Las Hoyas

Las Hoyas is a Cretaceous Konservat-Lagerstätten located near the city of Cuenca, Spain.

It is dated as Barremian (early Cretaceous), and is mostly known from its exquisitely preserved dinosaurs, especially enantiornithines.

As a Konservat-Lagerstätten, the preservation is exceptional. This may be a result of three factors: Microbial mats, Obruption and Stagnation.

Microbial mats may be responsible for the preservation of soft tissue in many fossils from Las Hoyas, like Pelecanimimus' crest. The iron carbonate depositions, a result from bacterial metabolism which covered the dinosaur's crest enhanced the preservation of those soft tissues. Evidence of these mats comes from the studies on microfacies and the fossils themselves.

Obruption is notable in the formation, due to the presence of highly articulated specimens. From actuotaphonomy studies on several different organisms it can be estimated that the burial of most entities was quick. Concornis may have been buried in less than 15 days, after a period of sub-areal exposition.

Las Hoyas was an inland lacustrine environment which presents an important aquatic and terrestrial flora (with many specimens of Charophytes, Montsechia, Weischelia or Frenelopsis) and diverse fauna, with specimens of at least five or six Phyla: Arthropods, Molluscs, Chordata and many vermiform soft bodied animals which might be Nemertines or Annelids.

Among vertebrates the most abundant and diverse group are fish. The presence of mostly articulated skeletons, exceptional preservation of tissue and lack of any other signs of transportation may indicate that these are demic and autochthonous entities (meaning that they lived and died in the same place where they fossilized).

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