ALBERT

Description: DNA-based divergence time estimates suggested major changes in the composition of epiphyte lineages of liverworts during the Cretaceous; however, evidence from the fossil record is scarce. We present the first Cretaceous fossil of the predominantly epiphytic leafy liverwort genus Radula in ca. 100 Myr old Burmese amber. The fossil's exquisite preservation allows first insights into the morphology of early crown group representatives of Radula occurring in gymnosperm-dominated forests. Ancestral character state reconstruction aligns the fossil with the crown group of Radula subg. Odontoradula; however, corresponding divergence time estimates using the software BEAST lead to unrealistically old age estimates. Alternatively, assignment of the fossil to the stem of subg. Odontoradula results in a stem age estimate of Radula of 227.8 Ma (95 % highest posterior density (HPD): 165.7–306.7) and a crown group estimate of 176.3 Ma (135.1–227.4), in agreement with analyses employing standard substitution rates (stem age 235.6 Ma (142.9–368.5), crown group age 183.8 Ma (109.9–289.1)). The fossil likely belongs to the stem lineage of Radula subg. Odontoradula. The fossil's modern morphology suggests that switches from gymnosperm to angiosperm phorophytes occurred without changes in plant body plans in epiphytic liverworts. The fossil provides evidence for striking morphological homoplasy in time. Even conservative node assignments of the fossil support older rather than younger age estimates of the Radula crown group, involving origins for most extant subgenera by the end of the Cretaceous and diversification of their crown groups in the Cenozoic.

Description: Open-Access-Publikationsfonds 2016

Description: Concerning the Bulk Silicate Earth (BSE), the depleted mantle and the continental crust are thought to balance the budget of refractory and lithophile elements, resulting in complementary trace element patterns. However, the two high field strength elements (HFSE) Niob and Tantal appear to contradict this mass balance. All reservoirs of the silicate Earth exhibit subchondritic Nb/Ta ratios, possibly as a result of Nb depletion. The two HFSE Zr and Hf on the other hand seem not to be fractionated between the silicate reservoirs. They show more or less chondritic Zr/Hf ratios. In this study a series of orogenic eclogites from different localities was analyzed to determine their HFSE concentrations and to contribute to the question if eclogites could form a hidden reservoir to account for the mass imbalance of the BSE...

Description: thesis

Description: Preservation of liverworts in amber, a fossilized tree resin, is often exquisite. Twenty-three fossil species of liverworts have been described to date from Eocene (35-50 Ma) Baltic amber. In addition, two inclusions have been assigned to the extant species Ptilidium pulcherrimum (Ptilidiales or Porellales). However, the presence of the boreal P. pulcherrimum in the subtropical or warm-temperate Baltic amber forest challenges the phytogeographical interpretation of the Eocene flora. A re-investigation of one of the fossils believed to be P. pulcherrimum reveals that this specimen in fact represents the first fossil evidence of the genus Tetralophozia, and thus is re-described here as Tetralophozia groehnii sp. nov. A second fossil initially assigned to P. pulcherrimum is apparently lost, and can be reassessed only based on the original description and illustrations. This fossil is morphologically similar to the extant North Pacific endemic Ptilidium californicum, rather than P. pulcherrimum. Divergence time estimates based on chloroplast DNA sequences provide evidence of a Miocene origin of P. pulcherrimum, and thus also argue against the presence of this taxon in the Eocene. Ptilidium californicum originated 25-43 Ma ago. As a result, we cannot rule out that the Eocene fossil belongs to P. californicum. Alternatively, the fossil might represent a stem lineage element of Ptilidium or an early crown group species with morphological similarities to P. californicum.

