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The genus name Glossopteris comes from the shape of these leaves: it means "tongue-shaped feather." These leaves are a typical fossil of Permian strata from continents of the southern hemisphere and were important for the development of the theory of continental drift. Specimen on display at the Chicago Field Museum of Natural History.
The dentition of this Permian gorgonopsian from South Africa shows features, such as elongated canines, interpreted as indicative of a carnivorous mode of life. The skull (about 20 cm in size) is on display at the Field Museum of Natural History, Chicago.
Current ripples are small asymmetric bedforms generated by movement of fine-grained sediment under unidirectional currents. The presence of climbing ripple lamination indicates rapid deposition from a sediment-laden flow. Upward transition from planar lamination to current ripple lamination is indicative of flow deceleration. Sequence of sedimentary structures (cf. Bouma sequence), grain size decrease, and cyclical repetition of bedding points to deposition from turbidity currents. Photo taken at the Varvito Park, Ito, Brazil, with exposures of Permian strata from the Itararé Group. Scale in cm.
When a fluid laden with sediment rapidly drops some of its load as it is flowing, a sedimentary structure named "climbing ripple lamination" can form. It is characterized by superimposed ripple crests (or ripple cross-sets) migrating in the direction of flow. Photo taken at the Varvito Park, Ito, Brazil, with exposures of Permian strata from the Itararé Group. Scale in cm.
Mesosaurus is an extinct, small-sized, Permian marine reptile. It is very important for the history of geology because its disjunct distribution (eastern South America and western Africa) was used to argue in favor of continental drift (an early version of plate tectonics). These impressions of a vertebral column and a few ribs were photographed at the Cruziero Quarry, where strata of the Irati Formation of the Paraná Basin of Brazil are exposed.
Dropstones are outsized rock clasts much larger than the average grain size of the surrounding sediment. Rather than being laterally transported by a flow, they show evidence (in the form of displacement of underlying lamination) of vertical sinking onto the substrate. The dropstone in the picture has a diameter of about 20 cm and is included in turbiditic deposits (Permian Itararé Group, Itu, Brazil).
Glaciers can levigate the bedrock over which they flow, smoothing irregularities into a glaciogenic landform called "roche moutonnée." This example from the rock record (Paranà Basin, Brazil) is interpreted as evidence for Permian glacial activity. The bedrock is granitic and it is overlain by patches of diamictite (reddish deposit). Several sedimentary processes can generate bedrock abrasion and a glaciogenic origin for features in the rock record should be presented with caution and based on a combination of multiple lines of evidence.
Diamicton is the term used to describe a poorly sorted, matrix-supported, clastic deposit with particles of a wide range of sizes. There are many processes that can generate diamicton, but this type of deposit is often associated with the action of glaciers. This photo shows a Permian example of lithified diamicton (diamictite), from the Paranà Basin, Brazil, found above a striated bedrock surface and traditionally interpreted as glaciogenic.
Cyclical bedding with alternating beds of black shale and dolomite. Permian Irati Fm., Brazil. A thickening-upwards of the beds is distinguishable. High-frequency cycliclity is one of the many patterns can be found in the sedimentary record. Vertical face is about 3 meters high.
Reconstruction of the skeleton of a dicynodont synapsid, from the Permian of South Africa, on display at the Field Museum of Natural History, Chicago. These large animals with big barrel-shaped trunks are thought to have been herbivores.