The mid-Miocene Zhangpu biota reveals an outstandingly rich rainforest biome in East Asia

During the Mid-Miocene Climatic Optimum [MMCO, ~14 to 17 million years (Ma) ago], global temperatures were similar to predicted temperatures for the coming century. Limited megathermal paleoclimatic and fossil data are known from this period, despite its potential as an analog for future climate conditions. Here, we report a rich middle Miocene rainforest biome, the Zhangpu biota (~14.7 Ma ago), based on material preserved in amber and associated sedimentary rocks from southeastern China. The record shows that the mid-Miocene rainforest reached at least 24.2°N and was more widespread than previously estimated. Our results not only highlight the role of tropical rainforests acting as evolutionary museums for biodiversity at the generic level but also suggest that the MMCO probably strongly shaped the East Asian biota via the northern expansion of the megathermal rainforest biome. The Zhangpu biota provides an ideal snapshot for biodiversity redistribution during global warming.

Synchrotron X-ray imaging of a dichasium cupule of Castanopsis from Eocene Baltic amber

PREMISE OF THE STUDY

The Eocene Baltic amber deposit represents the largest accumulation of fossil resin worldwide, and hundreds of thousands of entrapped arthropods have been recovered. Although Baltic amber preserves delicate plant structures in high fidelity, angiosperms of the "Baltic amber forest" remain poorly studied. We describe a pistillate partial inflorescence of Castanopsis (Fagaceae), expanding the knowledge of Fagaceae diversity from Baltic amber.

METHODS

The amber specimen was investigated using light microscopy and synchrotron-radiation-based X-ray micro-computed tomography (SRμCT).

KEY RESULTS

The partial inflorescence is a cymule, consisting of an involucre of scales that surround all four pistillate flowers, indicating a dichasium cupule. Subtending bracts are basally covered with peltate trichomes. Flowers possess an urecolate perianth of six nearly free lobes, 12 staminodia hidden by the perianth, and a tri-locular ovary that is convex-triangular in cross section. The exceptional three-dimensional preservation suggests that the fossil belongs to the extant East Asian genus Castanopsis. The amber inclusion represents the first record of Castanopsis from Baltic amber and the first pistillate inflorescence of Fagaceae from Eurasia.

CONCLUSIONS

The partial female inflorescence reported here provides an important addition to acorns of Castanopsis described from middle Eocene strata of Europe. Furthermore, the intercontinental distribution of Castanopsis in the Eocene is confirmed. The amber fossil also broadens the picture of the Baltic amber source area, indicating oligotrophic, sandy, bog-like habitats. Finally, this study underscores the great benefit of SRμCT as a powerful tool to investigate plant inclusions from amber in a nondestructive way.

Diverse early dwarf mistletoes (Arceuthobium), ecological keystones of the Eocene Baltic amber biota

PREMISE OF THE STUDY

Extant dwarf mistletoes (Arceuthobium M. Bieb., Viscaceae) are hemiparasites with complex roles in nature. They are one of the most severe pests in northern hemisphere conifer forests, but they also enhance the structural complexity and species diversity of the forests. Here, we describe the first pre-Miocene macrofossils of dwarf mistletoes. The fossils from Eocene Baltic amber provide new insights into the morphological evolution of the Arceuthobium lineage and its paleobiogeography.

METHODS

The amber inclusions were investigated with light microscopy and compared with extant Viscaceae and to historic descriptions of lost Baltic amber fossils with affinities to Viscaceae.

KEY RESULTS

Six fossil species of the Arceuthobium lineage, A. johnianum comb. nov., A. mengeanum comb. nov., A. conwentzii sp. nov., A. groehnii sp. nov., A. viscoides comb. nov. and A. obovatum sp. nov., occurred in source forests of Baltic amber, representing the oldest macrofossil evidence of dwarf mistletoes. They share morphological features of their bracts, internodes, fruits, and stomata with extant Arceuthobium. Differences from extant dwarf mistletoes, such as the perianth merosity, the nonfusion of squamate bracts and presence of oblanceolate expanded leaves, indicate their affiliation to an ancient lineage of the genus.

CONCLUSIONS

The occurrence of six species of dwarf mistletoes in a single amber deposit suggests Arceuthobium was a keystone taxon of the Baltic amber source area. As in extant conifer forests, they probably influenced the structural complexity of the forest, not only leading to more open woodlands but also increasing species diversity, at least at a microhabitat scale.

Species-level determination of closely related araucarian resins using FTIR spectroscopy and its implications for the provenance of New Zealand amber

Some higher plants, both angiosperms and gymnosperms, can produce resins and some of these resins can polymerize and fossilize to form ambers. Various physical and chemical techniques have been used to identify and profile different plant resins and have then been applied to fossilized resins (ambers), to try to detect their parent plant affinities and understand the process of polymerization, with varying levels of success. Here we focus on resins produced from today's most resinous conifer family, the Araucariaceae, which are thought to be the parent plants of some of the Southern Hemisphere's fossil resin deposits. Fourier transform infrared (FTIR) spectra of the resins of closely related Araucariaceae species were examined to test whether they could be distinguished at genus and species level and whether the results could then be used to infer the parent plant of a New Zealand amber. The resin FTIR spectra are distinguishable from each other, and the three Araucaria species sampled produced similar FTIR spectra, to which Wollemia resin is most similar. Interspecific variability of the FTIR spectra is greatest in the three Agathis species tested. The New Zealand amber sample is similar in key shared features with the resin samples, but it does differ from the extant resin samples in key distinguishing features, nonetheless it is most similar to the resin of Agathis australis in this dataset. However on comparison with previously published FTIR spectra of similar aged amber and older (Eocene) resinites both found in coals from New Zealand and fresh Agathis australis resin, our amber has some features that imply a relatively immature resin, which was not expected from an amber of the Miocene age.

Absolute cardiovascular disease risk and shared decision making in primary care: a randomized controlled trial

PURPOSE

We wanted to determine the effect of promoting the effective communication of absolute cardiovascular disease (CVD) risk and shared decision making through disseminating a simple decision aid for use in family practice consultations.

METHODS

The study was based on a pragmatic, cluster randomized controlled trial (phase III) with continuing medical education (CME) groups of family physicians as the unit of randomization. In the intervention arm, 44 physicians (7 CME groups) consecutively recruited 550 patients in whom cholesterol levels were measured. Forty-seven physicians in the control arm (7 CME groups) similarly included 582 patients. Four hundred sixty patients (83.6%) of the intervention arm and 466 patients (80.1%) of the control arm were seen at follow-up. Physicians attended 2 interactive CME sessions and received a booklet, a paper-based risk calculator, and individual summary sheets for each patient. Control physicians attended 1 CME-session on an alternative topic. Main outcome measures were patient satisfaction and participation after the index consultation, change in CVD risk status, and decisional regret at 6 months' follow-up.

RESULTS

Intervention patients were significantly more satisfied with process and result (Patient Participation Scale, difference 0.80, P<.001). Decisional regret was significantly lower at follow-up (difference 3.39, P = .02). CVD risk decreased in both groups without a significant difference between study arms.

CONCLUSION

A simple transactional decision aid based on calculating absolute individual CVD risk and promoting shared decision making in CVD prevention can be disseminated through CME groups and may lead to higher patient satisfaction and involvement and less decisional regret, without negatively affecting global CVD risk.