Biogeografía histórica de las clavatoráceas (carófitas fósiles). Estado actual del conocimiento

Abstract

The historical biogeography of Clavatoraceae (Mesozoic charophytes) is analysed on the basis of phylogenetic analysis and the data available about its distribution. The most plesiomorphic and oldest representatives of this family occurred during the Late Jurassic and were scattered in a few localities of the central par t of the peri-Tethyan domain (Western Europe and Northern Africa) and the margins of the North American seaway (Morrison Fm). In the Neocomian, clavatoraceans were abundant in the peri-Tethyan region and expanded eastwards to reach the Chinese basins in the Valanginian or Hauterivian. During Barremian and Aptian the clavatoraceans reached their maximum diversity in the peri-Tethyan region and their maximum paleogeographic extension worldwide. Thus, in the Early Barremian the family is recorded from southern America, where it migrated probably through Northwest Africa. Also in the Aptian, it was also present in North America. Only a few species were able to reach a cosmopolitan distribution during Barremian and Aptian. This is the case of the Atopochara trivolvis lineage. Some characters, such as the conjoint disposition of gametangia are extremely significant to understand the worldwide migration of this species. In the Albian the decline of the clavatoraceans began. After a significant gap in its fossil record, the latemost Cretaceous clavatoraceans are relict forms (Atopochara trivolvis var. ulanensis) or belong to newly evolved species of poorly known phylogenetic affinity (traditional Septorella). The history of Clavatoraceae largely agrees with the asymmetric biogeographic model of López-Martínez (2003)