N.Jb. Geol. Palaont. Mh. 1996, H. 8 473 — 484 Stuttgart, August 1996
A large pterodactyloid from the Morrison Formation
(Late Jurassic) of Garden Park, Colorado
By Jerald D. Harris and Kenneth Carpenter, Denver
With 4 figures and 1 table in the text
HARRis, J. D. st CARPENTER, K. (1996): A large pterodactyloid from the Morrison Formation (Late Jurassic) of Garden Park, Colorado. — N. lb. Geol. Palaont. Mh., 1996 (8}: 473 — 484; Stuttgart.
Abstract: A number of vertebrate fossils were recovered from the Small Stego- sarrrus Quarry during the excavation of a Stegosaurus srerrops specimen by the Denver Museum of Natural History in 1992. Among them were bones of a large pterodactyloid pterosaur, assignable to Keporiacrybrs insperarls n. g. n. sp. These fossils represent one of the largest Jurassic pterosaurs known, comparable in size to the roughly contemporary Prcrodactylls grurrdis from Germany. The pterodac- tyloid nature of the animal is confirmed by the length and morphology of the cervical vertebra and the absence on the wing phalanx of a longitudinal furrow. Zusammenfassung: Aus Material der Grabungen 1992 auf Stegosaurus sterrops stammen auch einige Flugsaurier-Knochen, die zur Aufstellung der neuen Gattung und Art Kepodacrylrrs insperatrrs fuhren. Es handelt sich um einen der gro8ten Flugsaurier aus dern Jura, vergleichbar mit Pterodacrylas grarrdis aus Deutschland.
Introduction
The history of pterosaur fossil discoveries in the Upper Jurassic of the North American continent is limited to five discoveries, all from the Morrison Formation of the Western Interior. The first, made by S. W. WILLIsTON, was a fragment of a right wing metacarpal found in Quarry 5 at Corno Bluff, Wyoming. MARsH (1878) identified the fragment as a pterodactyloid pterosaur, and based the species Pteroc/ricrylrcs montarrus on it. Later, MARsH (1881a) differentiated the metacarpal from the genus Pterorluctylsrs and renamed the animal Dcrmodactylus montanrzs. In the brief description, MARsH (1881a) also implied an associated first wing phalanx, a scapulocoracoid, some vertebrae, and some teeth belong to Dermodactylgs; none of these elements has been figured or described, but WELLNHoEER (1978: 65) states that they are too large to belong to the type of Dermodacrylus. Based on this material, MARsH {1881a) estimated a 1.5 — 1.8 m (5 — 6 ft.) wingspan for Dermodacrylns; WEILNHoEER (1991a), however, estimated only about 1 m, based on the metacarpal.
0028-3630/96/1996 — 0473 $3.00
O 1996 E. Schweizerbart'sche Uerlagsbuchhandlung, D-70176 Stuttgart
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Jerald D. Harris and Kenneth Carpenter
MARsH (1881b) also described an isolated braincase from Corno Bluff as belonging to a Jurassic bird, Laopteryx priscus. A later reanalysis of the fossil (OSTRQM 1986), has shown this fossil to be pterosaurian in nature, but is too fragmentary to be assigned to a higher taxon.
JENsEN sc OsTROM (1977) identified another pterodactyloid fossil, the proximal end of the proximal left wing phalanx, from the Dry Mesa Quarry, Colorado. They note only that it is of'similar proportions to the metacarpal of DermodactyEus. WELLNHoErR (1991a: 106) places it within the genus /irfesadacrylus.
Another isolated metacarpal was discovered in the Yale Peabody collections in material originally sent to, but not described by, MARsH. GALTQN {1981} identified this bone as that of a rhamphorhynchoid pterosaur, Comocfacrylus ostromi. Thus, both "rhamphorhynchoid" and pterodactyloid pterosaurs have been found in the Morrison Formation. Comodactylus was a large pterosaur, with an estimated wing span of 2,5 m {WELLNHOPER 1991a).
A third named pterosaur from the Morrison Formation has also been recovered from the Dry Mesa Quarry. JENsEN (1981) originally attributed many elements from this quarry to birds, including a partial right femur ofArcbacopterpx, a tibiotarsus belonging to the new avian species Paleop- teryx tbomsoni {which was not formally described in the paper) and many "avian-like" bones, including a synsacrum and a partial left femur. JENsEN st PADIAN (1989) redescribe the right femur as that of a manirap- toran theropod, and reidentify the "tibiotarsus" as the distal radius of an indeterminate theropod. The synsacrum was made the holotype of kfesaducry1us ornr'Ibospbyos. The left femur, and much additional post- cranial material, were also attributed to this genus. It is the most complete pterosaur known from the Morrison.
The 1992 paleontological expedition by the Denver Museum of Natural History (DMNH) to the Morrison Formation exposures at