Description: Open-Access Publikationsfonds 2015

Description: One of the most important issues in molecular dating studies concerns the incorporation of reliable fossil taxa into the phylogenies reconstructed from DNA sequence variation in extant taxa. Lichens are symbiotic associations between fungi and algae and/or cyanobacteria. Several lichen fossils have been used as minimum age constraints in recent studies concerning the diversification of the Ascomycota. Recent evolutionary studies of Lecanoromycetes, an almost exclusively lichen-forming class in the Ascomycota, have utilized the Eocene amber inclusion Alectoria succinic as a minimum age constraint. However, a re-investigation of the type material revealed that this inclusion in fact represents poorly preserved plant remains, most probably of a root. Consequently, this fossil cannot be used as evidence of the presence of the genus Alectoria (Parmeliaceae, Lecanorales) or any other lichens in the Paleogene. However, newly discovered inclusions from Paleogene Baltic and Bitterfeld amber verify that alectorioid morphologies in lichens were in existence by the Paleogene. The new fossils represent either a lineage within the alectorioid group or belong to the genus Oropogon.

Description: Open-Access-Publikationsfonds 2015

Description: Rapid eclogitisation of the Dabie–Sulu UHP terrane: Constraints from Lu–Hfgarnet geochronologyAlexander Schmidta,⁎, Stefan Weyera, Klaus Mezgerb, Erik E. Schererb, Yilin Xiaoc,d,Jochen Hoefsd, Gerhard P. BreyaaInstitut für Geowissenschaften, Facheinheit Mineralogie, JWG-Universität, Frankfurt, Altenhöferallee 1, 60438 Frankfurt, GermanybZentrallabor für Geochronologie, Institut für Mineralogie, Universität Münster, Corrensstr. 24, 48149 Münster, GermanycCAS Key Laboratory of Crust–Mantle Materials and Environments, School of Earth, and Space Sciences, University of Science and Technology of China, Hefei, 230026 ChinadGeowissenschaftliches Zentrum Göttingen, Universität Göttingen, Goldschmidtstr. 26 1-3, 37077 Göttingen, GermanyABSTRACTARTICLE INFOArticle history:Received 8 February 2008Received in revised form 18 June 2008Accepted 20 June 2008Available online 4 July 2008Editor: R.W. CarlsonKeywords:Lu–Hf geochronologySm–Nd geochronologyeclogiteultrahigh-pressureeclogitisationThe Qinling–Dabie–Sulu orogenic belt in eastern China is one of the largest ultrahigh-pressure (UHP)terranes worldwide. Mineral Sm–Nd- and zircon U–Pb dating has been widely used to reveal themetamorphic history of this collisional orogen. However, the exact timing of the UHP metamorphic event(s)remains controversial and ages ranging from 245 Ma to 220 Ma have been suggested. We present highprecision garnet–cpx Lu–Hf ages for six eclogites from the Dabie and Sulu areas. All ages fall in a narrowrange between 219.6 and 224.4 Ma. Five samples define a mean age of 223.0±0.9 Ma and one sample yields aslightly younger age of 219.6±1.4 Ma. This very tight age range is particularly remarkable considering thelarge regional distribution of sample localities (on the order of 100 km at the time of UHP metamorphism)and the wide variety of garnet and eclogite chemical compositions represented. Two samples yield Sm–Ndages that are indistinguishable from their Lu–Hf ages, albeit with larger uncertainties.The identical ages of eclogites from both the Dabie and the Sulu region emphasize their close geneticrelationship and similar metamorphic histories. The Lu–Hf results appear to date a punctuated event ofgarnet growth. Alternatively, the Lu–Hf garnet ages may represent the onset of rapid, contemporaneousuplift and subsequent cooling. However, trace element zoning of Lu and Hf is still preserved in garnetporphyroblasts, even in those with a homogeneous major element distribution. Thus, complete re-equilibration of the Lu–Hf system during peak-temperature conditions probably did not occur. The garnetforming event can be placed toward thefinal stage of the UHP metamorphism, in agreement with somepublished U–Pb zircon ages. A possible trigger for this short-lived and widespread mineral growth episodemay have been afluid that became available at that stage of the metamorphic history. Although HREE-depleted patterns of older zircon grains may indicate the presence of an older generation of garnet, completeeclogitisation may have been inhibited during the major part of the prograde P–T path due to dry conditionsduring most of the UHP metamorphism. The uniform Lu–Hf (and Sm–Nd) ages of all investigated Dabie andSulu eclogites suggest that garnet growth and thus possiblyfluid availability were limited to a short timeinterval over a remarkably large regional scale.

