Bennett—Smallest Pteranodon
Repositories and institutional abbreviations.—AMNH, American Museum of Natural History, New York, New York; BSP, Bayerische Staatssammlung für Paläontologie und Geologie, Munich,Germany; FHSM, SternbergMuseumofNaturalHistory, FortHays StateUniversity,Hays,Kansas; FMNH, FieldMuseum of Natural History, Chicago, Illinois; GPIT, Paläontologische Forschungs-, Lehr- und Schausammlung, Institut für Geo- wissenschaften (formerly the Geologische-Paläontologische Institut), Universität Tübingen, Tübingen, Germany; JME-SOS, JuraMuseum (Solnhofen Sammlung), Eichstätt, Germany; KUVP, Natural History Museum, University of Kansas, Lawr- ence, Kansas; LACM, Los Angeles County Museum of Natural History, Los Angeles, California; MTM, Hungarian Natural His- tory Museum, Budapest, Hungary; NHMW, Naturhistorisches Museum Wien, Vienna, Austria; NSM, National Science Museum, Tokyo, Japan; RAM, Raymond M. Alf Museum of Paleontology, Claremont, California; SM, Senckenberg Museum, Frankfurt,Germany; TM, TeylerMuseum,Haarlem,Netherlands; andYPM, Peabody Museumof Natural History, Yale University, New Haven, Connecticut.
Material and methods
The new specimen, FHSM 17956, was examined with stereo microscope, measured, and photographed. A small piece of cortical bone that was removed from the posterior side of the neck of metacarpal (Mc) IV, just proximal to the distal condyles, was sectioned, ground, and polished, and the resulting thin sections were examined and photographed with optical and polarizing microscopes. Measurements of other specimens of Pteranodon and Nyctosaurus were taken from Bennett (2001, and unpublished data). Wingspans in life were estimated using the method of Bennett (2001), in which span equals two times the summed lengths of the humerus, antebrachium, McIV, and wing phalanges (WP) 1–4; the omission of the pectoral girdle and carpus compensates for flexures of the elbow, wrist, and metacarpophalangeal joints and the curvature of the wingfinger. In addition, where elements were missing or incomplete, their lengths were calculated from linear regression equations calcu- lated from available samples (Bennett, 2001, 2007a, 2013a). Ontogenetic ages of specimens were determined using size- independent criteria reflecting the extent of ossification and
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fusion of the skeleton (Bennett, 1993, 1995), and unless other- wise stated all discussion of immaturity and maturity refers to osteological rather than sexual maturity. The ontogeny of pterosaurs is divided into six stages: eggs; hatchlings and young-of-the-year; small juveniles; large juveniles that are sig- nificantly smaller than mature adults; subadults with immature skeletons, but not significantly smaller than mature adults; and adults with mature skeletons. Kellner (2010) revised Pteranodon and split it into four
species in three genera, but that interpretation has not been generally accepted (e.g., Witton, 2013; Martin-Silverstone et al., 2017). Several errors in the revision have been identified and will be addressed elsewhere, therefore Bennett’s (1994a) taxo- nomic scheme is accepted here. A privately held fragmentary pterosaur specimen
from the Smoky Hill Chalk Member referred to as Tweety or Ptweety has been reconstructed and interpreted as a very small Pteranodon, even though it is within the size range of Nyctosaurus specimens. Based on my examinations of the specimen, the morphology of its notarium, humeri, and McIV is consistent with that of Nyctosaurus, but inconsistent with that of Pteranodon, so the specimen provides no evidence of a Pteranodon smaller than FHSM 17956. Unfortunately, the reconstruction so misused the specimen that it is of no scientific value whatsoever.
Description
The new specimen, FHSM 17956, is an incomplete right wing preserved in dorsal view on a roughly pentagonal slab of pale yellow chalk ~ 54 x 19 x 4 cm(Fig. 1). It was collected from the Smoky Hill Chalk Member of the Niobrara Formation in the SE¼, NE¼, SE¼ of Sec. 29, T11S, R23W of Trego County, Kansas by Mr. Glenn Rockers of Hays, Kansas, who prepared the specimen and donated it to the FHSM. Exposures in the E½, SE¼ of Sec. 29 have gray chalk at the base, ~2m of pale yellow chalk with a series of five very fine-grained bentonite seams spaced 25, 32, 20, and 27cm apart, and ~3.5m of massive bioturbated chalk caprock at the top, and preserve abundant Platyceramus platinus (up to 1.2m diameter) and Pseudoperna congesta. The caprock is Hattin’s (1982) Marker Unit 10 and the sequence of bentonite seams beneath it
Figure 1. Pteranodon sp. indet. (FHSM 17956). Photograph of incomplete right wing in dorsal view. Abbreviations: ca, carpus; mciv, metacarpal IV; pt, pteroid; ra, radius; ul, ulna; and wp1, wing phalanx 1. Scale bar is 10 cm.
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