Cyclophilin A retrotransposition into TRIM5 explains owl monkey resistance to HIV-1

In Old World primates, TRIM5-alpha confers a potent block to human immunodeficiency virus type 1 (HIV-1) infection that acts after virus entry into cells. Cyclophilin A (CypA) binding to viral capsid protects HIV-1 from a similar activity in human cells. Among New World primates, only owl monkeys exhibit post-entry restriction of HIV-1 (ref. 1). Paradoxically, the barrier to HIV-1 in owl monkey cells is released by capsid mutants or drugs that disrupt capsid interaction with CypA. Here we show that knockdown of owl monkey CypA by RNA interference (RNAi) correlates with suppression of anti-HIV-1 activity. However, reintroduction of CypA protein to RNAi-treated cells did not restore antiviral activity. A search for additional RNAi targets unearthed TRIMCyp, an RNAi-responsive messenger RNA encoding a TRIM5-CypA fusion protein. TRIMCyp accounts for post-entry restriction of HIV-1 in owl monkeys and blocks HIV-1 infection when transferred to otherwise infectable human or rat cells. It seems that TRIMCyp arose after the divergence of New and Old World primates when a LINE-1 retrotransposon catalysed the insertion of a CypA complementary DNA into the TRIM5 locus. This is the first vertebrate example of a chimaeric gene generated by this mechanism of exon shuffling.     

A Miocene ostrich fossil from Gansu Province,northwest China

A pelvic skeleton, recognized as a large terrestrial bird in the field, was recently collected by our paleomammalo-gist colleagues from the Institute of Vertebrate Paleontol-ogy and Paleoanthropology from the late Miocene sandy mudstones in the Linxia Basin in Gansu Province, north-west China. We have further referred this bird to as an early representative of ostrich. Ostrich fossils usually co-existed with the famous Hipparion Fauna from the Mio-cene to Pliocene. The Linxia Basin is we…     

A fossil skull probably of the genus Homo from Sterkfontein, Transvaal.

A skull with numerous Homo features was discovered at Sterkfontein, near Krugersdorp, Transvaal, in August 1976. It stems from member 5 of the Sterkfontein Formation, with stone tools and with fauna pointing to an age of 2.0-1.5 Myr. The underlying member 4 contains Australopithecus africanus, no stone tools, and fauna dated 3.0-2.5 Myr. The new find supports the view that the Sterkfontein toolmaker was not the earlier A. africanus, but a later hominid related to Homo habilis. By a remarkable double coincidence, the first pieces of the new skull, Stw 53, were found on August 9, 1976, 40 years to the day after Robert Broom's first visit to Sterkfontein, while the last part came to light on August 17, the 40th anniversary of Broom's first discovery of a hominid cranium at Sterkfontein. Although most of the fragments were found in a decalcified pocket of cave earth, one large part of the calvaria was still present in the calcified wall of the pocket, thus establishing indisputably the provenance of the specimen.     

Discovery of fossil monocotyledons from Yixian Formation, western Liaoning

This is the first reports of a few fossil monocotyledons, includingLiaoxia chenii gen. et sp. nov. (belonging to Cyperaceae),Eragrosites changii gen. et sp. nov. (Gramineae) and a monocotyledonous leaf-shoot, obtained from the Late Jurassic Yixian Formation of western Liaoning Province, NE China. These fossils are the oldest known angiosperms in the world. It may be inferred that the earliest angiosperms probably appeared even earlier than the Late Jurassic.     

A Chengjiang-type fossil assemblage from the Hongjingshao Formation （Cambrian Stage 3） at Chenggong,Kunming, Yunnan

A new Chengjiang-type fossil assemblage is reported herein from the lower part of the Hongjingshao Formation at Xiazhuang village of Chenggong,Kunming,Yunnan.The fossil assemblage,named as Xiazhuang fossil assemblage,yields predominantly soft-bodied fossils,including arthropods,brachiopods,priapulids,lobopods and some problematic taxa,with arthropods being the most dominant group.Preservation and composition of the fossil assemblage are very similar to the typical Chengjiang biota,which is preserved in the middle Yu’anshan Formation in the large area of eastern Yunnan.The associated trilobites demonstrate that the soft-bodied fossil assemblage belongs to the late Qiongzhusian in age(Stage 3,Cambrian),suggesting that the Hongjingshao Formation is probably a diachronous lithostratigraphic unit ranging from the upper Qiongzhusian to the lower Canglangpuan stages in eastern Yunnan.The fossil assemblage from the Xiazhuang area fills up the missing link between the typical older Chengjiang biota and the younger Malong and Guanshan biotas,making eastern Yunnan a unique area in the world to reveal the early evolutionary history of animals and palaeocommunity dynamics during the‘‘Cambrian explosion’’.     

