The Origin and Evolution of Mammals - Moodle

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a hierarchy of committees under the aegis of the IUGS (International Union of Geological Sciences) ratifies these decisions. The units themselves are organised hierarchically, and within the Phanerozoic Eon this is first into three Eras, Palaeozoic, Mesozoic, and Cenozoic. These are then divided successively into Periods, Epochs, and Stages as shown on the chart (Fig. 2.1). The final division is usually into Zones, which are defined by the presence of one, or a few characteristic fossil species. Zones are therefore primarily local rather than global, and typically less than 1 Ma in duration. Correlation is most problematic when comparing very different environments, for there may be virtually no geological markers shared between them. Because most sedimentary rocks are marine in origin, most of the global chronostratic timescale is based on these. There is particular difficulty in correlating marine and continental rocks, and therefore in relatively dating the latter. In a number of cases, the position in practice is that a local chronostratic timescale exists that has not yet been accurately correlated with the global scale. The new techniques, particularly stable isotope ratios are, however, rapidly improving the situation, a notable relevant example being the mammal-bearing Cenozoic rocks of North America. Traditionally a succession of North American Land Mammal Ages (NALMA) was recognised, whose relationship to the global Cenozoic timescale was poorly understood, but the correlation between the two is now virtually complete (Prothero 1997). The equivalent LMA’s of other parts of the world are not yet completely correlated with those of North America, but undoubtedly this work will be completed quite soon. Earlier continental deposits relevant here are less well correlated with the global timescale, especially the Permo-Carboniferous of North America, the Late Permian of South Africa and Russia, and the Triassic of South Africa, South America, and Asia. They are shown in Fig. 2.2. Chronometric timescale The only way of absolutely dating points in the chronostratigraphic timescale is radiometry, based on isotope decay rates. The principle is that there is a constant rate of spontaneous decay of a specified TIME AND CLASSIFICATION 7 radioactive isotope into its daughter product. By knowing the ratio of the isotopes at the start and at the end of a time period, and the rate of decay, the absolute elapsed time of the period can be calculated. However, since the ratio of isotopes at the start of the period cannot be measured, the technique depends on the assumption that at the time of formation of the sample being dated, it contained 100% of the mother isotope and none of the daughter product, which can only be true for a sample that was formed by crystallising out of molten rock. Therefore only igneous rocks can be radiometrically dated from their time of formation. Sedimentary rocks, including virtually all the fossil-bearing rocks, are a random mixture of particles of rocks of differing ages, derived by weathering processes going on somewhere quite other than where they finally settled. Fossils cannot be directly dated! The one exception to this assertion is radiocarbon dating which is somewhat different. It depends on the fact that while alive and metabolising, an organism’s tissues have the same ratio of the radioactive 14 C to the stable 12 C as in the atmosphere, about 1%. After death, the 14 C decays to 12 C and so, assuming the ratio in the atmosphere was the same at the time of death as it is today, the ratio in the organic sample depends only on the rate of decay. However, the halflife of this particular process is a mere 5,730 years, which is too short to date accurately organic samples much more than 50,000 years old. It is primarily an archaeological and not a palaeontological tool. The most widely used isotope pair for construction of the global chronometric timescale is potassium– argon, in which the isotope 40 K decays to 40 Ar, with a half-life of about 1,500 million years. Uranium–lead ( 235 Ur/ 207 Pb: half-life about 700 Ma), and Rubidium– Strontium ( 87 Rb/ 87 Sr: half-life 50,000 Ma) are also commonly used. The accuracy of radiometric dating can be compromised by several factors. Secondary loss or addition of isotopes may have occurred during the lifetime of the rock sample, particularly if it had been exposed to high temperatures. The half-life is difficult to measure with complete precision for such a slow process. Laboratory techniques for measuring what are often extremely small percentages introduce experimental errors. The outcome is that radiometric dates are generally only accurate to about 2%. While for many purposes this is adequate,
