Solved: The case of the missing bird bones

A new study of fossils and embryos of birds has uncovered a key element in the evolution of bird skulls.

It has been known for some time that bird skulls have fewer elements than their non-avian dinosaur relatives. Birds do not have the postorbital and prefrontal skull bones, located behind and in front of the eye sockets, that non-avian dinosaurs had.

An illustration of a dinosaur skull highlighting the postorbital and prefrontal bones around the eye, compared to a bird skull without.
Artwork by Luis Pérez López [CC BY 4.0]

The new study, published Nov. 19 in the journal Nature Ecology & Evolution, shows that in birds, these bones fuse to other bones early during the embryonic phase.

The research was conducted at the University of Chile. The first author is Daniel Smith-Paredes, formerly of the University of Chile and now a graduate student in geology and geophysics at Yale. Co-authors of the study are from the University of Chile, the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, and the University of Zurich.

Smith-Paredes also has written a “Behind the Paper” post about the research.


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