View - Kowalewski, M. - Virginia Tech

More documents

Recommendations

Info

PALEONTOLOGICAL SOCIETY PAPERS, V. 8, 2002FIGURE 1—Coprolites can have many morphologies, from easily recognizable forms to nondescriptmasses. (a) Very large Cretaceous coprolite from Alberta (Royal Tyrrell Museum, TMP 98.102.7). Thisspecimen was so fractured from weathering that it was removed in a plaster jacket. (b) Probable fishcoprolite from the Pennsylvanian black shale of Indiana (Field Museum of Natural History; FMNHPF2210; see Zangerl and Richardson, 1963). Photograph shows lateral view of sliced specimen; thespecimen originally appeared as a lump in the sediments, but was sliced through the center to revealthe coprolitic material sandwiched between the black shale. (c) Small coprolite with more typical,‘sausage’ fecal shape (Royal Tyrrell Museum, TMP 80.16.1098).little taxonomic information (Sawyer, 1981).Non-destructive analyses of coprolites shouldalso include careful examination of specimensurfaces for distinctive impressions or inclusions.These surfaces can be scanned with a stereomicroscope; if warranted, higher magnifications canbe obtained using scanning electron microscopy.Scrutiny of the outer surface of a coprolite mayreveal dietary inclusions protruding from thecoprolitic ground mass. Mineralized skeletalelements are commonly observed in carnivorecoprolites, and inclusions on outer surfaces may beaccentuated by weathering processes. Coproliteexteriors may also show three-dimensionalimpressions of the vegetation or detritus on whichthe feces were deposited. Such impressions are ofinterest, but should be distinguished from those thatrepresent dietary components.46
CHIN—ANALYSES OF COPROLITES PRODUCED BY VERTEBRATESBroken coprolites allow scrutiny of fracturedinternal surfaces. In most cases, recognizablefeatures evident in the interior of a specimen canbe confidently attributed to diet. This includesthree-dimensional impressions that may indicateundigested soft tissues.Destructive Analyses.—As a general rule,damage of fossil specimens should be studiouslyavoided. At the present state of our technology,however, destructive analyses appear to providesome of the most effective means to extractpaleobiological information from coprolites.<strong>Tech</strong>niques such as petrographic analysis or aciddissolution may reveal dietary components thataren’t evident on coprolite surfaces. Because suchanalyses destroy the morphological integrity of aspecimen, several factors should be consideredbefore a sample is altered. If numerous comparablecoprolites are available or if a specimen is verylarge and/or fragmented, the information obtainedfrom destructive tests is likely to compensate forthe loss of some coprolitic material. But thedecision of whether to perform destructive analysesbecomes more difficult if the tests will damage aunique specimen. When destructive analyses areplanned, they should be preceded by carefulmeasurements, photo-documentation, and scrutinyof accessible surfaces (see above).Thin sections of coprolites provideexceptionally informative views of specimencontents because they permit analysis withcompound microscopes. Such analyses may revealdietary inclusions with considerable histologicaldetail. They also shed light on patterns of diageneticmineralization. The jumbled nature of fecalcontents makes thin section sampling ratherunpredictable, however, because identification ofdietary components depends on fortuitous slicesthrough recognizable structures. Fortunately, somefeatures diagnostic of certain taxonomic groups(such as patterns of bone vascularization) may beevident on small fragments.Thin sections can be made from relatively smallpieces of coprolite, and careful scrutiny of coprolitefragments or intact specimens will help identifyoptimal sampling sites. When possible, thin sectionscan be taken from the end of a specimen in order topreserve more of the original morphology. Althoughtechniques for preparing coprolite thin sections aresimilar to those for preparing standard petrographicsections of rock, more efforts are made to minimizedamage to and loss of coprolitic material (seeWilson, 1994 for a useful discussion of methods forpreparing fossil thin sections).Saws with diamond-embedded blades are usedto reduce large samples to sizes that can be affixedto glass slides. A diamond saw is also necessary toshave off the thin sample slices that are mountedon slides (the sample can be sliced thin before orafter it is mounted on the slide). The use of aprecision saw with a thin