Kansas Geological Survey, Current Research in Earth Sciences, Bulletin 244, part 1
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Kansas Geological Survey, Current Research in Earth Sciences, Bulletin 244, part 1
Prev Page--Pteranodon ||
Next Page--Discussion
Pteranodon walkeri (FHSM VP 221)--This skull was collected by G. F. Sternberg from 2 mi (3.2 km) northeast of Penokee, sec. 13, T. 8 S., R. 24 W., Graham County, Kansas (Bardack, 1965). Locality 55 in sec. 13, T. 8 S., R. 24 W. has Marker Unit 18 in the middle of a 10-m (32-ft) exposure, and Localities 54 and 60 to the southwest and northeast, respectively, are both a little lower (fig. 3). In this case the exact locality is known and, although the exact horizon is not known, the type skull must have come from within 5 m (16 ft) above or below Marker Unit 18.
Fig. 3--Correlation of stratigraphic columns of localities in Graham County, Kansas. Black bands indicate bentonites, seams, and in a few instances a change in lithology; white indicates chalk. Localities are numbered across the top and arranged in order from west to east. The unnumbered column at right is the composite stratigraphic column from Hattin (1982). Hattin's marker units are identified by the numbers at right, and Russell's (1929) marker unit H is also indicated. The relative vertical position of different stratigraphic columns in the figure is not significant.
Pteranodon eatoni (YPM 1179)--This skull was collected in 1875 by E. W. Guild (alias E. S. Field) from the "Smoky Hill River, near Castle Rock, Trego Co." (according to field labels and YPM catalog). In an earlier report of this work (Bennett, 1990), I took "near Castle Rock" to mean within a couple of miles and concluded that the skull was collected between Marker Units 8 and 13. However, the fact that it was collected in Trego County should have suggested a greater distance. Analysis of the calcareous nannofossils in the matrix adhering to the specimen indicates that it came from between Marker Unit 4 and 6 (D. Watkins, 1991, personal communication). Wildcat Canyon in western Trego County and near Castle Rock has exposures ranging from Marker Units 2 to 4, so the range between Marker Units 4 and 6 is reasonable.
A plot of the stratigraphic positions of the type skulls as well as other important specimens (fig. 4) shows that skulls with upright occiputs are found from Marker Unit 3 up to Marker Unit 7 or perhaps 10, while skulls with reclined occiputs occur between Marker Units 13 and 20. Therefore, the two morphologies do not co-occur.
Fig. 4--Inferred stratigraphic positions or ranges of type and other important specimens of Pteranodon plotted against the composite stratigraphic column from Hattin (1982). Marker units are indicated by black lines or bands, or in the case of Marker Unit 10, the prominent caprock, by cross-hatching. Institutional abbreviations: AMNH, American Museum of Natural History, New York; DMNH, Denver Museum of Natural History; KUVP, Natural History Museum, University of Kansas, Lawrence; LACM, Los Angeles County Museum of Natural History; UALVP, Geology Museum, University of Alberta, Edmonton; "UNC", Uncatalogued specimen (see Bennett, 1991); USNM, U.S. National Museum, Washington, D.C; UUPI, Palaeontological Institute, University of Uppsala, Uppsala, Sweden; YPM, Yale Peabody Museum, New Haven.
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