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Actualistic studies of shell taphonomy in the marine subfossil record have found alteration in shell color to be a highly useful taphonomic indicator; however, the viability of shell discoloration for this purpose in the more profoundly altered material of the deep-time fossil record has not been explored. We investigated the relationship between the shell discoloration of Ordovician brachiopods and their taphonomic state to determine what information discoloration could provide about the conditions under which the shells were preserved. We examined 1033 specimens of Vinlandostrophia and Hebertella from type-Cincinnatian outcrops in southwestern Ohio and northern Kentucky, using a sampling design that allowed us to test the taphonomic significance of shell color in multiple stratigraphic units and across a wide geographic area. For each specimen, taphonomic data were recorded and multivariate analyses of the taphonomic attributes performed. Our results demonstrate that fossil shell discoloration is strongly related to overall taphonomic state, with darker colors associated with evidence of shell degradation. Further analyses suggest that shell color may be related to the incorporation of sulfide minerals and organic matter. Darker colors may reflect a higher residence time in the taphonomically active zone, in environments with slow sedimentation rates or multiple burial and exhumation cycles. Alternatively, darker colors may be indicative of environments with higher probabilities of discoloration, related to sediment and pore-water geochemistry. The strong correlation between shell discoloration and other indicators of taphonomic damage is evidence that discoloration reflects a taphonomic pathway from pristine to degraded shells, and may be a useful addition to taphofacies models.
More than two hundred subcircular to crescent-shaped depressions, often with radiating markings, were discovered on a 120 m2 bedding plane interpreted as base-of-slope carbonate deposits and belonging to the Lutetian–Bartonian Peschici Formation at San Lorenzo (Vieste, Gargano Promontory, Italy). The area was mapped using a high-resolution aerial camera (mounted on a kite) and a terrestrial laser scanner. The survey allowed detailed morphologic analysis and topographic mapping of the traces, in order to analyze the very regular distribution pattern. The ichnological study, combined with sedimentologic and stratigraphic analyses, identifies the depressions as fish feeding traces. Although the tracemaker cannot be definitely identified, the comparison with modern and fossil fish excavations suggests a higher affinity with bony fishes (e.g., sturgeons) than with rays. The trace fossils are here attributed to the ichnogenus Piscichnus and constitute the first discovery of this ichnotaxon in the middle Eocene of the Apulia Carbonate Platform and of Italy.
Exposures of the Chinle Formation in Petrified Forest National Park (PEFO), Arizona, preserve one of the most important Upper Triassic terrestrial faunal assemblages in the world: in it are found key elements in the global and regional correlation of continental deposits of Upper Triassic age. Rare components of the Chinle Formation faunal assemblage, including dinosaurs and small-bodied amniotes, appear to be mostly restricted to distinctive blue-colored horizons observed at only a few sites in PEFO. The blue sites represent paleosols formed in fine-grained, abandoned channel fills and contrast markedly with red-colored floodplain deposits and paleosols that characterize most fossil localities in the Chinle Formation. The distinctive blue color is interpreted as a weathered feature of hydromorphically reduced iron. The coincidence of rare taxa and sites bearing the blue-colored paleosols suggests that the stratigraphic positions of the sites and the rare taxa they contain appear to relate to fluvial sequence tracts in PEFO and may not reflect the true stratigraphic ranges of these taxa.
Pliocene papionin monkeys of Eurasia, such as Paradolichopithecus arvernensis, Procynocephalus subhimalayanus, and Macaca sp. indet. from Yushe, are large-bodied and interpreted as at least partly terrestrial. Terrestriality in primates has implications for the dietary items consumed. Dietary proclivities from the evaluation of pit and scratch counts under low-magnification (35×) were inferred to address whether the diets of these Eurasian papionins differ and whether they correspond to extant primates (Papio ursinus, n = 24, Pan troglodytes, n = 9, and Gorilla gorilla, n = 10), three Plio-Pleistocene southern African fossil papionins with known isotopic values (Parapapio broomi, n = 14; Papio robinsoni, n = 10; Theropithecus oswaldi danieli, n = 8), or a Pliocene bipedal hominin (Australopithecus africanus, n = 8). Macaca sp. indet. from Yushe most closely resembles Australopithecus africanus from South Africa, which is characterized by evidence of some hard-object feeding. Paradolichopithecus from Romania and to a lesser extent Procynocephalus from northern India also exhibit use-wear scars associated with the ingestion of grit possibly associated with the exploitation of corms and bulbs of CAM or C4 plants. The dental microwear signal of grassland foraging typical of such C4 grazers as Theropithecus oswaldi danieli does not characterize other Plio-Pleistocene papionins. Pliocene papionin diets converge with those of Australopithecus, suggesting that global climate cooling intensifying during the Pliocene may have led both early baboon-like monkeys and australopiths to increase consumption of nutrient-rich edible plant storage organs in these fragmented and partially open habitats of the temperate Old World.
Olenid trilobites are characteristic of low-oxygen environments in the early Paleozoic, and researchers have proposed that olenids may have harbored chemoautotrophic symbionts, allowing them to live in borderline sulfidic environments. Beds with soft-tissue preservation at the Beecher's Trilobite Bed site in the Frankfort Shale and the Martin Quarry in the Whetstone Gulf Formation (both Ordovician, New York State) are dominated by the olenid Triarthrus. A bed-by-bed analysis of the sedimentology, taphonomy, paleoecology, and ichnology demonstrates that the exceptionally preserved organisms did not undergo extensive transport, and that the intervals bearing Triarthrus accumulated predominantly in the lower part of the dysaerobic zone. These intervals contain a low-diversity benthic fauna occurring in relatively low abundance, and consisting primarily of small brachiopods and trilobites. The taphonomy, in particular localized pyritization, the associated fauna, and the distribution of Triarthrus elsewhere in the Taconic foreland basin demonstrate that the environments in which Triarthrus lived were not sulfidic, and that these trilobites were unlikely to have adopted a chemoautotrophic mode of life.
The timing of the development of the East Asian monsoon in the geologic past is critically important for paleoclimatological studies, yet few quantitative data are available. Based on palynomorphs from six formations, supplemented by leaf fossils from one of these formations in Fushun, northeastern China, we present a quantitative estimate of the evolution of precipitation in this area during the middle Paleocene–late Eocene. The results demonstrate that seasonal precipitation prevailed during the interval, suggesting that the monsoonal system had already developed by this time. Comparing Paleogene climatic results from different latitudes in eastern China, we conclude that the East Asian monsoon must have been significantly enhanced after the late middle Eocene (∼41–40 Ma), due to increased precipitation differentiation between wet and dry months as shown in the present study. The influence of both the uplift of the Da Hinggan Mountains in northeastern Asia on regional topography and the India-Asia collision globally may have contributed to early monsoon intensification by their influence on air mass movement and associated precipitation patterns in the monsoonal realm.
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