-Correspondence to: CICESE, P.O. Box 434844, San Diego, CA 92143, U.S.A. Journal of Arid Environments (2001) 49: 671–675 doi:10.1006/ jare.2001.0827, available online at http://www.idealibrary.com on Mortality of cattle on a desert range: paleobiological implications Eric Mellink*- & Paul S. Martin? *Centro de Investigacio H n Cientn H fica y de Educacio H n Superior de Ensenada, B.C., Apdo. Postal 2732, Ensenada, B.C., Me H xico @Desert Laboratory, Department of Geosciences, University of Arizona, Tucson, AZ 85721, U.S.A. (Received 13 December 1999, accepted 10 April 2001) Mortality of domestic livestock can reveal circumstances of death of interest to the taphonomist and paleobiologist. We present a case that involves a dieoff and incipient burial of cattle at the end of a severe drought in a ranch in north-western Sonora (Mexico). Regional environmental crisis, such as drought, have been suggested to explain massive death, but we contend that droughts suddenly broken by a severe storm or storms and steady rains would be more stressful. As a result, in arid lands mammals could have accumulated in fossil deposits in short bursts through time.  2001 Academic Press Keywords: drought; taphonomy; paleobiology; mortality; megaherbivores Mortality of domestic livestock can reveal circumstances of death of interest to the taphonomist and paleobiologist. Under the relatively unregulated, free-ranging condi- tion of the 1920s livestock stressed by unusual weather on the praries of east Texas drifted before the winds of an outburst of continental polar air (i.e. ‘Norte’) to find themselves trapped on the exposed tidal flats of Galveston Bay. Dying and dead animals were in the process of being buried in fine-grained marine sediments when Weigelt (1989) observed them. In his classic study, Weigelt (1989) treated range cattle as surrogates for understanding the relationship between death and entombment of native megaherbivores during the Cenozoic. Here we present a case of dieoff and incipient burial at the end of a severe drought. Dieoff occurred on Rancho La Bachata, 50 km west of Caborca, Sonora. Cattle occupied an arid range of approximately 1000 ha. On public ranges in the drier parts of the Sonoran Desert in Arizona (U.S.A.), the Bureau of Land Management issues seasonal grazing allotments only after ample precipitation, and private ranches are mostly devoted to the production of crops under irrigation. Thus, La Bachata, as well as other desert ranches in western Sonora, can provide unique information on the dynam- ics of large hervibore populations in arid lands. This part of the Sonoran Desert is dominated by open stands of gobernadora (or hediondilla, Larrea tridentata) and ambrosia (Franseria deltoidea), with woody legumes along ephemeral washes, including mezquite (Prosopis juliflora), palo fierro (Olneya tesota), palo verde (Cercidium microphyllum and C. floridum) and palo brea, 0140}1963/01/120671#05 $35.00/0  2001 Academic Press