The morphological details of both external and internal anatomy of a group of Palaeozoic fossil medusiform animals are described with the aid of text-figures and plates with explanatory drawings. This fossil group had a worldwide distribution with a stratigraphic range from the Lower Cambrian to the Upper Devonian and includes the following taxa:- Eldonia ludwigi Walcott 1911, E. eumorphus sp. nov., Rotadiscus grandis Sun and Hou 1987, Discophylluni peltatum Hall 1847, D. mirabile Chapman 1926, D. cryptophya (Clarke) 1900. Newly recognised anatomical structures for E. ludwigi include c.30, internal, radially-arranged, bifurcating lobes, a coelomic sac surrounding the alimentary canal, internal structures assumed to represent gonads and c.4 oral tentacles. E. eumorphus has c.44 internal bifurcating lobes associated with rows of pores on the ventral surface, which form a possible respiratory system. R. granclis has a possibly mineralised dorsal surface, rows of pores on the ventral surface and a tentacular appendage with arm-like extensions. Discophylluni 1s characterised by an ornamented dorsal surface with rows of elaborate pores. The nomenclature 1s revised, anatomical reconstructions are presented and modes of life in terms of feeding and benthic versus pelagic existence are discussed. It is concluded that this group, the Discophylla (equivalent in status to a new class), lies within the stem group Echinodermata. As a consequence, current understanding of the early evolution of the Echinodermata, especially with respect to internal anatomy, is questioned . A number of medusiforrn fossils, not studied in detail as part of this work, are discussed and tentatively assigned to the Discophylla.

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Penguins are middle- to large-sized sea birds and are widely distributed in the Southern Hemisphere. They have completely lost the capability for the aerial flight, but are highly efficient wing-propelled swimmers and divers. They have a long fossil record over 60 million years, and their origin could possibly extend back to the late Cretaceous. This study aims to elaborate the course of penguin evolution and driving force of changes based on fossil records of penguins. Numerous fossil penguin specimens have been collected and studied from New Zealand, Antarctica, South America, Australia, and Africa. Studies on fossil penguins have spanned about 150 years history since Huxley (1859). Previous works on fossil penguins have achieved excellent results, but at the same time, left considerable confusion on taxonomy and anatomical interpretation, mainly because of the poor nature of the penguin fossils in early studies. Examination of newly found materials and updated evaluation of previously studied materials are needed, using modern methods. During about 150 years of fossil penguins study since Huxley1859, more than 40 genera and 70 species have been described. The number of specimens listed in the published literature amounts to more than 1300. Chapter II reviews all those fossil penguins in a summarised and consistent style, aiming to present the taxonomy used in this study as a primary and essential resource for research. The chapter also provides other information on fossil penguins, such as geological data and an assessment of the skeletal association of the specimens referred to a species. Chapter III introduces the osteology of penguins, by describing and comparing the skeletal characteristics and variation of both extant and fossil species. Though previous works on penguins osteology are extensive, the interpretation of the homology, and resulted terminology, are occasionally inappropriate, or incorrect, because of the highly-specialised structure. Many of the new, yet undescribed, fossils prompt a comprehensive update of those previous studies, to understand the nature of morphological variation in penguins, and to correct or clarify confusion in previous works. The New Zealand fossil penguin fauna is one of the most significant for fossil penguin studies, but there are many undescribed fossil penguin specimens. Chapter IV provides accounts of such materials. Chapter IV also reviews previously-described New Zealand fossil penguins, usually re-evaluated using new materials. This chapter includes reassessment of the controversial, first-described fossil penguin Palaeeudyptes antarcticus, description of an enigmatic new species (Pakudyptes hakataramea gen. et sp. nov.) which could elucidate the evolutionary pattern of the penguin wing, description of new materials of Platydyptes revealing a unique structure and functional interpretation, and redescriptions with functional interpretation of Pachydyptes and Archaeospheniscus. Published relationships within penguins have not been adequately discussed but stated within rather rough frameworks, so that the relationships within penguins were unclear. Chapter V provides an explicit framework for the phylogeny of penguins. Osteology-based cladistic analysis was performed to seek out the relationships within penguins, using observations on both extant and fossil penguins. There are several important grades in penguin history, which are structurally distant from each other. Results also agree with the published views in which the extant penguins form a rigid group, but Simpson�s subfamily groupings are only partly supported. A postulated phylogenetic tree includes all known fossil penguin taxa including un-named ones. Chapter VI, as a synthesis of contents of previous chapters, provides a broad interpretation of penguin evolution through the Cenozoic: origin, body size increase, demise of 'giant penguins', and the emergence of modern penguins. The chapter gives a global picture of the interaction of penguins, pinnipeds, cetaceans, and temperature and sea-level change. Two main sections are: 'Origin of penguins' and 'Evolutionary process of penguins.' The loss of aerial flight and increase of body size were possibly triggered by the K/T mass extinction event which drastically reduced the predatory pressure for early penguins. The 'giant penguins' survived until the Late Oligocene but declined as the oceans modernised, and new forms of whales with advanced feeding function appeared. There is controversy about appearance of modern penguins. The fossil-based hypothesis (relatively recent origin for crown-penguins) contradicts the molecular-based one (ancient origin for crown penguins), though 'hard evidence' at present does not easily refute either hypothesis.

