40Ar/(39)Ar dating of Chemeron Formation strata encompassing the site of hominid KNM-BC 1, Tugen Hills, Kenya.

A fossil hominid temporal bone (KNM-BC 1) from surface exposures at Baringo Paleontological Research Project site BPRP#2 in the Chemeron Formation outcropping in a tributary drainage of the Kapthurin River west of Lake Baringo, Kenya has been attributed to Homo sp. indet. K-feldspar phenocrysts from lapilli tuffs bracketing the inferred fossiliferous horizon yield single-crystal(40)Ar/(39)Ar ages of 2.456+/-0.006 and 2.393+/-0.013 Ma. These age determinations are supported by stratigraphically consistent ages on higher tuff horizons and from nearby sections. In addition, new(40)Ar/(39)Ar ages on tuffaceous units near the base and top of the formation along the Kapthurin River yield 3.19+/-0.03 and 1.60+/-0.05 Ma respectively. The base of the formation along the Kapthurin River is thus approximately 0.5 Ma younger than the uppermost Chemeron Formation strata exposed at Tabarin, 23 km to the north-northwest. The upper half of the formation along the Kapthurin River was deposited at an average rate of approximately 11 cm/ka, compared to 21-23 cm/ka at Tabarin.     

Neogene paleobiogeography and East African paleoenvironments: contributions from the Tugen Hills rodents and lagomorphs.

A minimum of 28 genera of rodents and one genus of lagomorph were recovered from the Tugen Hills, Baringo District, Kenya, from localities dating from over 15.5 to about 4.4 Ma. The middle Miocene (sites dated between 15.8 and 15.3 Ma) rodent fauna recovered primarily from the Kipsaramon site complex, Muruyur Formation, includes a mixture of characteristically early Miocene taxa, and more derived forms. Composition of the African rodent fauna changes dramatically with the introduction of myocricetodontines, democricetodontines, and dendromurines, immigrants primarily from southern Asia. In the Tugen Hills, these taxa are first found in the Kabasero localities, Ngorora Formation, at sites dating from 12.5-12.33 Ma. A second major change in the African rodent fauna reflects the introduction of murines, immigrants from southern Asia. In the Tugen Hills murines are first encountered at Kapcheberek, Lukeino Formation, dated to 5.9-5.7 Ma. One rodent genus from the Lukeino Formation (Arvicanthis), and two from the Tabarin locality, Chemeron Formation (Heliosciurus, Paraxerus; 4.5-4.4 Ma), represent the earliest records of these extant African genera. A cricetomyine from the Ngorora Formation (12.5 Ma) is likely the earliest report of this exclusively African group. One of the earliest African records of porcupines (Hystricide) is from the Lukeino Formation. Lagomorphs are poorly represented, but include one of the earliest African occurrences of the family Leporidae from the Mpesida Beds (bracketed by dates of 7-6.2 Ma), and possibly a new genus of leporid from the Kapcheberek locality. Analysis of the Tugen Hills small mammals in association with other African records suggests several episodes of dispersal between Africa and Eurasia during the middle and late Miocene. Rodents from Kipsaramon are indicative of forests in conjunction with more open habitats. Those from the Kapcheberek locality are suggestive of a savanna habitat. The rodents from the Tabarin locality suggest a woodland environment.     

Integrated stratigraphy and 40Ar/39Ar chronology of early Middle Miocene sediments from DSDP Leg 42A,Site 372 (Western Mediterranean)

