A well‐preserved ‘charadriiform‐like’ fossil bird from the Early Eocene Fur Formation of Denmark

Abstract: We describe a new, exceptionally well‐preserved fossil bird recovered from marine deposits of the Early Eocene Fur Formation of Denmark. Morsoravis sedilis gen. et sp. nov. is known by a single specimen that consists of a three‐dimensional skull, vertebral column, ribs, pelvis, and left hindlimb and associated parts of the right hindlimb. Comparisons based on overall morphology and particularly characters of the skull, vertebrae and pelvis indicate that the new specimen is morphologically similar to charadriiform birds (the shorebirds and relatives). This similarity is also expressed by a phylogenetic analysis of higher neornithine (modern birds) taxa, which supports a close relationship between the new fossil and modern charadriiforms. The morphology of the hindlimbs, in particular, shows that the new fossil corresponds to a new taxon that is distinguishable from modern charadriiform clades. One interesting aspect of its morphology is the presence of hindlimb specializations that are most commonly found among perching birds – these suggest that ecologically the new Danish fossil bird may have differed from the wading habits typical of most charadriiforms.     

Stem CO2 efflux in six co‐occurring tree species: underlying factors and ecological implications

Stem respiration plays a role in species coexistence and forest dynamics. Here we examined the intra‐ and inter‐specific variability of stem CO₂ efflux (E) in dominant and suppressed trees of six deciduous species in a mixed forest stand: Fagus sylvatica L., Quercus petraea [Matt.] Liebl, Quercus pyrenaica Willd., Prunus avium L., Sorbus aucuparia L. and Crataegus monogyna Jacq. We conducted measurements in late autumn. Within species, dominants had higher E per unit stem surface area (E_s) mainly because sapwood depth was higher than in suppressed trees. Across species, however, differences in E_s corresponded with differences in the proportion of living parenchyma in sapwood and concentration of non‐structural carbohydrates (NSC). Across species, E_s was strongly and NSC marginally positively related with an index of drought tolerance, suggesting that slow growth of drought‐tolerant trees is related to higher NSC concentration and E_s. We conclude that, during the leafless period, E is indicative of maintenance respiration and is related with some ecological characteristics of the species, such as drought resistance; that sapwood depth is the main factor explaining variability in E_s within species; and that the proportion of NSC in the sapwood is the main factor behind variability in E_s among species.     

Double chitin synthetase mutants from the corn smut fungus Ustilago maydis

Using genetic crosses between single chs mutants of Ustilago maydis inoculated into maize ( Zea mays ) seedlings, two classes of double mutants affected in genes coding for chitin synthetases were isolated: chs3 / chs4 , and chs4 / chs5 . Analysis of the mutants showed almost no change in their phenotype compared with wild-type strains. Growth rate, effect of stress conditions, dimorphic transition and mating were not affected. The only salient differences were increased sensitivity to osmotics at acid pH, and decrease in chitin synthetase activity, especially when measured with CO²⁺, and in chitin content. Most significant was a decrease in virulence, although this appeared to be due a factor unrelated to CHS genes. These data can be taken as further evidence that multigenic control of chitin synthetase in fungi operates as a safety mechanism to guarantee fungal viability in changing and hostile environmental conditions.     

Ancient DNA reveals traces of Iberian Neolithic and Bronze Age lineages in modern Iberian horses

Multiple geographical regions have been proposed for the domestication of Equus caballus . It has been suggested, based on zooarchaeological and genetic analyses that wild horses from the Iberian Peninsula were involved in the process, and the overrepresentation of mitochondrial D1 cluster in modern Iberian horses supports this suggestion. To test this hypothesis, we analysed mitochondrial DNA from 22 ancient Iberian horse remains belonging to the Neolithic, the Bronze Age and the Middle Ages, against previously published sequences. Only the medieval Iberian sequence appeared in the D1 group. Neolithic and Bronze Age sequences grouped in other clusters, one of which (Lusitano group C) is exclusively represented by modern horses of Iberian origin. Moreover, Bronze Age Iberian sequences displayed the lowest nucleotide diversity values when compared with modern horses, ancient wild horses and other ancient domesticates using nonparametric bootstrapping analyses. We conclude that the excessive clustering of Bronze Age horses in the Lusitano group C, the observed nucleotide diversity and the local continuity from wild Neolithic Iberian to modern Iberian horses, could be explained by the use of local wild mares during an early Iberian domestication or restocking event, whereas the D1 group probably was introduced into Iberia in later historical times.     

