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Blesa Formation
Blesa Formation
Stratigraphic range: Barremian PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Maestrazgo Basin
Sub-units	Upper Blesa Sequence - Valdejunco Member; Middle Blesa Sequence - Josa Member; Lower Blesa Sequence - Cabezo Gordo Member, Morenillo member;
Underlies	Alacón Formation
Overlies	Unconformity with Jurassic strata
Thickness	Up to 150 m
Lithology
Primary	Clay, Marl, Limestone
Other	Conglomerate
Location
Region	Europe
	; Distribution of the Belsa Formation within the Oliete Sub-Basin (in olive)

The Blesa Formation is a geological formation in Teruel and La Rioja, Spain whose strata date back to the Barremian of the Early Cretaceous.^[1] Dinosaur remains as well as eggs^[2] are among the fossils that have been recovered from the formation.^[3] Along with the fragmentary anhanguerian pterosaur Iberodactylus.^[4] While the lower and upper parts of the formation were deposited in a continental setting, the middle portion of the formation is largely nearshore marine, with remains of plesiosaurs.

Stratigraphy and Lithology

The Belsa Formation is found within the Maestrazgo Basin. Within the stratigraphic sequence it overlies Jurassic rocks in a syn-rift unconformity, and underlies the Alacón Formation.

The formation is up to 150 metres thick and is divided into three distinct unconformity bounded units, which are called the Lower, Middle and Upper Blesa Sequences. The Lower Blesa sequence varies greatly in thickness from less than 10 m up to 100 m is divided up into two members, the lower Cabezo Gordo Member, which consists of red clays and the upper Morenillo Member, which consists of limestones and marls, both of these sequences were deposited in a continental setting. The Middle Blesa Sequence is of a fairly uniform 25-50 metre thickness. Most of the sequence consists of the Josa Member, which consists of oyster rich marls and limestones deposited in a coastal or shallow restricted bay environment. The Upper Blesa Sequence is of variable thickness from 15–70 m. The lower 1–10 m consists of continentally derived clays and marls with sandstone and conglomerate intercalations while the upper 10–60 m are dominated by carbonates.^[1]

Vertebrate paleofauna

Reptiles

Reptiles of the Blesa Formation
Taxa	Species	Presence	Material	Notes	Images
Iguanodontia	Indeterminate	Lower Blesa Sequence		3 distinct taxa, one of which has affinities with Delapparentia^[1]
Iguanodontia	Unnamed	Upper Blesa Sequence		"Vertebrae, ribs, left illium, partial sacrum, and partial left tibia."^[5]
Ankylosauria	Indeterminate	Lower Blesa Sequence	"Isolated teeth, dermal plates and vertebra"
Spinosauridae	Indeterminate	Lower, Upper Blesa Sequence	Isolated Teeth
Dromaeosauridae	Indeterminate	Lower Blesa Sequence	Isolated Teeth
?Carcharodontosauridae	Indeterminate	Lower, Upper Blesa Sequence	Isolated Teeth
Euhelopidae	Indeterminate	Lower Blesa Sequence	Isolated Teeth
Sauropoda	Indeterminate	Lower Blesa Sequence, La Cantalera-1	Post-cranial material
Crocodylomorpha	Indeterminate	Lower Blesa Sequence		Possibly four distinct taxa
Plesiosauria	Indeterminate	Middle Blesa Sequence

Pterosaurs

Pterosaurs of the Blesa Formation
Taxa	Species	Presence	Material	Notes	Images
Istiodactylidae	Indeterminate	Lower Blesa Sequence	Isolated Teeth
Ornithocheiridae	Indeterminate	Lower Blesa Sequence	Isolated Teeth
Iberodactylus	I. andreui	Middle Blesa Sequence	Partial skull

Mammals

Mammals of the Blesa Formation
Taxa	Species	Presence	Material	Notes	Images
Cantalera	C. abadi	Lower Blesa Sequence	Teeth	Pinheirodontid
Eobataar	Indeterminate	Lower Blesa Sequence	Teeth

