The world’s most paleontologically significant cement works is on the outskirts of the Bolivian city of Sucre. Some 5km beyond the colonial centre, with its whitewashed townhouses, churches and leafy plazas, a grey 100m-high cliff rises out of a limestone quarry.
As an officious security guard shepherded me into the Parque Cretácico Cal Orko – a grand name for a small fenced-off viewpoint high above the quarry – a stream of heavily-laden trucks chugged past, while looming chimneys belched out plumes of grey smoke.
At first glance the mottled, 1.2km-long cliff-face was nondescript. But as my eyes slowly focused, two indistinct pockmarks gradually formed into a giant pair of dinosaur footprints, each one bigger than my torso. Then I spotted another pair, and then two more, and then more than I could count. In total, there are over 5,000 footprints from around 150 types of dinosaur. It is easily the largest and most diverse such collection in the world.
Palaeontologists believe the footsteps are a snapshot of a 65-million-year-old “chase and kill” stampede in which a horde of scavengers followed predators – including a baby tyrannosaurus rex dubbed “Johnny Walker” by researchers – in pursuit of a menagerie of cretaceous prey. Beneficial climatic conditions preserved them, and the flat earth was pushed up over millennia of tectonic activity until it formed a cliff.
Despite the site’s significance, and local attempts to secure UNESCO World Heritage status, conservation attempts are notable by their absence. From the confines of the Parque Cretácico, I could only get within 150m of the cliff. Meanwhile, in the quarry below, explosions sounded and burly tractor drivers passed within touching distance of the footsteps.