Longitudinal expansion fitness of brachiopod genera controlled by the Wilson cycle

Abstract

The brachiopods constitute one of the major components of the marine metazoan fossil record. On the other hand their apparent decline in importance in forming benthic communities through the Phanerozoic is one of the most striking macroevolutionary and macroecological patterns. Here we analyzed changes in average latitudinal and longitudinal ranges – indices for success of spatial expansion of brachiopod genera – during post-Cambrian Phanerozoic, and compared their fluctuation and scaling behaviour to the changes in continental fragmentation. The results revealed that latitudinal ranges on the longest time scales were highly constrained, while longitudinal ranges shown persistent decrease. The scale-by-scale correlation analysis of Haar fluctuations revealed that there is positive functional dependence of longitudinal ranges at the longest time scales with continental fragmentation. Moreover the ratio of average longitudinal to latitudinal ranges was positively correlated to the continental fragmentation at all time scales. The long term minima in longitudinal ranges and the least elongated shapes in E-W direction of geographic ranges were found during the maximal amalgamation of the Pangaea during Triassic and Jurassic. The failure for brachiopods to regain the dominance in marine biosphere after P-Tr extinction should be related to the tectonic restrictions on their longitudinal ranges during the maximally supercontinental conditions of the planet. Therefore, the pattern exemplified by brachiopods shows that the spatial expansion success (fitness) of a major clade at an eon time scale could be a direct consequence of the multi-scale tectonic reconfigurations.