Correlation

Early Cretaceous stratigraphy of Iberia
Ma	Age	Paleomap \ Basins	Cantabrian	Olanyà	Cameros	Maestrazgo	Oliete	Galve	Morella	South Iberian	Pre-betic	Lusitanian
100	Cenomanian		La Cabana	Sopeira	Utrillas		Mosquerela					Caranguejeira
			Altamira		Utrillas
			Eguino
125	Albian		Ullaga - Balmaseda	Lluçà						Traiguera
			Monte Grande		Escucha		Escucha			Jijona
			Itxina - Miono		Escucha
	Aptian		Valmaseda - Tellamendi		Ol Gp. - Castrillo	Benassal		Benassal				Olhos
			Valmaseda - Tellamendi	Font	En Gp. - Leza	Morella/Oliete	Oliete	Villaroya	Morella	Capas Rojas		Almargem
			Patrocinio - Ernaga	Senyús	En Gp. - Jubela	Forcall				Villaroya	Upper Bedoulian	Figueira
	Barremian		Vega de Pas	Cabó	Abejar	Xert	Alacón	Xert		Huérguina	Upper Bedoulian	Assises
				Prada	Abejar	Artoles				Collado	Moutonianum	Papo Seco
				Rúbies	Tera Gp. - Golmayo	Alacón/Blesa	Blesa	Camarillas	Mirambel	Collado	Moutonianum	Papo Seco
150	Hauterivian				Ur Gp. - Pinilla	Llacova	Blesa	Castellar	Tera Gp. - Pinilla	Villares		Porto da Calada
						Llacova	hiatus			Villares
						Huerva			Gaita
	Valanginian		Villaro		Ur Gp. - Larriba				Ped Gp. - Hortigüela
					Ped Gp. - Hortigüela				Ped Gp. - Piedrahita
					Peñacoba			Galve		Miravetes
	Berriasian		Cab Gp. - Arcera		Valdeprado	hiatus		Alfambra		Miravetes
					TdL Gp. - Rupelo			Arzobispo	hiatus	Tollo
					On Gp. - Huérteles Sierra Matute			Arzobispo		Tollo
	Tithonian		Lastres		Tera Gp. - Magaña		Higuereles			Tera Gp. - Magaña		Lourinhã
					Tera Gp. - Magaña				Arzobispo
					Ágreda				Arzobispo
Legend		Major fossiliferous, oofossiliferous, ichnofossiliferous, coproliferous, minor formation
Sources

References

^ ^a ^b ^c Aurell, M.; Soria, A. R.; Bádenas, B.; Liesa, C. L.; Canudo, J. I.; Gasca, J. M.; Moreno-Azanza, M.; Medrano-Aguado, E.; Meléndez, A. (June 2018). "Barremian synrift sedimentation in the Oliete sub-basin (Iberian Basin, Spain): palaeogeographical evolution and distribution of vertebrate remains". Journal of Iberian Geology. 44 (2): 285–308. Bibcode:2018JIbG...44..285A. doi:10.1007/s41513-018-0057-3. S2CID 134667628.
^ Moreno-Azanza, Miguel; Canudo, José Ignacio; Gasca, José Manuel (September 2014). "Spheroolithid eggshells in the Lower Cretaceous of Europe. Implications for eggshell evolution in ornithischian dinosaurs". Cretaceous Research. 51: 75–87. Bibcode:2014CrRes..51...75M. doi:10.1016/j.cretres.2014.05.017.
^ Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Cretaceous, Europe)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. p. 561. ISBN 0-520-24209-2.
^ Holgado, Borja; Pêgas, Rodrigo V.; Canudo, José Ignacio; Fortuny, Josep; Rodrigues, Taissa; Company, Julio; Kellner, Alexander W. A. (December 2019). "On a new crested pterodactyloid from the Early Cretaceous of the Iberian Peninsula and the radiation of the clade Anhangueria". Scientific Reports. 9 (1): 4940. Bibcode:2019NatSR...9.4940H. doi:10.1038/s41598-019-41280-4. PMC 6426928. PMID 30894614. {{cite journal}}: |last6= has generic name (help)
^ Medrano-Aguado, E.; Parrilla-Bel, J.; Gasca, J.M.; Alonso, A.; Canudo, J.I. (April 2023). "Ornithopod diversity in the Lower Cretaceous of Spain: New styracosternan remains from the Barremian of the Maestrazgo Basin (Teruel province, Spain)". Cretaceous Research. 144: 105458. Bibcode:2023CrRes.14405458M. doi:10.1016/j.cretres.2022.105458.