The dicynodont genus Lystrosaurus, a relative of the Kannemeyerids, is one of few terrestrial vertebrate genera which can be found on both sides of the Permian-Triassic (P-T) boundary (Botha and Smith, 2006); indeed, a single species, Lystrosaurus curvatus, is known from both periods. In the Permian, Lystrosaurus was of average abundance relative to other genera. Shortly following the P-T extinction, it drastically increased in abundance until it dominated the faunas it was present in (Botha and Smith, 2006). To date, Lystrosaurus fossils have been found in South Africa, India, Antarctica, China, and Russia (Grine et al., 2006). Abundance, survivorship, and expansive geographic presence give Lystrosaurus extreme potential as a model organism for multiple questions involving ideas such as extinction survivorship, biogeography, and ecology; however, Lystrosaurus has been subject to the practice of an extreme version of "splitter" taxonomy in the past. Here I quantify Lystrosaurus morphology using geometric morphometrics. Chinese Lystrosaurus taxonomy has not been analyzed in light of this. My results show that they are different from Gondwanan Lystrosaurus and represent at least one if not two unique species.

The latest-Permian mass extinction was the greatest biotic crisis of the Phanerozoic. The extinction decimated both marine and terrestrial communities, and changed the evolutionary trajectory of multicellular life on the planet. The unique nature of the extinction’s aftermath has prompted attention from paleontologists seeking to understand the timing and pattern of the Triassic recovery. With this dissertation I have sought to shed additional light on the terrestrial side of the extinction by examining different patterns by which its survivors responded to the extinction. Temnospondyl amphibians were one of the few tetrapod clades that were able to take advantage of the extinction to expand their diversity. In Chapter 1 I examine the relationship between taxonomic and ecological diversity of temnospondyls across the Permian-Triassic (P-Tr) boundary in the Karoo Basin of South Africa. Ecomorphological diversity, as implied by differences in cranial shape, was incorporated into the study by the use of a landmark-based geometric morphometric analysis. Both taxonomic diversity and cranial disparity were low during the Permian and increased across the Permian-Triassic boundary. Taxonomic diversity was stable through the Triassic, but disparity showed subsequent increases during the Olenekian and Anisian. Temnospondyls were restricted in size immediately following the extinction, but size range fully rebounded by the Olenekian. Tests of phylogenetic signal demonstrate that cranial shape was heavily influenced by phylogenetic relatedness, and the observed increases in disparity may be partly the result of decreases in the net relatedness of coeval Karoo stereospondylomorph temnospondyls in younger faunas. The increase in community-level taxonomic diversity for temnospondyls in the Karoo following the latest-Permian mass extinction was likely facilitated by an influx of distantly related and ecologically distinct species from other parts of Pangea. In Chapter 2, I discuss the merits of different potential methods for quantifying rates of dispersal within clades. I then apply some of these methods to two very different scenarios, first the dispersal of crocodylians across oceanic barriers during the Late Cretaceous and Cenozoic, and second the dispersal of different groups of tetrapods across Pangea during the Permo-Triassic interval. For crocodylians, because they were dispersing across substantial geographic obstacles, I opted for a direct measurement approach utilizing the optimization of discrete dispersals onto phylogenies. I examined the history of crocodylian biogeography using both parsimony and maximum likelihood on three distinct topologies with several different methods for estimating branch lengths. Across all analyses, members of the clade Alligatoroidea consistently dispersed across oceanic barriers less frequently than did non-alligatoroids. This is consistent with the hypothesis that the greater degree of salt tolerance observed in extant crocodyloids and gavialoids played a role in shaping crocodylian biogeography. The phylogenetic and temporal distribution of high dispersal rates points to an acquisition of greater salt tolerance early in the history of Crocodyloidea and Gavialoidea, potentially near the base of Longirostres if the combined evidence topology is correct. Patterns observed for changes in dispersal rate within individual clades can be largely attributed to changes in global climate and continental configuration over their history. The greater geographic ambiguity represented by the Permo-Triassic continental configuration makes a direct measurement approach inappropriate. For this study I instead opted for a proxy measurement approach, using the phylogenetic clustering of taxa within a community, measured using the Net Relatedness Index. I examined temporal changes in the phylogenetic clustering of five major tetrapod clades that span the Permian-Triassic boundary (Stereospondylomorpha, Parareptilia, Neodiapsida, Anomodontia, and Eutheriodontia) in order to examine patterns of extinction and origination through time, as well as rates of geographic dispersal. Some clades (Stereospondylomorpha, Parareptilia, and Neodiapsida) show evidence of phylogenetically selective extinction across the boundary, but this is not a universal pattern. Only one clade, Stereospondylomorpha, shows an unambiguous increase in dispersal rate following the mass extinction event. Other clades either show no change in dispersal rate, or have results that are mixed, depending on the parameters used in the analysis. These results show that stereospondylomorph temnospondyls were dispersing between geographical regions at increased rates during the Early Triassic, and this may explain much of their apparent increase in diversity following the latest-Permian mass extinction. In Chapter 3, I perform a comparison between the timing of the Triassic recovery with that following the Cretaceous-Paleogene (K-Pg) mass extinction. Three terrestrial fossil-bearing successions were examined, the Lower Triassic Beaufort Group in South Africa and Cis-Ural succession in Russia, and the Paleocene faunas of the American northern Great Plains. A comparison of generic diversity of tetrapods through time for the post-extinction intervals reveals a temporal disparity between the length of terrestrial recovery after the latest-Permian and K-Pg extinctions. Both Permo-Triassic successions show a period of low taxonomic richness (4-5Myr) after the extinction event, followed by an eventual rise in richness. The North American K-Pg succession shows a different pattern, with an immediate rise in richness culminating in a plateau shortly after the extinction (1-3 Myr). This disparity in recovery times may result from prolonged deleterious environmental conditions following the P-Tr events, although several important differences exist between these sequential fossil assemblages that may be affecting the apparent speed of recovery.

