Credit: Kalliopi Monoyios for the University of Chicago
A new study of Tiktaalik roseae (middle), a 375-million-year-old transitional fossil, highlights an intermediate step between the condition in fish like Eusthenopteron (bottom) and that in early limbed forms like Acanthostega (top). The new data are described in a paper by Jason Downs, Ted Daeschler, and Neil Shubin in the October 16th edition of Nature. (Illustration by Kalliopi Monoyios)