"Paleontologists in Spain say you don't find a good fossil, the good fossil finds you." -Salvador Moyà-Solà, director of the Catalan Institute of Paleontology, 2004
Even a brief look at the paleontology of this country seems to bear this claim out. From bizarre dinosaurs to seminal primates, Spain's fossils leave burning impressions--as well as burning questions--about prehistoric life.
Las Hoyas (Castile-La Mancha, 130-125 million BCE)
Numerous dinosaur genera are known from Spain, especially ones from the Early Cretaceous Period (145-100 million BCE). These include the sauropod Turiasaurus, the largest known dinosaur in Europe, and Europelta, a well-preserved ankylosaur described late in 2013. Though both of these animals were discovered in Aragon, the richest Early Cretaceous bone bed in Spain is Las Hoyas, in Castile-La Mancha. Las Hoyas is a Lagerstätte--a site where organisms are unusually well-preserved and often have traces of soft tissue. Fossils from this ancient lakebed include petrified plants and insects, fish and crocodiles retaining their scales, and early birds with their feathers frozen in the rock.
Las Hoyas is also home to two non-avian theropods known only from Spain. The larger of the two is Concavenator, a twenty-foot long carcharodontosaur described in 2010. The original specimen of this predator possesses broad scales along its tail, as well as a series of bumps trailing down its arm. Some paleontologists believe these bumps anchored short, quill-like structures, if not primitive feathers. More obvious than either of these traits, though, are two of Concavenator's dorsal vertebrae, which are five times longer than those sprouting from its ribcage. In life, these structures may have supported a sort of sail for display or hump for fat storage.
The second unique theropod from Las Hoyas is Pelecanimimus, one of the smallest and earliest known ornithomimosaurs. Preserved with a soft pouch of skin beneath its lower jaw (for which is it named, since it resembles a pelican's), this dinosaur had over two-hundred tiny teeth--the most of any known theropod. Ironically, later ornithomimosaurs abandoned teeth altogether in favor of keratinous beaks, likely used to strip leaves from vegetation. With its fleshy pouch and numerous teeth, however, Pelecanimimus is thought to have fed on small fish and amphibians. According to this scenario, the animal would have lunged its head into the water, snatched up its slippery prey, then used its pouch to contain its victim while filtering excess water out of its mouth.
Pierolapithecus (Catalonia, 11.9 million BCE)
Today, the only non-human primate native to Europe today is the Barbary macaque, a monkey which inhabits the British territory of Gibraltar. Prior to the Ice Age, primates as a whole were known in Europe from as early as the Eocene Epoch (c. 49 million BCE). It wasn't until some thirty-five million years later--in the mid-Miocene--that true apes had evolved and had begun to invade Europe from Africa.
In 2002, a very well-preserved ape from the Late Miocene was discovered near the Spanish village of Els Hostalets de Pierola. Called Pierolapithecus, it has enough features to suggest that it was an early member of the so-called great apes (which include gorillas, chimpanzees, and humans). These features include a broad, flat ribcage, a rigid lower spine, and a wide pelvis--all adaptations which allow great apes to climb up and down and stand upright with much greater ease than other primates. Unlike later apes, however, Pierolapithecus had a set of rather short fingers, meaning it would have been less adept at swinging or suspending itself from branches.
Cerro de los Batallones (Madrid, 9 million BCE)
While herbivores tend to outnumber carnivores in most modern terrestrial ecosystems, the reverse is true at some fossil sites. Many sites of this kind have been interpreted as ancient predator traps, where herbivores would have become entrapped--perhaps in a bog or a cave--and attracted a disproportionately high number of carnivores. Before long, however, the carnivores would become trapped with them, succumbing to starvation and predation themselves.
Spain has one of the most impressive predator traps in the fossil record, known as the Cerro de los Batallones and dating back to the Late Miocene Epoch. This cluster of sites represents a series of deep pits, which contained stagnant pools of ground water from a nearby lake. Hoofed mammals such as rhinos, horses, and giraffes fell or were lured into these caves, where their cries and carcasses enticed saber-toothed cats, bears, and a host of other predators.
Sima de los Huesos (Castile-León, 400 thousand BCE)
Located deep in the Atapuerca Mountains, the cave known as La Sima de los Huesos ("the pit of bones") contains over six thousand bones belonging to roughly thirty individual hominins (the family of upright-walking great apes that all living and extinct humans belong to). These numbers make it the largest known assemblage of early human fossils in the world. The humans at this site were initially estimated to be around 600 thousand years old and identified as Homo heidelbergensis, the last known ancestor between Neanderthals (Homo neanderthalensis) and modern humans (Homo sapiens).
In 2012, however, a study by Chris Stringer of the Natural History Museum in London determined that these early humans were actually early Neanderthals. Stringer's argument hinged not only on similarities between the Sima bones and those of other Neanderthals, but on the contention that the Sima fossils were 200 thousand years younger than previously thought.
Late in 2013, a team of Spanish and German scientists sequenced the genome of the Sima hominins from a single femur and compared the mitochondrial DNA to that of other early humans. Though the study supported Stringer's dating of the fossils, the mitochondrial DNA most closely resembled that of the Denisovans (no scientific name yet), Russian relatives and contemporaries of Neanderthals. Yet this revelation only adds fuel to the burning question of identity, as scientists debate and examine the role that hominin interbreeding may have played in the development of this early Spanish human.
What is the most important fossil discovery made in Spain?
Other Spanish fossil sites
Murero Lagerstätte- Mid-Cambrian site in Zaragosa known for fossilized trilobites and sponges.
Puertollano- Late Carboniferous fossils have been excavated near this city in Castile-La Mancha. These include bones of Iberospondylus, one of the earliest known amphibians with a tolerance for saltwater.
Tremp Formation- Latest-Cretaceous site in Catalonia. In addition to hundreds of titanosaur eggs, this site is known for two native ornithopods, Arenysaurus and Pararhabdodon. Both of these dinosaurs were lambeosaurs, crested herbivores that had been replaced by broader-billed, crestless hadrosaurs in North America by this time.
Incarcal- Pliocene site located in Girona. Another potential predator trap, containing the bones of saber-toothed cats and hyenas, as well as mammoths and ancient hippos.
Gran Dolina- Another Pleistocene hominin site in Castile-León. Slightly older than Sima de los Huesos, this cave contains at least six young individuals of a hominin called Homo antecessor, along with hundreds of stone tools and butchered animal bones. Deep cut marks made by these tools are found in the some of the antecessor bones, suggesting that these early humans occasionally resorted to cannibalism.
Jarama VI and Zafarraya- Pleistocene sites located in Madrid and Granada, respectively. Long regarded as some of the most recent Neanderthal sites, along with Figueira Brava in Portugal and Gorham's Cave Complex in Gibraltar. Yet the notion that Iberia was this species' final stronghold was recently challenged by a study published in 2013, which found that Jarama VI and Zafarraya were fifteen thousand years older than previously thought.
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http://www.yacimientolashoyas.es/ (Las Hoyas homepage; written in Spanish)