PALEOZOIC MESOZOIC CENOZOIC Neogene 23.5 Paleogene 65 Cretaceous 135 Jurassic 203 Triassic 250 Permian 295 Carboniferous 355 Devonian 410 Silurian 435 Ordovician 500 Cambrian 540 (i) See Column (iii) CRETACEOUS JURASSIC TRIASSIC PERMIAN CABRBON. L 96 STAGE Maastrichtian Campanian Santonian Coniacian Turonian Cenomanian 65 72 83 87 88 92 96 Albian 108 E 135 U 154 M 175 Aptian Barremian Hauterivian Valanginian Berriasian Tithonian Kimmeridgian Oxfordian Callovian Bathonian Bajocian Aalenian Toarcian 113 117 123 131 135 141 146 154 160 164 170 175 184 L 203 Pliensbachian Sinemurian Hettangian Rhetian 191 200 203 ? U Norian Carnian 220 M L 260 ? U M 27 L 295 Ladinian Anisian Olenekian Induan Changhsingian Wuchiapigian Capitanian Wordian Roadian Kungurian Artinskian Sakmarian Asselian Gzhelian Kazimovian Moscovian 230 233 240 ? 250 ? ? ? ? 272 ? 280 ? 295 Bashkirian (ii) 320 PENNSYL. NEOGENE 1.75 STAGE PLEISTOCENE Gelasian 5.3 Piacenzian Zanclean Messinian Tortonian Serravallian Langhian Burdigalian 3.4 5.3 7.3 11.0 14.3 15.8 20.3 22.5 Aquitanian 23.5 PLIO- CENE 33.7 53 65 Chattian Rupelian Priabonian Bartonian Lutetian Ypresian Thanetian Selandian Danian (iii) Figure 2.1 The International Stratigraphic Chart for the Phanerozoic (2000 version) modified from Briggs and Crowther (2001). PALEOGENE MIOCENE OLIGOCENE EOCENE PALEOCENE 28.0 33.7 37.0 40.0 46.0 53 59 61 65
Page 2 and 3: The Origin and Evolution of Mammals
Page 4 and 5: The Origin and Evolution of Mammals
Page 6 and 7: Preface This book arose from twin a
Page 8 and 9: For Mal /gosia with love and thanks
Page 10 and 11: Contents 1 Introduction The definit
Page 12 and 13: CHAPTER 1 Introduction There are ab
Page 14 and 15: transversely occluding molar teeth
Page 16 and 17: the Mesozoic mammals, is to do with
Page 20 and 21: it means that a 200 Ma igneous rock
Page 22 and 23: een a more fundamental impact than
Page 24 and 25: Table 2.3 Classification of marsupi
Page 26 and 27: (a) (b) (c) humerus radius aquatic
Page 28 and 29: (a) Westlothiana Limnoscelis PO Wes
Page 30 and 31: the ankle bones to form an astragal
Page 32 and 33: (b) (c) (a) Casea rutena Casea broi
Page 34 and 35: (Fig. 3.2(f)), is actually an ophia
Page 36 and 37: the first one is enlarged, often to
Page 38 and 39: Even at their initial appearance in
Page 40 and 41: (a) Nikkasaurus (b) (d) Reiszia (e)
Page 42 and 43: Nikkasauridae The family Nikkasauri
Page 44 and 45: has figured large in discussions of
Page 46 and 47: (c) Figure 3.9 (continued). Syodon
Page 48 and 49: a mixture of progressively more spe
Page 50 and 51: animal with interdigitating, but no
Page 52 and 53: (e) (a) Anomocephalus Ulemica (b) S
Page 54 and 55: mandibulae musculature. This, as in
Page 56 and 57: To date the postcranial skeleton of
Page 58 and 59: ecognised four subgroups, based mai
Page 60 and 61: the presence of a deep, longitudina
Page 62 and 63: collected from the Lystrosaurus Ass
Page 64 and 65: (a) (d) (c) (b) Leontocephalus V PA
Page 66 and 67: (a) (c) Lycosuchus Oliveria (d) EVO
Page 68 and 69:
separate families. Lycosuchidae (Fi
Page 70 and 71:
consist of a large labial cusp and
Page 72 and 73:
Procynosuchus (d) Procynosuchus (a)
Page 74 and 75:
They constitute the monophyletic gr
Page 76 and 77:
Although there is no mammal-like co
Page 78 and 79:
Cynognathidae Cynognathus (Fig. 3.2
Page 80 and 81:
(e) (f) Figure 3.22 (continued). Ma
Page 82 and 83:
(c) (d) (a) (b) Kayentatherium EVOL
Page 84 and 85:
Pachygenelus (e) (a) (c) Therioherp
Page 86 and 87:
palatal, and orbitosphenoid bones,
Page 88 and 89:
Wible and Hopson 1993). The interor
Page 90 and 91:
published a cladogram based on rece
Page 92 and 93:
310-320 Ma. By this time, the great
Page 94 and 95:
are forms such as Casea itself, var
Page 96 and 97:
lakes and swamps in the low-lying l
Page 98 and 99:
urrowing and subsisting on a diet o
Page 100 and 101:
Eothyris Haptodus sphenacodontine B
Page 102 and 103:
z (a) (c) a.pt.m. M B PO P P SQ P M
Page 104 and 105:
(b) a.pt.m. temp.m. a.pt.m. temp.m.
