{{Short description|Geological formation in Spain}} {{Infobox rockunit | name = La Huérguina Formation | image = File:Las Hoyas - 2018 field works 02.jpg | caption = Lithographic limestones of the Las Hoyas locality | type = Geological formation | period = Barremian | age = Barremian<br />~{{fossil range|125}} | prilithology = Limestone, marl | otherlithology = Conglomerate | namedfor = Huérguina | namedby = | region = Cuenca, Castile-La Mancha | country = Spain | coordinates = {{coord|40.0897|N|1.8978|W|source:wikidata|display=inline}} | unitof = | subunits = | underlies = Contreras Formation or Unconformity with the Utrillas Group | overlies = Tragacete Formation | thickness = {{convert|60|-|100|m|ft|abbr=on}} | extent = South Iberian Basin | area = | map = {{Location map+ | Spain#Spain Castile-La Mancha | relief = 1 | width = 250 | float = center | places = {{Location map~ | Spain#Spain Castile-La Mancha | lat_deg = 40.0897 | lon_deg = -1.8978 | mark = Green pog.svg | marksize = 10 }} }} | map_caption = }} 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 stage of the Early Cretaceous.<ref>Martínez et al., 2017</ref> '''Las Hoyas''' is a Konservat-Lagerstätte within the formation, located near the city of Cuenca, Spain. The site is mostly known for its exquisitely preserved dinosaurs, especially enantiornithines.<ref name="cretaceousdistribution">Weishampel et al., 2004, pp.556-563</ref> The lithology of the formation mostly consists of lacustrine limestone deposited in a freshwater wetland environment.
== Las Hoyas ==
=== Taphonomy ===
[[File:Las Hoyas fossil site map.jpg|thumb|left|Map showing the Las Hoyas site (star), and Mesozoic strata of the Iberian Ranges]] 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''<nowiki/>' 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.
=== Paleoenvironment === 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, chordates 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).
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 knobs 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'' shows the first report of an alula or "bastard wing", which means it had a flight manoeuvrability analogous to that of modern birds. The date of the Las Hoyas age is constrained to Late Barremian by charophyte and ostracod assemblages.<ref>{{Cite web |title=Lyell Collection |url=https://www.lyellcollection.org/action/cookieAbsent |access-date=2026-05-07 |website=Lyell Collection |language=en |doi=10.1144/jgs2022-079}}</ref>
=== 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 and the National University of Distance Education, in collaboration with the Museo de las Ciencias de Castilla-La Mancha, which is responsible for the fossil record from the area.
== Fossil content == {{paleobiota-key-compact}}
=== Crustaceans === {| class="wikitable" align="center" |- ! colspan="7" align="center" | Crustaceans |- ! Genus ! Species ! Location ! Stratigraphic position ! Material ! Notes ! Images |- | ''Austropotamobius'' | ''A. llopisi'' | rowspan="6" | Las Hoyas | | rowspan="2" |Numerous specimens<ref name=":0">{{Cite journal |last1=Barrios-de Pedro |first1=Sandra |last2=Chin |first2=Karen |last3=Buscalioni |first3=Ángela D. |date=June 2020 |title=The late Barremian ecosystem of Las Hoyas sustained by fishes and shrimps as inferred from coprofabrics |url=https://linkinghub.elsevier.com/retrieve/pii/S0195667119304628 |journal=Cretaceous Research |language=en |volume=110 |article-number=104409 |doi=10.1016/j.cretres.2020.104409|bibcode=2020CrRes.11004409B |hdl=10486/695365 |s2cid=213738761 |hdl-access=free }}</ref> | A crayfish | |- |''Delclosia'' |''D. martinelli'' | |An atyid shrimp | |- |''Lahuerguinagrapta''<ref name=":1">{{Cite journal |last1=Gallego |first1=Oscar F. |last2=Monferran |first2=Mateo D. |last3=Zacarías |first3=Iracema A. |last4=Jiménez |first4=Victoria C. |last5=Buscalioni |first5=Angela D. |last6=Liao |first6=Huanyu |date=June 2020 |title=Clam shrimp fauna (Diplostraca-Spinicaudata and Estheriellina) from the Lower Cretaceous of Las Hoyas, Cuenca (Spain) |url=https://linkinghub.elsevier.com/retrieve/pii/S0195667119302721 |journal=Cretaceous Research |language=en |volume=110 |article-number=104389 |doi=10.1016/j.cretres.2020.104389|bibcode=2020CrRes.11004389G |s2cid=214213415 |url-access=subscription |hdl=11336/136132 |hdl-access=free }}</ref> |''L. multicostata'' | | |A clam shrimp belonging to the family Afrograptidae | |- |''Skyestheria''<ref name=":1" /> | rowspan="2" |Indeterminate | | |A clam shrimp belonging to the family Polygraptidae | |- |''Pseudestherites''<ref name=":1" /> | | |A clam shrimp belonging to the family Antronestheriidae | |- |''Spinogriphus'' <ref>{{Cite journal |last1=Jaume |first1=Damià |last2=Pinardo-Moya |first2=Eva |last3=Boxshall |first3=Geoff A. |date=January 2013 |title=A presumed spelaeogriphacean crustacean from an upper Barremian wetland (Las Hoyas; Lower Cretaceous; Central Spain) |journal=Palaeontology |language=en |volume=56 |issue=1 |pages=15–28 |doi=10.1111/j.1475-4983.2012.01144.x |bibcode=2013Palgy..56...15J |issn=0031-0239|doi-access=free }}</ref> |''S. ibericus'' | | |A member of Peracarida belonging to Spelaeogriphacea | |}
=== Chondrichthyes === {| class="wikitable" align="center" |- ! colspan="7" align="center" | Chondrichthyes |- ! Genus ! Species ! Location ! Stratigraphic position ! Material ! Notes ! Images |- | ''Lonchidion''<ref>{{Cite journal |last1=Marugán-Lobón |first1=Jesús |last2=Martín-Abad |first2=Hugo |last3=Buscalioni |first3=Ángela D. |date=2023-04-03 |title=The Las Hoyas Lagerstätte: a palaeontological view of an Early Cretaceous wetland |journal=Journal of the Geological Society |volume=180 |issue=3 |doi=10.1144/jgs2022-079 |issn=0016-7649|doi-access=free |hdl=10486/710760 |hdl-access=free }}</ref> | Indeterminate | Las Hoyas | |A full body impression of a juvenile | Hybodont | |}
=== Osteichthyes === {| class="wikitable" align="center" |- ! colspan="7" align="center" | Osteichthyes |- ! Genus ! Species ! Location ! Stratigraphic position ! Material ! Notes ! Images |- |''Caturus'' | ''Caturus'' sp. | Las Hoyas | | | Amiiformes | |- |''Gordichthys'' | ''G. conquensis'' | Las Hoyas | | | Gonorynchiform | |- |''Hispanamia''<ref>{{Cite journal |last1=MartÍn-Abad |first1=Hugo |last2=Poyato-Ariza |first2=Francisco JosÉ |date=2017-06-05 |title=A new genus and species for the amiiform fishes previously assigned to Amiopsis from the Early Cretaceous of Las Hoyas, Cuenca, Spain |journal=Zoological Journal of the Linnean Society |volume=181 |issue=3 |pages=604–637 |doi=10.1093/zoolinnean/zlx010 |issn=0024-4082|doi-access=free }}</ref> | ''H. newbreyi'' | Las Hoyas | | | Amiid, originally described as ''Amiopsis'' | |- |cf. "''Holophagus''"<ref>{{Cite journal |last1=Martín-Abad |first1=Hugo |last2=Martínez |first2=Marian Fregenal- |date=2021-12-02 |title=The ecology of the Lower Cretaceous coelacanths from Las Hoyas Konservat- Lagerstätte (Cuenca, Spain): A new insight after the integration of palaeontological and sedimentological data |url=https://ojs.uv.es/index.php/sjpalaeontology/article/view/21966 |journal=Spanish Journal of Palaeontology |language=en |volume=36 |issue=2 |pages=191–204 |doi=10.7203/sjp.36.2.21966 |issn=2660-9568|doi-access=free |hdl=10486/718757 |hdl-access=free }}</ref> | Indeterminate | Las Hoyas | | | Coelacanth | |- |''Hoyasotes'' | ''H. tanyrhis'' | Las Hoyas | | | rowspan="2" | Member of Lepidotidae, originally described as ''Lepidotes''<ref>{{Cite journal |last1=Paiva |first1=Hanna Carolina Lins de |last2=Gallo |first2=Valéria |date=2018-12-01 |title=Quasimodichthys gen. nov. (Neopterygii: Semionotiformes): A morphological and ontogenetic study |url=https://www.sciencedirect.com/science/article/pii/S0895981118301950 |journal=Journal of South American Earth