Description: Resin protects wounded trees from microbial infection, but also provides a suitable substrate for the growth of highly specialized fungi. Chaenothecopsis proliferatus is described growing on resin of Cunninghamia lanceolata from Hunan Province, China. The new fungus is compared with extant species and two new fossil specimens from Eocene Baltic and Oligocene Bitterfeld ambers. The Oligocene fossil had produced proliferating ascomata identical to those of the newly described species and to other extant species of the same lineage. This morphology may represent an adaptation to growing near active resin flows: the proliferating ascomata can effectively rejuvenate if partially overrun by fresh, sticky exudate. Inward growth of fungal hyphae into resin has only been documented from Cenozoic amber fossils suggesting comparatively late occupation of resin as substrate by fungi. Still, resinicolous Chaenothecopsis species were already well adapted to their special ecological niche by the Eocene, and the morphology of these fungi has since remained remarkably constant.

Description: The monospecific fern genus Cystodium (Cystodiaceae; Polypodiales) occurs exclusively in the tropical forests of the Malay Archipelago, the Admiralty Islands, the Louisiade Archipelago, and the Solomon Islands. Divergence time estimates suggest that the genus originated in the Mesozoic; however, fossil evidence to validate this suggestion has been lacking. Amber from Myanmar (Burmese amber) is an important source of new information on the diversity of vascular cryptogams in the Cretaceous. This paper describes the fossil taxon Cystodium sorbifolioides nov. sp. based on a fragment of a fertile leaf preserved in Burmese amber that represents the first fossil evidence of the family Cystodiaceae. Cystodium sorbifolioides is used to obtain a minimum age estimate for the Cystodiaceae and the closely related, monogeneric Lonchitidaceae and Lindsaeaceae. The fossil strengthens the hypothesis that the forest ecosystems of Malesia and Melanesia represent refugia for many tropical plant lineages that originated in the Cretaceous.

Description: Background: Lejeunea is a largely epiphytic, subcosmopolitan liverwort genus with a complex taxonomic history. Species circumscriptions and their relationships are subject to controversy; biogeographic history and diversification through time are largely unknown. Methodology and Results: We employed sequences of two chloroplast regions (trnL-trnF, rbcL) and the nuclear ribosomal ITS region of 332 accessions to explore the phylogeny of the Harpalejeunea-Lejeunea-Microlejeunea complex. Lejeunea forms a well-supported clade that splits into two main lineages corresponding to L. subg. Lejeunea and L. subg. Crossotolejeunea. Neotropical accessions dominate early diverging lineages of both main clades of Lejeunea. This pattern suggests an origin in the Neotropics followed by several colonizations from the Neotropics into the Paleotropics and vice versa. Most Afro- Madagascan clades are related to Asian clades. Several temperate Lejeunea radiations were detected. Eighty two of the 91 investigated Lejeunea species could be identified to species level. Of these 82 species, 54 were represented by multiple accessions (25 para- or polyphyletic, 29 monophyletic). Twenty nine of the 36 investigated species of L. subg. Lejeunea were monoicous and 7 dioicous. Within L. subg. Crossotolejeunea, 15 of the 46 investigated species were monoicous and 31 dioicous. Some dioicous as well as some monoicous species have disjunct ranges. Conclusions/Significance: We present the first global phylogeny of Lejeunea and the first example of a Neotropical origin of a Pantropical liverwort genus. Furthermore, we provide evidence for the Neotropics as a cradle of Lejeunea lineages and detect post-colonization radiations in Asia, Australasia, Afro-Madagascar and Europe. Dioicy/monoicy shifts are likely nonrandomly distributed. The presented phylogeny points to the need of integrative taxonomical studies to clarify many Lejeunea binomials. Most importantly, it provides a framework for future studies on the diversification of this lineage in space and time, especially in the context of sexual systems in Lejeuneaceae.

Description: Open-Access-Publikationsfonds 2013