Theropoda was one of the most successful dinosaurian clades during the Mesozoic and has remained a dominant component of faunas throughout the Cenozoic, with nearly 10,000 extant representatives. The discovery of Archaeopteryx provides evidence that avian theropods evolved at least 155 million years ago and that more than half of the tenure of avian theropods on Earth was during the Mesozoic. Considering the major changes in niche occupation for theropods resulting from the evolution of arboreal and flight capabilities, we have analyzed forelimb and hindlimb proportions among nonmaniraptoriform theropods, nonavian maniraptoriforms, and basal avialans using reduced major axis regressions, principal components analysis, canonical variates analysis, and discriminant function analysis. Our study is the first analysis on theropod limb proportions to apply phylogenetic independent contrasts and size corrections to the data to ensure that all the data are statistically independent and amenable to statistical analyses. The three ordination analyses we performed did not show any significant groupings or deviations between nonavian theropods and Mesozoic avian forms when including all limb elements. However, the bivariate regression analyses did show some significant trends between individual elements that suggested evolutionary trends of increased forelimb length relative to hindlimb length from nonmaniraptoriform theropods to nonavian maniraptoriforms to basal avialans. The increase in disparity and divergence away from the nonavian theropod body plan is well documented within Cenozoic forms. The lack of significant groupings among Mesozoic forms when examining the entire theropod body plan concurrently suggests that nonavian theropods and avian theropods did not substantially diverge in limb proportions until the Cenozoic. J. Morphol. 276:152-166, 2015.

Several Cenozoic endocarp remains from the northern hemisphere have been described with strong affinities to either Menispermum L. or Sinomenium Diels, a monophyletic group of menispermous vines. It has been proposed that all of these fossil species are synonymous and should be included within Sinomenium. In order to evaluate this suggestion, we have studied the morphological variation ranges in the menispermous endocarps with geometric morphometrics, and then the ranges of the selected fossil endocarps is compared to the ranges of modern endocarps. The shape of each endocarp is described using eight landmarks and 17 semilandmarks, accounting for the outline and the positions of lateral ridge and foramen on the endocarps. Endocarp ornamentation is studied by statistical comparisons of the number of transverse ridges. It is concluded that the ranges of variation within the fossil genera, all morphologically related to horseshoe-shaped endocarps in Menispermaceae, are found not to be greater than that in the only extant species of Sinomenium, S. acutum (Thunb.) Rehder & Wilson. Sinomenium macrocarpum Liu & Jacques, 2010 differs from the other fossil species of Sinomenium by its higher number of transverse ridges. All other fossil species of Sinomenium, except S. macrocarpum, and Wardensheppeya Eyde, 1970 are synonymous. Menispermum? taylori Chandler, 1964 is transferred to Sinomenium. The fossil genus Palaeosinomenium Chandler, 1961 is confirmed through the obliquity of its endocarp, but all species are found to be synonymous. Menispermicarpum rariforme Chandler, 1961 is also included in Palaeosinomenium.

Prairie (Microtus ochrogaster) and woodland (Microtus pinetorum) voles, which exhibit distinctly different ecological preferences (grassland versus forest), commonly co-occur in paleontological deposits in eastern North America. Despite their ecological differences, their molar morphology is similar. Assuming that those ecologic differences occurred in the past, differentiation of these two taxa is important for paleoenvironmental reconstruction. A sample of 51 lower first molars from living populations were viewed via scanning electron microscope to qualify and quantify schmelzmuster (enamel microstructure) to species-specific standards applicable to the fossil record. The most obvious differences between schmelzmuster of the two taxa are the relatively thicker bands of radial enamel on the leading edges of triangles of M. ochrogaster, as well as the consistent retention of tangential or primitive tangential enamel on the trailing edges and posterior enamel band of the posterior loop of M. pinetorum. Discriminant analysis of landmark data from the same 51 specimens established morphological boundaries for these taxa and successfully separated the recent m1s of M. ochrogaster from those of M. pinetorum. To test identification confidence from previous work, and to add an independent means of identification for future work (at any site), both techniques were applied to a sample of three-closed triangle (“M. ochrogaster” type) m1s from the late Pleistocene Wapsipinicon Local Fauna of Jones County, Iowa. Identifications of the specimens from the Wapsipinicon l.f. based on schmelzmuster and morphometric analysis are consistent with those reached using traditional morphology. Such methods serve as independent “check” of traditional (qualitative) identification, highlight new species-level characters, and quantify previously described features, for discrimination of these taxa.

