CONTRIBUTIONS FROM THE MUSEUM OF PALEONTOLOGY UNIVERSITY OF MICHIGAN VOL.VII, No. 5, pp. 91-105 (2 figs.) MARCH2, 1949 PLIOCENE SAW ROCK CANYON FAUNA IN KANSAS BY CLAUDE W. HIBBARD UNIVERSITY OF MICHIGAN PRESS ANN ARBOR CONTRIBUTIONS FROM THE MUSEUM OF PALEONTOLOGY UNIVERSITY OF MICHIGAN Director: LEWIS B. KELLUM The series of contributions from the Museum of Paleontology is a medium for the publication of papers based entirely or principally upon the collections in the Museum. When the number of pages issued is sufficient to make a volume, a title page and a table of contents will be sent to libraries on the mailing list, and also to individuals upon request. Correspondence should be directed to the University of Michigan Press. A list of the separate papers in Vol- umes 11-VI will be sent upon request. VOL. I. The Stratigraphy and Fauna of the Hackberry Stage of the Upper Devonian, by C. L. Fenton and M. A. Fenton. Pages xi+260. Cloth. $2.75. VOL. 11. Fourteen papers. Pages ix+240. Cloth. $3.00. Parts sold separately in paper covers. VOL. 111. Thirteen papers. Pages viii+275. Cloth. $3.50. Parts sold separately in paper covers. VOL. IV. Eighteen papers. Pages viii+295. Cloth. $3.50. Parts sold separately in paper covers. VOL. V. Twelve papers. Pages viii+318. Cloth. $3.50. Parts sold separately in paper covers. VOL. VI. Ten papers. Pages viii+336. Paper covers. $3.00. Parts sold separately. (Continued on inside back cover) VOL. VII. NO. 5. pp . 91-105 (2 figs.) MARCH2. 1949 PLIOCENE SAW ROCK CANYON FAUNA IN KANSAS By CLAUDE W . HIBBARD CONTENTS Introduction ......................................................... 91 Rexroad formation ................................................... 92 Saw Rock Canyon section ......................................... 93 Cimarron River section ........................................... 94 Wolf Canyon section .............................................. 94 Discussion of outcrop areas ........................................ 95 Saw Rock Canyon fauna ............................................... 97 Mollusca ......................................................... 97 Vertebrata ....................................................... 98 Osteoborus progressus Hibbard ................................. 98 Perognathus mclaughlini. sp. nov ............................... 98 Dipoides wilsoni. sp. nov ...................................... 100 Baiomys rexroadi Hibbard .....................................103 Cosomys primus Wilson .......................................103 Discussion ........................................................... 1W Literature cited .......................................................105 INTRODUCTION RICH fossil-bearing locality discovered in Saw Rock Canyon. A Seward County. Kansas. in June 1943. by Thad G McLaughlin and Hibbard. yielded Pliocene vertebrates. from two adjacent lith- ologic units . An upper 12-foot layer of sandy silt has yielded remains of mastodon and land turtles. and an underlying sandy silt and clay bed about 10 feet thick remains of a beaver and "boneeating" dog. The name XI member (new name) is proposed for this lower sandy silt and clay unit . The invertebrate and vertebrate fauna which it contains is known as the Saw Rock Canyon local fauna . The purpose 9 2 CLAUDE W. HIBBARD of this paper is to describe the Saw Rock Canyon fauna and to dis- cuss the stratigraphic position of the XI member. The occurrence of vertebrate fossils at this locality was briefly described by the author in 1944. The fossils were interpreted to be of Middle Pliocene age and the strata were referred to the Ogallala. Subsequent visits have furnished additional vertebrate material for study and have given more precise data on its stratigraphic occur- rence. The mastodon and the land turtle described in 1944, as Plio- mastodon adamsi and Testudo riggsi, respectively, are now known to belong to the Rexroad fauna, sensu stricto, and to come from an upper fossiliferous unit which is recognized to be of Blancan, Up- per Pliocene age. The presence of the beaver (Dipoides), obtained in the early collection, had caused the whole assemblage to be considered of Middle Pliocene age. Dipoides has been regarded in the past as a Hemphillian form. Osteoborus progressus, the bone-eating dog, is recognized in its evolutionary development to be intermediate be- tween 0. cynoides (Martin) of Hemphillian age and Borophagus diversidens Cope of Blancan age. The strata of the lower fossil- iferous unit are intermediate in age between those from which the Hemphill fauna and the Blanco fauna were recovered, that is, near the boundary line of Middle and Upper Pliocene time. The co-operation of Robert W. Wilson, curator of Paleontology in the University of Kansas ~useumof Natural