Dung and Over: De

1989 Cranium, jrg. 6, no. 1, pag. 29-44, april 29 Pleistocene Dung and the Extinct Herbivores of the Colorado Plateau, Southwestern USA Jim+I. Mead and Larry+D. Agenbroad Samenvatting kan worden De auteur beschrijft hoe en welke informatie verkregen van fossiele mest van grote herbivoren. Op grond van de morfologie en de grote van de fractie ( drooggewicht in gr.) en soms op kan welke het haarinhoud, van fossiele mest bepaald worden van herbivoor afkomstig is. Bovendien kan uit de inhoud ervan conclusies getrokken worden over: de vegetatie, het dieet van het dier, het seizoen, de ouderdom van het fossiel d.m.v. koolstofisotoop-datering, eventu- ele veranderingen in het dieet, mogelijke oorzaak van uitsterven, de sexe van het dier dat de in mest heeft achtergelaten en veranderingen het milieu. overzicht locaties het Colorado Plateau waar is Er wordt een gegeven van (grotten) op mest Mammuthus shastensis en Oreamnos gevonden van Bison sp., sp., Nothrotheriops (grondluiaard) harringtoni (uitgestorven berggeit). De volgende conclusies worden getrokken over de dieetsamenstelling van de hiervoor genoemde soorten van het Colorado Plateau: de mammoet: verschillende plantensoorten, maar overwegend (1/3 deel van de totale mest- inhoud) grassen; de uitgestorven berggeit: vnl. grassen en ook jonge scheuten; de grondluiaard: vnl. jonge scheuten en daarbij ook grassen; de bizon: merendeels grassen en daarbij jonge scheuten. The vertebrate paleontologist is typically Although a wide variety of extinct megaher- concerned with a plethora of isolated skele- bivores are known from skeletal remaines tal remains from which to reconstruct (ANDERSON, 1984; KURTeN and ANDERSON, extinct species or faunal communities. If 1980), only a few are recorded by preserved lucky, the paleontologist will happen along dung and hair specimens. Here we review of late land an articulated skeleton (THEWISSEN and the Pleistocene (Rancholabrean mammal the FRANZEN, 1987), which permits an unusually age) dry cave localities of Colo- detailed osteological examination of a parti- rado Plateau, Southwestern USA, that con- cular species. The paleontologist will be able tain preserved dung deposits, and the variety to describe the skeleton of an extinct animal of analyses that can be performed on the than Because the fairly well, but more often not diet is unique remains. study of glacial- at best hypothesized, based on tooth mor- age dung remains is in its infancy in North phology, and the local plant community is America, we will examine only four of the inferred from an associated pollen recon- best known species: Mammuthus struction. (Proboscidea,Nothrotheriopsmammoth), Water, the provider of life, is also the pro- shastensis (Xenarthra Megalonychidae, Shasta motor of decay. Invariably the taphnonomic ground sloth), Bison (Artiodactyla, Bovidae situation of an animal carcass is such that Bovini, bison), and Oreamnos harringtoni Bovidae: stomach contents, skin, muscle, organs, and (Artiodactyla: Rupicaprini, mountain hair/keratin decay away relatively quickly. Harrington's goat). Even in arid regions of the desert South- Use of preserved dung for reconstrucution of in west, USA or the Arctic, provide enough diet and environments began the arid moisture to permit slow but certain decay of Southwest when EAMES (1930) examined non-skeletal remains - unless protected. Two dung of extinct Shasta ground sloth from environmental situations typically allow for New Mexico, and LAUDERMILK and MUNZ soft-tissue preservation: identified macrobotanical fragments from 1) regions of the Holarctic permafrost (PO- similar dung from Gypsum Cave, Nevada POV, 1948; VERESHCHAGIN, 1977; VERESH- (1934), and Rampart and Muav caves, Arizona CHAGIN and NIKOLAEV, 1982), and (1938; LAUDERMILK, 1949). the 2) xeric cave deposits of deserts MARTIN et al (1961) later identified pollen (EAMES, 1930; MARTIN et al, 1961). from Shasta ground sloth dung in Rampart 30 Cave (western Grand Cannyon, southwestern- are rare. See MEAD and AGENBROAD (sub- most Colorado Plateau; fig. 1). IBERALL mitted 1988) for a more detailed field and (1972; now, ROBBINS et al., 1984) went a laboratory guide to extinct and modern her- step further in paleoecological reconstruc- bivore dung of North America MURIE (1954) when she used tions microhistological ana- provides the best overall field guide to dung lyses (plant cuticle and other remains) to identification of living North American mam- identity the diet of the extinct Harrington's mals (an equally good field guide to dung mountain goat form Stanton's Cave (northern identification of Australian native and intro- end of Colorado River in the Grand Canyon, duced animals is provided by MORRISON, Arizona). HANSEN (1978) used the same 1981; an excellent book to observe how a technique to re-examine the Shasta ground dung guide is to be used). sloth dung from Rampart and Muav caves. Long (LONG and MARTIN, 1974; LONG et Identification