An integrated magneto-biostratigraphic framework is presented for Middle Miocene sediments of DSDP Site 372 located in the Western Mediterranean. Detailed biostratigraphic analysis shows a nearly complete sequence of early Middle Miocene calcareous plankton bioevents in the Mediterranean, including the LCO (Last Common Occurrence) of the nannofossil Sphenolithus heteromorphus which has been astronomically dated in the Ras il Pellegrin (RIP) section on Malta Island [Abels, H.A., Hilgen, F.J., Krijgsman, W., Kruk, R.W., Raffi, I., Turco, E., Zachariasse, W.J., 2005. Long-period orbital control on middle Miocene global cooling: integrated stratigraphy and astronomical tuning of the Blue Clay Formation on Malta, Paleoceanography, 20, PA4012. doi: 10.1029/2004PA001129. 11 pp]. Thermal demagnetization of discrete samples revealed a characteristic low-temperature component with dual polarities despite a weak paleomagnetic signal. The resultant magnetostratigraphic record, combined with the calcareous plankton biostratigraphy, is straightforwardly correlated to the geomagnetic polarity time scale (CK95) of Cande and Kent [Cande, S.C., Kent, D.V., 1995. Revised calibration of the Geomagnetic Polarity Time Scale for the Late Cretaceous and Cenozoic, J. Geophys. Res., 100, 6093–6095] and the Astronomical Tuned Neogene Time Scale (ATNTS04) of Lourens et al. [Lourens, L.J., Hilgen, F.J., Laskar, J., Shackleton, N.J., Wilson, D., 2004. The Neogene Period. In: Gradstein F.M., Ogg J.G., Smith A.G. (Eds.), A Geologic Time Scale, Cambridge Univ. Press, pp. 409–440]. The subchrons recorded in Site 372 succession range from C5Br up to C5AAr. To confirm the magnetostratigraphic calibration, ⁴⁰Ar/³⁹Ar dating was performed on feldspar of two volcanic ash layers. The radio-isotopic dating indicates a younger age for these two ash layers compared to the magnetostratigraphic calibrated ages according to the CK95 and ATNTS04 age models. However, if the astronomically calibrated age of 28.21 ± 0.04 Ma is used for the Fish Canyon standard (FCs), the age for the older ash layer exactly matches its ATNTS04 age. Ages for bioevents were calculated assuming constant sedimentation rates between magnetostratigraphic age-tie points. The S. heteromorphus LCO has an age of 13.54 Ma and 13.63 Ma according to CK95 and ATNTS04, respectively, which is consistent with the astronomical tuned age of 13.65 Ma determined at RIP section [Abels, H.A., Hilgen, F.J., Krijgsman, W., Kruk, R.W., Raffi, I., Turco, E., Zachariasse, W.J., 2005. Long-period orbital control on middle Miocene global cooling: integrated stratigraphy and astronomical tuning of the Blue Clay Formation on Malta, Paleoceanography, 20, PA4012. doi:10.1029/2004PA001129. 11 pp]. We therefore conclude that the magnetostratigraphic calibration of DSDP Site 372 is correct and that, for the time being, this site can be considered as a reference section for the early Middle Miocene of the Mediterranean region.     

Late Cretaceous radiolarian biochronology of the Pedro Brand section,Tireo Group,eastern Central Cordillera,Dominican Republic: A contribution to the stratigraphy of the Caribbean Large Igneous Province

The Tireo Group in the eastern Central Cordillera (Dominican Republic) is part of the Jarabacoa Block, composed of a Pacific-type Jurassic ocean floor (Loma La Monja, overlain by the El Aguacate ribbon Chert), intruded and overlain by an early CLIP (Carribean Large Igneous Province)-type plateau, the Duarte Complex, which is in turn unconformably overlain by arc-type rocks of the Tireo Group. This group exhibits a 3-km thick sequence of arc-related volcanic and volcano-sedimentary rocks, including tuffaceous chert and mudstone studied for radiolarians in this paper. The Siete Cabezas Formation, considered to be the last Campanian–Maastrichtian CLIP-type volcano-sedimentary sequence, overlies the Tireo Group. A controversy about earlier radiolarian dating of the Tireo Group, considered until now as part of the Siete Cabezas Formation, encouraged us to study a well-exposed section located 3 km NE of Pedro Brand village. Seven samples of laminated siliceous mudstones and cherts yielded around 40 common and well-preserved radiolarian taxa. Based on maximum ranges of taxa published in several regional zonations and on a comparison with a Turonian–Coniacian sample calibrated by planktonic foraminifera (the Deva Beds from Romania), we determine a Turonian–Coniacian age for the Pedro Brand section. A ⁴⁰Ar–³⁹Ar whole rock age of 75.1 ± 1.1 Ma, obtained in a basalt dyke crosscutting the radiolarian bearing rocks, provides a Late Campanian consistent minimum age for the pelagic–hemipelagic Pedro Brand section. Including the re-interpretation of earlier radiolarian work, we conclude that the studied rocks of the Tireo Group are older than the Maastrichtian ⁴⁰Ar–³⁹Ar ages on plagioclase of the Siete Cabezas Formation. The studied dyke in the Pedro Brand section geochemically resembles the overlying Siete Cabezas and Pico Duarte basalts and could be a feeder dyke of those. However, a tectonic superposition of the Siete Cabezas cannot be excluded, since earlier ⁴⁰K–⁴⁰Ar basalt ages of this unit are Aptian–Albian and Cenomanian–Turonian. The Jarabacoa Block is considered as the most complete outcrop section of Pacific ocean crust overlain by a first (Aptian–Albian) phase of CLIP-type activity, followed by the development of a Cenomanian–Santonian intraoceanic arc, which is in turn overlain by a late Campanian–Maastrichtian CLIP-like phase.     

