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The La Huérguina Formation (also known as the Calizas de La Huérguina Formation, La Huérguina Limestone Formation or as the Una Formation) is a geological formation in Spain whose strata date back to the
Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is precede ...
stage of the Early Cretaceous.Martínez et al., 2017 Las Hoyas is a Konservat-
Lagerstätte A Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These f ...
within the formation, located near the city of
Cuenca, Spain Cuenca () is a city and municipality of Spain located in the autonomous community of Castilla–La Mancha. It is the capital of the province of Cuenca. Etymology Its name may derive from the Latin ''conca'' meaning "river basin", referring ...
. The site is mostly known for its exquisitely preserved
dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
s, especially
enantiornithines The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...
.Weishampel et al., 2004, pp.556-563 The lithology of the formation mostly consists of lacustarine
limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
deposited in a freshwater wetland environment.


Las Hoyas


Taphonomy

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.


Paleoenvironement

Las Hoyas was an inland lacustrine environment which presents an important aquatic and terrestrial
flora Flora is all the plant life present in a particular region or time, generally the naturally occurring (indigenous (ecology), indigenous) native plant, native plants. Sometimes bacteria and fungi are also referred to as flora, as in the terms '' ...
(with many specimens of Charophytes, '' Montsechia'', '' Weischelia'' or '' Frenelopsis'') and diverse
fauna Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is ''flora'', and for fungi, it is ''funga''. Flora, fauna, funga and other forms of life are collectively referred to as ''Biota (ecology ...
, with specimens of at least five or six Phyla: arthropods,
molluscs Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estim ...
, Chordata and many
vermiform Vermiform (ˈvərməˌfôrm) describes something shaped like a worm. The expression is often employed in biology and anatomy to describe usually soft body parts or animals that are more or less tubular or cylindrical. The word root is Latin, ''ve ...
soft bodied animals which might be Nemertines or
annelids The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecolog ...
. Among
vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...
the most abundant and diverse group are
fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...
. 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). Crocodylomorphs are the most abundant amniotes from Las Hoyas. Dinosaurs from Las Hoyas (avian and non avian) are unique in many ways. The first ornithomimosaur dinosaur described in Europe, '' Pelecanimimus polyodon'', shows some characters previously unknown in these dinosaurs which enhanced the knowledge on the evolution of the group, such as a high number of teeth. '' Concavenator corcovatus'' presents two unique features: very tall neural spines on the vertebrae near the hip, which look like a hump, and a structure on its forearm, which if homologous to
quill knob The pennaceous feather is a type of feather present in most modern birds and in some other species of maniraptoriform dinosaurs. Description A pennaceous feather has a stalk or quill. Its basal part, called a ''calamus'', is embedded in the skin ...
s would push back the origin of feathers earlier in theropod evolution. Las Hoyas birds are enantiornithes, the most diverse Cretaceous bird clade, which became extinct at the end of the period. '' Iberomesornis romerali'' shows both derived ("avian") and primitive ("dinosaurian") characters. Within the derived characters we can underline the presence of a pygostile, although it is still very large compared to that of modern neornithines and the presence of a quilled sternum. ''
Eoalulavis hoyasi ''Eoalulavis'' (from the Ancient Greek: ''Éōs'', "dawn"; ''alula'', "bastard wing"; ''avis'', "bird") is a monotypic genus of enantiornithean bird that lived during the Barremian, in the Lower Cretaceous around 125 million years ago. The only ...
'' shows the first report of an
alula The alula , or bastard wing, (plural ''alulae'') is a small projection on the anterior edge of the wing of modern birds and a few non-avian dinosaurs. The word is Latin and means "winglet"; it is the diminutive of ''ala'', meaning "wing". The al ...
or "bastard wing", which means it had a flight manoeuvrability analogous to that of modern birds.


Research

The Las Hoyas site has been studied for more than two decades by researchers from the Universidad Autónoma de Madrid, the
Universidad Complutense de Madrid The Complutense University of Madrid ( es, Universidad Complutense de Madrid; UCM, links=no, ''Universidad de Madrid'', ''Universidad Central de Madrid''; la, Universitas Complutensis Matritensis, links=no) is a public research university lo ...
and the
National University of Distance Education The National Distance Education University, known in Spanish as ''Universidad Nacional de Educación a Distancia'' (UNED), is a public research university of national scope. The university was founded in 1972 under the Ministry of Universities. ...
, in collaboration with the Museo de las Ciencias de Castilla-La Mancha, which is responsible for the fossil record from the area.


Fossil content


Amphibians


Turtles


Squamates


Mammals


Crocodyliformes


Ornithodirans


Correlation


See also

*
List of dinosaur-bearing rock formations This list of dinosaur-bearing rock formations is a list of geologic formations in which dinosaur fossils have been documented. Containing body fossils * List of stratigraphic units with dinosaur body fossils ** List of stratigraphic units with ...
* Paja Formation, contemporaneous Lagerstätte of Colombia *
Yixian Formation The Yixian Formation (; formerly transcribed as Yihsien Formation) is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans the late Barremian and early Aptian stages of the Early Cretaceous. It is known for its exq ...
, contemporaneous Lagerstätte of China


References


Bibliography

* * * * Thomas Martin, Jesús Marugán-Lobón, Romain Vullo, Hugo Martín-Abad, Zhe-Xi Luo & Angela D. Buscalioni (2015). A Cretaceous eutriconodont and integument evolution in early mammals. Nature 526, 380–384. doi:10.1038/nature14905 * Ortega, F., Escaso, F. & Sanz, J. L. (2010): A bizarre, humped Carcharodontosauria (Theropoda) from the Lower Cretaceous of Spain ''
Nature Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are ...
'' 467: 203-206
HTML abstract
* * Sanz, José L.; Chiappe, Luis M.; Pérez Moreno, Bernardino P.; Buscalioni, Ángela D.; Moratalla, José J.; Ortega, Francisco & Poyato Ariza, Francisco J. (1996): An Early Cretaceous bird from Spain and its implications for the evolution of avian flight. ''
Nature Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are ...
'' 382(6590): 442-445. (HTML abstract) * Pérez Moreno, B. P., Sanz, J. L., Buscalioni, A. D., Moratalla, J. J., Ortega, F., and Raskin-Gutman, D. (1994). "A unique multitoothed ornithomimosaur from the Lower Cretaceous of Spain." Nature, 30: 363-367. * Sanz, J. L. & Bonaparte, José F. (1992): A New Order of Birds (Class Aves) from the Lower Cretaceous of Spain. ''In'': Jonathan J. Becker (ed.): Papers in Avian Paleontology Honoring Pierce Brodkorb. ''Natural History Museum of Los Angeles County Contributions in Science'' 36: 38-49. * Sanz, J. L. & Buscalioni, A.D. (1992): A new bird from the Early Cretaceous of Las Hoyas, Spain, and the early radiation of birds. '' Palaeontology'' 35(4): 829-845
PDF fulltext


External links


Las Hoyas site website
{{DEFAULTSORT:Calizas De La Huergina Formation Geologic formations of Spain Lower Cretaceous Series of Europe Cretaceous Spain Limestone formations Marl formations Lacustrine deposits Cretaceous paleontological sites of Europe Paleontology in Spain Formations