Birth of the modern world: The Tertiary
The Osteoglossomorpha are a clade of primitive teleostean fishes with modern representatives in five biogeogeographic regions and fossil representatives on six continents. The centre of modern diversity is in Africa but the centre of fossil diversity is in E Asia. Key fossil taxa include: †Phareodus, †Joffrichthys, and †Ostariostoma in N America; †Lycoptera, †Paralycoptera, and †Huashia among others in E Asia; †Brychaetus and possibly †Thaumaturus in Europe; †Palaeonotopterus, †Singida, and †Chauliopareion in Africa; †Tavernichthys in India; and †Musperia in SE Asia.
Morphological phylogenies to date have disagreed on three main points: the relationships of †Lycoptera, of Pantodon, and of Notopterids and Mormyrids. Molecular phylogenies have similarly differed on the last two points. In this study a combined set of morphological data was generated from previous studies, including data from three recently described or redescribed taxa (the African †Singida and †Chauliopareion and the Chinese †Xixiaichthys) and maximum parsimony was used to generate a revised hypothesis of relationships. Our analysis recovered †Lycoptera, †Paralycoptera+ †Tanolepis, and †Xixiaichthys as stem-group osteoglossomorphs, †Singida as sister to Pantodon within Osteoglossidae, †Chauliopareion as a stem osteoglossid, †Ostariostoma as a stem osteoglossiform, and Notopteridae as sister to Mormyroidea and †Palaeonotopterus.
These results do not lend themselves to easy explanations of osteoglossomorph biogeography involving either dispersal from a centre of origin or vicariant division of a widely distributed ancestor. Recent suggestions of an ancient (Palaeozoic) origin for osteoglossomorphs are flawed. The evidence, instead, is consistent with an origin within the Mesozoic and the biogeographic explanation involves extensive extinction of clades from continents where they occurred in the past.