Nuttalliella namaqua: A Living Fossil and Closest Relative to the Ancestral Tick Lineage: Implications for the Evolution of Blood-Feeding in Ticks

Ticks are monophyletic and composed of the hard (Ixodidae) and soft (Argasidae) tick families, as well as the Nuttalliellidae, a family with a single species, Nuttalliella namaqua. Significant biological differences in lifestyle strategies for hard and soft ticks suggest that various blood-feeding adaptations occurred after their divergence. The phylogenetic relationships between the tick families have not yet been resolved due to the lack of molecular data for N. namaqua. This tick possesses a pseudo-scutum and apical gnathostoma as observed for ixodids, has a leathery cuticle similar to argasids and has been considered the evolutionary missing link between the two families. Little knowledge exists with regard to its feeding biology or host preferences. Data on its biology and systematic relationship to the other tick families could therefore be crucial in understanding the evolution of blood-feeding behaviour in ticks. Live specimens were collected and blood meal analysis showed the presence of DNA for girdled lizards from the Cordylid family. Feeding of ticks on lizards showed that engorgement occurred rapidly, similar to argasids, but that blood meal concentration occurs via malpighian excretion of water. Phylogenetic analysis of the 18S nuclear and 16S mitochondrial genes indicate that N. namaqua grouped basal to the main tick families. The data supports the monophyly of all tick families and suggests the evolution of argasid-like blood-feeding behaviour in the ancestral tick lineage. Based on the data and considerations from literature we propose an origin for ticks in the Karoo basin of Gondwanaland during the late Permian. The nuttalliellid family almost became extinct during the End Permian event, leaving N. namaqua as the closest living relative to the ancestral tick lineage and the evolutionary missing link between the tick families

Changes to the Fossil Record of Insects through Fifteen Years of Discovery

The first and last occurrences of hexapod families in the fossil record are compiled from publications up to end-2009. The major features of these data are compared with those of previous datasets (1993 and 1994). About a third of families (>400) are new to the fossil record since 1994, over half of the earlier, existing families have experienced changes in their known stratigraphic range and only about ten percent have unchanged ranges. Despite these significant additions to knowledge, the broad pattern of described richness through time remains similar, with described richness increasing steadily through geological history and a shift in dominant taxa, from Palaeoptera and Polyneoptera to Paraneoptera and Holometabola, after the Palaeozoic. However, after detrending, described richness is not well correlated with the earlier datasets, indicating significant changes in shorter-term patterns. There is reduced Palaeozoic richness, peaking at a different time, and a less pronounced Permian decline. A pronounced Triassic peak and decline is shown, and the plateau from the mid Early Cretaceous to the end of the period remains, albeit at substantially higher richness compared to earlier datasets. Origination and extinction rates are broadly similar to before, with a broad decline in both through time but episodic peaks, including end-Permian turnover. Origination more consistently exceeds extinction compared to previous datasets and exceptions are mainly in the Palaeozoic. These changes suggest that some inferences about causal mechanisms in insect macroevolution are likely to differ as well

A description of the sedimentology and palaeontology of the Late Triassic–Early Jurassic Elliot Formation in Lesotho

Sedimentological studies of the Late Triassic to Early Jurassic Elliot Formation (Karoo Supergroup) in Lesotho have proved to be a fundamental element in our research into the development of the main Karoo Basin of southern Africa. Complementing previous research in SouthAfrica, studies of the architecture of the sedimentary units in the Elliot Formation reveal that there are two contrasting types of sandstone body geometries, each resulting from different fluvial depositional styles. In the lower part of the formation, the sandstones resemble multi-storey channel-fills, interpreted as deposits of perennial, moderately meandering fluvial systems. On the other hand, the upper part of the formation is characterized by mostly tabular, multi-storey sheet sandstones which resulted from ephemeral fluvial processes. Based mainly on changes in the fluvial style and palaeocurrent pattern within the formation, the regional lithostratigraphic subdivision applied to the Elliot Formation in South Africa is applicable in Lesotho as well. This study adds detail and therefore refines the stratigraphic subdivision documented for the South African succession, and as such forms an important framework for palaeontological, palaeoecological and biostratigraphic studies in Lesotho.Palaeo-anthropology Scientific Trust National Research Foundatio

A giant dinosaur from the earliest Jurassic of South Africa and the transition to quadrupedality in early sauropodomorphs

