FOUND: A Dinosaur That Shed Its Teeth and Grew a Beak - Atlas Obscura
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FOUND: A Dinosaur That Shed Its Teeth and Grew a Beak

The mouths of these dog-sized T-Rex relatives changed with their diets.

A typical limusaurus.
A typical limusaurus. Nobu Tamura/CC BY 3.0

New fossil research has revealed the existence of a strange little dinosaur that was born with teeth, but shed them to grow an adult beak.

According to The Verge, these unique beasts are the first reptiles ever discovered that underwent such a drastic dental metamorphosis. Called the Limusaurus inextricabilis (“inextricable mud lizard”), the dinosaur was a bipedal relative of the Tyrannosaurus Rex, but much smaller, only standing thigh-high to a modern human.

The process (a form of extreme ontogenetic variation) is thought to have developed to allow the little guys to change their diet as they matured. A young limusaurus would have rows of teeth that allowed it to survive on a more omnivorous diet while young, but move into an increasingly herbivorous diet as they got older, so as to avoid competing with other omnivores.

While the newly discovered change may be unique to the Limusaurus inextricabilis, according to a vertebrate expert quoted in Science Magazine, there may be many more such species that go through a similar transformation, we just haven’t found their skulls yet. The mature beak could lead researchers to a better understanding of how beaks developed and how modern birds sprung up from their saurian roots.