Cal Orck’o, Bolivia 2019
While trekking in Southern Bolivia, I found myself staying at Sucre for the night. There, I had the opportunity to visit Cal Orck’o site. The Cal Orck’o is home to the world’s largest and most diverse collection of dinosaur footprints from the Cretaceous Period. It is only 4.4 km North-West of Sucre.
The limestone cliff hosts about 12,000 dinosaur footprints, with many dating back 68 million years. Discovered on the grounds of the local cement company Fancesa in 1985, the cliff was closed off to tourists after mining conditions and erosion began damaging the area.
Four years later, when a team of scientists led by a famed Swiss paleontologist was able to visit, the wall was named “the largest site of dinosaur tracks found so far.” There are so many tracks, actually — and they’re placed in such strange patterns — that some scientists refer to the area as a “dinosaur dance floor.”
So far, six different types of dinosaur prints have been identified. One special track that measures 347 meters is the longest dinosaur track-way ever discovered and was made by a small Tyrannosaurus rex like dinosaur called a Teropodo. Eight other limestone walls with dinosaurs tracks have been found in the region. Millions of years ago, when dinosaurs walked the earth, this area was part of a huge shallow lake.
Towards the end of the Cretaceous period, (68 million years ago), a large saline lake stretched from the South Atlantic coast crossing what is now Argentina, what until then was the low valley of Potasi in Bolivia. It was a time of temperate climate characterized by periodic flooding, in a landscape dominated by gingko, conifer pine, cycads and magnolias.
Through a natural bridge that had formed between the here to fore isolated North America and South America, an interesting and diverse faunal exchange occurred, that would bring the first dinosaur species typical of the northern hemisphere to the southern hemisphere. Among the immigrant species of plant-eating dinosaurs there were the gregarious hadrosaurs that traveled in large herds involving adults and juveniles; ankylosaurus and ceratopsians that accompanied these migrant groups in search for food and also predators followed their traces.
Enormous Titanosaurs, the last giant long-necked dinosaurs, roamed the plains leaving their footprints in the clay soil of what is now Cal Orck’o. During the rainy season these lands were flooded with mud forming a layer of sediment that encapsulated and preserved the footprints leaving a new scenario prepared for the registration of new traces.
Animal tracks (ichthyofauna) are associated with mud and sand deposited in plains, deltas and lake. The site of Cal Orck’o and their equivalents Maastrichtian age are part of a real dinosaur highway, a mega-site that extends from the south of Peru (Vilquechico Formation) through the Central Andes Bolivianos (El Milino Formation) to the province of Salta in the north of Argentina (Yacoraite Formation).
The tectonic plate shifts during the Tertiary period that formed the great Andes Mountains also pushed some of these limestone walls out from the bed of the lake. The rock cliff measures about 325 feet tall and juts into the sky at a 70 degree angle. In Cal Orck’o there were strata folded, form synclines and anticlines that caused the high dip of footprint bearing rocks and each with its characteristic traces and an age slightly different than the layers next to it.
The Cal Orcko is considered to be in the geographical area of the Altiplano/Cordillera Oriental. The tracks are found in the geological El Molino Formation (Cretaceous). Oolitic fossiliferous limestone, associated with large, freshwater stromatolites and nine levels of dinosaur tracks (a.k.a. trace fossils) in the El Molino Formation document an open lacustrine environment. Lacustrine is a geological term for lake.
The high-resolution mapping of the site from 1998 to 2015 revealed a total of 12,092 individual dinosaur tracks in 465 dinosaur track-ways.
Nine different morphotypes of dinosaur tracks have been documented. Amongst them are several trackways of theropods, ornithopods, ankylosaurs and sauropods, with the latter group accounting for 26% of the trackways.