科研之友
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摘要
A regional survey of the caves of the state of Rio Grande do Sul, Brazil, listed hundreds of caves with varied origins. Among these, we identified two large caves with special characteristics, one located in the city of Santa Cruz do Sul and the other in the municipality of Vale Real. Both evolve in an approximately horizontal plane, extend tens of meters into the interior of the respective elevations, and do not show any signs of present or past underground drainage. Concave surfaces on the walls stand out in their morphologies, which suggest that the caves originally constituted a system of ellipsoidal chambers, each chamber with original height of approximately 1.5 m and diameter between 3.5 and 7 m. The individual chambers were connected by relatively short tunnels.These chambers are best preserved in the cave of Santa Cruz do Sul; the cave of Vale Real appears to have been much disfigured, both because of inorganic processes and anthropogenic action. The general characteristics of these two caves enable us to propose that they originated from the activity of digging ground sloths of the South American Megafauna. Their dimensions suggest that they were excavated and inhabited not by individual animals, but by groups of sloths. The original polished walls suggest that the caves were used for extended periods, possibly in the order of centuries. Their morphology is so different from other tunnel systems that were excavated by the Megafauna and found in southern Brazil, that we suggest that this morphology of chamber systems is associated with a specific species of ground sloth, whose identification will be very difficult.
- 出版日期2015-8