A 300-million-year record of atmospheric carbon dioxide from fossil plant cuticles

To understand better the link between atmospheric CO2 concentrations and climate over geological time, records of past CO2 are reconstructed from geochemical proxies. Although these records have provided us with a broad picture of CO2 variation throughout the Phanerozoic eon (the past 544 Myr), inconsistencies and gaps remain that still need to be resolved. Here I present a continuous 300-Myr record of stomatal abundance from fossil leaves of four genera of plants that are closely related to the present-day Ginkgo tree. Using the known relationship between leaf stomatal abundance and growing season CO2 concentrations, I reconstruct past atmospheric CO2 concentrations. For the past 300 Myr, only two intervals of low CO2 (<1,000 p.p.m.v.) are inferred, both of which coincide with known ice ages in Neogene (1-8 Myr) and early Permian (275-290 Myr) times. But for most of the Mesozoic era (65-250 Myr), CO2 levels were high (1,000-2,000 p.p.m.v.), with transient excursions to even higher CO2 (>2,000 p.p.m.v.) concentrations. These results are consistent with some reconstructions of past CO2 (refs 1, 2) and palaeotemperature records, but suggest that CO2 reconstructions based on carbon isotope proxies may be compromised by episodic outbursts of isotopically light methane. These results support the role of water vapour, methane and CO2 in greenhouse climate warming over the past 300 Myr.     

甘肃金塔及其附近早白垩世介形类

报道了首次发现于花海－金塔盆地花海凹陷花探９井、湖西新村、阿拉善左旗早白垩世介形类化石。根据它们的组合面貌及其在国内外分布的主要层位,认为：湖西新村原划归为上侏罗统并含有丰富介形化石的这套地层应属下白垩统;花探９井和阿拉善左旗塔塔水沟含化石地层的时代应为早白垩世。这些新的研究成果为建立该地区中生代地层层序奠定了基础,特别是对认识花海－金塔盆地的形成与演化,及进一步的油气勘探提供了新的资料     

Bird-like fossil footprints from the Late Triassic

The study of fossilized footprints and tracks of dinosaurs and other vertebrates has provided insight into the origin, evolution and extinction of several major groups and their behaviour; it has also been an important complement to their body fossil record. The known history of birds starts in the Late Jurassic epoch (around 150 Myr ago) with the record of Archaeopteryx, whereas the coelurosaurian ancestors of the birds date back to the Early Jurassic. The hind limbs of Late Triassic epoch theropods lack osteological evidence for an avian reversed hallux and also display other functional differences from birds. Previous references to suggested Late Triassic to Early Jurassic bird-like footprints have been reinterpreted as produced by non-avian dinosaurs having a high angle between digits II and IV and in all cases their avian affinities have been challenged. Here we describe well-preserved and abundant footprints with clearly avian characters from a Late Triassic redbed sequence of Argentina, at least 55 Myr before the first known skeletal record of birds. These footprints document the activities, in an environment interpreted as small ponds associated with ephemeral rivers, of an unknown group of Late Triassic theropods having some avian characters.     

The gait of Hipparion sp. from fossil footprints in Laetoli, Tanzania

Three Hipparion trails, two from adults and one from a juvenile dating from about 3.5 Myr ago, have now been found in Laetoli. Comparison of the Hipparion footprints with a variety of imprints made by domestic horses showed that the animals moved with a running walk over the soft and slippery soil of Laetoli: in the alternative hind-fore-hind-fore footfall sequence one foot is always close to the ground and can take over the body weight if the supporting foot slides. The smaller juvenile was taking relatively longer strides than the adult. Body support was provided mainly by the third main toe. The evidence indicates that volcanic ash was falling at the time the footprints were made, suggesting that the animals were passing through the area at about the same time. The criss-cross pattern in the trails of the juvenile and adult Hipparion can be seen in the travelling behaviour of mares and foals of living horses. Evidence that the Hipparion were moving with a running walk supports the view that this gait is not 'man-taught' for rider-comfort, but a natural ability in modern horses.     

