The Origin and Evolution of Mammals - Moodle

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navicular facet, 19 or more thoracic vertebrae, and the third molar tooth larger than the second in both upper and lower tooth rows. It is on the basis of this limited morphological evidence, that the two extinct orders, Embrithopoda and Desmostylia are regarded as members too, although hardly surprisingly there is no agreement about their exact respective relationships, either to one another or to other paenungulates. From time to time certain Asian fossils have been tentatively attributed to the Paenungulata, to the extent of implying an Asian rather than an African origin for the group as a whole (Beard 1998; Fischer and Tassy 1993). Minchenella is represented by lower jaws from the Late Palaeocene of China. Its molar teeth are ‘condylarth’-like but there are minor features somewhat reminiscent of those of the primitive proboscidean Moeritherium. Anthracobunids (Fig. 7.15(b)), which may be related to Minchenella, are an Early to Middle Eocene family centred on Pakistan (Wells and Gingerich 1982). Depending on fine details of molar morphology (Tassy and Shoshani 1988), anthracobunids have been interpreted by various authors, respectively, as basal members of Proboscidea, or Desmostylia, or Tethytheria (Proboscidea plus Sirenia). The interrelationships of the four other modern orders of placentals that have been shown to be members of Afrotheria are not yet well resolved, and elucidation is little helped by the very poor fossil record of all four. Two of them, Chrysochlorida, the golden moles, and Tenrecida, the tenrecs and otter shrews, are probably sister-groups and included in a super-ordinal taxon Afrosoricida (Scally et al. 2002; Asher et al. 2003). The other two are Macroscelidea, the elephant shrews, and the solitary species of Tubulidentata, the aardvark. Hyracoidea The hyracoids are represented today by only about a dozen species in three closely related genera, all of quite small body size. Surprisingly therefore, they were at one time the most abundant medium and large-sized herbivores in Africa, playing this role long before the perissodactyls and artiodactyls arrived on the continent (Rasmussen 1989). Hyracoids also dispersed into much of Asia. The earliest record is from the Late Eocene and Oligocene LIVING AND FOSSIL PLACENTALS 253 of Fayum, where they ranged in size from Thyrohyrax, which was about the size of a modern hyrax, through Megalohyrax (Fig. 7.16(a)) with a 40 cm long skull (Thewissen and Simons 2001), to the giant Titanohyrax which was as large as a small rhinoceros, and bigger than any contemporary proboscideans. The morphology of the cheek teeth was also enormously variable, from simple bunodont to fully lophodont and selenodont molars. As the major, principally forest dwelling group of medium to large-sized browsers, there were species equivalent to the pigs antelopes, and small rhinos of today (Rasmussen and Simons 2000). By the Miocene, hyracoids had declined in diversity, an event presumably connected with the arrival in Africa of several artiodactyl and perissodactyl families. By this time, a second radiation had occurred, the pliohyracines, which spread from Africa throughout Europe and Asia. In these northern areas they underwent a modest increase in diversity, evolving high-crowned, hypsodont cheek teeth for feeding on more abrasive plant material. Most of the hyracoids had become extinct by the Pliocene, although one highly specialised lineage, procaviids, survived as the living members of the order. Proboscidea As mentioned, anthracobunids (Fig. 7.15(b)) are represented by dentitions of mid-Eocene age from India and Pakistan, which have one or two proboscidean characters (Wells and Gingerich 1983), and accordingly they have been accepted by several authors as the most basal members of the group (e.g. Fischer and Tassy 1993; Shoshani et al 1996). However, earlier-dated, undisputed proboscideans have since been discovered in North Africa. These are from the earliest Eocene in age and are part of the Ouled Abdoun Basin fauna of Morocco. Gheerbrant et al. (1996; 1998) described isolated upper teeth of Phosphatherium (Fig. 7.17(a)). They were from a relatively small animal, with a body weight estimated from tooth size of 10–15 kg. The molar teeth have the true lophodont condition of crests running transversely and uninterrupted by conules, that characterises proboscideans, and in this form there are two such lophs, bilophodonty, which is the primitive proboscidean condition. Daouitherium (Fig. 7.17(b)) is a very much larger
254 THE ORIGIN AND EVOLUTION OF MAMMALS (a) (b) (e) (d) Arsinoitherium (embrithopod) Megalohyrax (hyracoid) (c) Pezosiren (sirenian) Palaeoamasia (embrithopod) Paleoparadoxia (desmostylian) Figure 7.16 Paenungulate afrotheria. (a) Skull in lateral view and upper cheek teeth in occlusal view of the Oligocene hyracoid Megalohyrax. Length of skull approx. 30 cm (Romer 1966, and Carroll 1988, after Andrews). (b) The Miocene desmostylian Paleoparadoxia. Length approx. 2.2 m (Domning 2002). (c) The Eocene sirenian Pezosiren. Length approx. 2.1 m (redrawn after Domning 2001). (d) Skeleton of the embrithopod Arsinoitherium. Length approx. 1.8 m (Savage and Long 1986, after Andrews). (e) Upper cheek teeth in occlusal view of the Asian Oligocene embrithopod Palaeoamasia (Savage and Long 1986, after Sen and Heintz).