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the dentary bone above the level of
Page 108 and 109:
the therocephalian grade was not on
Page 110 and 111:
A balance was also achieved in the
Page 112 and 113:
Locomotion Ancestral amniote grade
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screw-shaped: the front part faces
Page 116 and 117:
For the recovery phase, the relativ
Page 118 and 119:
SC PRC p.i.f.i tr.min (c) dp.cr ect
Page 120 and 121:
the therocephalian pelvis and hindl
Page 122 and 123:
spc s.sp s.sp SC PRC (d) delt T AST
Page 124 and 125:
no significant novelties to what ha
Page 126 and 127:
(a) (c) (e) (g) D D ex. au.m C tym
Page 128 and 129:
(a) (c) (d) PMX (f) V n.turb mx.tur
Page 130 and 131:
ol.b (a) (b) cer.hem gorgonopsian t
Page 132 and 133:
(a) (b) (i) (ii) (iii) (iv) (v) a g
Page 134 and 135:
cold stress, the part that usually
Page 136 and 137:
conducted the experiment of wrappin
Page 138 and 139:
mammals themselves that the enlarge
Page 140 and 141:
elevation of maximum aerobic activi
Page 142 and 143:
a mammal. The difficulty with all s
Page 144 and 145:
collection, ingestion, and assimila
Page 146 and 147:
were edaphosaurid and caseid pelyco
Page 148 and 149:
CHAPTER 5 The Mesozoic mammals The
Page 150 and 151:
(a) (d) AL condylar foramina are se
Page 152 and 153:
evidence to relate the haramiyidans
Page 154 and 155:
postcranial skeleton, and Graybeal
Page 156 and 157:
side of the head can be in action a
Page 158 and 159:
the lower molars is relatively high
Page 160 and 161:
morganucodontan teeth. However, des
Page 162 and 163:
adjacent lower molars. A small exte
Page 164 and 165:
(a) (b) (d) P4 P4 Plagiaulax P4 Pau
Page 166 and 167:
American Morrison Formation genus C
Page 168 and 169:
a self-sharpening property. As the
Page 170 and 171:
near parasagittal gait (Fig. 5.11(e
Page 172 and 173:
pass through the birth canal. Relat
Page 174 and 175:
(a) 1 (b) (d) me (c) me.d 3 styl st
Page 176 and 177:
(a) (c) Henkelotherium Crusafontia
Page 178 and 179:
pubis is excluded from the acetabul
Page 180 and 181:
Cretaceous, (Aptian or Albian) of M
Page 182 and 183:
eautifully preserved placentals fro
Page 184 and 185:
subsequent specimens revealed that
Page 186 and 187:
Minimal divergence of tribosphenida
Page 188 and 189:
(c) (a) M 1 M 1 M 2 Steropodon M 2
Page 190 and 191:
(b) (a) (c) pa.d pr.d me.d Ambondro
Page 192 and 193:
crown-group therians) is accepted b
Page 194 and 195:
form of the tooth, must reflect sub
Page 196 and 197:
of feasibility that a taxon of endo
Page 198 and 199:
mammals, by creating environmental
Page 200 and 201:
the 11 species of marsupial, of whi
Page 202 and 203:
(d) (a) pa A Dasyuromorphia B C pr
Page 204 and 205:
earing two huge claws on digits thr
Page 206 and 207:
that contains the independent ances
Page 208 and 209:
(b) (d) (a) Glasbius Alphadon (c) D
Page 210 and 211:
elieved to be Late Cretaceous in ag
Page 212 and 213:
(Fig. 6.5(c)). The dentition exhibi
Page 214 and 215:
(d) Figure 6.6 (continued). Thylaco
Page 216 and 217:
(a) (c) Caroloameghina and Procarol
Page 218 and 219:
(a) (e) (d) Proargyrolagus Groeberi
Page 220 and 221:
(a) (b) Djarthia Thylacotinga (c) (
Page 222 and 223:
LIVING AND FOSSIL MARSUPIALS 211 M
Page 224 and 225:
Extinct Notoryctemorphia At present
Page 226 and 227:
(f) (g) Wakaleo Diprotodon optatum
Page 228 and 229:
fossil mammals, which might help cl
Page 230 and 231:
30 40 50 60 Figure 6.13 Southern Go
Page 232 and 233:
the Diprotodontia also included gen
Page 234 and 235:
1. Placentalia 2. Edentata 3. Epith
Page 236 and 237:
effectively absent. However, increa
Page 238 and 239:
Asioryctes (a) (b) (d) Cimolestes p
Page 240 and 241:
and Prokennalestes, although it doe
Page 242 and 243:
(a) Leptictidium Palaeoryctidans we
Page 244 and 245:
(a) Purgatorius (c) are part of the
Page 246 and 247:
(a) (d) (e) (g) Protoungulatum Meso
Page 248 and 249:
(a) (f) (e) Hyopsodus Phenacodus (d
Page 250 and 251:
Titanoides (pantodont) (a) (c) (b)
Page 252 and 253:
(a) (b) (d) Trogosus (tillodont) Es
Page 254 and 255:
Mioclaenus Paulacoutoia (didolodont
Page 256 and 257:
their presence. The five orders may
Page 258 and 259:
Xenungulata. Only two Late Palaeoce
Page 260 and 261:
(a) (b) (d) (c) Oxyaena Patriofelis
Page 262 and 263:
continuously growing, and form a gr
Page 264 and 265:
navicular facet, 19 or more thoraci
Page 266 and 267:
(a) (c) Phosphatherium Numidotheriu
Page 268 and 269:
coexist with other characters that
Page 270 and 271:
The salient feature of Widanelfasia
Page 272 and 273:
1 (a) 1. Perissodactyla 2. Titanoth
Page 274 and 275:
(a) (b) BUNODONTIA or SUIFORMES SUI
Page 276 and 277:
time, which suggests that it was on
Page 278 and 279:
condition. This particular combinat
Page 280 and 281:
etween Primates, Dermoptera (colugo
Page 282 and 283:
have postcranial adaptations for ar
Page 284 and 285:
undoubtedly related at a supraordin
Page 286 and 287:
indisputably to occur prior to the
Page 288 and 289:
The Late Cretaceous mammal record i
Page 290 and 291:
interordinal divergences in the Lat
Page 292 and 293:
diversity on Earth (Janis 1993). Fu
Page 294 and 295:
effect of the surrounding sea. Trop
Page 296 and 297:
was high. It lasted from 5 to 3 Ma
Page 298 and 299:
and thus remain in their preferred
Page 300 and 301:
agreement about exactly when within
Page 302 and 303:
References Abdala, F. Redescription
Page 304 and 305:
Ax, P. 1987. The phylogenetic syste
Page 306 and 307:
Bramble, D. M. 1978. Origin of the
Page 308 and 309:
Colbert, E.H. 1948. The mammal-like
Page 310 and 311:
Duvall, D. 1986. A new question of
Page 312 and 313:
Gow, C.E. 1980. The dentitions of t
Page 314 and 315:
Ivakhnenko, M.F. 1990. The late Pal
Page 316 and 317:
Kemp, T.S. 1988a. A note on the Mes
Page 318 and 319:
cladogenesis in dasyurid marsupials
Page 320 and 321:
(eds) Evolution of Tertiary mammals
Page 322 and 323:
McKenna, M.C. and Bell, S.K. 1997.
Page 324 and 325:
(ed) The phylogeny and classificati
Page 326 and 327:
Ray, S. 2000.Endothiodont dicynodon
Page 328 and 329:
Rubidge, B.S., Kitching, J.W., and
Page 330 and 331:
Simpson, G.G. 1970. The Argyrolagid
Page 332 and 333:
Thewissen, J.G.M. 1990. Evolution o
Page 334 and 335:
Novacek, M.J., and McKenna, M.C. (e
Page 336 and 337:
Index Note: Page numbers in italics
Page 338 and 339:
Equoidea 262 Equus 262 Erethizon 28
Page 340 and 341:
Overkill hypothesis 289, 290 Oxyaen
Page 342:
Tulerpeton 14, 18 Tylopoda 264 Ukha
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