Concordant phylogeography and cryptic speciation in two Western Palaearctic oak gall parasitoid species complexes

Little is known about the evolutionary history of most complex multi‐trophic insect communities. Widespread species from different trophic levels might evolve in parallel, showing similar spatial patterns and either congruent temporal patterns (Contemporary Host‐tracking) or later divergence in higher trophic levels (Delayed Host‐tracking). Alternatively, host shifts by natural enemies among communities centred on different host resources could disrupt any common community phylogeographic pattern. We examined these alternative models using two Megastigmus parasitoid morphospecies associated with oak cynipid galls sampled throughout their Western Palaearctic distributions. Based on existing host cynipid data, a parallel evolution model predicts that eastern regions of the Western Palaearctic should contain ancestral populations with range expansions across Europe about 1.6 million years ago and deeper species‐level divergence at both 8–9 and 4–5 million years ago. Sequence data from mitochondrial cytochrome b and multiple nuclear genes showed similar phylogenetic patterns and revealed cryptic genetic species within both morphospecies, indicating greater diversity in these communities than previously thought. Phylogeographic divergence was apparent in most cryptic species between relatively stable, diverse, putatively ancestral populations in Asia Minor and the Middle East, and genetically depauperate, rapidly expanding populations in Europe, paralleling patterns in host gallwasp species. Mitochondrial and nuclear data also suggested that Europe may have been colonized multiple times from eastern source populations since the late Miocene. Temporal patterns of lineage divergence were congruent within and across trophic levels, supporting the Contemporary Host‐tracking Hypothesis for community evolution.     

Biological controls upon the physical taphonomy of exceptionally preserved salamanders from the Miocene of Rubielos de Mora,northeast Spain

McNamara, M.E., Orr, P.J., Manzocchi, T., Alcalá, L., Anadón, P. & Peñalver, E. 2011: Biological controls upon the physical taphonomy of exceptionally preserved salamanders from the Miocene of Rubielos de Mora, northeast Spain. Lethaia, Vol. 45, pp. 210–226. The middle Miocene Rubielos de Mora Konservat‐Lagerstätte of northeast Spain is hosted within profundal, finely laminated, lacustrine mudstones. The diverse biota includes abundant salamanders. Most individuals died during separate episodes and sank rapidly postmortem. Specimens are typically preserved in dorso‐ventral aspect, the most hydrodynamically stable orientation. The near‐cylindrical morphology of the body, however, allowed some carcasses to settle in or subsequently re‐orientate into, lateral orientations. Loss of skeletal elements (i.e. reduced completeness) reflects their location within the body and followed a distal to proximal trend. Two stages are identified: initial loss of a small number of phalanges, followed by loss of more proximal limb bones plus additional phalanges. Disarticulation is more complex: it occurred via several mechanisms (notably, abdominal rupture and re‐orientation of part of the body and limbs during decay) and shows no consistent pattern among specimens. The physical taphonomy of the salamanders is controlled predominantly by intrinsic biological factors, i.e. the geometry of the body and of individual skeletal elements, the orientation, inherent strength and location of specific joints and the extent to which soft tissues, particularly the skin, persist during decay. These biological factors probably control patterns of physical taphonomy of other fossil tetrapods with a similar skeletal configuration. □Articulation, completeness, Konservat‐Lagerstätten, orientation, quantitative taphonomy, salamanders.