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Corpus Systématique Animale

Titre du document

The late Cenozoic ampullariidae (mollusca, gastropoda) of the Albertine Rift Valley (Uganda-Zaire)

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Springer (journals)
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Type de document
Mots-clés d'auteur
  • Africa
  • autapomorphic characters
  • convergence
  • evolution
  • freshwaters snails
  • Lanistes
  • Mollusca
  • palaeolimnology
  • palaeontology
  • Pila
  • predator/prey coevolution
  • riftlakes
  • taxonomy
  • punctuated equilibrium
Nom du fichier dans la ressource
  • Dirk van Damme 1
  • Martin Pickford 2
  • 1) Laboratory of Palaeontology, University of Ghent, Krijgslaan 281/58, B-9000, Gent, Belgium
  • 2) Chaire de Paléoanthropologie et de Préhistoire du College de France, 11, Place Marcellin Berthelot, F-75005, Paris, France

The Albertine Rift Valley (Uganda-Zaire) contains vast sedimentary sequences of late Cenozoic age. They were deposited in an extensive riftlake, Lake Obweruka, which existed from c. 8 Ma to 2.5 Ma and was comparable in size and depth to the present L. Tanganyika. Many freshwater molluscs that occur in these lacustrine deposits are characterised by their aberrant shell morphology, their extreme ornamentation and general form, making them resemble marine species. This convergence, rare in freshwater molluscs, is called thalassoidism and extreme ornamentation in marine as well as in freshwater molluscs is considered to be the result of a gradual process of prey/predator coevolution. In the present paper the Albertine representants of the ampullariid genera Lanistes and Pila, most of which are new to science, are taxonomically described and their phylogenetic relation, based upon apomorphic characters, is given. In addition the evolutionary history of these freshwater snails in the basin has been reconstructed. In the pre-riftlake environment 3 species of Lanistes occurred, with no special shell adaptations against predation. After the formation of a riftlake, 2 of these, colonising the new lacustrine ecospace, changed morphologically and radiated. The 3 derived lines show minor adaptations against predation. After the extinction of the dominant Lanistes species group around 6 Ma, the sole surviving lacustrine Lanistes suddenly radiates, the ancestral line persisting next to the 3 new daughter lines. This second morphological shift is spectacular as it produces shells with distinct thalassoid features. All the Lanistes species of L. Obweruka became extinct during a cataclysmic event around 4.5 Ma. Populations of the genus Pila colonised lacustrine habitats after this event, the derived form also showing striking thalassoid characters. There is no doubt that the intense morphological change occurred during a brief period, geologically speaking. The degree of morphological change in molluscs appears hence not to be linked with time. After the sudden radiation all lineages remain morphologically stable until they became extinct c. 1 Ma later. This pattern corresponds to the punctuated equilibrium model. Other groups (viviparids, thiarids) show more gradual changes.

Catégories Science-Metrix
  • 1 - natural sciences
  • 2 - biology
  • 3 - marine biology & hydrobiology
Catégories INIST
  • 1 - sciences appliquees, technologies et medecines
  • 2 - sciences biologiques et medicales
  • 3 - sciences biologiques fondamentales et appliquees. psychologie
  • 4 - vecteurs d'importance medicale, nuisances, depredateurs des denrees et materiaux: surveillance des populations et lutte
Catégories Scopus
  • 1 - Life Sciences ; 2 - Agricultural and Biological Sciences ; 3 - Aquatic Science
Catégories WoS
  • 1 - science ; 2 - marine & freshwater biology
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  • Mollusques
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