Ar/Ar dating, paleomagnetism, and tephrochemistry of Pliocene strata of the hominid-bearing Woranso-Mille area, west-central Afar Rift, Ethiopia

⁴⁰Ar/³⁹Ar dating of tuffs and mafic lavas, tephra geochemistry, and paleomagnetic reversal stratigraphy have been used to establish the chronostratigraphy of the Pliocene hominid-bearing fossiliferous succession at Woranso-Mille, a paleontological study area in the western part of the central Afar region of Ethiopia. The succession in the northwestern part of the study area ranges in ⁴⁰Ar/³⁹Ar age from 3.82-3.570 Ma, encompassed by paleomagnetic subchron C2Ar (4.187-3.596 Ma). One of the major tuff units, locally named the Kilaytoli tuff, is correlative on the basis of age and geochemistry to the Lokochot Tuff of the Turkana Basin. A hominid partial skeleton (KSD-VP-1) was found in strata whose precise stratigraphic position and age is still under investigation, but is believed to correspond to the later part of this interval. Woranso-Mille fills a significant gap in the fossil record of northeastern Africa at the time of the lower to middle Pliocene transition, when many extant species lineages of African fauna were established.     

Late Miocene hominoid from Niger

African Late Miocene hominoids are rare, having been reported from six localities in Kenya, Ethiopia and Chad ranging in age from 10.5 to 5.5 Ma. We here report the occurrence of a hominoid in Niger associated with a vertebrate fauna which indicates an age of between 11–5 Ma. The Niger fossil locality is 940 km north of the nearest known extant hominoids, 1000 km west of the nearest recorded fossil hominoid from Chad.     

Repeated freezing induces oxidative stress and reduces survival in the freeze-tolerant goldenrod gall fly,Eurosta solidaginis

Freeze tolerant insects must not only survive extracellular ice formation but also the generation of reactive oxygen species (ROS) during oxygen reperfusion upon thawing. Furthermore, diurnal fluctuations in temperature place temperate insects at risk of being exposed to multiple freeze–thaw cycles, yet few studies have examined metrics of survival and oxidative stress in freeze-tolerant insects subjected to successive freezing events. To address this, we assessed survival in larvae of the goldenrod gall fly Eurosta solidaginis, after being subjected to 0, 5, 10, 20, or 30 diurnally repeated cold exposures (RCE) to −18 °C or a single freeze to −18 °C for 20 days. In addition, we measured indicators of oxidative stress, levels of cryoprotectants, and total aqueous antioxidant capacity in animals exposed to the above treatments at 8, 32, or 80 h after their final thaw. Repeated freezing and thawing, rather than time spent frozen, reduced survival as only 30% of larvae subjected to 20 or 30 RCE successfully pupated, compared to those subjected to fewer RCE or a single 20 d freeze, of which 82% pupated. RCE had little effect on the concentration of the cryoprotectant glycerol (4.26 ± 0.66 μg glycerol·ng protein⁻¹ for all treatments and time points) or sorbitol (18.8 ± 2.9 μg sorbitol·mg protein⁻¹ for all treatments and time points); however, sorbitol concentrations were more than twofold higher than controls (16.3 ± 2.2 μg sorbitol·mg protein⁻¹) initially after a thaw in larvae subjected to a single extended freeze, but levels returned to values similar to controls at 80 h after thaw. Thawing likely produced ROS as total aqueous antioxidant capacities peaked at 1.8-fold higher than controls (14.7 ± 1.6 mmol trolox·ng protein⁻¹) in animals exposed to 5, 10, or 20 RCE. By contrast, aqueous antioxidant capacities were similar to controls in larvae subjected to 30 RCE or the single 20 d freeze regardless of time post final thaw, indicating these animals may have had an impaired ability to produce primary antioxidants. Larvae lacking an antioxidant response also had elevated levels of oxidized proteins, nearly twice that of controls (21.8 ± 3.2 mmol chloramine-T·mg protein⁻¹). Repeated freezing also lead to substantial oxidative damage to lipids that was independent of aqueous antioxidant capacity; peroxides were, on average, 5.6-fold higher in larvae subjected to 10, 20 or 30 RCE compared to controls (29.1 ± 7.3 mmol TMOP·μg protein⁻¹). These data suggest that oxidative stress due to repeated freeze–thaw cycles reduces the capacity of E. solidaginis larvae to survive freezing.     

