Crocodile-like sensory scales in a Late Jurassic theropod dinosaur

Early in amniote evolution, epidermal scales evolved in stem reptiles as an efficient barrier against water loss and ultraviolet radiation, making them a key development in the transition to a fully terrestrial existence [1]. Accordingly, epidermal scales are not simple inert structures but highly-evolved organs suited to perform a broad suite of functions. Here, we provide new data on the epidermal complexity of a non-avian theropod, <I>Juravenator starki</I>, from the Torleite Formation (upper Kimmeridgian), Bavaria, Germany [2]. Although epidermal scales have been noted previously on the tail of <I>Juravenator</I>, we report a unique scale type with distinctive circular nodes that we identify as integumentary sense organs, analogous to those in modern crocodylians. The surprising presence of such structures suggests the tail had a sensory function, which is nevertheless congruent with the inferred ecology of Juravenator and the evolution of integumentary sense organs among archosaurs.