blue-water ocean in which the Smoky Hill Chalk was deposited, the Kiowa Shale was laid down as near-shore mud in a relatively high-energy environment. Working some ten meters below the level of the sur-
rounding wheat fields in an active shale quarry near Marquette, we collected a much older shark fauna along with the scattered, fragmentary remains of fish, turtles, crocodiles, and plesiosaurs. Again, many of the teeth were quite small, though not as small as those from the Lovewell fauna. Most of the teeth and other remains were literally picked up from the surface of a rapidly weathering layer of pyritized sandstone. Expanding on the work of Beamon (1999), several relatively "new to Kansas" species were collected, including "Polyacrodus sp." (Everhart, 2004a), Onchopristis dunklei, and Pseudobypolophus mcnultyi, with Leptostyrax macrorhiza and Carcharias amonensis (Fig. 4.8) being the most common sharks.
In August 2 003, a visitor (Keith Ewell) to the Sternberg Museum asked for assistance in identifying Permian-age shark teeth he had collected near Manhattan, Kansas. After making contact with Keith, I visited the site with him and saw his specimens. We then assisted him in collections made at three sites in Geary County that produced more than two hundred teeth of Cladodus sp., Petalodus sp., Acrodus sp., and Chomodus sp., dorsal spines of Ctenacan-thus, Physonemus and Hybodus, and calcified cartilage (Ewell and
Figure 4.8. Teeth of two species of sharks from the Early Cretaceous Kiowa Shale ofMcPherson County, Kansas: Leptostyrax macrorhiza (left) and CarcharÃas amonensis (both in lingual view). (Scale = cm)
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