This paper is the second in a series of two works detailing the descriptive and comparative anatomy of the xenarthran ear region (basicranium and its immediate surrounds, including the middle but not the inner ear). The study was begun by Patterson and Segall in 1 945 and continued until Patterson's departure from the Field Museum in 1955, but was never completed. Part I (Patterson et al., 1989) covers the anatomy of the auditory region in cingulates, i.e., armadillos, pampatheres, and glyptodonts. This paper examines the auditory anatomy of the Pilosa, i.e., sloths and anteaters, and the Palaeanodonta. Descriptions are provided for 20 extinct and extant sloth genera, four living and extinct genera of anteaters, and three genera of the extinct suborder Palaeanodonta. In addition, a section detailing the morphology of the auditory ossicles of all groups of living and extinct xenarthrans, both cingulates and pilosans, is included. The comparative anatomy of this region of the xenarthran skull provides new evidence in support of a monophyletic grouping of palaeanodonts and xenarthrans exclusive of pangolins, and a diphyletic origin of the living tree sloths, with Choloepus being linked to the extinct family Megalonychidae and Bradypus to the extinct family Megatheriidae. The suggestion is also put forward (although somewhat weakly supported) that the Megatheriidae and Megalonychidae form a monophyletic clade, with the family Mylodontidae as the sister group to this clade. I (Cingulates), the original outline of the study called for an introduction with a general discussion of the anatomy of the auditory region, a main systematics section, and a conclusion. Unfortunately, no text has been found for either the first or last section, although undoubtedly such text existed at some time in the past. We have thus written a brief introduction and conclusion ourselves. The introduction, as in Part I, is an attempt to provide a framework for the study as a whole, taking into account the probable thinking of the two original authors. The conclusions, which are discussed in a separate section at the end of the work, were drawn solely by Turnbull and Gaudin.We have tried to stress the implied and stated conclusions of the first two authors while taking into account our current understanding of pilosan phylogeny and palaeanodont relationships. The systematic portion of the manuscript (Descriptive Anatomy) contains entirely new descriptions of 27 fossil and Recent taxa, as well as an additional section on xenarthran auditory ossicles. More substantial changes have been made to this part of the study than was the case in Part I. These changes were made necessary by the incompleteness of the manuscript, and by the fact that in places the original authors' intended organization of the manuscript was unclear. Several descriptions had to be written for specimens that had been figured by Patterson and Segall but lacked an accompanying text. Other descriptions were written for specimens that were unavailable to the first two authors....
Novacek and co-workers recognized a monophyletic clade Epitheria, comprising all eutherians except edentates and the extinct palaeoryctoids, on the basis of two synapomorphies: a stirrupshaped stapes and a foramen ovale enclosed within the alisphenoid. To evaluate this phylogenetic hypothesis, we reexamined the distributions of stapedial morphologies and positions of the foramen ovale across Recent and extinct mammals and nonmammalian cynodonts. The states and distributions of the stapes and foramen ovale characters used by Novacek and coworkers were modified by recognizing two stapedial characters (one relating to shape of the crura, the other to the nature of the foramen) and a single, multistate foramen ovale character (within, behind, and lateral to the alisphenoid). The taxon-character matrix used by Novacek (1989Novacek ( , 1992b, substituting our amended stapedial and foramen ovale characters and adding several previously unscored extinct taxa and three new characters, was subjected to a series of PAUP manipulations. Identified among the most parsimonious trees were three major topologies for the base of Eutheria: (1) a polytomy including an Edentata/Ungulata clade, (2) a polytomy with Edentata and Ungulata as separate clades, and (3) Edentata and (when included) Palaeoryctoidea as the successive outgroups to a monophyletic Epitheria. We conclude that topology 2 best reflects the current state of knowledge. An edentate/ungulate clade is supported by three characters (from the mastoid region and subarcuate fossa); however, other morphological studies require modification of the distributions of these characters in xenarthrans and bassal ungulates, thereby eliminating support for this clade. In nearly all manipulations, obtaining a monophyletic Epitheria required that one or two steps be added to the most parsimonious trees. When a monophyletic Epitheria was obtained, it was supported by a triangular stapes and, in some ti~ees, the reappearance of a stapedial artery (lost earlier at the level of Recent therians) and a transpromontorial internal carotid artery. In the most parsimonious trees, a foramen ovale within the alisphenoid was an equivocal synapomorphy of Recent therians or euthefians, and a stapes with strongly convex crura (our state closest to the stirrup-shaped state of Novacek and co-workers) appeared independently within various eutherian lineages. The reduction or loss of the stapedial foramen wag identified as an independent event in monotremes and within marsupials and various eutherian lineages.
Brachipposideros 65 Bradyodonti evolution 521 tooth histology 523 Brain condylarth 323 notoungulate 416 Bridgerian 574 Brittsia problematica 315 Burrows, Permo-Carboniferous 271 Callianassa 288 Calycocoelia 9 Campodus 532 Canis lupus 145 Capra hircus aegagrus 145 Capra ovis, indet. 145 Caproberyx 363 superbus 367 Carinodens fraasi 237 Carodnia 409 Carolozittelia 397 ''eluta'' 409 tapiroides 409 Cephalopoda Mississippian Rayonnoceras 511 Ceratodus parvus 47 Cervus elaphus 145 Chelonia, Chelydridae,
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