The Origin and Evolution of Mammals - Moodle

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Extinct Notoryctemorphia At present the sole fossil relatives of the marsupial mole are teeth and isolated skeletal elements from the Riversleigh deposits. The molar teeth are not as extremely modified as those of Notoryctes (Fig. 6.1(g)), and when a description is published it may indicate how the notoryctid-like version of the zalambdodont condition evolved from a basic marsupial tooth (Archer et al. 1991). Extinct Diprotodontia As the principal herbivorous Order of Australian marsupials, diprotodonts are, as expected, the most abundant and diverse component of the fossil, as well as of the living, fauna. In fact, the family level diversity of the group at their first appearance in the Late Oligocene and through the Early Miocene exceeds that of the present day. Of the total of 16 diprotodont families recognised by McKenna and Bell (1997), only two are not known during this period, the monospecific Tarsipedidae (honey possum), and dispecific Acrobatidae (feather-tailed glider and feather-tailed possum). On the other hand, eight of the mid-Cenozoic families have subsequently disappeared. These extinct families include some very peculiar and highly specialised diprotodonts. Wynyardiidae. Members of this family only occur in the Late Oligocene/Early Miocene, although they were fairly abundant during this time. Two complete skeletons of Muramura (Fig. 6.12(a)) from the Etadunna Formation of the Lake Eyre Basin have been found (Pledge 1987), so it is a particularly well-known group. Muramura was dog-sized and its unspecialised syndactyl hindfeet indicate a simple, terrestrial quadrupedal locomotion. The molars had a primitive degree of development of transverse lophs, and the stylar cusps on the uppers are still distinguishable. As far as the details of the wynyardiid braincase are concerned, Aplin (1987) believed it to be the most plesiomorphic of all diprotodonts. Therefore, on dental, cranial, and postcranial structure, the wynardiids appear to be close to the base of the diprotodont radiation. Diprotodontidae. The diprotodontids (Fig. 6.12(i) and (j)) include the largest marsupials ever to LIVING AND FOSSIL MARSUPIALS 213 evolve, ranging in size from that of a sheep to giants larger than hippos. The Late Pleistocene Diprotodon optatum was almost 3 m long, stood 2.6 m high at the shoulder, and weighed as much as 2.78 tonnes (Wroe et al. 2003). The diprotodontid dentition was modified for browsing on relatively soft vegetation, with enlarged, bilophodont molar teeth. Unlike the other major herbivore family, the macropodids, diprotodontids remained fully quadripedal. The group finally became extinct in the Late Pleistocene, as part of the general megafaunal mass extinction of that time. Palorchestidae. This family consisted of forms quite similar to diprotodontids and they were at one time actually included in the latter family. Also like the diprotodontids, they survived until the Late Pleistocene, when the best-known genus Palorchestes was the size of a horse. However, palorchestids do differ from diprotodontids in details of the dentition, and also in the structure of the ear region, in which they more closely resemble the wombats. Very large, powerful claws tended to develop on the forelimbs suggesting a diet of tubers and roots, and in the later forms such as Palorchestes the snout was elongated in a manner that suggests that it bore a mobile proboscis or short trunk. Thylacoleonidae. Famously the most extraordinary diprotodonts of all were the marsupial lions, which are also one of the comparatively rare examples of the evolution of a carnivore from a specialised herbivorous ancestor. The Late Oligocene–Early Miocene thylacoleonid Priscileo was a relatively small, cat-sized animal (Rauscher 1987), and Wakaleo (Murray et al. 1987) had a 15-cm skull (Fig. 6.12(f)). By the Plio-Pleistocene, Thylacoleo (Fig. 6.12(g)) had evolved into the size and general form of a leopard. The dentition is modified for extreme carnivory (Nedin 1991), or perhaps a hyaena-like scavenging that included dealing with large bones. The first upper and sole lower incisors are enlarged and caniniform. The upper third premolar (Fig. 6.12(h)) is an enormous shearing blade that worked against the almost equally large lower third premolar plus the first molar. The rest of the molars are reduced in both number and relative size.
214 THE ORIGIN AND EVOLUTION OF MAMMALS (d) (a) (b) Muramura Ilaria (c) (e) Ektopodon Djilgaringa (pilkipildrid) Miralina Figure 6.12 Extinct diprotodontians. (a) Muramura williamsi: occlusal views of upper and lower last premolar and first molars. Skull length approx. 13 cm (Pledge 1987). (b) Ektopodon stirtoni upper last premolar and first two molars in occlusal view. Length of fragment approx. 1.8 cm (Woodburne 1987). (c) The pilkipildrid Djilgaringa gillespiei lower dentition in occlusal and buccal views. Length of fragment approx. 1.9 cm (Archer et al. 1987). (d) Ilaria illumidens upper and lower cheek teeth. Length of upper dentition approx. 1.0 cm (Rich 1991). (e) Miralina doylei, lower right molar (Woodburne et al. 1987). (f) Skull of the basal thylacoleonid Wakaleo vanderleuri. Skull length approx. 18 cm (Murray et al. 1987). (g) Skull of Thylacoleo carnifex. Skull length approx. 27 cm (from Rich 1991, after Lydekker 1887). (h) Comparison of occlusal views of the upper dention of Wakaleo (Miocene), Thylacoleo crassidentatus (Pliocene) and Thylacoleo carnifex (Pleistocene) showing enlargement of PM3. (i) Upper and lower cheek dentition of Diprotodon (Murray 1991). (j) Reconstruction of the skeleton of Diprotodon optatum. Length approx. 3 m (Murray 1991).
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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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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
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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
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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 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
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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
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(a) (b) BUNODONTIA or SUIFORMES SUI
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time, which suggests that it was on
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condition. This particular combinat
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etween Primates, Dermoptera (colugo
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have postcranial adaptations for ar
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undoubtedly related at a supraordin
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indisputably to occur prior to the
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The Late Cretaceous mammal record i
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interordinal divergences in the Lat
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diversity on Earth (Janis 1993). Fu
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effect of the surrounding sea. Trop
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was high. It lasted from 5 to 3 Ma
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and thus remain in their preferred
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agreement about exactly when within
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References Abdala, F. Redescription
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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
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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
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
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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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