University of Kansas Publications
Museum of Natural History
Volume 12, No. 4, pp. 217-240, 12 figs.
May 2, 1960
BY
THEODORE H. EATON, JR., AND PEGGY LOU STEWART
University of Kansas
Lawrence
1960
University of Kansas Publications, Museum of Natural History
Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Robert W. Wilson
Volume 12, No. 4, pp. 217-240, 12 figs.
Published May 2, 1960
University of Kansas
Lawrence, Kansas
PRINTED IN
THE STATE PRINTING PLANT
TOPEKA, KANSAS
1960
28-2495
BY
THEODORE H. EATON, JR., AND PEGGY LOU STEWART
A slab of shale obtained in 1955 by Mr. Russell R. Camp from aPennsylvanian lagoon-deposit in Anderson County, Kansas, hasyielded in the laboratory a skeleton of the small amphibian Hesperoherpetongarnettense Peabody (1958). This skeleton providesnew and surprising information not available from the holotype,No. 9976 K. U., which consisted only of a scapulocoracoid,neural arch, and rib fragment. The new specimen, No. 10295 K. U.,is of the same size and stage of development as the holotype and itis thought that both individuals are adults.
The quarry, University of Kansas Museum of Natural HistoryLocality KAN 1/D, is approximately six miles northwest of Garnett,Anderson County, Kansas, in Sec. 5, T. 19S, R. 19E, 200 yards southwestof the place where Petrolacosaurus kansensis Lane was obtained(see Peabody, 1952). The Rock Lake shale, deposited underalternately marine and freshwater lagoon conditions, is a thin memberof the Stanton limestone formation, Lansing group, Missourianseries, and thus is in the lower part of the Upper Pennsylvanian.
Peabody (1958) placed Hesperoherpeton in the order Anthracosauria,suborder Embolomeri, family Cricotidae. Study of thesecond and more complete specimen reveals that Hesperoherpetonis unlike the known Embolomeri in many important features. Thelimbs and braincase are more primitive than those so far describedin any amphibian. The vertebrae are comparable to those of Ichthyostegalia(Jarvik, 1952), as well as to those of Embolomeri. Theforelimb is transitional between the pectoral fin of Rhipidistia andthe limb of early Amphibia. The pattern of the bones of the forelimbclosely resembles, but is simpler than, that of the hypotheticaltransitional type suggested by Eaton (1951). The foot seeminglyhad only four short digits. The hind limb is not known.
The new skeleton of Hesperoherpeton lies in an oblong block oflimy shale measuring approximately 100 × 60 mm. After preparationof the entire lower surface, the exposed bones and matrixwere embedded in Bioplastic, in a layer thin enough for visibility[Pg 220]but giving firm support. Then the specimen was inverted and thematrix removed from the opposite side; this has not been coveredwith Bioplastic. The bones lie in great disorder, except that someparts of the roof of the skull are associated, and the middle sectionof the vertebral column is approxim