The development of an atypical Hirnantia Fauna in the late Ordovician of Gondwana was coeval with a slow eustatic fall induced by the abstraction of water into a growing ice sheet. This event is dated as early Hirnantian in age and occurred in tandem with the start of a major mass extinction. A tectonic episode in the Caradoc-Ashgill of North Africa differentiated the continental shelf into highs and lows and may have formed the land required for the accumulation of a permanent snow cover. Depositional lows were filled by regressive shallow-marine deposits in the early Hirnantian. During the mid-Hirnantian, advance and retreat of an ice sheet on the continental shelf resulted in the deposition of glaciomarine sediments above these regressive deposits. The demise of an atypical Hirnantia Fauna is attributed to deglaciation and the associated flooding of the continental shelf by a stratified anoxic water column. This glacioeustatic sea-level rise occurred in the late Hirnantian.

Little is known regarding the internal anatomy of thelodonts, with most of the available information coming from a single specimen, the holotype of Turinia pagei (Powrie). Previous descriptions have led to many partial, or conflicting interpretations. Herein, we describe fully the anatomy of T. pagei based on the holotype and additional material. T. pagei possessed a branchial system composed of eight pairs of gills, a buccal/nasohypophyseal region lined with minute denticles, comparable to buccopharyngeal denticles of sharks, and possessed a stomach which is preserved by sediment infill in the holotype specimen. Contrast between the petrological character of the gut infill and the sediment in which the animal is preserved suggests that the gut was infilled in vivo and that T. pagei was probably a deposit feeder. Phylogenetic analysis resolves T. pagei and the Galeaspida as sister-taxa, comprising a sister-group to the Osteostraci plus jawed vertebrates. In contrast to the view that has prevailed hitherto, thelodonts with a dorsoventrally compressed cross-sectional profile comprise a monophyletic group, of which T. pagei is the least derived member. The furcacaudiforms are resolved as an unnatural group, one taxon being the sister taxon to the ‘conventional’ thelodont clade, and the other, the sister taxon to this clade plus galeaspids, osteostracans and jawed vertebrates. The analysis agrees with the earlier view that thelodonts lack distinct synapomorphies, but we argue that distinct synapomorphies are not a requisite of monophyly.

A re-examination of the lectotype of Sus giganteus Falconer & Cautley, 1847, reveals that it is a suine, as originally thought by its discoverers, and not a tetraconodont as recently published. It may belong to the genus Propotamochoerus as proposed by Azzaroli in 1989. This reassessment radically modifies tetraconodont systematics published recently by Van der Made (1999).

Devonian rhizodontid fishes from East Gondwana include Gooloogongia loomesi Johanson & Ahlberg 1998 from near Canowindra, New South Wales (NSW), Australia and Aztecia mahalae gen. nov., sp. nov. from southern Victoria Land, Antarctica. Gooloogongia loomesi is known from well-preserved cranial and postcranial material, and as such represents the most complete rhizodont known. Newly discovered elements (braincase, pelvic girdle) are described for the first time. Aztecia mahalae gen. nov., sp. nov. is based on shoulder girdle material formerly assigned to Notorhizodon Young et al. 1992, which, based on skull and lower jaw morphology, is a member of the Tristichopteridae. The presence of several plesiomorphic characters suggests that Gooloogongia occupies a basal phylogenetic position within the Rhizodontida, while Aztecia n. gen. possesses a more derived shoulder girdle. We argue that the Rhizodontida evolved on the Gondwanan landmass. Notorhizodon occupies a relatively derived position within the Tristichopteridae, but is contemporary with the earliest and phylogenetically most basal Laurussian members of the group. This shows that the tristichopterids achieved a worldwide distribution considerably earlier than previously thought.

The stem tetrapod Eucritta melanolimnetes is described in full from five specimens. The animal is compared in detail with the contemporary and superficially similar temnospondyl Balanerpeton woodi, and with baphetids (=loxommatids). Growth of Eucritta skulls approaches isometry, and lies on the same trajectory as skulls belonging to the genus Baphetes. The function of the temporal embayment is discussed; it was probably not associated with an air-borne hearing device. The axial skeleton of Eucritta was ossified in larger specimens. Ribs in Eucritta gain expanded distal ends with growth, and the animal probably breathed by buccal pumping. An updated cladistic analysis is presented, incorporating data from a fifth specimen. Eucritta remains as a probable basal baphetid, but the sister group to the baphetids remains uncertain.

A new genus and species of felid, Ginsburgsmilus napakensis, is described from Napak, Uganda. Material from Songhor, Kenya, previously identified as Afrosmilus turkanae by Schmidt-Kittler (1987) is assigned to this species. A new species of Afrosmilus, A. hispanicus, is described from Artesilla, Spain. These new felid species combine sabre-tooth canines of maochairodont type with cheek teeth similar to those of Pseudailurus. Phylogenetically they are close to Afrosmilus turkanae which shows a greater specialisation towards markedly machairodont forms. On the basis of dental features, we propose a close relationship between these two genera (which we group into the new tribe Afrosmilini) and the tribe Barbourofelini (Sansanosmilus and Barbourofelis), the transition between the two being represented in the fossil record by Prosansanosmilus peregrinus Heizmann et al. 1980.