A mammalian fossil from the Dingqing Formation in the Lunpola Basin, northern Tibet, and its relevance to age and paleo-altimetry

The distal extremity of a rhinocerotid humerus from the upper part of the Dingqing Formation at the Lunbori locality in Baingoin County, northern Tibet, is the first mammalian fossil found in Cenozoic deposits of the Lunpola Basin. The medial condyle of the distal trochlea of the humerus specimen from Lunbori gradually contracts from medially to laterally. The margin of the medial surface of the medial condyle is not prominent, the well-developed medial epicondyle strongly extends posteriorly, and is divided from the articular facet of the medial condyle by a groove; all of which are characteristic for the Rhinocerotidae. The medial condyle is wide at the bottom and narrow at the top. The medial collateral ligament fossa is relatively shallow, and the medial collateral ligament tubercle is very weak. The medial part of the upper margin of the medial condyle smoothly connects to the bony surface above, but there is no clear boundary between them. All of these characteristics are identical with those of Plesiaceratherium. These comparisons imply that the Lunbori specimen is closest to Plesiaceratherium gracile in the Shanwang Fauna from Linqu, Shandong Province, in size and morphology. Thus, its age is suggested to be the late Early Miocene (Shanwangian Age), about 18?C16 Ma. Discovery of the rhinocerotid fossil suggests that the upper part of the Dingqing Formation deposited in the Neogene. While adjusting to paleo-temperatures of the Early Miocene, a paleo-ecosystem reconstruction indicates that the paleo-elevation was close to 3000 m in the Lunpola Basin during this time.     

Discovery of Corallina fossil from the Middle Cambrian of Taijiang County, Guizhou Province, China

Abundant and well-preserved macroalgae fossils have been discovered in silty mudstones and shales from the Middle Cambrian of Taijiang County, Guizhou Province, China. CorallinaParaamphiroa siniansis gen. et sp. nov. in the Kaili Fm., is the earliest Corallina fossil, which usually coexists with other carbonaceous macroalgae fossils on the bedding planes of mudstone and shale and is different from the calcareous and phosphatized Precambrian-Cambrian thallus discovered in the Lower Cambrian of Siberia and the Doushantou phosphate rocks of Weng’an County, Guizhou Province, China. The discovery of calcified thallus in the Kaili Fm. bears great importance on the study of phylogeny and evolution of early calcareous macroalgae.     

On fossil remains of Early Pleistocene tapir (Perissodactyla, Mammalia) from Fanchang, Anhui

The materials of Tapirus from Renzidong,Fanchang, Anhui Province, are the best ones among the early most Pleistocene findings in China up to now, not only in richness, but also in completeness. The fossils contain complete tooth rows of both the upper and the lower, as well as most parts of the postcranial skeletons. These materials are very helpful in understanding the evolutionary level of this kind of animal. In morphology, the materials from Fanchang appear to be very similar to Tapirus sanyuanensis, and can be placed within this species. The materials from Fanchang provided sound evidence to distinguish the Early Pleistocene tapirs and the living form Tapirus indicus. As to the geological distribution, it can be tentatively concluded that Tapirus sanyuanensis and Tapirus sinensis only appeared in Early Pleistocene, Megatapirus appeared after Early Pleistocene,and lasted until Holocene. The Early Pleistocene tapirs of South China resemble Megatapirus more closely than Tapirus indicus.     

A new ichnotaxon of fossil bird track from the Early Cretaceous Tianjialou Formation （Barremian-Albian）, Shandong Province, China

It is well known that fossil bird tracks are geological records of ancient birds walking on the sediments. Prior to the 1980s, little attention was paid to fossil bird tracks partly because of the difficulties of field discrimination. Over the last decade, new discoveries on the bird origin and early evolution, as well as their relation to dinosaurs[1] have greatly stimulated dinosaur and ancient bird studies.Accordingly, the paleoenvironmental, paleoecological and early evolutional significan…     

Evolutionary speed limits inferred from the fossil record.

The dynamics of extinction and diversification determine the long-term effects of extinction episodes. If rapid bursts of extinction are offset by equally rapid bursts of diversification, their biodiversity consequences will be transient. But if diversification rates cannot accelerate rapidly enough, pulses of extinction will lead to long-lasting depletion of biodiversity. Here I use spectral analysis of the fossil record to test whether diversification rates can accelerate as much as extinction rates, over both short and long spans of geological time. I show that although the long-wavelength variability of diversification rates equals or exceeds that of extinctions, diversification rates are markedly less variable than extinction rates at wavelengths shorter than roughly 25 million years. This implies that there are intrinsic speed limits that constrain how rapidly diversification rates can accelerate in response to pulses of extinction.