?67 PaleoBios Museum of Paleontology University of California, Berkeley Number 20________________________________________January 12, 1976 A MANDIBLE OF BECKIA (MAMMALIA: MUSTELIDAE) FROM CONTRA COSTA COUNTY, CALIFORNIA BY STEPHEN W. EDWARDS1 ABSTRACT A second specimen of Beakia Bryant, from the Mio-Pliocene un- differentiated Contra Costa Group in Contra Costa County, Califor- nia, closely resembles the type of Beakia gvangerensis Bryant. The Kendal1-Mallory local fauna, which includes the specimen of Beakia, appears to be slightly older than the Black Hawk Ranch local fauna, and late Clarendonian in age. INTRODUCTION The mandible described here (UCMP 112158) is from the Kendall- Mai lory locality (UCMP V6107), which is exposed by a roadcut in the undifferentiated Contra Costa Group in Bolinger Canyon, Contra Costa County, California. The lithology of the locality, which produced most of the Kendal 1-Mai lory local fauna, is a light gray to dark olive-green fluvial siltstone and mudstone. A prominent pebble-cobble conglomerate, interbedded with brown, poorly sorted sandstone, rests conformably on the fine clastic beds, fifteen feet above the quarry. The only previously reported specimen of Beakia is the holotype (LACM 10642) from Yakima County, Washington. The California speci- men extends our knowledge of the paleogeographic distribution of this genus, as well as of the tribe Mellivorini, fossil remains of which are extremely rare in the Nearctic. Abbreviations used in this paper are: LACM - Los Angeles County Museum of Natural History, and UCMP - University of California Department of Paleontology, University of California, Berkeley, California 9^720. 2 PaleoBios No. 20 Museum of Paleontology. ACKNOWLEDGEMENTS I am thankful to Daryl Domning, Bruce Lander, Jens Munthe, Dr. D. E. Savage, and especially Hugh Wagner, for reading this paper and offering helpful advice. Lynne and Richard Clinnick are ack- nowledged for their perfect comradeship in the field, and for do- nating their extensive collections from UCMP V6107 to the Museum of Paleontology. Figure 1 was drawn by Museum of Paleontology staff artist Jaime Patricia Lufkin. SYSTEMATICS Order CARNIVORA Bowdich, 1821 Family MUSTELIDAE Swainson, 1835 Subfamily MELLIV0R1NAE Gill, 1872 Genus Beakia Bryant, 1968 Type: Beakia gvangerensis Bryant, LACM 106*t2, right horizon- tal ramus with P-j-M, and roots of C to P., Bryant, L. J., 1968, Los Angeles County Museum Contributions in Science, number 139, figs. 1-2. Type Locali ty: LACM 1oc. 6^31, Granger Clay Pit, Yakima County, Washington; Ellensburg Formation. Beakia of. B. grangerensis Figure 1 Material: UCMP 112158, UCMP locality V6107; fragment of left horizontal ramus with M. (broken), roots of P, ., posterior part of alveolus of C; fragment of right horizontal ramus with P/,"Mi (both broken). Descri ption: The teeth are well worn. The entoconid region of M, is obscured by wear. A small entoconid may have been pres- ent, but if so was very reduced relative to the large hypoconid. The paraconid is longer than the talonid. There is no metaconid. There is no cinguium surrounding the hypoconid (as in the holo- type), but this may be an artifact of enamel breakage and loss. Pi is two-rooted, and shows a small posterior cinguium and a very slight posterior accessory cusp between the cinguium and the main cusp. P?_o are both two-rooted. P, is very reduced, and single- rooted. The anterior end of P, is oriented labially, and labial- ly overlaps the posterior end of P.. P? shows the same orien- tation as P,, but is even more oblique. The anterior root of P- is small, and the very reduced single root of P, is mesiolingual to it. The canine root, based on alveolus size, was substantial. The symphysis is not expanded. There are two mental foramina, one below the roots of P_, the other below the posterior root of V 1976 BECKIA 3 B 1 cm. Figure I. Beakia of. B. grangerensis, UCMP 112158, loc. UCMP V6107. A. Left horizontal ramus with M,, external view. B. fragment, showing P. root and alveoli for P2_r, occlusal Fragment of right horizontal ramus, with P/."M, , external Same v i ew. C. view. k PaleoBios No. 20 Discussion: UCMP 112158 resembles the holotype of Beakia gran- gerensis in most details. Although the anterior mental foramen is below the roots of P. in UCMP 112158, and below the anterior root of P, in the holotype, even this character is remarkably close in the two individuals, considering how variable this feature tends to be in other mustelids (Gulo and Taxidea). However UCMP 112158 is not definitely assigned to B. grangerensis, because wear has made development of the M. entoconid region uncertain; and because the structure of the anterior premolar crowns is unknown. Age and Correlation: The type specimen of Beakia grangerensis Bryant is from LACM loc. 6431, in "the upper or Naches Member of the Ellensburg Format ion...above the Wenas Basalt" (Bryant, 1968, p. 3). Bryant {op. ait., p. 3) reports Hipparion ?anthonyi from the same locality. Several well-worn cheek teeth of Nannippus aff. tehonensis were found at UCMP V6367, below the Wenas Basalt. This indicates the holotype of Beakia may be of late Clarendonian age. Hemphillian age is also a possibility, suggested by Hipparion ?anthonyi, which was recorded by Merriam et at. (1925, P- 80) from the Hemphillian Rattlesnake beds. The mandible described