Sauropod dinosaurs were dominant, bulk-browsing herbivores for 130 million years of the Mesozoic, attaining gigantic body masses in excess of 60 metric tons [1, 2]. A columnar-limbed, quadrupedal posture enabled these giant body sizes [3], but the nature of the transition from bipedal sauropodomorph ancestors to derived quadrupeds remains contentious [4, 5, 6]. We describe a gigantic, new sauropodomorph from the earliest Jurassic of South Africa weighing 12 metric tons and representing a phylogenetically independent origin of sauropod-like body size in a non-sauropod. Osteohistological evidence shows that this specimen was an adult of maximum size and approximately 14 years old at death. Ledumahadi mafube gen. et sp. nov. shows that gigantic body sizes were possible in early sauropodomorphs, which were habitual quadrupeds but lacked the derived, columnar limb postures of sauropods. We use data from this new taxon and a discriminant analysis of tetrapod limb measurements to study postural evolution in sauropodomorphs. Our results show that quadrupedality appeared by the mid-Late Triassic (Norian), well outside of Sauropoda. Secondary reversion to bipedality occurred in some lineages phylogenetically close to Sauropoda, indicating early experimentation in locomotory styles. Morphofunctional observations support the hypothesis that partially flexed (rather than columnar) limbs characterized Ledumahadi and other early-branching quadrupedal sauropodomorphs. Patterns of locomotory and body-size evolution show that quadrupedality allowed Triassic sauropodomorphs to achieve body sizes of at least 3.8 metric tons. Ledumahadi’s Early Jurassic age shows that maximum body mass in sauropodomorph dinosaurs was either unaffected or rapidly rebounded after the end-Triassic extinction event

Suspected microbial mat-related crack-like sedimentary structures in the Palaeoproterozoic Magaliesberg Formation sandstones, South Africa

The occurrence of patchy preservation of ripples and of palimpsest ripples on many sandstone bed surfaces of the c. 2.1 Ga Magaliesberg Formation (Pretoria Group, Transvaal Supergroup), South Africa, suggests that microbial mats grew within the upper parts of sandy deposits of the braid-deltaic-tidally controlled epeiric marine coastline palaeoenvironment inferred for this stratigraphic unit. Recently, limited occurrences of petee ridges, cracked sand layers, "elephant skin textures", wrinkle structures and "Manchuriophycus"-like cracks have been found, substantiating the envisaged role for microbial mats, binding sandy sediment and providing cohesion during active sedimentation by fluvial and tidal processes. Ripple marks associated with most of these biogenic sedimentary structures enable evaluation of genetic processes for the ripples (currents, waves, wind) as well as estimation of wave heights and water depths (cf. Tanner, W.F., 1967. Ripple mark indices and their uses. Sedimentology 9, 89-104. Tanner, W.F., 1971. Numerical estimates of ancient waves, water depths and fetch. Sedimentology 16, 71-88.). The petee ridges are interpreted as reflecting spring low tidal desiccation which cracked the mats, followed by disruption of sand beneath the mat due to loading from incoming tides or subsequent deposits. Slightly sinuous sand cracks on ripple crests are related to a similar combination of low tidal desiccation (and formation of wind ripples) with subsequent high tides providing the deeper water conditions and larger wave heights calculated from the (Tanner, W.F., 1971. Numerical estimates of ancient waves, water depths and fetch. Sedimentology 16, 71-88.) formula. Synaeresis cracking is inferred for both "elephant skin" cracks and "Manchuriophycus" structures. These inferred suspect-microbial sedimentary structures, when studied in relation to data derived from associated ripples, thus enable better estimation of depositional conditions within the Magaliesberg palaeoenvironment, and indicate minimum epeiric tidal ranges of c. 112cm. In general, these structures are found associated with evidence for shallower water and higher energy conditions, which probably protected the microbial mats from degradation by heterotrophic bacteria, through fast burial. A possible association of such mat-related structures with epeiric marine or passive margin coastline conditions may be pertinent for much of the Precambrian clastic record. (c) 200

The first megatheropod tracks from the Lower Jurassic upper Elliot Formation, Karoo Basin, Lesotho

A palaeosurface with one megatheropod trackway and several theropod tracks and trackways from the Lower Jurassic upper Elliot Formation (Stormberg Group, Karoo Supergroup) in western Lesotho is described. The majority of the theropod tracks are referable to either Eubrontes or Kayentapus based on their morphological characteristics. The larger megatheropod tracks are 57 cm long and have no Southern Hemisphere equivalent. Morphologically, they are more similar to the Early Jurassic Kayentapus, as well as the much younger Upper Cretaceous ichnogenus Irenesauripus, than to other contemporaneous ichnogenera in southern Africa. Herein they have been placed within the ichnogenus Kayentapus and described as a new ichnospecies (Kayentapus ambrokholohali). The tracks are preserved on ripple marked, very fine-grained sandstone of the Lower Jurassic upper Elliot Formation, and thus were made after the end-Triassic mass extinction event (ETE). This new megatheropod trackway site marks the first occurrence of very large carnivorous dinosaurs (estimated body length >8-9 meters) in the Early Jurassic of southern Gondwana, an evolutionary strategy that was repeatedly pursued and amplified in the following ~135 million years, until the next major biotic crisis at the end-Cretaceous