The Origin and Evolution of Mammals - Moodle

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(a) (c) (d) PMX (f) V n.turb mx.turb SMX vno mx.turb Didelphis Massetognathus mx.turb eth.turb n.turb eth.turb SMX eth.turb Glanosuchus MX Procynosuchus (g) (e) (b) n.turb eth.turb N SMX EVOLUTION OF MAMMALIAN BIOLOGY 117 vno npd Dimetrodon nld vno eth.turb nld gorgonopsian H.g l.g Figure 4.10 Olfactory structures. (a) Internal structure of the snout of a mammal Didelphis to show turbinal bones (Hillenius 1994). Internal views of snouts to show possible turbinal attachment sites of (b) the pelycosaur Dimetrodon (c) the therocephalian Glanosuchus and (e) the eucynodont Massetognathus (Hillenius 1994). (e) Internal surface of the skull roof of a gorgonopsian Leontocephalus (Kemp 1969b). (f) Duvall’s interpretation of the septomaxilla and Jacobson’s organ in Procynosuchus (Duvall 1986). (g) Hillenius’ interpretation of the position of the septomaxilla and Jacobson’s Organ in a generalised therapsid (Hillenius 2000). (h) The Harderian gland, Jacobson’s organ, and naso-lachrymal duct in a mammal. (Hillenius 2000). eth.turb, ethmo turbinal; H.g, Harderian gland; l.g, lachrymal gland; MX, maxilla; mx.turb, maxillo turbinal; N, nasal; nld, nasolachrymal duct; npd, nasopalatine duct; n.turb, nasoturbinal; PMX, premaxilla; SMX, septomaxilla; V, vomer; vno, vomero nasal organ. (h)
118 THE ORIGIN AND EVOLUTION OF MAMMALS interpreted as the sites of attachments of sheets of turbinals that were cartilaginous rather than bony, and which presumably enlarged the area of olfactory epithelium available several-fold. Jacobson’s, or the vomero-nasal organ, is a characteristic tetrapod olfactory organ situated in the floor of the nasal cavity, utilised primarily in social signalling by detecting pheromones (Duvall 1986). Undoubtedly the organ was present in all the mammal-like reptiles since it is still present and often well developed in modern mammals, but there has been much debate and confusion about its position and possible relationship with the prominent foramen and adjacent canal in the septomaxillary bone of the snout region of synapsids (Fig. 4.10(f)). In a detailed comparison with living tetrapods, Hillenius (2000) concluded that in non-mammalian synapsids, Jacobson’s organ was a paired tubular structure lying in the floor of the front part of the nasal cavity, and that it had an association with the naso-lacrimal, or tear duct. He proposed that this duct ran from the glands in the orbit, particularly a Harderian gland, through the snout and opened at the septomaxillary foramen (Fig. 4.10(g)). He assumed that, as in many living tetrapods, the exudate of the Harderian gland is a serous fluid that moistens the nasal area, so that it collects odour molecules, which then pass backwards to Jacobson’s organ for detection. In living mammals, the situation has changed (Fig. 4.10(h)). Jacobson’s organ receives molecules directly from the oral cavity, usually via a naso-palatine duct. The naso-lacrimal duct no longer has a direct association with Jacobson’s organ, but discharges directly to the external nostril and fleshy rhinarium of the snout. The nature of the fluid derived from the Harderian gland has also altered, and is high in lipids. It serves two functions, one is to deliver pheromones to the body surface, and the other is to provide waterproofing material to be spread over the fur. This changed function in mammals is associated with reduction of the septomaxilla bone and loss of its foramen and canal, and therefore this osteological modification may be an indication of the presence of insulating fur, and of more complex social behaviour. Related to this, Duvall (1986) speculated that social signalling by pheromones was an essential precursor of the evolution of lactation and mammalian levels of maternal care. Cynodonts still possessed the primitive form of septomaxilla, foramen, and canal, whereas mammals from Morganucodon onwards have the reduced version lacking the foramen. Perhaps this is evident that cynodonts were uninsulated and lacked complex behaviour, though it is hard to be convinced by such tenuous reasoning. Brain The external features of the brains of mammals and birds are indicated very well by the impressions on the inner surfaces of the braincase because the brain is almost entirely enclosed within bone. The relatively much smaller brains of other amniotes are not so enclosed and therefore it is impossible to reconstruct completely the size, or the relative sizes of the different parts from cranial material alone. Typically the hindbrain, medulla oblongata, and cerebellum are determinable, and also the form of the dorsal surface. But the sides and floor of the midbrain and forebrain, including the cerebral hemispheres are not. Therefore, there is scope for considerable disagreement about the anatomical evolution of brains in synapsids. An endocast of the brain of a specimen of the pelycosaur Dimetrodon was described long ago by Case (1897; Hopson 1979), and indicates a primitive, tubular structure lacking evidence for large expansions of any of its regions. For the basal therapsids, Kemp (1969b) reconstructed the brain of gorgonopsians on the basis of a number of acetic acid-prepared braincases of large specimens (Fig. 4.11(a)). One of these has sheets of a crystalline material that may have replaced cartilaginous sheets present in life, and if this interpretation is correct, then a fairly complete representation of the external form of its brain is possible. Compared to the pelycosaur endocast, the cerebellum was significantly larger and there is an impression of a relatively large optic lobe. There is no room for the cerebrum to have been greatly enlarged, but it is possible that it was significantly larger than the pelycosaur tubular form. Several authors have attempted to reconstruct the brain of cynodonts, with inconsistent results. According to Hopson’s (1979) review of endocranial casts, all cynodonts possessed a tubular brain at the upper end of the size range of those of
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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
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.
Page 106 and 107: 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
Page 114 and 115: 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 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
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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
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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
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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
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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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