Morphological disparity trends in Devonian trilobites from North Africa

Abstract The Devonian was a time of drastic environmental change that shaped the morphology trilobites. This study aims to investigate their morphological evolution and show influence some abiotic biotic factors (bathymetry, feeding habits visual abilities) on shape. A dataset compiled shape three structures (cephalon as whole, central part cephalon, pygidium) trilobites from North Africa, using geometric morphometric approach. Based empirical morphospaces, changes were quantified through stages. results reveal important variations in disparity glabella shape, facial suture location, pygidial length presence spines. In Lochkovian, low, subsequently increased Pragian with numerous innovations, reached maximum Emsian. If morphospace occupancy remained until Eifelian, severe loss occurred Givetian, known for changes. Disparity then low Late Devonian. shapes inherited Silurian persisted throughout whereas novelties most affected by losses. These persistent more versatile adaptation, helping those survive events. Similarly, trilobite orders survived events had wide spectrum better adapted withstand change.