al., 1974) was the first to use multiple ra- diocarbon dating (beta particle technique) to Two analyses (morphology and size fraction; locate the last use of Rampart Cave by the and sometimes a third, hair content) are ground sloth. Analysis of dried dung on the used to identify the species of the herbivore greater Colorado Plateau began in earnest which produced the dung. Herbivores consu- when HANSEN (1980) provided the identifi- me large quantities of vegetation and much from in of cations the fragmented remains Cow- the bulk is expelled as waste. Conse- Utah boy Cave, (northern-most locality on quently, the dung is deposited as one large It fig. 1). was this study that heralded a mass, or as a large number of fecal pellets new era of dietary and faunal community which are reasonably regular in size and studies in this arid region. shape, sometimes distinctly so. The dung, when broken open, can be seen to be com- Analyses posed of evenly cut twigs or chaff-like vegetation. The size of the contents is often a of indicative of of animals. Although variety analyses are currently a type or group conducted on preserved dung remains, it Overall morphology of a particular species of should be remembered that the study, in its dung can change somewhat with the moisture fullest spectrum, is just beginning. The use content of the ingested vegetation. tool the in of dung as a for paleontologist is Proboscideans general produce an extre- endless. that Besides indicating a particular mely big bolus, larger than other dung mas- animal inhabited the area of the deposit, ses produced by other herbivores. Mammoth dung of extinct megafauna can be used: dung (fig. 2) is approximately 230 by 170 by 1) to determine some of the local plant com- 85 mm in size (DAVIS et al, 1984; MEAD et munity components, al., 1986c), full of graze remnants, and is 2) to directly reconstruct the diet identical in size and content to those bolu- 3) to identify the season(s) of occupation ses of the living elephants, Loxodonta and direct 4) as a means to radiometrically date Elephas (WING and BUSS, 1970). Although the species the large size is a certain identifying cha- determine the the 5) to possibly time of demise, racter, often boluses are trampled into the species smaller fragments (HANSEN, 1980) leaving 6) to define possible changes in diet through the identification to the size fraction ana- time, the up to time of extinction lysis. Fractional analysis of the dung con- to examine of extinction 7) possible causes tents is expressed as dry weight in grams or 8) to identify the sex of species leaving the percent of dry weight according to size deposit (<0.25, 0.25 - 0.5, 0.5-1.0, 1.0-2.0,>2.0 mm 9) to environmental - identify changes to (fig.3). Lenghts and widths of grass stems The name but a few uses. major items will and twigs in modern elephant dung measure be discussed here. up to 70.0 by 5.0 mm, similar to the 60.0 by Analysis of dried dung is divided into three 4.5 mm observed in the mammoth dung from steps: Bechan Cave, Utah. the 1) identification of producing species The Shasta ground sloth is a browser and determination of the 2) contents (a large and produces dung boluses as linear-connected varied category) thick plates (MARTIN el al., 1961; MARTIN 3) paleoenvironmental and paleoecological 1975; fig.4). In addition to the distinctive reconstructions. The first step of identifica- shape, the twig contents are all clipped tion is the most critical analysis. Published short (HANSEN, 1980; SPAULDING and accounts and comparative collections of dung MARTIN, 1979). Size fractional analysis illu- 31 fig. 1 Map of the arid Southwest of the United States locating the Colorado Plateau and the (stippled line) various caves containing late Pleistocene age dung deposits (dots). fig. 2 A single bolus ofMammuthus from Bechan Cave, Utah. Note the coprophagus insect made the holes when dung was still wet. 32 strates that Equus (horse) dung can be similar to that of the Shasta ground sloth (fig. 5). However, the size (width and length) of the largest twigs of Nothrotheriops and My- lodon (mylodont ground sloth, Chilean sam- ple) is usually much shorter than that of Equus, even when the horse eats woody shrubs (fig. 6). Shasta ground sloth was the first species of a North American extinct megafauna to have a directly reconstructed diet (MARTIN et al., 1985; THOMPSON et al, 1980). Artiodactyls produce a variety of dung mor- phologies. Bison dung will change from basi- in cally circular plates aligned a row when dry food is eaten, to the typical amorphous of when pile ("chip") waste green or wet vegetation is consumed (fig. 7). In conjuncti- on with the distinctive shape, the size fraction of the contents permit identification. will Although graze versus browse ingestion change the coar seness of the contents, the overall fractional components and morphology remain approximately the same.

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