Mammalian skull heterochrony reveals modular evolution and a link between cranial development and brain size

• DOI: 10.1038/ncomms4625
• Publication Date: 2014-04-04T12:31:52Z
• Authors: Daisuke Koyabu; Ingmar Werneburg; Naoki Morimoto; Christoph P. E. Z...; Analia M. Forasiepi; Hideki Endo; Junpei Kimura; Satoshi D. Ohdachi; Nguyen Truong Son; Marcelo R. Sánche...
• Keywords: Heterochrony; Neurocranium; Endochondral ossification; Neoteny; Evolutionary developmental biology; Evolution of mammals; Endocast; Encephalization

The multiple skeletal components of the skull originate asynchronously and their developmental schedule varies across amniotes. Here we present embryonic ossification sequence 134 species, covering all major groups mammals close relatives. This comprehensive data set allows reconstruction heterochronic modular evolution condition last common ancestor mammals. We show that mode (dermal or endochondral) unites bones into integrated evolutionary modules changes imposes constraints on cranial heterochrony. However, some skull-roof bones, such as supraoccipital, exhibit degrees freedom in these constraints. Ossification timing neurocranium was considerably accelerated during origin Furthermore, association between supraoccipital brain size identified among argue heterochrony has occurred concert with encephalization but within a conserved organization. develop at different times Here, Koyabu et al.show bone constrains formation find an size.