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Abstract: Providing scientific explanations for natural phenomena is a fundamental aim of science; therefore, scientific explanation has been selected as one of the key practices in science education policy documents around the world. To further elaborate on existing educational frameworks of scientific explanation in K–12, we propose a learning progression of scientific explanation based on the Phenomenon‐Theory‐Data‐Reasoning (PTDR) framework. To examine the validation of the PTDR framework for scientific explanation and the learning progression based on it, we developed the Scientific Explanation Progression Assessment to investigate students’ performance (Grades 8–12 students, N = 4,554) on scientific explanations. A Rasch analysis and other statistical tests together indicated the validity of the PTDR framework for scientific explanation and the learning progression derived from this framework. We end with a discussion of the implications for future design of instruction and assessment. © 2017 Wiley Periodicals, Inc. J Res Sci Teach 55: 299–317, 2018 [ABSTRACT FROM AUTHOR]

Palynological analysis of 24 samples from four types of natural pollen traps (Lugu Lake bottom sediments, surface soil, bark samples, and moss cushions) in four sites at different altitudes from the Lugu Lake area, southwest China, has been undertaken to investigate pollen dispersal and deposition in a mountainous area and assist with the interpretation of fossil pollen analysis. Detailed comparisons between the palynological assemblage and the modern vegetation in the Lugu Lake region have been carried out. Preliminary interpretations of the correlation between pollen assemblage and vegetation at the different vertical vegetational zones can be recognized by the percentages of the main taxa, and most of the pollen taxa except Pinus are expected to be underrepresented. Exotic pollen grains can be transported over mountains more than 70 km away by wind. Upslope or downslope transport of pollen grains is crucial when reconstructing palaeoclimate in mountainous areas. We summarize the altitudinal distributions of modern woody plants whose pollen grains are present at three sites, and reveal that pollen grains are more readily carried uphill than downhill. These findings have important implications regarding the reconstruction of vegetation in mountainous regions and the interpretion of palaeoelevations. [ABSTRACT FROM AUTHOR]

A new conifer, Austrohamia acanthobractea, sp. nov., is described from the Jurassic Daohugou flora, Inner Mongolia Autonomous Region, China. The material consists of impressions represented by well-preserved leafy twigs and branches as well as ovulate cones. Leafy shoots with at least two orders of branching; ultimate branchlets alternate or sub-opposite with helically arranged leaves, decurrent at base with distal rounded tip; dorsiventrally flattened and univeined. Ovuliferous cones elliptical, less than 1 cm long, terminally borne on ultimate and penultimate branches, composed of helically arranged bracts with ovules disposed on their adaxial surfaces. The presence of similar, if not identical taxa, on both sides of the Pacific indicates the cosmopolitan distribution of primitive Cupressaceae between East Asia (Eurasia) and South America in the Pangaea. [ABSTRACT FROM AUTHOR]