Stature,body mass,and brain size: A two-million-year odyssey

Physical size has been critical in the evolutionary success of the genus Homo over the past 2.4 million-years. An acceleration in the expansion of savannah grasslands in Africa from 1.6 Ma to 1.2 Ma witnessed concomitant increases in physical stature (150–170 cm), weight (50–70 kg), and brain size (750–900 cm³). With the onset of 100,000 year Middle Pleistocene glacial cycles (“ice ages”) some 780,000 years ago, large-bodied Homo groups had reached modern size and had successfully dispersed from equatorial Africa, Central, and Southeast Asia to high-latitude localities in Atlantic Europe and North East Asia. While there is support for incursions of multiple Homo lineages to West Asia and Continental Europe at this time, data does not favour a persistence of Homo erectus beyond ～400,000 years ago in Africa, west and Central Asia, and Europe. Novel Middle Pleistocene Homo forms (780,000–400,000 years) may not have been substantially taller (150–170 cm) than earlier Homo (1.6 Ma–800,000 years), yet brain size exceeded 1000 cm³ and body mass approached 80 kg in some males. Later Pleistocene Homo (400,000–138,000 years) were ‘massive’ in their height (160–190 cm) and mass (70–90 kg) and consistently exceed recent humans. Relative brain size exceeds earlier Homo, yet is substantially lower than in final glacial H. sapiens and Homo neanderthalensis. A final leap in absolute and relative brain size in Homo (300,000–138,000 years) occurred independent of any observed increase in body mass and implies a different selective mediator to that operating on brain size increases observed in earlier Homo.     

The Zanclean palaeofloras around the Mont-Dore strato-volcano: A window into upper Neogene vegetation and environments in the Massif Central (Puy de Dome,France)

New Pliocene macrofloras and microfloras perfectly preserved from the Mont-Dore (Puy-de-Dôme, Massif central, France) have been reinvestigated. Samples come from different stratigraphical levels collected from three localities, Lac Chambon, La Gratade and Pont de Chocol. The ⁴⁰Ar/³⁹Ar radiometric datings bracketing the Chambon Lake and La Gratade fossil-bearing horizons give 4.46 ± 0.05 Ma and 3.94 ± 0.04 Ma, respectively, representative of the Zanclean Stage (= Brunssumian B and C), a period of the early Pliocene (5.32 to 3.6 Ma), much older than previously thought (i.e., Piacenzian). Pont de Chocol is considered to be close biostratigraphically, or even identical in age to La Gratade. Detailed morphological evaluation of leaf morphotypes completed with pollen analysis contributed to the better taxonomic knowledge of these palaeofloras. The overview focuses on floristic and phytostratigraphical characteristics of the defined stratigraphical units and their dating and correlation with previously defined palaeofloristic units of the Massif central. The study provides detailed identifications of plants representing 11 gymnosperms among which Pinaceae (pollen and winged seeds), Cupressaceae including “Taxodioid” pollen grains and Sciadopitaceae families (only pollen). Besides, different angiosperm trees and shrubs have been determined from both micro- and macro-remains. Fagaceae is the most diversified with several foliage of beech and deciduous oaks, while diversified Juglandaceae contribute mainly as abundant leaf remains of Carya, Pterocarya and Juglans; Ulmaceae with numerous leave of two Zelkova species, and also Ulmus. Various other deciduous dicotyledonous such as Alnus, Betula, Carpinus, Populus, Acer laetum and A. interrigenum are well documented. Leguminosae are recorded by a small number of leaflet imprints. Evergreen shrubs of Buxaceae (Buxus pliocenica) are scarce. All these taxa contribute to a rich biodiversity of these Pliocene assemblages. All three sites point towards riverine forest habitats dominated by hygrophilic diversified woody plants while in the surrounding plains and slopes the thermophilic elements were scarce and mesophilic taxa abundant as temperate elements. This vegetation can be compared with mixed mesophytic forests depicting a climate cooling during the two considered periods (ca. 4.46 and 3.95 Ma).     

