Article contents
Old World Tethyan occurrences of Lyrischapa (Gastropoda; Volutidae) and biogeographic implications
Published online by Cambridge University Press: 20 May 2016
Abstract
Lyrischapa Aldrich (1911), originally described from the Eocene of North America, is represented in the Old World Tethyan paleobiotic province by three species that previously have been referred to other genera: L. haimei (d'Archiac), from the late Paleocene or early Eocene upper Ranikot Formation of Pakistan; L. sismondai (d'Archiac), from the upper Ranikot Formation and the late Paleocene Hangu Shales of Pakistan; and L. soudanense (Douvillé), from the late Paleocene Kalambaina Formation in the Republic of Niger. A fourth unnamed species of Lyrischapa may be represented by an internal mold from the middle Eocene Khirtar Formation of Pakistan. Lyrischapa probably originated within the ancient Tethys seaway between Eurasia and the Gondwana continents of Africa and southern India because its oldest known occurrence (late Paleocene) and closest relatives (Indovoluta Eames, 1952; Gosavia Stoliczka, 1865, 1868; possibly also Diconomorpha Wenz, 1943) are in that region. It has no apparent ancestor among described American Paleogene or Cretaceous Volutidae. Because its large protoconch suggests that it lacked a teleplanic larval stage, the trans-Atlantic migration of Lyrischapa to the New World probably resulted from chance dispersal, either by rafting of egg masses attached to floating plant debris or by drift of floating egg capsules.
- Type
- Research Article
- Information
- Copyright
- Copyright © The Paleontological Society
References
- 3
- Cited by