A phylogeny of Diprotodontia (Marsupialia) based on sequences for five nuclear genes

Even though the marsupial order Diprotodontia is one of the most heavily studied groups of Australasian marsupials, phylogenetic relationships within this group remain contentious. The more than 125 living species of Diprotodontia can be divided into two main groups: Vombatiformes (wombats and koalas) and Phalangerida. Phalangerida is composed of the kangaroos (Macropodidae, Potoroidae, and Hypsiprymnodontidae) and possums (Phalangeridae, Burramyidae, Petauridae, Pseudocheiridae, Tarsipedidae, and Acrobatidae). Much of the debate has focused on relationships among the families of possums and whether possums are monophyletic or paraphyletic. A limitation of previous investigations is that no study to date has investigated diprotodontian relationships using all genera. Here, we examine diprotodontian interrelationships using a nuclear multigene molecular data set representing all recognized extant diprotodontian genera. Maximum parsimony, maximum likelihood, and Bayesian methods were used to analyze sequence data obtained from protein-coding portions of ApoB, BRCA1, IRBP, Rag1, and vWF. We also applied a Bayesian relaxed molecular clock method to estimate times of divergence. Diprotodontia was rooted between Vombatiformes and Phalangerida. Within Phalangerida, the model-based methods strongly support possum paraphyly with Phalangeroidea (Burramyidae + Phalangeridae) grouping with the kangaroos (Macropodiformes) to the exclusion of Petauroidea (Tarsipedidae, Acrobatidae, Pseudocheiridae, and Petauridae). Within Petauroidea, Tarsipedidae grouped with both Petauridae and Pseudocheiridae to the exclusion of Acrobatidae. Our analyses also suggest that the diprotodontian genera Pseudochirops and Strigocuscus are paraphyletic and diphyletic, respectively, as currently recognized. Dating analyses suggest Diprotodontia diverged from other australidelphians in the late Paleocene to early Eocene with all interfamilial divergences occurring prior to the early Miocene except for the split between the Potoroidae and Macropodidae, which occurred sometime in the mid-Miocene. Ancestral state reconstructions using a Bayesian method suggest that the patagium evolved independently in the Acrobatidae, Petauridae, and Pseudocheiridae. Ancestral state reconstructions of ecological venue suggest that the ancestor of Diprotodontia was arboreal. Within Diprotodontia, the common ancestor of Macropodidae was reconstructed as terrestrial, suggesting that tree kangaroos (Dendrolagus) are secondarily arboreal.     

Fossil plant evidence for Early and Middle Jurassic paleoenvironmental changes in Lanzhou area, Northwest China

Estimating the paleoclimate changes through CO₂ levels has become a promising area of geological research. This paper focuses on analysis of fossil Ginkgo in continuous sedimentary series in northwestern China using plant anatomy and organic geochemistry approaches. The CO₂ variation curve during Early and Middle Jurassic is reconstructed based on the stomatal ratio method, which is consistent with the estimated results of GEOCARB III. In comparison with the carbon isotopic composition measured from the fossil leaves of Ginkgo, we suggest that the stomata-based CO₂ concentrations for the Jurassic are generally consistent with the predictions of the geochemical model, ranging from 1000 to 1600 ppmv. Measurements of carbon isotope values demonstrate that the water use efficiency of the fossil Ginkgo in a “green house” world is higher than that of the living Ginkgo. Investigations of physiological responses of plants to the increasing CO₂ level at the present and in the future should help demonstrate this effect. The cause of the carbon isotopic shift at the boundary between Aalenian and Bajocian for the Yaojie Basin is unclear and therefore needs further investigation.     

A hominoid humeral fragment from the Pliocene of Kenya

The purpose of this communication is to describe and provide a preliminary interpretation of a hominoid proximal humeral fragment recovered from sediments more than 4.0 m.y. old in the Baringo District, Kenya. The geological and chronological context of the fossil is examined and associated fauna is analyzed.     

Molecular paleobiology — Progress and perspectives

Molecular paleobiology is a subfield of paleontology that uses molecular biological methods on extant organisms to address geoscientifically relevant questions. Progress in the field was last reviewed in 2007, and here we highlight some of the more recent developments, with a focus on ancient animal evolution, in areas such as the application of molecular clocks to estimate clade ages, the evolution of biomineralization, and the evolution of key traits. We argue that molecular paleobiology has much to offer and will be central to paleontological research and evolutionary biology in general, but we also discuss some remaining challenges and future directions of the discipline.     