in this report was collected at UCMP V6107, in association with the following mammalian taxa: Sciuridae ?Protospermophitus sp. Can i dae Aeturodon aff. haydeni Osteoborus of. diabtoensis Gomphotheri idae Gen. et sp. indet. Equidae Nannippus of. tehonensis Merycoidodontidae Ustatoahoerus profeotus Camelidae Gen. et sp. indet. UCMP V6107 is situated about three miles west of the Black Hawk Ranch quarry (UCMP V3310). Both localities are in continental rocks overlying the marine "Neroly" Formation (sensu Webb and Woodburne, 1964, p. 71). The Black Hawk Ranch quarry lies approx- imately 1,900 feet stratigraphically above a local Astrodapsis tumidus zone in the Neroly. UCMP V6107 lies approximately 1,800 feet above an Astrodapsis tumidus bed in the Neroly of Las Trampas Ridge (flanking Bolinger Canyon). Neither Nannippus of. tehonensis nor Ustatoahoerus profeotus, both recovered at V6107, have been found in the Black Hawk Ranch quarry. However, the Black Hawk Ranch quarry occurs about 300 feet upsection from a locality (UCMP V5509) which has produced N. of. tehonensis teeth virtually identical to those from V6107 in Bolinger Canyon. Juvenile Usta- toahoerus specimens from V3310 appear to fall within the size- range of U. major, which is larger than U. profeotus, and later 1976 BECKIA 5 in age in the Great Plains. The Kendal 1-Mai lory local fauna ap- pears to be slightly older than the Black Hawk Ranch local fauna. Nannippus of. tehonensis teeth, much like teeth from V6107, occur near the middle of the type Grizzly Peak Formation (UCMP V1001), the base of which has been potassium/argon dated at 9-8- 10.0 million years (Dr. Garniss H. Curtis, oral commun.). Usta- toahoevus profeatus has been found in the lower Ricardo Formation. The lower Ricardo (in part) has been dated at 10.0 million years (Evernden et at., 1964, KA 453)- On the basis of these dates, UCMP V6107 would be considered late Clarendonian in the sense of Evernden et al. (1974, P- 164), and either late Clarendonian or early Hemphillian in the sense of Berggren and Van Couvering (1974, fig- 11)- This would clearly be older than the Ellensburg Formation locality which produced the Beekia holotype, if Hippcw~ ion ?anthonyi from that locality indicates proximity in age to the Rattlesnake fauna. MEASUREMENTS P, antero-posterior diameter P. antero-posterior diameter Pr transverse diameter M. antero-posterior diameter M. transverse diameter PJ-M] length Depth of mandible below mid M. UCMP 112158 LACM 106' 9.4 (alveoli) 10.1 12.7 (alveoli) 12.9 5-7 6.34 19-8 19.4 7-3 8.3 51-5 - - 23.3 19.65 Holotype measurements are from Bryant, 1968, p. 6. LITERATURE CITED Berggren, W. A., and Van Couvering, 1974. The late Neogene: bio- stratigraphy, geochronology and paleoclimatology of the last 15 million years in marine and continental sequences. Palaeogeo- graphy, Palaeoclimatology, Palaeoecology, 16:1-216. Bryant, L. J., 1968. A new genus of mustelid from the Ellensburg Formation, Washington. Los Angeles County Museum Contributions in Science, no. 139, pp. 1"6. Evernden, J. F., D. E. Savage, G. H. Curtis, and G. T. James, 1964. Potassium-argon dates and the Cenozoic mammalian chronology of North America. Amer. Jour. Sci., 262: 145-198. Merriam, J. C, C. Stock, and C. L. Moody, 1925. The Pliocene Rattlesnake Formation and Fauna of eastern Oregon, with notes on the geology of the Rattlesnake and Mascall deposits. Cam. Inst. Wash. Publ., 347, pp. 43"92. Webb, S. D., and M. 0. Woodburne, 1969- The beginning of conti- nental deposition in the Mount Diablo area. Guidebook, Ann. Field Trip, Geol. Soc. Sacramento, 1964, pp. 70-78. Manuscript received 8-15-1975; accepted 10-20-1975- PaleoBios No. 20 PaleoBios is a series of occasional papers published under the supervision of the Graduate Students in the Department of Paleontology of the University of California, Berkeley, California 9^720, with the technical assistance of the academic and nonacademic staff of the Museum of Paleontology. Managing Editor, Jens Munthe; Co-editor, Michael J. Novacek; Editorial Assistant, Beagle Browne. Purchase of a single article or more at the prices quoted below may be made by sending a check to the Managing Editor, PaleoBios, at the above address. Subscriptions to future numbers are available at $2.00 per year. Recent Issues Number Title Price 15 The Hemingfordian mammal fauna of the Vedder locality, $0.30 Branch Canyon Formation, Santa Barbara County, Cali- fornia. Part I: Insectivora, Chiroptera, Lagomorpha, and Rodentia (Sciuridae). By J. Howard Hutchison and Everett H. Lindsay, 19 PP- (197*0. 16 The Hemingfordian mammal fauna of the Vedder locality, $0.50 Branch Canyon Formation, Santa Barbara County, Cali- fornia. Part II: Rodentia (Eomyidae and Heteromyidae). By Everett H. Lindsay, 19 pp. (197*0. 17 Heptranahias howellii (Reed, I9*t6) (Selachii: Hexandri- $0.60 dae) in the Eocene of the United States and British Columbia. By Bruce J. Wei ton, 15 pp. 097*0. 18 Pathology of Two Fossil Sea Cows (Mammalia: Sirenia). $0.35 By Daryl P. Domning and Frederic L. Frye, *t pp. (1975)- 19 Collection of taphonomic information from fossil and $0.40 recent vertebrate specimens with a selected bibliography. By Kathleen Munthe and Samuel A. McLeod, 12 pp. (1975). 20 A mandible of Beckia (Mammalia: Mustelidae) from Contra $0.30 Costa County, California. By Stephen W. Edwards, 5 pp. (1976).