Consider the row of pits visible in the "upper lip" area (and to some extent, the "lower lip" too) of this T-Rex skull at the Palais de la Découverte, Paris (picture from Wikipedia):

Tyrannosaurus rex, Palais de la Découverte, Paris

I noticed similar pits in a Deinonychus skull a few weeks ago when I visited the American Museum of Natural History in New York:

Deinonychus, American Museum of Natural History, New York

What are they?


1 Answer 1


They are called Nutrient Foramen which are innervation of blood vessels and nerves, you see the same thing in reptile and bird skulls (mammals tent to pack it all into one or two large openings). They feed blood vessels and nerves to the gums, lips, and face.

Dinosaurs do seem to have more of them, but size making them more noticable is also a factor. The increase in dinosaurs may be involved with pressure sensitive scales as seen in crocodiles or alternatively something like lips, or both. Here is a great article on them. Paleontologist are hampered here becasue the related animals are birds (who have beaks) and crocodiles (which are entirely scaly). So it is hard to pin down exactly what a dinosaur oral facial anatomy would look like.

  • $\begingroup$ Excellent; and great link! $\endgroup$
    – dlf
    Aug 24, 2018 at 12:17

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