U–Pb SHRIMP age for the Tuchengzi Formation,northern China,and its implications for biotic evolution during the Jurassic–Cretaceous transition

The Late Jurassic–Early Cretaceous Tuchengzi Formation is widespread in North China. Its clastic deposits indicate a tropical, dry, and hot paleoclimate, different from the subtropical, humid, and seasonal climate in the early Middle Jurassic. The sudden environmental change from the Middle to Late Jurassic resulted in a rapid disappearance of the Yanliao/Daohugou Biota, with more than 90% of the species of the Yanliao/Daohugou Biota dying out and replaced by the Early Cretaceous Jehol Biota. Eolian sandstones with large-scale cross-bedding occur within the uppermost part of the Tuchengzi Formation in North China. The sandstones are stratigraphically higher than the tuff previously dated as 139 Ma. We obtained two SHRIMP zircon U/Pb ages from the tuff beds. One sample was collected from the tuff in the basal Tuchengzi Formation in northern Hebei and the other from the tuff intercalated in the eolian cross-bedded sandstones in the uppermost Tuchengzi Formation in western Liaoning. Our results show that 154 Ma is the oldest age constraint for the Tuchengzi Formation and 137 Ma is the youngest age estimate of the formation, providing an age constraint for the transition from the Yanliao Biota to the Jehol Biota.     

High-precision Ar/Ar age for the Jehol Biota

Abundant fossils of the terrestrial Jehol Biota, including plants, insects, dinosaurs, birds, mammals and freshwater invertebrates, were discovered from the Yixian Formation and the overlying Jiufotang Formation in Inner Mongolia, Hebei Province and Liaoning Province, northeastern China. Because of the exceptional preservation of fossils, the Jehol Biota is one of the most important Mesozoic lagerstätten and is referred to as a “Mesozoic Pompeii”. The Jehol Biota has provided a rare opportunity to address questions about the origin of birds, the evolution of feathers and flight, the early diversification of angiosperms and the timing of placental mammal radiation. Six tuff samples and two basalt samples collected from the Tuchengzi, the Yixian and the Jiufotang formations near the classic outcrops in western Liaoning, NE China yielded high-precision ⁴⁰Ar/³⁹Ar ages. We obtain an age of 129.7 ± 0.5 Ma for a basaltic lava from the bottom of the Yixian Formation and an age of 122.1 ± 0.3 Ma for a tuff from the lowermost part of the overlying Jiufotang Formation. Our age results provide an age calibration of the whole Yixian Formation and show that the whole formation was deposited entirely within Early Cretaceous time over an interval of ~ 7 Ma.     

Purification,kinetic and thermodynamic characterization of soluble acid invertase from sugarcane (Saccharum officinarum L.)

We report for the first time kinetic and thermodynamic properties of soluble acid invertase (SAI) of sugarcane (Saccharum officinarum L.) salt sensitive local cultivar CP 77-400 (CP-77). The SAI was purified to apparent homogeneity on FPLC system. The crude enzyme was about 13 fold purified and recovery of SAI was 35%. The invertase was monomeric in nature and its native molecular mass on gel filtration and subunit mass on SDS-PAGE was 28 kDa. SAI was highly acidic having an optimum pH lower than 2. The acidic limb was missing. Proton transfer (donation and receiving) during catalysis was controlled by the basic limb having a pKa of 2.4. Carboxyl groups were involved in proton transfer during catalysis. The kinetic constants for sucrose hydrolysis by SAI were determined to be: k_m = 55 mg ml^?1, k_cat = 21 s^?1, k_cat/k_m = 0.38, while the thermodynamic parameters were: ΔH* = 52.6 kJ mol^?1, ΔG* = 71.2 kJ mol^?1, ΔS* = ?57 J mol^?1 K^?1, ΔG*_E–S = 10.8 kJ mol^?1 and ΔG*_E–T = 2.6 kJ mol^?1. The kinetics and thermodynamics of irreversible thermal denaturation at various temperatures 53–63 °C were also determined. The half -life of SAI at 53 and 63 °C was 112 and 10 min, respectively. At 55 °C, surprisingly the half -life increased to twice that at 53 °C. ΔG*, ΔH* and ΔS* of irreversible thermal stability of SAI at 55 °C were 107.7 kJ mol^?1, 276.04 kJ mol^?1 and 513 J mol^?1K^?1, respectively.     

