Boyer diss 2009 1046..
Boyer diss 2009 1046.. Boyer diss 2009 1046..
INTRODUCTION Plesiadapid cranial material has been previously described as sharing a number of features with crania of the Carpolestidae, the proposed sister taxon of the Plesiadapidae (Bloch and Silcox, 2006; Bloch et al., 2007). However, these taxa also exhibit a number of cranial morphological differences. Some of these differences appear to be the result of plesiadapid autapomorphies, while others appear to reflect carpolestid autapomorphies. Features currently thought to be shared by and to reflect a close relationship between plesiadapids, carpolestids, and in some cases (features 1-2 below) anatomically modern primates (see Chapter 1: Fig. 1.1) (= Euprimates: Hoffstetter, 1977), include the following: (1) a petrosally derived tympanic bulla, (2) a posterior carotid foramen with a posteromedial position, (3) a separate foramen rotundum and superior orbital fissure, (4) orbital contact between the maxilla and frontal bones in the orbital cavity and (5) a nasal bone that becomes mediolaterally narrow at its caudal extent where it contacts the frontal bone (Bloch and Silcox, 2006; Bloch et al., 2007). On the other hand, some major cranial features of plesadapids that currently appear to separate them from the Carpolestidae include the following: (1) premaxillae that contact the frontal bones, (2) an external auditory meatus that is expanded into a tube-like form and (3) an internal carotid artery with non-functional stapedial, promontorial and main stem branches. If the cladistic hypothesis that plesiadapids and carpolestids are sister taxa is correct, basal plesiadapids may lack some of the autapomorphies separating more derived members of the group from the Carpolestidae. Furthermore, basal plesiadapids should retain synapomorphies apparently shared by carpolestids and more derived plesiadapids. 14
Information on the cranium of basal plesiadapids is necessary to determine with more confidence whether the ancestral plesiadapid lacked or retained the apparent autapomorphies and synapomorphies of more derived members. I provide detailed descriptions of new plesiadapid cranial material, as well as new observations on, and comparisons among, all currently known plesiadapid crania. This information will ultimately allow a better-supported reconstruction of the ancestral form of the clade. A specific major contribution of this work is the comprehensive description of the first cranial material of Pronothodectes based on specimens of Pr. gaoi (Fox, 1990a) from the middle part of the Paleocene of Alberta. These new cranial specimens are particularly important to reconstructing the ancestral pattern of the family because species of this genus, including Pr. gaoi, are dentally more primitive than all other plesiadapids in retaining a lateral lower incisor and a P 2 with “premolariform,” rather than “peg-like,” morphology (Gingerich, 1976; Fox, 1990a) (see Chapter 5). Another important contribution of this work is the relatively large sample of petrosals available for examination in Pr. gaoi (n = 4) and P. tricuspidens (n = 11). Controversies in the literature (e.g., MacPhee et al. 1983 vs. Szalay et al., 1987) make it especially important to document morphological features in these bones and to establish constraints on the intraspecific variability in these features. Some of the disagreements regarding the anatomical significance of the morphological patterns of the petrosal bone can be distilled down to different interpretations of “reconstructed morphology” (e.g., Russell, 1964; MacPhee and Cartmill, 1986; Szalay et al., 1987; Bloch and Silcox, 2001) and differing inferences regarding species-level variability (MacPhee et al., 1983). A better understanding of the tympanic cavity is important for discussions of phylogenetic 15
- Page 1 and 2: NEW CRANIAL AND POSTCRANIAL REMAINS
- Page 3 and 4: Stony Brook University The Graduate
- Page 5 and 6: postcranial anatomy more accurately
- Page 7 and 8: Table of Contents List of Figures .
- Page 9 and 10: Zygomatic. . . . . . . . . . . . .
- Page 11 and 12: Zygomatic. . . . . . . . . . . . .
- Page 13 and 14: Humerus . . . . . . . . . . . . . .
- Page 15 and 16: Description . . . . . . . . . . . .
- Page 17 and 18: Description . . . . . . . . . . . .
