page_title: Bajo de Véliz Formation
section_title: Discovery
hierarchical_section_title: Bajo de Véliz Formation / Discovery
caption_attribution_description: English: Distribution of four Permian and Triassic fossil groups used as biogeographic evidence for continental drift, and land bridging, and forms the basis of the popular schematic that is often attributed to Wegener.
context_page_description: The Bajo de Véliz Formation is stratigraphic formation of the Paleozoic located in the Paganzo Basin, Argentina. This formation lies in the northwestern sector of San Luis, about 25 km west of Santa Rosa de Conlara. Containing a slice of the Carboniferous-Permian transition, it is one of the key upper Paleozoic successions characterizing that era in westernmost Gondwana, which South America was a part of in the Paleozoic.
  It consists of Cautana, Pallero, and Lomas units. Based on the paleoflora found in the middle upper Pallero unit, it was suggested to be of earliest Cisuralian age of the early Permian, though there is still ambiguity as insects associated with that layer have been assigned to the late Pennsylvanian of the Carboniferous.
  It is one of the key windows into the fossil life of the Gzhelian to Asselian, and is known as the formation where the thought-to-be-spider Megarachne, actually a giant eurypterid, was discovered.
context_section_description: The Bajo de Véliz Formation was deﬁned by Flores in 1969, and then studied in greater detail by Hünicken and Pensa, in 1972. Hünicken and Pensa estimated a geological column of 168 meters in thickness.
  For several years the area was exploited in order to extract slab stone. In the course of this activity, an extraordinary fossil was found due to its conservation status and its size, which was handed over to the Argentine paleontologist Mario Hünicken who in 1980 described it as Megarachne servinei. Research carried out subsequently produced remarkable findings in successive strata, several of which present evidence of insect fossils, bryophytes and paleozoic flora. It is estimated that this formation is 286 million years old. 
  The stratum is part of a protected natural park, Bajo de Véliz Provincial Park. The main geographical feature is a 12 km long depression. The Cautana Creek runs along most of its length. The stratigraphic succession of Bajo de Véliz is exposed by rocky outcrops such as a rock wall revealing the Pallero unit, and there are escarpments because the formation is cut and carved out of older crust.
caption: A map of Pangaea, with Gondwana in the southwest. Glossopteris is preserved in the Bajo de Veliz Formation.[3]
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