New palaeoanthropological research in the Plio-Pleistocene Omo Group,Lower Omo Valley,SNNPR (Southern Nations,Nationalities and People Regions), Ethiopia

Through previous works in the early 1930s by C. Arambourg and in the 1960–1970s by the International Omo Research Expedition (IORE) initiated by F. C. Howell, the Omo Group deposits of the Lower Omo Valley provided decisive data on Plio-Pleistocene environmental change and hominid evolution in eastern Africa. Y. Coppens directed the IORE French component with Arambourg, then alone from 1970 to 1976. After 30-year hiatus, the Omo Group Research Expedition reinitiated field work on Shungura Formation deposits aged between 3 Ma and 2 Ma. In 2006 and 2007, renewed methods led to the collection of more than 600 vertebrate specimens with a particularly precise record of contextual data. These specimens include significant hominid remains dated to 2.5 Ma and slightly older. Changes in faunal distributions were also recorded. Additionally, the Shungura Formation archaeological record is reconsidered. These first results are indicative of future advances in the study of biodiversity evolution and its relationship with global and regional environmental changes.     

Pectinase and cellulase activity in the digestive system of the elm leaf beetle,Xanthogaleruca luteola Muller (Coleoptera: Chrysomelidae)

The elm leaf beetle, Xanthogaleruca luteola, is a serious pest of elm trees in urban areas. Partial biochemical characterization of pectinases and cellulases was conducted using the larval digestive system of the pest. Midgut extracts from larvae showed optimum activity for pectinase and cellulase against pectin and carboxymethyl cellulose, respectively, under acidic conditions (pH 6). Pectinases and cellulases were respectively more stable under acidic conditions (pH 4–7) and slightly acidic conditions (pH 5–7) than under highly acidic and alkaline conditions. However, the enzymes were more stable in slightly acidic conditions (pH 6) when incubation time was increased. Maximum activity for the pectinases and cellulases incubated at different temperatures was observed at 45 and 50 °C, respectively. Mg²⁺ remarkably increased pectinase activity, and cellulase activity increased significantly in the presence of Ca²⁺ and Mg²⁺. Sodium dodecyl sulfate significantly decreased pectinase and cellulase activity. The Michaelis–Menten constant (K_M) and the maximal reaction velocity (V_max) values for pectinase were 2 mg·mL^? 1 and 0.017 mmol·min^? 1·mg^? 1 protein toward pectin, respectively. Zymogram analyses revealed the presence of one and five bands of pectinase and cellulase activity, respectively, in the larval midgut extract.     

The silk cocoon of the silkworm,Bombyx mori: Macro structure and its influence on transmural diffusion of oxygen and water vapor

The cocoon of insect larvae is thought to help conserve water while affording mechanical protection. If the cocoon is a barrier to water loss, then it must also impose a barrier to inward oxygen diffusion. We tested this hypothesis in pupae of the silkworm, Bombyx mori. The rate of water loss and oxygen uptake (V?O₂) at 25 °C was measured in control pupae in their naturally spun cocoon and in exposed pupae experimentally removed from their cocoon. Additional measurements included the oxygen diffusion coefficient, DO₂, of the cocoon wall and dimensions and density of the cocoon fibers. Water loss (as % body mass loss) in both control and exposed pupae was ～ 1%^.day^? 1, and was not significantly different between populations. Similarly, V?O₂ was statistically identical in both control and exposed pupae, at 0.22 ± 0.01 and 0.21 ± 0.02 mL g^? 1 · h^? 1, respectively. The silk fiber diameter was significantly different in the outer fibers, 26 ± 1 µm, compared with 16 ± 1 µm for the inner fibers lining the cocoon. Inner fibers were also spun significantly more densely (20.8 ± 1.2 mm^? 1 transect) than outer fibers (8.3 ± 0.2). Mean DO₂ at 25 °C was 0.298 ± 0.002 cm² · s^? 1, approximately the same as unstirred air. These data indicate that the cocoon, while creating a tough barrier offering mechanical protection to the pupa, imposes no barrier to the diffusion of oxygen or water vapor.     