The limb skeleton of tapirs (Perissodactyla: Tapirus spp.) was traditionally thought to exhibit morphological variation only as a result of changes in body size. Here, we test whether forelimb variation exhibited by Tapirus is solely an artefact of size fluctuations through the tapir fossil record or whether it is influenced by habitat differences. We investigated the forelimb osteology of 12 species of Tapirus using three-dimensional geometric morphometrics on laser surface scans. Aligned shape coordinates were regressed against intrinsic bone size to account for allometry. Taxa of equivalent body mass exhibited significant differences in size-corrected bone shape. Stable carbon isotope values were averaged per species as a proxy for habitat density. Multivariate regressions of the humerus, pisiform, cuneiform, unciform, third and fourth metacarpals revealed no significant influence of size on shape. The lateral carpals (pisiform, cuneiform, unciform) demonstrated variation across the habitat density gradient. Observed variation is likely driven by species in the extinct subgenus Helicotapirus tapirs, which inhabited drier, more open woodland than modern taxa. We conclude that tapir forelimb variation is not exclusively an artefact of body size, with lateral wrist bones displaying notable differences across a habitat density gradient, beyond that resulting from size and phylogenetic effects.

Sex estimation is one of the most important, and arguably the first, parts of the biological profile that is estimated for purposes of human identification. This study will examine the utility of the distal humerus in sex estimation. The goal of this research is to corroborate the usefulness of the distal humerus in sex estimation and the usefulness of geometric morphometrics in sex estimation, as well as validate metric and visual methods for sex estimation using the distal humerus. Multiple methods of sex estimation are necessary because complete skeletons are rarely found, and often only fragments are discovered. Three methods of sex estimation utilizing the distal humerus are used in this study: epicondylar breadth (n=448), nonmetric traits per Rogers (1999) and Vance et al. (2011 (n=444)), and geometric morphometrics via a Microscribe digitizer and MorphoJ software (n=227). The sample was taken from the William M. Bass Donated Skeletal Collection and was primarily composed of White Americans. The male to female ratio was approximately equal. The results of the metric aspect of the study showed a classification accuracy of 88.84% with low intra-observer and inter-observer error rates. The results of the nonmetric aspect of the study showed a classification accuracy of 77% when all traits were combined with low intra-observer and high inter-observer error rates. The results of the geometric morphometric aspect of the study showed a classification accuracy of 55% for all landmarks, 57% for anterior landmarks, and 63% for posterior landmarks. The results show that not only is the epicondylar breadth a reliable and effective method of sex estimation, it is easily repeatable by other observers. The nonmetric method is useful when epicondylar breadth cannot be measured or when an observer is familiar with the method. The geometric morphometric method is not as strong as the other two methods, but with further research and modifications may become a feasible option for sex estimation using the distal humerus. The author concludes that the distal humerus is sexually dimorphic and can be used to estimate sex accurately.

No description available.

Documenting biodiversity, at and below the species level, is a persistently challenging task for biologists. Poor understanding of biodiversity may lead to incorrect interpretations of observed variation. The underlying basis of variation can be understood by quantifying multiple sources of information. Nine morphometric characters and plastid DNA sequences (2511 bps) were quantified in a highly variable orchid species, Platanthera dilatata, to evaluate taxonomy of the three named varieties and to understand patterns of evolution. Three morphological groups, identified in a cluster analysis, were distinct in multiple floral traits. Additionally, the three clusters were consistently genetically divergent as indicated by infrequent haplotype sharing, significantly different haplotype frequencies, and significant values of the genealogical sorting index. This level of genetic divergence suggests three species rather than varieties in this complex. The divergent floral morphologies suggest that pollinator-mediated selection may be a driving factor for speciation in this complex.

Antisymmetry is a striking, yet puzzling form of biological asymmetry. The livebearing fish Xenophallus umbratilis exhibits antisymmetry in the male intromittent organ and provides a system that is well-suited for studying the nature of variation in antisymmetrical traits. Using geometric morphometrics, I test the hypothesis that because the gonopodium is critical to fitness there will not be significant differences in gonopodium shape between the two gonopodial morphs in this species. My results are consistent with this prediction, though I found that gonopodium shape did differ with gonopodium size.