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Shell fragments are important components of many Recent and fossil marine benthic ecosystems and can provide crucial information on past and present environmental conditions. Interpreting such fragments requires integrated knowledge in various fields and the information potential is therefore rarely optimally utilized. This paper uses the definition of a fragment as being a piece of shell having less than 90% of its original form. It then outlines the potential characteristics, pathways, and fates that shells and their fragments can have.Fragmentation is a key factor shaping the shelly part of death assemblages, but it is difficult to interpret because it can be broadly caused by ecological, biostratinomic or diagenetic processes and also depends on shell strength. Strength, in turn, reflects multifunctionality during ontogeny and depends on a complex set of skeletal and taphonomic factors. Therefore, no particular shell parameter clearly determines strength, but thickness, microstructure type and degree of organic matrix have the strongest influence on pre- and post-mortality strength. Size measurements are usually less important for shell strength than thickness, although ecologically complex size refuges from predation do exist. Similarly, shell shape, sculptural features and specific aperture types (in gastropods) provide various defence strategies rather than increasing strength per se.Key ecological factors of fragmentation include predation due to crushing, peeling, along with mistaken predation, self-inflicted damage during predation and burrowing, and more physical aspects such as impacts by stones. Modern studies must consider damage by benthic commercial fisheries or dredging by scientific vessels. Key biostratinomic factors include transport-induced abrasion (littoral zone of surf-washed beaches), bioerosion and dissolution (mainly sublittoral environments). Diagenetically, fragmentation during compaction mainly occurs when shells are in direct contact with one another or with coarser grains; taphonomic features (e.g., drillholes) have only minor influence.A key step in interpreting fragments is to categorize breakage into repaired versus unrepaired, diagnostic versus non-diagnostic, and severe versus localized damage. Quantifying the above categories can then provide useful information on breakage patterns and underlying processes. Understanding the many characteristics of shells and their fragments is a significant interpretive tool in maximizing the information gain in palaeoecological and taphofacies analyses. [Copyright &y& Elsevier]

With a depositional history spanning the early Aptian to early Albian (~19 mys), the Lower Cretaceous Xinminpu Group in Jiuquan, NW China provides detailed record of an inland ecosystem responding to global climatic and environmental changes. The Xinminpu Group exhibits the most typical elements of the Jehol Biota found outside NE China, a highly diverse avifauna and a mid-Cretaceous angiosperm flora. The absence of a comprehensive stratigraphical framework for this area however limits the degree to which the unit can be interpreted relative to coeval sections and the geological records in genera. Recent fossil discoveries and radio-isotopic age data can provide a more detailed biostratigraphical and chronostratigraphical framework for Lower Cretaceous units around Jiuquan. The data complied here indicate that the Chijinpu Formation correlates with the middle-upper Yixian and lower Jiufotang formations of NE China making it early Aptian in age, and the Xiagou Formation correlates with the upper Jiufotang and Shahai formations making it late early Aptian-early Albian in age. This research further reports a novel zircon U-Pb age constraint of 112.4 ± 0.3 Ma for a basalt sample from the lowermost Zhonggou Formation, which is supported to be correlated with the Fuxin Formation of early Albian age. The Chijinpu Formation contains typical elements of the Jehol Biota, i.e. the Eosestheria - Lycoptera - Ephemeropsis trisetalis assemblage, confirming the interpretation that the Jehol Biota had reached Jiuquan during its second evolutionary stage. The Xiagou Formation contains the amphibious avifauna appearing just above OAE1a, indicating a close link between the early Ornithuromorpha evolution and early Aptian global climate changes. The Zhonggou Formation in Jiuquan records the first appearance of an angiosperm flora above OAE1b. Depositional indicators suggest a humid climate with a gradual shift to arid conditions during this time. This review paper laid foundation for the systematic study of the well-preserved Early Cretaceous ecosystem in Jiuquan, allowing to understand correlations between inland and marine environments as recorded in sediments from this critical period. • We establish the stratigraphy and time scales for the Lower Cretaceous in Jiuquan. • We review how a Cretaceous inland ecosystem responded to global climatic change. • This study summarizes the detailed fossil records for the Jehol Biota in NW China. • Robust age for the less-studied outcrops allows to test the Jehol radiations. • A close link existed between early Ornithuromorpha evolution and OAE1a. [ABSTRACT FROM AUTHOR]