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Evolutionary innovations are scattered throughout the tree of life, and have allowed the organisms that possess them to occupy novel adaptive zones. While the impacts of these innovations are well documented, much less is known about how these innovations arise in the first place. Patterns of covariation among traits across macroevolutionary time can offer insights into the generation of innovation. However, to date, there is no consensus on the role that trait covariation plays in this process. The evolution of cranial asymmetry in flatfishes (Pleuronectiformes) from within Carangaria was a rapid evolutionary innovation that preceded the colonization of benthic aquatic habitats by this clade, and resulted in one of the most bizarre body plans observed among extant vertebrates. Here, we use three-dimensional geometric morphometrics and a phylogenetic comparative toolkit to reconstruct the evolution of skull shape in carangarians, and quantify patterns of integration and modularity across the skull. We find that the evolution of asymmetry in flatfishes was a rapid process, resulting in the colonization of novel trait space, that was aided by strong integration that coordinated shape changes across the skull. Our findings suggest that integration plays a major role in the evolution of innovation by synchronizing responses to selective pressures across the organism. 

Abstract Decisions related to the production of lithic technology involve landscape-scale patterns of resource acquisition and transport that are not observable in assemblages from any one single site. In this study, we describe the stone artifacts from a discrete cluster of stone artifacts assigned to the Robberg technocomplex (22-16 ka) at the open-air locality of Uitspankraal 9 (UPK9), which is located near two major sources of toolstone in the Doring River catchment of Western Cape, South Africa.OSLdating of the underlying sediment unit provides aterminus post quemage of 27.5 ± 2.1 ka for the assemblage. Comparison of near-source artifact reduction atUPK9 with data from three rock shelter assemblages within the Doring watershed – Putslaagte 8 (PL8), Klipfonteinrand Rock Shelter (KFR), and Mertenhof Rock Shelter (MRS) – suggests that “gearing-up” with cores and blanks occurred along the river in anticipation of transport into the wider catchment area. The results reveal an integrated system of technological supply in which raw materials from different sources were acquired, reduced, and transported in different ways throughout the Doring River region.