BIOSTRATIGRAPHIC SURVEYS IN THE SIWALIKS OF PAKISTAN:
A METHOD FOR STANDARDIZED SURFACE SAMPLING OF THE VERTEBRATE FOSSIL RECORD

ABSTRACT

Much of the vertebrate fossil record consists of fragmentary specimens that are widely dispersed across eroding outcrops. This paper describes a method of standardized surface surveying that samples fragmentary surface fossil assemblages for information relating to biostratigraphy, taphonomy, and paleoecology that is not usually available from more traditional approaches to paleontological collecting. Biostratigraphic surveys have been used in the Miocene Siwalik sequence of northern Pakistan since 1979 to better define important faunal appearance and extinction events and to learn more about the taphonomy and overall productivity of the highly fossiliferous fluvial deposits. The surveys record all bones encountered during walking transects in specified stratigraphic intervals, which are well exposed and delimited by strike valleys between tilted sandstones. High quality or informative specimens are collected, and dense patches of fossils are designated as formal localities and treated separately. The resulting survey data permits analysis through time of variables such as fossil productivity per search hour, proportions of different skeletal parts and vertebrate groups, and ratios of abundant mammal families such as Equidae and Bovidae, as well as tests for correlations between these and other variables. Biostratigraphic survey data compliment other types of paleontological information about faunal evolution in the Siwalik sequence and provide new insights on biotic versus environmental correlates of changes in the abundances of particular groups through time. The methodology can be adapted and used for other fossiliferous sequences throughout the vertebrate record.

Anna K. Behrensmeyer. Department of Paleobiology, National Museum of Natural History, MRC 121, P.O. Box 37012, Smithsonian Institution, Washington, DC 20013-7012, USA.
John C. Barry. Peabody Museum, Harvard University, Cambridge, MA 02138, USA. 

KEY WORDS: Siwaliks, Pakistan, Miocene, taphonomy, biostratigraphy, sampling methods, paleoecology

PE Article Number: 8.1.15
Copyright: Society of Vertebrate Paleontology May 2005
Submission: 12 December 2004. Acceptance: 20 March 2005