Fish gill fossils gnaw at ideas of jaw evolution
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2014/04/ticker_fishskull_free.jpg?fit=860%2C460&ssl=1)
This three-dimensional reconstruction shows the skull of the sharklike Ozarcus mapesae. The braincase appears in light gray, the jaw in red, the gill arches in yellow and the horseshoe-shaped hyoid bone in blue.
A. Pradel, AMNH