The Origin and Evolution of Mammals - Moodle

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has figured large in discussions of early therapsid evolution, being regarded as more advanced than Biarmosuchus. Kemp (1982) and Hopson and Barghusen (1986) both expressed as cladograms the view that Biarmosuchus was more basal, and that Eotitanosuchus was more closely related to advanced carnivorous therapsids. In her review of primitive carnivorous therapsids, Sigogneau-Russell (1989) went so far as to place the two genera in different Infraorders, which is to say the least astonishing. At the other extreme, Ivakhnenko et al. (1997; Ivakhnenko 1999) reviewed all the material of Biarmosuchus and Eotitanosuchus and came to the conclusion that the two are the same species, differing only insofar as they are different growth stages. The skull length of the type specimen of Biarmosuchus tener is about 16.5 cm while that of the type specimen of Eotitanosuchus olsoni is over twice the length, at about 34.5 cm. Other specimens from the same locality lie between these extremes and illustrate a morphological transformation. Whether they really are conspecific may be debated, but there can be little doubt that they are extremely similar and certainly should be treated as congeneric, with Eotitanosuchus a junior synonym of Biarmosuchus. Li and Cheng (1995) have described the Chinese genus Biseridens as a member of the group, but no biarmosuchians have yet been found in the South African Eodicynodon Assemblage Zone. However, there are specimens from later dates in South Africa that are included in the group (Sigogneau-Russell 1989; Hopson 1991). Hipposaurus is from the Tapinocephalus Assemblage Zone, which lies immediately above the Eodicynodon Assemblage Zone, and for which the skull and most of the skeleton has been described (Boonstra 1965; Sigogneau 1970, 1989). It has retained the primitively convex dorsal outline of the skull, relatively small temporal fenestra, broad intertemporal region and dentition of simple sharp teeth dominated by a large canine found in Biarmosuchus. A small number of minor derived characters shared between the two have been noted by Hopson (1991), including details of the zygomatic arch and fusion of the fourth and fifth tarsals of the hind foot. There are several other South African biarmosuchians, including Ictidorhinus (Fig. 3.8(b)), which occurs in the Dicynodon EVOLUTION OF MAMMAL-LIKE REPTILES 33 Assemblage Zone at the very end of the Permian. A well-preserved skull of Lemurosaurus (Fig. 3.8(c)) has been described recently by Sidor and Welman (2003) and confirms the presence of interdigitating incisor teeth and a sclerotic ring in the group. The family Burnetiidae was erected originally for two genera, one South African and the other Russian. Burnetia from the Dicynodon Assemblage Zone of South Africa, and Proburnetia (Fig. 3.8(d)) from the Late Tatarian of Russia are extremely similar primitive carnivores. They are relatively small therapsids, with a skull length around 20 cm and are characterised by heavily pachyostosed skulls bearing numerous bony protuberances and bosses. Taxonomically burnetiids were at one time linked to dinocephalians on the basis of the pachyostosis, and at another to gorgonopsians on the basis of their carnivorous dentition and generally primitive skull. However, appreciation of the absence of any discernable derived characters between burnetiids and gorgonopsians led Sigogneau-Russell (1989) to consider them as biarmosuchians. With the assistance of new South African specimens, Rubidge and Sidor (2002) endorsed the latter view, and a cladogram of all the biarmosuchians and burnetiids by Sidor and Welman (2003) points to Lemurosaurus as the sister group of Burnetiidae. This particular genus has incipient bosses on various parts of the skull suggesting an early stage in the full development of the burnetiid pachyostosis. Dinocephalia The dinocephalians (Fig. 3.9) are a group of large, heavily built animals that are among the first therapsids to appear in the fossil record in Russia, South Africa, and China, at the beginning of the Late Permian. The very doubtful possibility that fragmentary remains of Guadalupian age in North America may be dinocephalians has been mentioned earlier and isolated teeth have been found in Brazil (Langer 2000). After a brief period as the commonest therapsids, dinocephalians disappeared well before the close of the Permian, not having been discovered later than the Tapinocephalus Assemblage Zone of South Africa or its equivalent in Russia. Historically, the carnivorous and herbivorous dinocephalians were separated into two groups,
34 THE ORIGIN AND EVOLUTION OF MAMMALS related respectively to more advanced carnivore and herbivore therapsid taxa (Watson and Romer 1956). However, later work made it clear that the similarities between the carnivores are plesiomorphic, and the Dinocephalia have been recognised as a welldefined monophyletic taxon. The characters that define the group include the following. 1. Incisor teeth bearing a slight heel on the lingual face at the base of the crown. Uppers and lowers interdigitate, but this also occurs in biarmosuchians and gorgonopsians, so is probably a primitive therapsids character. (b) (a) 2. Enlargement of the temporal fenestra in such a way that temporal musculature attachment expands upwards and forwards onto the dorsal surface of the parietal and postorbital bones. 3. Forwards shift in the jaw articulation, shortening the length of the jaw. 4. A strong tendency towards thickening of the skull bones, to the point of heavy pachyostosis in many forms. The relationships of the Dinocephalia to other therapsid groups has also been a matter of some debate, particularly as many of their characteristics are Titanophoneus Moschops Figure 3.9 (left) Dinocephalians. Postcranial skeleton of (a) Titanophoneus potens. (Orlov). (b) Moschops, total length about 2.5 m (Sues 1986b, modified from Gregory). (right) Dinocephalians. Skulls of (c) Syodon efremovi (Orlov, modified by Battail and Surkov 2000) (d) Jonkeria vanderbyli with lower jaw of J. truculenta (King 1988, modified from Broom). (e) Anteosaurus magnificus (King 1988, modified from Boonstra). (f) Ulemosaurus svigagensis, with enlarged view of incisor teeth and their interlocking action (King 1988, and Kemp 1982, from Efremov).
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 18 and 19: a hierarchy of committees under the
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 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
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Eothyris Haptodus sphenacodontine B
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z (a) (c) a.pt.m. M B PO P P SQ P M
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(b) a.pt.m. temp.m. a.pt.m. temp.m.
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the dentary bone above the level of
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the therocephalian grade was not on
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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
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the therocephalian pelvis and hindl
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spc s.sp s.sp SC PRC (d) delt T AST
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no significant novelties to what ha
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(a) (c) (e) (g) D D ex. au.m C tym
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(a) (c) (d) PMX (f) V n.turb mx.tur
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ol.b (a) (b) cer.hem gorgonopsian t
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(a) (b) (i) (ii) (iii) (iv) (v) a g
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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
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a mammal. The difficulty with all s
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collection, ingestion, and assimila
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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
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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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The Origin and Evolution of Mammals - Moodle

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