The Origin and Evolution of Mammals - Moodle

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SC PRC p.i.f.i tr.min (c) dp.cr ect FIB Fexion extension COR Rotation and flexionextension CALC F (a) tr.maj il.fem rotation T ent IL Fexionextension rotation AST p.i.f.i tr.min dp.cr (e) CL EVOLUTION OF MAMMALIAN BIOLOGY 107 IC tr.maj (d) il.fem sc.hum.ant (b) sbc.sc spc R U tr.min. tr.int. tr.maj. tr.min. Figure 4.7 Basal therapsid-grade limb function. (a) Lateral view of left scapulocoracoid and dorsal and ventral views of left humerus of gorgonopsian (Kemp 1982, from a drawing by David Nicholls). (b) Diagram of the orientation of the humerus at the start and the end of a stride, as seen in lateral view, with illustration of the successive points of contact, 1 to 3, between the glenoid cavity and the head of the humerus. (c) Therocephalian ilium and femur in the parasagittal mode, in lateral, and posterior views. (d) The same in sprawling mode, in distal, anterior and dorsal views. (e) Hind view of the lower hind leg, indicating the distribution of possible movements between the five joints involved. (e) Diagrammatic illustration of the action of the ankle joint in the parasagittal mode (above) and sprawling mode (below). AST, astragalus; CALC, calcaneum; CL, clavicle; COR, coracoid; dp.cr, delto-pectoral crest; ect, ectepicondyle; ent, entepicondyle; F, femur; FIB, fibula; IC, interclavicle; il.fem, ilio-femoralis muscle; p.i.f.i, pubo-ischio femoralis internus muscle; PRC, procoracoid; sbc.sc, subcoraco-scapularis muscle; SC, scapula; sc.hum.ant, scapulo-humeralis anterior muscle; spc, supracoracoideus muscle; T, tibia; tr.int, trochanter internus; tr.maj, trochanter major; tr.min, trochanter minor; U, ulnax (Kemp 1982). T AST PES T PES CALC F FIB FIB CALC AST CALC 2 1 3 1 2 3
108 THE ORIGIN AND EVOLUTION OF MAMMALS stride, the front part of the articulating surface of the humerus contacted the front of the glenoid, making contact at two points, one on the upper and one on the lower part of the glenoid. In this position, the shaft of the humerus extended laterally and horizontally and its leading edge was elevated so that the radius and ulna ran antero-ventrally to the forefoot, which was placed on the ground further forwards. The humerus was then retracted while remaining in the horizontal plane, and simultaneously rotated about its long axis. The movement was controlled by the rolling of the cylindrical humerus surface across the convex glenoid surface, there always being two points of contact between the two. By the final position, the humerus was still horizontal but retracted by about 45º, and the rotation about its long axis had placed the forefoot further back relative to the end of the humerus. The structure of the joint prevented adduction of the humerus below the horizontal, but did permit elevation to occur at any stage. This, along with a certain amount of freedom over the extent of the long axis rotation gave the humerus a much wider variety of movement than the highly constrained movement found in the pelycosaurs. The reason for this unusual joint mechanism may be related in a very particular way to the musculature that activated it (Kemp 1982). With the freeing of the shoulder girdle, there was a need to separate the muscles responsible for movement of the humerus relative to the girdle from those responsible for movement of the girdle relative to the ribcage. The roller mechanism causes the front and the hind points of the humerus head to move medially and laterally during the stride cycle. Therefore muscles attached to these points can run medially and so attach exclusively to the girdle, rather than to the body wall. Under these circumstances, the shoulder girdle was left unhampered to undergo its own independent movements relative to the body, controlled by muscles running between the shoulder girdle and the ribcage, body fascia and back of the skull. This unexpected design of the shoulder joint is manifestly weak. First, with so little area of direct contact between the articulating faces of the glenoid and humerus, even after allowing for a generous layer of cartilage the joint could not have withstood particularly large imposed forces. Second, mobility of the pectoral girdle on the body wall using only soft tissues for attachment would also limit the size of locomotor forces that could be imposed without disarticulation. All this points again to the fundamental principle of tetrapod locomotion mentioned, that the primary function of the forelimb was to support the weight of the front part of the animal, and not to generate locomotor forces. The actual musculature of the shoulder girdle did not differ greatly from the sphenacodontine grade. The main retractor was the subcoraco-scapularis, originating on the internal face of the scapulocoracoid, emerging immediately above and behind the glenoid, and inserting on the posterior part of the proximal head of the humerus. The main retractor musculature consisted of muscles from the procoracoid and lower part of the scapula inserting on the anterior part of the humerus head. The probable origin of a supracoracoideus muscle is indicated by a shallow concave area in front of the glenoid, and of a scapulo-humeralis anterior by a large area in the antero-ventral region of the scapular blade. Adduction remained the function of a large pectoralis muscle running ventrally from the still massive delto-pectoral crest of the humerus, and elevation was the consequence of the action of deltoideus and latissimus dorsi muscles. The functioning of the lower forelimb was not radically different from the sphenacodontine stage. As there, here also the radius and ulna were as stout as one another, and shorter than the humerus. The design of the joints was similar, with the sigmoid notch of the ulna making a strong hinging joint at the elbow and also resisting the powerful torque arising from long-axis rotation of the humerus. The radius, by contrast, accommodated the rotation at the elbow. At the wrist, the roles were reversed, with the ulna forming a rotatory joint and the radius a hinge joint with the manus. The manus itself is short and robust, with approximately equal lengths of digits although this was achieved by reduction in size of some of the phalanges: the phalangeal formula of biarmosuchians and gorgonopsians is still 2-3-4-5-3. Although never studied in detail, the relatively short metacarpals indicate that manus was probably plantigrade. Hindlimb. The pelvic girdle and hindlimb of the primitive therapsid grade of evolution was also radically modified from the sphenacodontine grade, and Kemp (1978) proposed that the anatomy 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
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
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 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 128 and 129: (a) (c) (d) PMX (f) V n.turb mx.tur
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
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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
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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
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Index Note: Page numbers in italics
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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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