A Jurassic promenade
In the rugged Baysuntau mountains of southern Uzbekistan, a limestone slab records a procession of giants. Around 160 million years ago, during the Oxfordian age of the Late Jurassic, this area was a warm, shallow coastal flat. Dinosaurs walked across the soft carbonate mud, leaving behind tracks that would harden into stone and persist through geologic time. The site contains dozens of trackways, preserving the movements of both bipedal, three-toed theropods and colossal, four-legged sauropods.
The science of ichnology, the study of trace fossils like footprints, allows for a detailed reconstruction of these long-extinct animals' lives. The most common track type belongs to a large theropod, given the ichnospecies name Megalosauripus uzbekistanicus. Some of these carnivorous dinosaurs left footprints measuring 50 centimeters in length. They walked alongside much larger sauropods, whose round, deep impressions show a more placid, herbivorous lifestyle. The preservation of these tracks on a single surface shows the different dinosaurs that shared this coastal ecosystem.
Timed to perfection
The most remarkable data from the Baysun trackways concerns the walking speed of the sauropods. By measuring the distance between consecutive footprints (the stride length) and estimating the animal's leg length from the print's size, paleontologists can calculate how fast it was moving. The analysis reveals a consistent walking speed of approximately 4 kilometers per hour. This precise speed is identical to the average migration speed of modern African elephants, suggesting a similar energy-efficient gait for long-distance travel.
The theropod tracks also show movement. While none show the high-speed running seen at other sites, their narrow trackways and long strides indicate an efficient walking gait. Some trackways extend for considerable distances, with one theropod trackway in the wider Central Asian region measuring an astonishing 311 meters. The presence of multiple parallel trackways made by smaller dinosaurs suggests they may have moved in groups. These fossilized paths show the anatomy of the dinosaurs' feet, but also provide direct evidence of their behavior millions of years before the first humans.