Some 70 million years ago in the regions of what is now Mongolia and Northern China was a species of a pint-sized dinosaur that had night vision and acute hearing to survive larger dinosaurs and thrive as a nocturnal hunter.
A new study, appearing in the journal Science, examines the evolution of vision and hearing among theropods - a dinosaur group mostly characterized by their hollow bones and three-toed limbs.
Particularly, researchers report the results of examining a group of bones that surround the pupil, as well as a bony tubular structure inside the skull that houses the hearing organ, in a small dinosaur called Shuvuuia deserti.
According to the report entitled "Evolution of vision and hearing modalities in theropod dinosaurs," this pint-sized nighttime hunter has vision and hearing comparable to the extant barn owl, which suggests that it could also hunt in total darkness.
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Sensory Capabilities of Predatory Dinosaurs
Researchers demonstrated that predatory dinosaurs generally had hearing senses better than the average, which helped them navigate and search for prey. However, their sense of sight was optimized to work during the daytime. On the other hand, this small dinosaur Shuvuuia deserti was built for hunting in the dark.
The dinosaur Shuvuuia was a bipedal - two-legged - dinosaur that lived during the Cretaceous Period some 145.5 to 65.5 million years ago. It was as large as a pheasant and due to its thin, awkward frame, estimated to weigh as much as an average house cat.
Furthermore, this night hunter did not share the strong jaws and sharp teeth that were common among the carnivorous predators of the time. Instead, it had a remarkably thin frame, like those of birds, and a lightly built skull. Its teeth, while numerous along its jaw, were more like "grains of rice."
Its skeletal frame, small skull, connected together by a neck of an average length, it was described as something like an "awkward chicken." However, unlike most avians, it had short yet powerful arms ending in a large claw, which was most likely used for digging.
Small, Quick Running Night Hunter
"Shuvuuia might have run across the desert floor under cover of night, using its incredible hearing and night vision to track small prey such as nocturnal mammals, lizards and insects," explains paleontologist Jonah Choiniere, the lead author of the study from the University of the Witwatersrand in South Africa, in a news article from Reuters. "With its long legs it could have rapidly run down such prey, and used its digging forelimbs to pry prey loose from any cover such as a burrow."
Additionally, fellow paleontologist Roger Benson, co-author of the study from England's University of Oxford, explains that Shuvuuia was a "strange animal" that scientists long wondered what the dinosaur "was actually doing."
A particular structure examined by the researchers was the lagena: a curved, finger-shaped sac that rests in a cavity in the dinosaur's skull bones near the brain. This is also connected to the part of the ear associated with the sense of balance among reptiles and birds, particularly in keeping it steady as they move around.
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