- Page 19 and 20: Craniodental material of Plesiadapi
- Page 21 and 22: Figure 2.25. MNHN CR 965 Plesiadapi
- Page 23 and 24: Figure 4.24. UM 87990 Plesiadapis c
- Page 25 and 26: Table List Chapter 2 Table 2.1. Num
- Page 27 and 28: Table 4.30. Caudal vertebrae measur
- Page 29 and 30: CHAPTER 1: INTRODUCTION Plesiadapif
- Page 31 and 32: primates, sharing many dental featu
- Page 33 and 34: were acquired. Specifically, the
- Page 35 and 36: of the plesiadapiform skeleton. Ext
- Page 37 and 38: Gervais, M.P., 1877. Enumération d
- Page 39 and 40: Szalay, F.S., 1972. Cranial morphol
- Page 41: CHAPTER 2: A REEVALUATION OF CRANIA
- Page 45 and 46: petrosal bulla predicts that a sutu
- Page 47 and 48: History of descriptive study of ple
- Page 49 and 50: Gingerich (1971) rebutted Szalay (1
- Page 51 and 52: 9c, Gingerich (1976) labeled a groo
- Page 53 and 54: portion of the bulla medial to the
- Page 55 and 56: Bloch and Silcox (2006) described t
- Page 57 and 58: MATERIALS AND METHODS Material exam
- Page 59 and 60: whitening, dark and light areas on
- Page 61 and 62: SYSTEMATIC PALEONTOLOGY Class MAMMA
- Page 63 and 64: efore meeting a large, anteroposter
- Page 65 and 66: The canine is a simple, single-root
- Page 67 and 68: existence and/or nature of contacts
- Page 69 and 70: outlined. This includes description
- Page 71 and 72: eneath it while also extending post
- Page 73 and 74: y a pair of parallel grooves (Fig.
- Page 75 and 76: the skull (Fig. 2.1). The length of
- Page 77 and 78: margin clearly had a posteriorly pr
- Page 79 and 80: groove measures about 0.29 mm in di
- Page 81 and 82: 2.13: 50). The suture with the supr
- Page 83 and 84: preserved (Fig. 2.15: 55). In fact,
- Page 85 and 86: the posterior septum, a deeply inci
- Page 87 and 88: Plesiadapis tricuspidens MNHN CR 12
- Page 89 and 90: is roughly 2.8 mm long. Medial to t
- Page 91 and 92: is not convoluted like many other s
Information on the cranium of basal plesiadapids is necessary to determine with more<br />
confidence whether the ancestral plesiadapid lacked or retained the apparent<br />
autapomorphies and synapomorphies of more derived members. I provide detailed<br />
descriptions of new plesiadapid cranial material, as well as new observations on, and<br />
comparisons among, all currently known plesiadapid crania. This information will<br />
ultimately allow a better-supported reconstruction of the ancestral form of the clade.<br />
A specific major contribution of this work is the comprehensive description of the<br />
first cranial material of Pronothodectes based on specimens of Pr. gaoi (Fox, 1990a)<br />
from the middle part of the Paleocene of Alberta. These new cranial specimens are<br />
particularly important to reconstructing the ancestral pattern of the family because<br />
species of this genus, including Pr. gaoi, are dentally more primitive than all other<br />
plesiadapids in retaining a lateral lower incisor and a P 2 with “premolariform,” rather<br />
than “peg-like,” morphology (Gingerich, 1976; Fox, 1990a) (see Chapter 5).<br />
Another important contribution of this work is the relatively large sample of<br />
petrosals available for examination in Pr. gaoi (n = 4) and P. tricuspidens (n = 11).<br />
Controversies in the literature (e.g., MacPhee et al. 1983 vs. Szalay et al., 1987) make it<br />
especially important to document morphological features in these bones and to establish<br />
constraints on the intraspecific variability in these features. Some of the disagreements<br />
regarding the anatomical significance of the morphological patterns of the petrosal bone<br />
can be distilled down to different interpretations of “reconstructed morphology” (e.g.,<br />
Russell, 1964; MacPhee and Cartmill, 1986; Szalay et al., 1987; Bloch and Silcox, 2001)<br />
and differing inferences regarding species-level variability (MacPhee et al., 1983). A<br />
better understanding of the tympanic cavity is important for discussions of phylogenetic<br />
15
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