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The Origin and Evolution of Mammals
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The Origin and Evolution of Mammals
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Preface This book arose from twin a
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For Mal /gosia with love and thanks
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Contents 1 Introduction The definit
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CHAPTER 1 Introduction There are ab
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transversely occluding molar teeth
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the Mesozoic mammals, is to do with
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a hierarchy of committees under the
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it means that a 200 Ma igneous rock
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een a more fundamental impact than
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Table 2.3 Classification of marsupi
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(a) (b) (c) humerus radius aquatic
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(a) Westlothiana Limnoscelis PO Wes
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the ankle bones to form an astragal
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(b) (c) (a) Casea rutena Casea broi
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(Fig. 3.2(f)), is actually an ophia
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the first one is enlarged, often to
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Even at their initial appearance in
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(a) Nikkasaurus (b) (d) Reiszia (e)
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Nikkasauridae The family Nikkasauri
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has figured large in discussions of
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(c) Figure 3.9 (continued). Syodon
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a mixture of progressively more spe
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animal with interdigitating, but no
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(e) (a) Anomocephalus Ulemica (b) S
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mandibulae musculature. This, as in
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To date the postcranial skeleton of
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ecognised four subgroups, based mai
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the presence of a deep, longitudina
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collected from the Lystrosaurus Ass
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(a) (d) (c) (b) Leontocephalus V PA
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(a) (c) Lycosuchus Oliveria (d) EVO
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separate families. Lycosuchidae (Fi
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consist of a large labial cusp and
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Procynosuchus (d) Procynosuchus (a)
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They constitute the monophyletic gr
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Although there is no mammal-like co
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Cynognathidae Cynognathus (Fig. 3.2
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(e) (f) Figure 3.22 (continued). Ma
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(c) (d) (a) (b) Kayentatherium EVOL
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Pachygenelus (e) (a) (c) Therioherp
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palatal, and orbitosphenoid bones,
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Wible and Hopson 1993). The interor
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published a cladogram based on rece
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310-320 Ma. By this time, the great
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are forms such as Casea itself, var
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lakes and swamps in the low-lying l
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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
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Locomotion Ancestral amniote grade
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screw-shaped: the front part faces
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For the recovery phase, the relativ
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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
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conducted the experiment of wrappin
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mammals themselves that the enlarge
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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
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CHAPTER 5 The Mesozoic mammals The
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(a) (d) AL condylar foramina are se
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evidence to relate the haramiyidans
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postcranial skeleton, and Graybeal
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side of the head can be in action a
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the lower molars is relatively high
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morganucodontan teeth. However, des
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adjacent lower molars. A small exte
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(a) (b) (d) P4 P4 Plagiaulax P4 Pau
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American Morrison Formation genus C
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a self-sharpening property. As the
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near parasagittal gait (Fig. 5.11(e
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pass through the birth canal. Relat
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(a) 1 (b) (d) me (c) me.d 3 styl st
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(a) (c) Henkelotherium Crusafontia
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pubis is excluded from the acetabul
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Cretaceous, (Aptian or Albian) of M
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eautifully preserved placentals fro
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subsequent specimens revealed that
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Minimal divergence of tribosphenida
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(c) (a) M 1 M 1 M 2 Steropodon M 2
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(b) (a) (c) pa.d pr.d me.d Ambondro
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crown-group therians) is accepted b
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form of the tooth, must reflect sub
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of feasibility that a taxon of endo
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mammals, by creating environmental
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the 11 species of marsupial, of whi
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(d) (a) pa A Dasyuromorphia B C pr
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earing two huge claws on digits thr
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that contains the independent ances
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(b) (d) (a) Glasbius Alphadon (c) D
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elieved to be Late Cretaceous in ag
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(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
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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
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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 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
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cladogenesis in dasyurid marsupials
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(eds) Evolution of Tertiary mammals
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McKenna, M.C. and Bell, S.K. 1997.
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(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
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Simpson, G.G. 1970. The Argyrolagid
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Thewissen, J.G.M. 1990. Evolution o
Page 334 and 335:
Novacek, M.J., and McKenna, M.C. (e
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Index Note: Page numbers in italics
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Equoidea 262 Equus 262 Erethizon 28
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Overkill hypothesis 289, 290 Oxyaen
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Tulerpeton 14, 18 Tylopoda 264 Ukha
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The Origin and Evolution of Mammals - Moodle

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