All fossil sites capture a specific interval of geologic time, but Lark Quarry in Australia may be the record-holder in this regard: the footprints preserved here appear to have been laid down in the course of a few seconds, as an unidentified tyrannosaur scattered a pack of equally mysterious ornithopods and small theropods known as coelurosaurs. Researchers have uncovered over 3,000 footprints here, which seem to account for a total of about 150 dinosaurs (one of which was must have been very hungry).
Amazingly, experts in trackmarks have not only been able to identify what kinds of dinosaurs left these footprints, but how fast they were running. In their panic, the theropods reached a top speed of 12 miles per hour, and the slightly bigger ornithopods ranged from 7 to 12 mph. The tyrannosaur, which left a handful of characteristic, three-toed footprints, appears to have charged the combined herds at a speed of 8 mph.
By the way, if you don’t recognize the creatures listed in the "dinosaurs found" entry immediately above--Skartopus, Wintonopus and Tyrannosauropus--there’s a good reason. These are examples of "ichnogenuses," names assigned to unidentified creatures on the basis of their footprints. The giveaway is the "pus" on the end, which is Greek for "foot."
