Interspecific diversity in the neuronal composition of the mammalian cortex arises from heterochrony in neurogenesis. - Yamauchi YY; Sheu XD; Tarfder R; Kumamoto T; Hatakeyama J; Sato H; Rouillard P; Bilgic M; Deguchi S; Nakamura T; Kishi Y; Emoto K; et al. (The EMBO journal, 2026)