Holdfast aggregation in relation to morphology,age, attachment and drag for the kelp Ecklonia radiata

This study quantified the prevalence of holdfast aggregation (fusion of holdfasts) for the kelp Ecklonia radiata on subtidal reefs in southwestern Australia, and tested whether morphology, age, attachment or drag were different between kelps growing alone (solitary) or in aggregates. Wave-sheltered in-shore reefs consistently had fewer aggregates than wave-exposed off-shore reefs (15–20% versus 20–30%). On average, individual thalli from aggregates were longer (97.8 cm ± 2.2 S.E. versus 88.0 cm ± 2.0 S.E.) and had smaller holdfasts (32.9 g fresh wt ± 1.7 S.E. versus 45.8 g fresh wt ± 2.9 S.E.) than solitary thalli, whereas there were no significant differences in other morphological characters, including total biomass (805.1 g fresh wt ± 38.7 S.E. versus 831.5 g fresh wt ± 38.5 S.E.), stipe length (7.93 cm ± 0.47 S.E. versus 7.65 cm ± 0.40 S.E.) and stipe diameter (12.6 mm ± 0.23 S.E. versus 13.0 mm ± 0.25 S.E.). There was no difference in age between solitary (2.7–3.0 years) and aggregated (2.4–2.8 years) individuals. While the attachment force of whole aggregates (256.5 N ± 21.6 S.E.) was found to be significantly larger than attachment force for solitary individuals (162.5 N ± 12.9 S.E.), attachment areas were also larger for aggregates (90.7 cm² ± 5.40 S.E. versus 64.3 cm² ± 5.54 S.E.) and consequently there were no differences in attachment strength between aggregates (2.92 N cm⁻² ± 0.26 S.E.) and solitary thalli (2.71 N cm⁻² ± 0.22 S.E.). Aggregates had significantly smaller (17%) roughness factors (equivalent to drag coefficients) than solitary individuals and a negative relationship (r = −0.68) between roughness factors and biomass suggested that this was related to the scope for compaction and rearrangement of the thalli. Further, there was no relationship between roughness factors of solitary individuals and the aggregates they produced when combined, suggesting that roughness factors are not additive or multiplicative. The spatial distribution of holdfast aggregates, the morphological differences between solitary and aggregated individuals as well as their attachment and drag characteristics were all consistent with aggregation reducing the rate of fatal kelp dislodgment.     

Structures,magnetic properties,and XPS of cyanide-bridged NdIII/SmIII/GdIII–CrIII complexes

Synthesis, structural characterization, and spectroscopic and magnetic properties of three new cyano-bridged 3d–4f bimetallic complexes, Ln^III(DMF)₄(H₂O)₃Cr^III (CN)₆ · nH₂O (Ln = Nd, Sm, Gd), have been described. The Nd–Cr complex crystallizes in the monoclinic P2₁/n space group with the following unit cell parameters: a = 20.063(7) Å, b = 8.967(4) Å, c = 18.023(6) Å, b = 96.12(3)°, V = 3224(2) Å³, and Z = 4. The neodymium (III) ion, which adopts anti-prism eight-coordination environment, is linked to the [Cr^III(CN)₆]³⁻ moiety through a bridging cyanide ligand with Nd–N = 2.550(4) Å and Nd–N–C = 164.4(4)°. The variable-temperature (0.5 T at 2–300 K) and variable-field (0–5 T at 2 and 5 K) magnetic measurements reveal that the weak interaction of Gd–Cr complexes differs from that of Nd–Cr and Sm–Cr ones mainly because of the lack of orbital angular momentum. The XPS and diffuse reflectance electronic spectra were also measured to discuss charge transfer transitions concerning π-backdonation from the viewpoint of magneto-optical functions.     