Thesis (M. Sc.)--University of Stellenbosch, 2000. / Includes bibliographical references. Also available via the Internet.

The aims of this thesis are: 1. To examine patterns of morphological variation in the crania of extant species {Pan, Gorilla, Pongo, and H. sapiens) to determine if any common pattern of primate sexual dimorphism exists which could be used in the assessment of fossil hominid sexual dimorphism; 2. To examine patterns of between species variability among the crania of the above extant species to determine if characters exist which could be useful as taxonomic indicators, especially of specific distinctiveness in fossil Hominidae; and 3. To assess the validity of using traits which are dimorphic and/ or variable within species as taxonomic indicators in systematic analyses. This thesis entails an analysis of inter- and intra-specific diversity among the early hominids based on models derived from samples of modern H. sapiens and pongids. Metrical cranial characters were surveyed in order to assess the implications of their variability within the available early hominid sample {A. afarensis, A. africanus, A. robustus, A. boisei, H. habilis, and H. erectus) using univariate, multi variate, and cladistic analytical techniques. The univariate analysis found no common pattern of primate sexual dimorphism but it did identify characters of low sexual dimorphism and low variability common to all the extant hominoids. These were used to test the homogeneity of the fossil groups and indicated the possible heterogeneity of H. erectus, H. habilis, A. afarensis, and A. boisei. The remaining characters revealed an apparent trend among the hominids (fossil and modern) of dimorphic regions of the skull including the areas of nuchal and temporal muscle attachment, kyphosis of the basicrania, width of the palate, mandible, and base, and facial prognathism. The multivariate analyses used the patterns of variability and dimorphism known from the modern comparators to assess sex, degrees of sexual dimorphism, and homo geneity of the fossil samples. These analyses revealed the possible heterogeneity of H. erectus and A. afarensis, the sex of some individual specimens, and some interesting contrasts in the patterns of sexual dimorphism between the fossil and modern species. They also isolated KNM-ER 1805 as having unique basicranial proportions. Two different types of characters were used in cladistic analyses to determine which type produced the most parsimonious trees and the implications of their use for future cladistic analyses. The results show that non-variable, non-dimorphic traits generally produce more parsimonious trees than variable, dimorphic ones, thus demonstrating the importance of assessing within- and between-group variability of characters prior to cladistic analyses. The method of coding the data prior to the cladistic analysis was tested for its objectivity. The analyses showed that the constant used to code the data into discrete character states had a substantial effect upon the resultant trees. This study has demonstrated that characters have different properties due to the amount they vary or are dimorphic within groups and that utilising these characters for different purposes has the potential to enhance future systematic/ phyletic studies.

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