Boyer diss 2009 1046..
Boyer diss 2009 1046.. Boyer diss 2009 1046..
trochleae of the proximal phalanges. The dorsal and ventral margins extend proximally roughly equal distances, relative to the proximodistal axis of the shaft. However, the ventral margin is usually slightly more proximally projecting, which makes the proximal articular surface face slightly dorsally, relative to the shaft axis. The proximal end is usually slightly greater in its dorsoventral depth than its proximodistal width, with a couple of exceptions for certain manual elements. The ventral surface is marked by prominent tubercles that project ventrally. These appear to be either the flexor sheath tubercles or insertion points for the flexor digitorum superficialis tendons. Beyond the proximal end, the shaft shape is similar to that of proximal phalanges, narrowing in its mediolateral dimension until roughly the proximodistal midpoint of the shaft, and narrowing in its dorsoventral dimension for the entire length of the shaft. For much of the shaft length, the dorsoventral dimension is greater than the mediolateral dimension. The shafts are essentially straight, except for the three longest (probably pedal) elements, which show the slightest amount of dorsal convexity (Boyer and Bloch, 2008). The distal ends of the intermediate phalanges have a single groove down the center of their distal articular surface, rather than two grooves, as in the case of proximal phalanges. In lateral profile it can be seen that distal articular surface has a fairly constant radius of curvature and ~180° of arc to it, although one phalanx (Fig. 4.21G) appears to have well over 180°. Furthermore, in dorsal and lateral view it can be seen that the articular surfaces have a greater amount of ventral-facing area than dorsal-facing area, although they are not as retricted in the amount of dorsal area as the proximal phalanx distal articlar facets. Function.—The dorsoventrally deep shafts of the intermediate phalanges suggest that they were resistant to parasagittal stresses experienced due to body weight during 322
antipronograde clinging postures, or due solely to the force of contraction of the digital flexor muscles. The form and orientation of the distal articular surface suggests that the distal phalanges would have had a large range of flexibility and could have attained substantially dorsiflexed configurations (unlike the intermediate phalanx at the proximal interphalangeal joint). However, when joint surfaces are maximally overlapped, the distal phalanx is strongly ventriflexed (Godinot and Beard, 1991). Comparison.—Compared to other plesiadapids, the intermediate phalanges of P. cookei differ most substantially in their proximal end dimensions (Table 4.14: BSV). The dorsoventral depth of this region is greater relative to its mediolateral width than for most other plesiadapids and many arboreal mammals (Boyer and Bloch, 2008). One exception is P. n. sp. from the earliest Eocene Le Quesnoy locality in France. It is similar to P. cookei in this regard. An ANOVA of on BSV (proximal end dorsoventral depth over mediolateral width) for P. cookei, Nannodeces, P. tricuspidens and P. n. sp. shows significant among group variance (df=3, F=38.64, P
- Page 299 and 300: Gingerich and Gunnell (1992) publis
- Page 301 and 302: prehensility they provide, is an in
- Page 303 and 304: euarchontans (Fig. 1.1). Their anal
- Page 305 and 306: for comparison. These include isola
- Page 307 and 308: plesiadapid samples have the same m
- Page 309 and 310: Organization of results Each bone i
- Page 311 and 312: Bloch and Boyer (2002) and N. inter
- Page 313 and 314: clavicle reflects some basic aspect
- Page 315 and 316: Humerus Description.—The right an
- Page 317 and 318: epicondyle actually projects somewh
- Page 319 and 320: cookei is absolutely longer than an
- Page 321 and 322: tuberosity. This crest probably del
- Page 323 and 324: olecranon process to estimate its t
- Page 325 and 326: distinct, convex distal radial face
- Page 327 and 328: of the midcarpal joint), and its pr
- Page 329 and 330: (there is no evidence for more than
- Page 331 and 332: matches the opposing facet on the t
- Page 333 and 334: mobility at the trapezoid-trapezium
- Page 335 and 336: Function.—The three proximal carp
- Page 337 and 338: the bone presently being described:
- Page 339 and 340: the “set 2” MC II is a larger,
- Page 341 and 342: differs from MC II and III in havin
- Page 343 and 344: even more pronounced. The distal en
- Page 345 and 346: etween the distal carpals and the
- Page 347 and 348: have stouter shaft diameters for th
- Page 349: difference makes them more like kno
- Page 353 and 354: foramina, and faces slightly proxim
- Page 355 and 356: spine at the superior tip of the il
- Page 357 and 358: the thigh (Gambaryan, 1974). The ha
- Page 359 and 360: The femoral shaft is smooth, lackin
- Page 361 and 362: lacking a lateral extension of its
- Page 363 and 364: The anteromedial side of the tibial
- Page 365 and 366: fibular notch and the strong crest
- Page 367 and 368: to the peroneal surface. The perone
- Page 369 and 370: could even be described as having t
- Page 371 and 372: Function.—The functional features
- Page 373 and 374: flexor fibularis groove surface. Ex
- Page 375 and 376: tubercle, which is centrally locate
- Page 377 and 378: Cuboid Description.—The right cub
- Page 379 and 380: Ectocuneiform Description.—A left
- Page 381 and 382: Metatarsals Hallucal metatarsal des
- Page 383 and 384: articulation with the entocuneiform
- Page 385 and 386: medial side facet on MT IV from a v
- Page 387 and 388: Vertebral column Vertebral column d
- Page 389 and 390: measurements, see caption of Fig. 4
- Page 391 and 392: transverse processes, and the poste
- Page 393 and 394: taxa appear to have slightly more p
- Page 395 and 396: dorsoventrally than craniocaudally.
- Page 397 and 398: The zygapophyses increase in size b
- Page 399 and 400: vertebrae. It is also similar to th
antipronograde clinging postures, or due solely to the force of contraction of the digital<br />
flexor muscles. The form and orientation of the distal articular surface suggests that the<br />
distal phalanges would have had a large range of flexibility and could have attained<br />
substantially dorsiflexed configurations (unlike the intermediate phalanx at the proximal<br />
interphalangeal joint). However, when joint surfaces are maximally overlapped, the distal<br />
phalanx is strongly ventriflexed (Godinot and Beard, 1991).<br />
Comparison.—Compared to other plesiadapids, the intermediate phalanges of P.<br />
cookei differ most substantially in their proximal end dimensions (Table 4.14: BSV). The<br />
dorsoventral depth of this region is greater relative to its mediolateral width than for most<br />
other plesiadapids and many arboreal mammals (<strong>Boyer</strong> and Bloch, 2008). One exception<br />
is P. n. sp. from the earliest Eocene Le Quesnoy locality in France. It is similar to P.<br />
cookei in this regard. An ANOVA of on BSV (proximal end dorsoventral depth over<br />
mediolateral width) for P. cookei, Nannodeces, P. tricuspidens and P. n. sp. shows<br />
significant among group variance (df=3, F=38.64, P
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