Two recent studies using CT scanning technology are the first to compare the auditory and visual anatomy of dinosaurs and living creatures, and they've come up with some surprising conclusions.
In one of the studies, the three-dimensional scans enabled scientists to view the rock-encased inner ear of a theropod that roamed the dry habitats Mongolia some 66 million years ago.
Based on what we know of modern creatures and their night-stalking abilities, the chicken-sized dinosaur, Shuvuuia deserti, probably went out to seek its meals after the sun went down. "It's a somewhat odd dinosaur," said Lars Schmitz, an associate professor of biology at the W.M. Keck Science Center at Claremont McKenna, Pitzer and Scripps colleges. "What we see are really large pupils, an elongated inner ear canal. Supersensitive eyes. It really rivals the nocturnal specialists today like barn owls and bats."
Modern-day creatures with an elongated inner ear also have well-developed vocal capabilities, noted Bhart-Anjan Bhular, senior author of the other recent study, published in the journal Science, and an assistant professor of earth and planetary sciences and an assistant curator of the Yale Peabody Museum of Natural History. It is likely, he said, that this ancestor of birds could sing. To go further, the ability to emit high-pitched calls, he said, and to hear them, could be linked to parenting offspring (like nestlings calling for attention).
Added Schmitz, "We think [Shuvuuia deserti] would have stalked its prey--small mammals--at night when the temperatures were cooler."
By contrast, super-sized theropods like T. rex used their outstanding day vision and good hearing to hunt during normal business hours. Other dinos, such as the Velociraptor, Schmitz said, probably opted for dusk to dine.
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