Discover Spain and Explore the Fossils of Las Hoyas Near Cuenca
- Wayne Munday
- Nov 30, 2024
- 3 min read
Updated: 3 days ago
Las Hoyas in central Spain is one of the most important Early Cretaceous fossil sites in the world, renowned for exceptional soft tissue preservation. Dating to the Barremian Age between 125 and 110 million years ago, this konservat-lagerstätte preserves over 20,000 plant and animal specimens. Fossils are found within the finely laminated limestones of the La Huérguina Formation, representing a calm freshwater wetland of shallow lakes and vegetated floodplains. The site records early flowering plants, dinosaurs, reptiles, birds, mammals, fish, and invertebrates preserved in remarkable detail. Located within the Serranía de Cuenca basin near the UNESCO World Heritage city of Cuenca, Las Hoyas offers visitors a rare opportunity to explore Cretaceous ecosystems, fossilisation processes, and key stages in plant and animal evolution.
Las Hoyas is found within the larger Serrania de Cuenca basin of the Southwestern Iberian Range of Central Spain. This area is part of a broader karst landscape known as the Monumento Natural de los Palancares y Tierra Muerta designated for its extraordinary wealth of plant biodiversity. Located only a 2.5 hour drive south-east of Madrid it is recommended to also visit and stay in the medieval fortified UNESCO designated World Heritage city of Cuenca.
In Cuenca you have an opportunity to walk the cobbled streets and visit the modern and contemporary Museo de Paleontología de Castilla-La Mancha. Here the regions fossils are displayed including the Iberomesornis a key species linking dinosaurs and modern birds, the Spinolestes an early furry mammal and also a terrifying 6 meter fossil skeleton of a Concavenator a large meat eating theropod dinosaur from the Carcharodontosaur group of 'shark-toothed lizards'.
The main fossil site in Las Hoyas is managed by the museum and has been protected by the Bien de Interés Cultural (BIC) Site of Cultural Interest by the Spanish government since 2016.
The walled city of Cuenca was built by the Moors during the time of the Caliphate of Córdoba an Arab Islamic state ruled by the Umayyad dynasty from between 929 - 1031 that oversaw most of the Iberian Peninsula, the Balearic Islands, and parts of North Africa before it was conquered by the Castilians in the 12th century.
The geodiversity of Cuenca itself plays it role in the construction of the hanging houses of casas colgadas built suspended from the city's sheer cliffs overlooking the Huécar river.
The La Huérguina Formation is made up of a finely laminated limestone with a mix of palustrine or marsh and Lacustrine or lake bottom sediments that enabled the preservation of fossils. A combination of fossil preservations occur in the La Huérguina Formation such as the rapid burial by sediment (obrution) creating an immediate lack of oxygen, or perennial anoxic conditions from the lake bottom waters that can slow down the decay process, which can help with fossilisation known as stagnation and finally by sealing organic matter by colonies of microbial matts growing during the hot dry seasons.
The sediments and fossils of the La Huérguina Formation have among the most significant discoveries including the oldest angiosperms, the smallest species of chondrichtians and lizards and snakes (squamates), new theropod dinosaurs, several now extinct enantiornithine birds, the first European tapejarid pterosaur and the most complete eutriconodont mammal.
The preservation of the fossils of Las Hoyas has unlocked a number of steps in plant and animal evolution from the Cretaceous Period. Whether that has been illustrating the early developments and structures in flowering plants; the stages of growth in arthropods from larvae, moults into adults; The scales, stomach contents of bromalites, eye structures and muscle in fish; The scales, skin and emergence of hair or fur among tetrapod’s, birds and early mammals. The fossil record of Las Hoyas also helps to map the distribution of the Tapejaridae family of pterodactyloid pterosaurs.