History, who grant- ed permission to use the specimens in the museum as a basis for this publication, is gratefully acknowledged. REXROAD FORMATION The Rexroad formation was named by H. T. U. Smith (1940, p. 95) from exposures along the tributaries of Crooked Creek on the Rexroad Ranch, in sec. 22, T. 33 S., R. 29 W., Meade County, Kan- sas. For a further discussion of these beds in this region see Mc- Laughlin (1946, pp. 33, 133) and Byrne and McLaughlin (1948, pp. 31, 34, 73). At the beginning of deposition of the Rexroad formation, the topography of the Seward County area was very irregular. This PLIOCENE FAUNA IN KANSAS 93 irregularity accounts for differences in the thickness of the Rexroad formation from place to place and for variations in the lithologic character of its basal beds. Some of the relief on the pre-Rexroad surface was due to faulting (sink-hole development) which affected the Laverne formation but not the Rexroad (Byrne and McLaugh- lin, 1948, p. 73). The topographically highest parts of the Laverne were exposed almost until the end of the Rexroad deposition, when the braided streams began to fill the valleys which occupied the surface depressions and spread a thin veneer of sand over the flood plain in the interstream areas where outliers of the Laverne still remained. The Laverne formation on these uplifted blocks of the interstream areas is characteristically capped with a thin deposit of Rexroad sand. A series of measured sections and a discussion of the sections that outcrop in the.genera1 region of Saw Rock Canyon follows. Saw Rock Canyon Section Type section of XI member of the Rexroad formation. Mi~au~hlinand Hibbard, 1943. Near the center of the west line in sec. 36, T. 34 S., R. 31 W., Seward County, Kansas. Thickness Meade formation feet 7. Meade Gravels member. Sand and gravel, cemented .with cal- cium carbonate. A few pebbles are as much as l inch in diameter. Forms prominent bench. ....................... 2.7 Disconformity Rexroad formation 6. Silt, hesand, red, containing lenses of fine gravel and coarse sand ...................................................12.0 5. Caliche, silicious, very hard, white. Forms prominent ledge. ... 2.7 4. Silt, reddish buff, containing fine sand (holotype of Plwmm- todon adamsi taken at top of bed, and the remains of Testudo riggsi near the base of bed) .............................. 10.5 Disconformity 3. XI member. Clay, greenish gray to blue gray, some silt and hesand near base, containing abundant remains of inverte- brates, pond and river turtles and beaver (Saw Rock Canyon fauna) .................................................. 5.6 2. Caliche, containing yellow-green to rusty-brown chert nodules.. 1.4 CLAUDE W. HZBBARD 1. Sand, fine to coarse, cross-bedded, poorly consolidated, yellow to rusty brown .........................................17.3 Unconformity (angular) Laverne formation Cimarron River Section Sec. 20, T. 34 S., R. 30 W., Meade County, Kansas. Thickness Crooked Creek formation feet 7. Pearlette Ash member. Volcanic ash ....................... 4.0 6. Silt, sandy, reddish (invertebrates) varies from 1 to 3 feet.. .. 3.0 5. Zone of pebbles .......................................... 0.4 Unconformity Meade formation 4. Missler member. Silt, sandy, reddish with stringers of caliche.. 12.0 3. Meade Gravels member. Sand and gravel (basal 3 to 5 feet consolidated) ............................................15.0 Unconformity Rexroad formation 2. Clay, blue gray to brown (varies from 2 to 12 feet). ......... 10.0 1. Silt, reddish, sandy (Testdo riggsi) ........................ 10.0 (Base not exposed) Wolf Canyon Section Modified from Byrne and McLaughlin, 1948, p. 74. In secs. 7 and 18, T. 35 S., R. 30 W., .Meade County, Kansas. Topsoil on caliche rubble Thickness Meade formation feet 16. Silt, fine, sandy, grading upward into massive caliche at top, (from 2 to 8 feet thick) ................................. 26.0 15. Silt, sandy, calcareous, ash gray at base, grading upward into gray tan to light tan; weathers to a resistant bench.. ...... 7.5 14. Meade Gravels member. Sands and gravels, coarse; locally cemented with calcium carbonate ......................... 11.0 Disconformity Rexroad formation 13. Silt, sandy, reddish to pinkish, zones of caliche (approximately middle of bed, a blue-gray zone 4 inches to 2 feet thick con- taining invertebrates) .................................... 40.0 12. Silt, fine, sandy, reddish, with lenses of clay at top of bed, massive caliche (weathers to hard resistant bench, 1 foot to 4 inches) ...............................................4.75 PLIOCENE FAUNA IN KANSAS 95 11. Silt, fine, sandy, reddish, streaked with caliche, grading upward into a gray clay ........................................ 10.