Sciences |language=en |volume=88 |pages=132–143 |doi=10.1016/j.jsames.2018.08.010 |bibcode=2018JSAES..88..132P |s2cid=134986658 |issn=0895-9811|url-access=subscription }}</ref> | |- | ''Lepidohyas'' | ''L. microrhis'' | Las Hoyas | | | |- | ''Notagogus'' | ''N.'' aff. ''N. ferreri'' | Las Hoyas | | |Macrosemiid | |- | ''Pleuropholis'' | ''P.'' sp. | Las Hoyas | | | | |- | ''Propterus'' | ''P.'' sp. | Las Hoyas | | |Macrosemiid | |- | ''Rubiesichthys'' | ''R. gregalis'' | Las Hoyas | | | Gonorynchiform | |- | ''Stenamara'' | ''S. mia'' | Las Hoyas | | | rowspan="2" | Pycnodont | |- | ''Turbomesodon'' | ''T. praeclarus'' | Las Hoyas | | | |- |''Vidalamia'' | ''V.'' cf. ''catalunica'' | Las Hoyas | | | Amiid | |}
=== Amphibians === {| class="wikitable" align="center" |- ! colspan="7" align="center" | Amphibians |- ! Genus ! Species ! Location ! Stratigraphic position ! Material ! Notes ! Images |- | ''Albanerpeton'' | Indeterminate | Uña | | Frontals | rowspan="3" | Albanerpetontid | |- | rowspan="2" | ''Celtedens'' | ''C. ibericus'' | Las Hoyas | | |center|frameless |- | ''C. megacephalus'' | Uña | | | |- | ''Gracilibatrachus'' | ''G. avallei'' | Las Hoyas | | | Pipimorph frog | |- | ''Hylaeobatrachus'' | Indeterminate | Las Hoyas | | | Salamander | |- | ''Iberobatrachus'' | ''I. angelae'' | Las Hoyas | | | Frog | |- | ''Valdotriton'' | ''V. gracilis'' | Las Hoyas | | | Salamander | |- | ''Wealdenbatrachus'' | ''W. jucarensis'' | Uña | | | Frog | |}
=== Turtles === {| class="wikitable" align="center" |- ! colspan="7" align="center" | Turtles |- ! Genus ! Species ! Location ! Stratigraphic position ! Material ! Notes ! Images |- | ''Hoyasemys'' | ''H. jimenezi'' | Las Hoyas | | | align=center | A eucryptodire<ref>Pérez García et al., 2012</ref> | center|frameless |- | Pleurosternidae | Indeterminate | Uña | | | | |- | Pelomedusidae | Indeterminate | Uña | | | | |}
=== Squamates === {| class="wikitable" align="center" |- ! colspan="7" align="center" | Squamates |- ! Genus ! Species ! Location ! Stratigraphic position ! Material ! Notes ! Images |- | ''Becklesius'' | Indeterminate, ''B. cataphractus'' | Uña | | | Paramacellodid lizard | |- | ''Cuencasaurus'' | ''C. estesi'' | Uña | | | | |- | ''Hoyalacerta'' | ''H. sanzi'' | Las Hoyas | | | | |- | ''Jucaraseps'' | ''J. grandipes'' | Las Hoyas | | | Scleroglossa | |- | rowspan="2" | ''Meyasaurus'' | ''M. diazromerali'' | Las Hoyas | | | rowspan="2" | Teiioid lizard | |- | ''M. unaensis'' | Uña | | | |- | ''Paramacellodus'' | ''P. sinuosus'' | Uña | | | Paramacellodid lizard | |- | ''Scandensia'' | ''S. ciervensis'' | Las Hoyas | | | | |}
=== Mammals === {| class="wikitable" align="center" |- ! colspan="7" align="center" | Mammals |- ! Genus ! Species ! Location ! Stratigraphic position ! Material ! Notes ! Images |- | ''Crusafontia'' | ''C. cuencana'' | Uña | | | Dryolestid | |- | ''Eobaatar'' | ''E. hispanicus'' | Uña | | | Eobaatarid multituberculate | |- | ''Galveodon'' | ''G. nannothus'' | Uña | | | Paulchoffatiid multituberculate | |- | ''Spinolestes''<ref>Martin et al., 2015</ref> | ''S. xenarthrosus'' | Las Hoyas | | Exceptionally complete specimen, preserving soft tissues such as pelage, ears and internal organs. | Gobiconodont eutriconodont | |- |}
=== Crocodyliformes === {| class="wikitable" align="center" |- ! colspan="7" align="center" | Crocodyliformes |- ! Genus ! Species ! Location ! Stratigraphic position ! Material ! Notes ! Images |- | ''Bernissartia'' | Indeterminate | Uña | | | | center|150px |- | ''Cassissuchus'' | ''C. sanziuami'' | Las Hoyas | | | Gobiosuchid | |- | ''Montsecosuchus'' | Indeterminate | Las Hoyas | | | | center|150px |- | ''Sabresuchus'' | ''S.ibericus'' | Uña | | | | |- | ''Unasuchus'' | ''U. reginae'' | Uña | | | | |- | Bernissartiidae | Indeterminate | Las Hoyas | | | | |}