Magnetostructural correlations and catecholase-like activities of μ-alkoxo-μ-carboxylato double bridged dinuclear and tetranuclear copper(II) complexes

Two μ-alkoxo-μ-carboxylato bridged dinuclear copper(II) complexes, [Cu₂(L¹)(μ-HCO₂)] (1) ((H₃L¹ = 1,3-bis(5-bromosalicylideneamino)-2-propanol)), [Cu₂(L²)(μ-HCO₂)] · dmf (2) (H₃L² = 1,3-bis(3,5-chlorosalicylideneamino-2-propanol)), and two μ-alkoxo-μ-dicarboxylato doubly bridged tetranuclear copper(II) complexes, [{Cu₂(L³)}₂(μ-O₂C–C(CH₃)₂–CO₂)] · 5H₂O · 3CH₃OH (3) ((H₃L³ = 1,3-bis(salicylid-deneamino)-2-propanol)) and [{Cu₂(L³)}₂(μ- O₂CCH₂–C₆H₄–CH₂CO₂)] · 2H₂O (4) have been prepared and characterized. The single crystal X-ray analysis shows that the structures of complexes 1 and 2 are dimeric with two adjacent copper(II) atoms bridged by μ-alkoxo-μ-carboxylato ligands with the Cu⋯Cu distances and Cu–O(alkoxo)–Cu angles are 3.511 Å and 132.85° for 1, 3.517 Å and 131.7° for 2, respectively. Complexes 3 and 4 consist of μ-alkoxo-μ-dicarboxylato doubly bridged tetranuclear Cu(II) complexes with mean Cu–Cu distances and Cu–O–Cu angles of 3.158 Å and 108.05° for 3 and 3.081 Å and 104.76° for 4, respectively. Magnetic measurements reveal that 1 and 2 are strong antiferromagnetically coupled with 2J = −156 and −152 cm⁻¹, respectively, while 3 and 4 exhibit ferromagnetic coupling with 2J = 86 and 155.2 cm⁻¹, respectively. The 2J values of 1–4 are linearly correlated to the Cu–O–Cu angles. Dependence of the pH at 25 °C on the reaction rate of oxidation of 3,4-di-tert-butylcatechol (3,5-dtbc) to the corresponding quinone catalyzed by 1–4 was studied. Complexes 1–4 exhibit high catecholase-like activity at pH 9.0 and 25 °C for oxidation of 3,5-di-tert-butylcatechol.     

New Bovid fossils from the Late Miocene Hasnot (Siwaliks,Pakistan)

The Siwalik Late Miocene bovids from the Hasnot deposits of Northern Pakistan are described here. The bovids are represented predominantly by boselaphines. The Hasnot outcrops range 7–5 Ma and correspond to the fauna of the Late Miocene–Early Pliocene of Eurasia and Africa. The associated fauna of Hasnot is suggestive a vast open land environment depicting sporadic dry and flood seasons, forcing a mosaic of ecotonal habitats with countless number of niches.     

Updated chronology for Middle to Late Miocene mammal sites of the Daroca area (Calatayud-Montalbán Basin,Spain)

The micromammal sequence of the Calatayud-Montalbán Basin in Northeast Central Spain is exceptional in terms of its faunal richness and dating accuracy. However, until now, several classical localities with ages close to the Middle to Late Miocene transition have never been directly tied to the Geomagnetic Polarity Time Scale. Here, we present an updated stratigraphic framework for the Daroca area, resulting in new and better-constrained ages for the micro- and macromammal-bearing sites of Toril, Carrilanga, and Pedregueras, and the macromammal site Los Andurriales. Toril is correlated to chron C5Ar.1r with an age of 12.7 Ma. Carrilanga and Los Andurriales are dated at 11.3 Ma, slightly older than the nearby sites Nombrevilla 9–10 (11.2 Ma). The fauna of these latter sites just pre-dates the entry of Hipparion, which is supposed to have its first appearance in Europe also at 11.2 Ma. The age of Pedregueras 2A is estimated at 10.6 Ma, constraining the local Zone H–I boundary and the first Iberian occurrence of Cricetulodon to 10.7 or 10.6 Ma. With an age of 10.4 Ma, the site of Pedregueras 2C is documenting the presence of very rare Murinae in Europe long (ca. half a million years) before their attainment of general dominance.