Hominid molars from a Middle Stone Age level at the Mumba Rock Shelter, Tanzania

Three hominid molars were recovered from a depth of 7.0-7.1 meters in the Mumba Shelter at Lake Eyasi, northern Tanzania. Geological context of the finds and archaeological data indicate that people with a Middle Stone Age technology were using the Mumba locality intermittently whenever retreat of lake waters allowed access to the site. Uranium series dates suggest an age on the order of 130,000 years bp for the teeth and stone tools. Based on morphological analyses, the dental remains probably belonged to one individual and appear to be the crowns of two upper permanent M2s and one lower permanent M2. Crown areas are very small, even in comparison to the variation exhibited by recent African populations. Crown patterns have no archaic features. These teeth are smaller than any verifiable archaic Homo sapiens examples; thus, they may represent early anatomically modern Homo sapiens.     

Evidence of mycoparasitism and hypermycoparasitism in Early Cretaceous amber

Evidence of mycoparasitism and hypermycoparasitism is demonstrated in Early Cretaceous Burmese amber. The agaric, Palaeoagaracites antiquus gen. sp. nov., is parasitized by the mycoparasite, Mycetophagites atrebora gen. sp. nov., which in turn is parasitized by the hyperparasite, Entropezites patricii gen. sp. nov. This discovery shows that sophisticated patterns of fungal parasitism were well developed some 100 Myrago.     

Taxonomy of a platy coral association from the Late Cenomanian of the southern Corbières (Aude,France)

The Upper Cenomanian cover of the Palaeozoic Mouthoumet Massif (southern Corbières, Aude, France), on the southern flank of the Bézu anticline, shows accumulations of large platy corals. However, while being already presented in stratigraphic, palaeoecological and sedimentological contexts, these organisms have not been the subject of a palaeontological study. The coral fauna encompasses 16 species of the families Leptophylliidae, Microsolenidae, and Siderastraeidae and is here presented in detail.     

Significance of stromatoporoids in Jurassic reefs and carbonate platforms—concepts and implications

Although many case studies describe stromatoporoid-rich Jurassic reefs, there are only few reliable data as to their distribution pattern. This is in part due to a largely taxonomic and systematic focus on the enigmatic stromatoporoids which now are interpreted as a polyphyletic informal group of demosponges by most specialists. The common co-occurrence of Jurassic scleractinian corals and stromatoporoids might, at first hand, point to very similar environmental demands of both organismic groups, but autecological considerations as well as evaluation of stromatoporoid distribution patterns should allow for a much more refined interpretation. This study concludes that Jurassic corals and stromatoporoids show a relatively broad overlap of environmental demands but their maximum ecological tolerances appear to differ considerably. Jurassic corals were dominating in mesotrophic to mildly oligotrophic, slightly deeper settings, where they largely outcompeted stromatoporoids. On the other hand, stromatoporoid growth was particularly favoured in very shallow water, strongly abrasive, high-energy settings as well as in possibly overheated waters. Many taxa and growth forms were very tolerant towards frequent reworking and redistribution, a feature which is compatible with the sponge nature of the stromatoporoids. As such, stromatoporoid facies may be common in low-accommodation regimes, giving rise to frequent “shelf shaving” and redistribution across wide shelf areas. The mixed coral-stromatoporoid reefs from the margins of isolated Intra-Tethys platforms are interpreted to be indicative of oligotrophic normal marine waters. This is corroborated by statistical cluster analysis of stromatoporoid taxa from representative areas. In addition, Arabian stromatoporoid occurrences might have been adapted to overheated and slightly hypersaline waters. There also are a few exceptional stromatoporoid taxa which might have had environmental tolerances different from the bulk tolerances of other Jurassic stromatoporoids. Part of our interpretations are preliminary and should stimulate further research. However, the present results already help explain the observed compositional differences between Jurassic North Tethys/North Atlantic, Intra-Tethys, and South Tethys shallow-water reefs and platforms.     

The influence of mass,volume and density on the frequency of recovery of fossil hominid hand and wrist bones

A study of the mass, volume and density of each of the wrist and hand bones of male and female human skeletons was undertaken. It was found that the mass and volume (i.e. size) of the bones are well correlated with the relative frequencies of preservation ofAustralopithecus and earlyHomo wrist and hand bones from fossil hominid sites in Africa. In general, the larger the bone, the greater its preservation frequency. In contrast to findings on bovid bones, the density of hand and wrist bones is not well correlated with the frequency of such bones recovered from these sites. These findings may be explained in terms of the agents of deposition of the bones, the physical nature of the deposit, and the methods of extraction of the fossils from the deposit.