The Origin and Evolution of Mammals - Moodle

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(b) (c) (a) Casea rutena Casea broilii (d) (e) EVOLUTION OF MAMMAL-LIKE REPTILES 21 Oedaleops Aerosaurus Elliotsmithia Figure 3.4 Caseid and varanopeid pelycosaurs. (a) Skull of Oedaleops campi in dorsal and lateral views (Kemp 1982 after Langston 1965). (b) Skull of Casea rutena in dorsal, ventral, lateral and posterior views (Sigogneau-Russell and Russell 1974). (c) Reconstruction of the skeleton of Casea broilii (Romer and Price 1940). (d) Skull of Aerosaurus wellesi in lateral view (Langston and Reisz 1981). (e) Skull of Elliotsmithia as preserved, seen in left side view, showing orbit, temporal fenestra, and posterior teeth (Dilkes and Reisz 1996).
22 THE ORIGIN AND EVOLUTION OF MAMMALS and a presumably correlated tendency towards a forward tilt of the very front of the pointed snout. However, they are highly modified for herbivory (Reisz and Sues 2000). The skull is short and low, the temporal fenestra large, and the jaw articulation depressed below the level of the tooth row. These are features relating to enlargement of the adductor musculature to increase the force of the bite. The dentition consists of a homodont marginal dentition in which each individual tooth is stout, blunt, and somewhat bulbous. The palate bears several rows or areas of small palatal teeth which, since there are no comparable teeth on the inner surface of the lower jaw, presumably worked in conjunction with a tough, muscular tongue, an interpretation supported by the presence of a particularly welldeveloped hyoid apparatus in the floor of the mouth. The skeleton of caseids is also characteristic of a herbivore (Fig. 3.4c). Proportionately the skull is small and the neck vertebrae reduced. The body is barrel-shaped, as indicated by the ribcage, implying that there was a very large alimentary canal with a fermentation chamber somewhere along its length. There is a wide size range in caseids (Olson 1968). Casea broilii, for example, had a body length of around a metre, while the largest species known is Cotylorhynchus hancocki with a length of at least 4 m and a body weight estimated to have been in excess of 500 kg. Langston (1965) suggested that Oedaleops was a good model for the ancestry of the caseids. The Caseidae appear relatively late in the fossil record, not until into the Early Permian, but on the other hand were one of the last surviving pelycosaur groups, being known from the Late Permian rocks of the San Angelo and Flowerpot Formations of Texas (Olson 1968). They are also amongst the few pelycosaur taxa with representatives from other parts of the world. There is a beautifully preserved Early Permian specimen named Casea rutena (Fig. 3.4b) from France (Sigogneau-Russell and Russell 1974), and Ennatosaurus is from the Kazanian Zone II of the Late Permian of Russia (Ivakhnenko 1991). Eupelycosauria: Varanopseidae All other pelycosaurs are included in the Eupelycosauria, characterised by elongation and narrowing of the snout, the frontal bone forming at least one-third of the dorsal orbital margin, the supratemporal bone narrow and set in a groove, and the pineal foramen set relatively further back in the parietal bone (Reisz 1986; Reisz et al. 1992). The members of the family Varanopseidae are the least derived of the eupelycosaurs. Relative to other pelycosaurs, they were small, long-limbed, agile animals with a long row of sharp teeth and little development of caniniforms, and presumably they led an active, predatory mode of life. The best known are Varanosaurus itself and Aerosaurus (Langston and Reisz 1981), both from the Early Permian (Fig. 3.4(d)). However, the family is actually the longest lived and most widely distributed of all pelycosaur families. Some specimens of Aerosaurus also date from the Upper Carboniferous, while other taxa share with the caseids the distinction of surviving into the Late Permian. Varanodon occurs in the Chickasha Formation of Oklahoma, and there is also a Russian Late Permian form, Mesenosaurus (Reisz and Berman 2001). Even more remarkably, a genus of varanopseid occurs in the southern hemisphere. Elliotsmithia (Fig. 3.4e) has long been known from a poorly preserved skull from the Late Permian Tapinocephalus Assemblage Zone of the South African Karoo, and Dilkes and Reisz (1996; Reisz et al. 1998) confirmed the impression of several earlier authors including Romer and Price (1940) that Elliotsmithia is indeed properly referred to the varanopseids. Modesto et al. (2001) have described a second specimen further confirming this conclusion. So far this is the only well-established record of pelycosaurs from Gondwana, although another form, Anningia, has been claimed to be a South African pelycosaur. Unfortunately, the sole specimen is a skull which is too incomplete and poorly preserved for confirmation to be possible (Reisz and Dilkes 1992). Eupelycosauria: Ophiacodontidae The traditional taxon Ophiacodontia was regarded as the most primitive group of pelycosaurs by Romer and Price (1940), but they included the eothyridids as well as the eupelycosaurian family Ophiacodontidae, and it was therefore paraphyletic. Taken alone, the latter family is a monophyletic group of eupelycosaurs containing a number of markedly long snouted forms (Berman et al. 1995). The earliest adequately known pelycosaur, Archaeothyris
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 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
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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
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(d) Figure 6.6 (continued). Thylaco
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(a) (c) Caroloameghina and Procarol
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(a) (e) (d) Proargyrolagus Groeberi
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(a) (b) Djarthia Thylacotinga (c) (
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LIVING AND FOSSIL MARSUPIALS 211 M
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Extinct Notoryctemorphia At present
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(f) (g) Wakaleo Diprotodon optatum
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fossil mammals, which might help cl
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30 40 50 60 Figure 6.13 Southern Go
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the Diprotodontia also included gen
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1. Placentalia 2. Edentata 3. Epith
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effectively absent. However, increa
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Asioryctes (a) (b) (d) Cimolestes p
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and Prokennalestes, although it doe
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(a) Leptictidium Palaeoryctidans we
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(a) Purgatorius (c) are part of the
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(a) (d) (e) (g) Protoungulatum Meso
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(a) (f) (e) Hyopsodus Phenacodus (d
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Titanoides (pantodont) (a) (c) (b)
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(a) (b) (d) Trogosus (tillodont) Es
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Mioclaenus Paulacoutoia (didolodont
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their presence. The five orders may
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Xenungulata. Only two Late Palaeoce
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(a) (b) (d) (c) Oxyaena Patriofelis
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continuously growing, and form a gr
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navicular facet, 19 or more thoraci
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(a) (c) Phosphatherium Numidotheriu
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coexist with other characters that
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The salient feature of Widanelfasia
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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
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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