Examination of the skull revealed the most important peculiarity of the new species: The shape and expression of the skull base shows that the cochlea of Onychonycteris was smaller than that of all echolocating bat species today. Their size is similar to that of fruit bats, frugal relatives of bats that do not have the ability to echolocation. This clearly states that the animals first learned to fly and then to locate with the help of the echo, the researchers explain. From the jaw and shape and texture of the teeth, the scientists also concluded that onychonycteris has been nourished by insects. Without the help of echolocation, they had to rely on either their eyes, their sense of smell or their passive hearing to hunt.
It is unknown whether the bats of the past times were active at night, day or dusk. Without the senses of today's bats, nocturnal animals would need to have had enlarged eyes to navigate the dark. However, investigators could not verify this: the orbits of the extinct species could not be measured because the skulls of the two specimens found so far were crushed during the fossilization. Probably, however, the animals were dusk-active and did not put their active times into the night until the development of the echolocation system, write Simmons and her team. In this way they might have escaped other flying predators that evolved after dinosaur extinction.Nancy Simmons (Natural History Museum, New York) et al .: Nature, Vol. 451, p. 818 ddp / science.de? Livia Rasche advertisement