=== Ornithodirans === {| class="wikitable" align="center" |- ! colspan="7" align="center" | Ornithodirans |- ! Genus ! Species ! Location ! Stratigraphic position ! Material ! Notes ! Images |- | ''Concavenator'' | ''C. corcovatus'' | Las Hoyas | | "Nearly complete and articulated skeleton." | Carcharodontosaur dinosaur<ref name="Concadescription">Ortega et al., 2010</ref> | center|frameless |- | ''Concornis''<ref name="calizas">"15.9 Provincia de Quenca, Spain; 4. Calizas de La Huergina Formation," in Weishampel et al., 2004, pp.561-562</ref> | ''C. lacustris''<ref name="calizas" /> | Las Hoyas | | "Postcranial skeleton."<ref name="table-11-1-212">"Table 11.1," in Weishampel et al. , 2004, p.212</ref> |Enantiornithean bird | center|frameless |- | ''Eoalulavis''<ref name="calizas" /> | ''E. hoyasi''<ref name="calizas" /> | Las Hoyas | | "Thoracic region and forelimbs."<ref name="table-11-1-212" /> | Enantiornithean bird | center|frameless |- | ''Euronychodon''<ref name="euro">Listed as "cf. ''Euronychodon'' sp." in "15.9 Provincia de Quenca, Spain; 4. Calizas de La Huergina Formation," in Weishampel et al., 2004, p.561</ref> | Indeterminate | Las Hoyas | | | Theropod dinosaur | |- | ''Europejara'' | ''E. olcadesorum'' | Las Hoyas | | | Tapejarid pterosaur | center|150px |- |''Gorgonavis''<ref name="Gorgonavis">{{Cite journal|last1=Nebreda |first1=Sergio M. |last2=Chiappe |first2=Luis M. |last3=Navalón |first3=Guillermo |last4=Terol |first4=Javier C. |last5=Serrano |first5=Francisco J. |last6=Buscalioni |first6=Ángela D. |last7=Marugán-Lobón |first7=Jesús|title=An isolated skull from Las Hoyas (Early Cretaceous, Spain) informs the early evolution towards elongated rostra in enantiornithine birds (Aves, Ornithothoraces) |year=2026 |journal=Swiss Journal of Palaeontology |volume=145 |pages=251–265 |doi=10.3897/sjp.145.182813 |doi-access=free |issn=1664-2384}}</ref> |''G. alcyone'' |Las Hoyas | | Partial skull | Enantiornithean bird |frameless |- | ''Iberomesornis'' | ''I. romerali'' | Las Hoyas | | Postcranial skeleton | Enantiornithean bird<ref name="calizas" /><ref name="table-11-1-213">"Table 11.1," in Weishampel et al., 2004, p.213</ref> | center|150px |- | ''Mantellisaurus'' | ''M. atherfieldensis'' | Las Hoyas | | "incomplete but fully-articulated right hindlimb" | Iguanodontian dinosaur<ref>Serrano et al., 2013</ref> | center|frameless |- | ''Pelecanimimus'' | ''P. polyodon'' | Las Hoyas | | "Skull and partial skeleton" | Ornithomimosaurian dinosaur<ref name="calizas" /><ref name="table-6-1-138">"Table 6.1," in Weishampel et al., 2004, p.138</ref> | center|220x220px|frameless |- | ''Paronychodon''<ref name="paro">Listed as "cf. ''Paranychodon'' sp." in "15.9 Provincia de Quenca, Spain; 4. Calizas de La Huergina Formation," in Weishampel et al., 2004, p.561</ref> | Indeterminate | Las Hoyas | | | Theropod dinosaur | |- | ''Richardoestesia'' <ref name="ricard">Listed as "cf. ''Ricardoestesia'' sp." in "15.9 Provincia de Quenca, Spain; 4. Calizas de La Huergina Formation," in Weishampel et al., 2004, p.561</ref> | Indeterminate | Las Hoyas | | | Theropod dinosaur | |- |}
== Correlation == {{Early Cretaceous stratigraphy of Iberia}}
== See also == * List of dinosaur-bearing rock formations * Paja Formation, contemporaneous Lagerstätte of Colombia * Yixian Formation, contemporaneous Lagerstätte of China
{{clear}}
== References == {{Reflist}}
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== External links == * [http://www.yacimientolashoyas.es Las Hoyas site website] {{Webarchive|url=https://web.archive.org/web/20200222154655/http://www.yacimientolashoyas.es/ |date=2020-02-22 }}
{{DEFAULTSORT:Calizas De La Huergina Formation}} Category:La Huérguina Formation Category:Geologic formations of Spain Category:Lower Cretaceous Series of Europe Category:Cretaceous Spain Category:Limestone formations Category:Marl formations Category:Lacustrine deposits Category:Cretaceous paleontological sites of Europe Category:Paleontology in Spain Formations