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The taxa of fossil Mollusca introduced by Hermann von Ihering

1996; Volume: 65; Issue: 3 Linguagem: Inglês

10.5962/p.226632

1943-6300

J. J. Parodiz,

Mollusks and Parasites Studies

Between 1896 and 1921 Hermann von Ihering described or named 352 taxa of fossil molluscs, from genera to subspecies, and many "varieties."Most of the taxa were from southern Argentina (Patagonia), but some were from Chile, Uruguay, and Brazil.When combined with other species described by Arnold E. Ortmann in 1902, these fossils constitute the basis of our knowledge of the Tertiary malacofauna of the region.Ihering's collection was acquired in 1920 by the Museo Argentine de Ciencias Naturales, and during the 1940s the author organized and catalogued the collection of more than 900 lots.This paper deals with Ihering's taxa and: 1) updates the taxonomic nomenclature for both genera and species; 2) indicates the correct type localities, many of which were uncertain at the time of description; 3) clarifies the stratigraphic position and geologic age of the deposits where the fossils were found; and 4) reconsiders some of Ihering's conclusions about the origin and distribution of the fauna in relation to climatic changes in the region during the Tertiary.Ihering's stratigraphy overestimated the age of deposits.There were no intercalations between the Cretaceous and Eocene; Paleocene species were believed to be Cretaceous; marine formations of the Miocene were dated as Eocene, and so on.He also subdivided formations in order to indicate that parts of them were older.The relative ages of strata were based on the proportion of extinct species versus surviving ones.When synonyms are recognized, and many infrasubspecific names eliminated as nontaxonomic variations, such estimation is untenable.Most of the mid-Tertiary species belong to genera that are represented in the Recent, and from zones warmer than the present climate in the Patagonian and Magellanian regions.Climatic changes were not local phenomena but the consequence of plate tectonics.Movements of plates not only changed their location, but also the orientation of the masses of land by clockwise rotation.The plates, formerly separated, united into a new continent, and rotation reversed to counterclockwise bringing them into their present position.Ihering considered them a single, unique mass, and named them Archhelenis (the northeastern part including Brasilia) and Archiplata (the southwestern part).Although land-bridge theories have been replaced by interpretations from plate tectonics, Ihering's nomenclature for the land masses is still useful and valid.New combinations are proposed for 32 species, and lectotypes are designated for Mactra indistincta Ihering (1897), Neoinoceramus ameghinoi Ihering (1902), Nucula tricesima Ihering (1897), Phacoides rocana Ihering (1907), Panopea thomasi Ihering (1914), and Potamides patagonensis Ihering (1897).Aturia (Sphenaturia) brueggeni Ihering, 1921, is selected as the type species of Sphenaturia Ihering, 1921 (Nautilidae). Parodiz--Ihering Mollusca 187Bajo de la Pava, Lowland in the vicinity of Puerto Deseado, with "Sierra Laziar strata" (Laziarense), Araucanean Formation, Pliocene.Bajo de las Flechas.Lowland near the lower section of the Rio Deseado, southeast of Cerro Moro, near the coast of Santa Cruz.Bajo de San Julian.See San Julian.Boqueron.Punta Boqueron.On Bahia Inutil, Magellan Strait, Tierra del Fuego