Cal Orcko is a paleontologic site in Bolivia, located in a quarry wall near the city of Sucre, in Chuquisaca. This place represents the best spot in the world for dinosaur tracks with its over 5,000 tracks of 294 different species. The discovery was an enormous contribution to history and science and disclosed important data to the end of the Cretaceous period and the beginning of the Tertiary period, around 66 millions of years ago documenting this way the great diversity of the dinosaurs better than any other site ever found. Up until its discovery, the biggest and most important site was Khjoda-Pil-ata, in Turkmenistan, while others were located in Portugal, Great Britain, Spain and Swiss. The site of Cal Orcko has a way superior amount of finds, in a sense that the previous sites could count a maximum of 220 tracks of just 2 species.
Below: the upland photographed by far. Picture by Hay Kranen shared via Wikipedia – licence Creative Commons
The tracks are in the East side of the city of Sucre. The site is located on a mountain with a slope of 73 degrees, 80 m high (260 ft) and 1,200 m wide (almost 1200 ft).
History of the site
The first sign of its existence dates back to 1985 but it was between 1994 and 1998 that a team of Bolivian European and American paleontologists led by Christian Meyer, studied thoroughly the tracks of the reptiles, discovering many new information about the history of dinosaurs.
Cal Orcko represents a paleontological stroke of luck for several reasons. The size of the calcareous wall is impressing, with beyond 25,000 m² (270,000 ft²) full of tracks. Meyer demonstrated in his studies that around 68 millions of years ago many dinosaurs were living along the bank of the not too deep lake with warm freshwater running from the current Perù and Bolivia all the way to Argentina.
Below: tracks of titanosauria. Picture by Mhwater shared via Wikipedia – licence Creative Commons
The lake was massive yet not very deep, so the dinosaurs were used to walking through it. During the Tertiary period, when the Andes Mountains were taking shape, the tectonic movements rose that which was a flat surface all the way to make it become the cliff that it is nowadays visible to us. During the last years 8 further sites have been found, which are progressively becoming focus of studies for paleontologists from all over the world.
One of the most impressing discoveries was the one about the tracks of the Ankylosauria, four footed dinosaurs similar to gigantic armadillos of 8 tonnes, with bone-made spurs all along their spines. Thanks to the evaluation of the tracks it has been discovered that the animal, hypothesised as clumsy and big, was instead tall and lean with slender legs and a a fast pace.
The detected tracks were also coming from herbivorous sauropods, including the majestic titanosauria which was 25 m tall (80 ft) and used to leave tracks 70 cm long (27.5 inch), as well as the ones of the great predators of the theropods, like the giganotosaurus which was leaving tracks of 35 cm (14 inch).
The tracks found are not only coming from dinosaurs but also from tortoises, crocodiles, fishes, algae, witnesses which let the scientists to historically contextualise the cohabitation between different species.
In 2010 a section of the upland went lost, destroying some tracks yet showing an underlying layer. It is today common opinion that under the visible part many other layers of fossils hide.
The Cretaceous Park
For the preservation of this site it has been opened in March 2006 a Cretaceous Park, place where it is possible to enjoy the view of replicas of the different species of dinosaurs which left tracks on the site.