The role of taphonomy in cladistic analysis: A case study in Permian bivalves.

• Guimarães Simões, Marcello ^[1] ; Marques, Antonio Carlos ^[2] ; Cruz de Mello, Luiz Henrique ^[3] ; Pirani Ghilardi, Renato ^[3]
  1. [1] lnstituto de Biociencias-UNESP
  2. [2] FFCLRP-USP
  3. [3] Inst. Geociencias-USP

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• Localización: Spanish journal of palaeontology, ISSN 2255-0550, Vol. 15, Nº. 2, 2000 (Ejemplar dedicado a: REVISTA ESPAÑOLA DE PALEONTOLOGÍA), págs. 153-164
• Idioma: inglés
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• Resumen

  • The Megadesmidae (Bivalvia, Anomalodesmata) fossil record was examined in order to assess the role of taphonomy in cladistic analysis. Megadesmids are thick-shelled, infaunal, suspension-feeding bivalves. Our data indicate that their fossil record seems biased in favor of thick-shelled, shallow-burrowing genera and/or deep­burrowing forms. Consequently, there is a relation between the mode of life (shallow versus deep) and the resolution and quality of the fossil record. Deep-burrowers (Vacunella) are often preserved in life position offering a more accurate (temporal and spatial) fossil record, adequate for paleoecological inferences, while shallow-burrower shells (Plesiocyprinella), that are more prone to post-mortem transport and temporal mixing, offer a record with poor spatial and temporal resolution. The identification of homoplasy among infauna! bivalves constitutes a major challenge for their cladistic analysis. Within Megadesmidae intrinsic (bauplan limitations) and extrinsic (better preservational potential) factors favor the occurrence and preservation of homoplasy among the deep-burrowers. The implications are: a) clustering of deep-burrowing bivalves (Vacunella, Roxoa) due to parallel homoplasies, forming "adaptive", not necessarily "evolutive" taxa, and b) lower consistency indices in their cladistic analysis.