diamond wafering bladewill facilitate more accurate cuts and help reduceloss of coprolite material during the cuttingoperation. In a few cases, indurate coprolites canbe cut with a precision saw without embedding,but fragile or fractured specimens should beembedded in or impregnated with an epoxy orpolyester resin before being cut.The cut surface of a specimen must be groundsmooth before it is affixed to a microscope slidewith a strong epoxy bonding agent. Standardpetrographic slides are 27 × 46 mm, but specimenscan also be mounted on larger slides (or glass plates)as well. Grinding/polishing machines or lappingwheels are used to grind and polish the sample toan appropriate thickness (around 30–40 µm,depending on the nature of the sample). Slides canthen be cover-slipped for examination with a lightmicroscope, or finely polished for chemical analyseswith a microprobe or scanning electron microscope.In a few studies, coprolites have beenmechanically disaggregated in order to releasedietary residues from the ground mass. Thistechnique will be most effective when the prey havebeen poorly digested, and it may reveal thepresence of small prey taxa that are not otherwiserepresented in a faunal assemblage. Aciddissolution may also facilitate chemical andmorphological studies of amorphous organicresidues (e.g., Hollocher et al., 2001). Some of thetechniques used in the acid preparation ofvertebrate fossils may be modified for use on47
Page 1:
THE PALEONTOLOGICAL SOCIETYPAPERSVo
Page 4 and 5:
The Paleontological Society Special
Page 6 and 7:
AuthorsRICHARD K. BAMBACHBotanical
Page 9 and 10: THE FOSSIL RECORD OF PREDATIONMicha
Page 13 and 14: INTRODUCTIONTHE FOSSIL RECORD OF PR
Page 15: KOWALEWSKI—ANALYTICAL METHODSTHE
Page 18 and 19: PALEONTOLOGICAL SOCIETY PAPERS, V.
Page 108 and 109:
PALEONTOLOGICAL SOCIETY PAPERS, V.
Page 110 and 111:
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
Page 130 and 131:
Page 132 and 133:
Page 134 and 135:
Page 136 and 137:
Page 138 and 139:
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
Page 148 and 149:
Page 150 and 151:
Page 152 and 153:
Page 154 and 155:
Page 156 and 157:
Page 158 and 159:
Page 160 and 161:
Page 162 and 163:
Page 164 and 165:
Page 166 and 167:
Page 168 and 169:
Page 170 and 171:
Page 172 and 173:
Page 174 and 175:
Page 176 and 177:
Page 178 and 179:
Page 180 and 181:
Page 182 and 183:
Page 184 and 185:
Page 186 and 187:
Page 188 and 189:
Page 190 and 191:
Page 192 and 193:
Page 194 and 195:
Page 196 and 197:
Page 198 and 199:
Page 200 and 201:
Page 202 and 203:
Page 204 and 205:
Page 206 and 207:
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
Page 218 and 219:
Page 220 and 221:
Page 222 and 223:
Page 224 and 225:
Page 226 and 227:
Page 228 and 229:
Page 230 and 231:
Page 232 and 233:
Page 234 and 235:
Page 236 and 237:
Page 238 and 239:
Page 240 and 241:
Page 242 and 243:
Page 244 and 245:
Page 246 and 247:
Page 248 and 249:
Page 250 and 251:
Page 252 and 253:
Page 254 and 255:
Page 256 and 257:
Page 258 and 259:
Page 260 and 261:
Page 262 and 263:
Page 264 and 265:
Page 266 and 267:
Page 268 and 269:
Page 270 and 271:
Page 272 and 273:
Page 274 and 275:
Page 276 and 277:
Page 278 and 279:
Page 280 and 281:
Page 282 and 283:
Page 284 and 285:
Page 286 and 287:
Page 288 and 289:
Page 290 and 291:
Page 292 and 293:
Page 294 and 295:
Page 296 and 297:
Page 298 and 299:
Page 300 and 301:
Page 302 and 303:
Page 304 and 305:
Page 306 and 307:
Page 308 and 309:
Page 310 and 311:
Page 312 and 313:
Page 314 and 315:
Page 316 and 317:
Page 318 and 319:
Page 320 and 321:
Page 322 and 323:
Page 324 and 325:
Page 326 and 327:
Page 328 and 329:
Page 330 and 331:
Page 332 and 333:
Page 334 and 335:
Page 336 and 337:
Page 338 and 339:
Page 340 and 341:
Page 342 and 343:
Page 344 and 345:
Page 346 and 347:
Page 348 and 349:
Page 350 and 351:
Page 352 and 353:
Page 354 and 355:
Page 356 and 357:
Page 358 and 359:
Page 360 and 361:
Page 362 and 363:
Page 364 and 365:
Page 366 and 367:
Page 368 and 369:
Page 370 and 371:
Page 372 and 373:
Page 374 and 375:
Page 376 and 377:
Page 378 and 379:
Page 380 and 381:
Page 382 and 383:
Page 384 and 385:
Page 386 and 387:
Page 388 and 389:
Page 390 and 391:
Page 392 and 393:
Page 394 and 395:
Page 396 and 397:
Page 398 and 399:
Page 400 and 401:
Page 402 and 403:
Page 404 and 405:
Page 406 and 407:
Page 408 and 409:
Page 410 and 411:
Page 412:
THE PALEONTOLOGICAL SOCIETY PAPERSP
show all

View - Kowalewski, M. - Virginia Tech

Create successful ePaper yourself

Delete template?

Save as template?