Earth:Paja Formation

Short description: Early Cretaceous geologic formation of central Colombia

Paja Formation Stratigraphic range: Late Hauterivian-Late Aptian ~130–113 Ma PreЄ Є O S D C P T J K Pg N
Desmatochelys padillai from the Paja Formation
Type	Geological formation
Sub-units	Lutitas Negras Inferiores, Arcillolitas Abigarradas & Arcillolitas con Nódulos Huecos Members
Underlies	San Gil Group, Simití & Tablazo Formations
Overlies	Ritoque & Rosablanca Formations
Area	450 km (280 mi)
Thickness	up to 940 m (3,080 ft)
Lithology
Primary	Black shale, claystone, sandstone and limestone concretions
Other	Gypsum, chalcopyrite, galena, malachite, pyrite, sphalerite
Location
Coordinates
Paleocoordinates	[ ⚑ ] 3.7°N 42.2°W / 3.7; -42.2
Region	Bolívar, Boyacá, Cundinamarca & Santander
Country	Colombia
Extent	Altiplano Cundiboyacense Eastern Ranges, Andes Middle Magdalena Valley
Type section
Named for	Quebrada La Paja
Named by	Wheeler
Year defined	1929?
Coordinates	[ ⚑ ] 7°01′33.4″N 73°19′27.8″W
Region	Betulia, Santander
Thickness at type section	625 m (2,051 ft)
Outcrops of the Paja Formation near Villa de Leyva

The Paja Formation (Spanish: Formación Paja, K1p, Kip, Kimp, b3b6p) is an Early Cretaceous geologic formation of central Colombia. The formation extends across the northern part of the Altiplano Cundiboyacense, the Western Colombian emerald belt and surrounding areas of the Eastern Ranges of the Colombian Andes. In the subsurface, the formation is found in the Middle Magdalena Valley to the west. The Paja Formation stretches across four departments, from north to south the southernmost Bolívar Department, in Santander, Boyacá and the northern part of Cundinamarca. Well known fossiliferous outcrops of the formation occur near Villa de Leyva, also written as Villa de Leiva, and neighboring Sáchica.

The formation was named after Quebrada La Paja in Betulia, Santander, and stretches across 450 kilometres (280 mi) from northeast to southwest. The Paja Formation overlies the Ritoque and Rosablanca Formations and is overlain by the San Gil Group and the Simití and Tablazo Formations and dates from the late Hauterivian to late Aptian. The Paja Formation comprises mudstones, shales and nodules of sandstones and limestones, deposited in an anoxic environment, in the warm and shallow sea that covered large parts of the present Colombian territory during the Cretaceous.

Initially considered to host Colombian emeralds, the emerald-bearing part was redefined as a separate formation; the Muzo Formation. The Paja Formation Lagerstätte is famous for its vertebrate fossils and is the richest Mesozoic fossiliferous formation of Colombia. Several marine reptile fossils of plesiosaurs, pliosaurs, ichthyosauras and turtles have been described from the formation and it hosts the only dinosaur fossils described in the country to date; Padillasaurus. The formation also has provided many ammonites, fossil flora, decapods and the fossil shark Protolamna ricaurtei.

Description

The Paja Formation was first described by O.C. Wheeler, according to Morales (1958), and named after Quebrada La Paja, a tributary of the Sogamoso River. The type section is exposed on the northern banks of the quebrada at the confluence of the Sogamoso River in Betulia, Santander.

The formation is divided into the Lutitas Negras Inferiores, Arcillolitas Abigarradas and Arcillolitas con Nódulos Huecos Members, and stretches across 450 kilometres (280 mi) from northeast to southwest. The Paja Formation overlies the Ritoque and Rosablanca Formations and is overlain by the Simití and Tablazo Formations and dates from the Hauterivian to Late Aptian.

Outcrops

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Type locality of the Paja Formation in Santander

The type section of the Paja Formation is found at the banks of Quebrada La Paja in Betulia, Santander, where the formation has a thickness of 625 metres (2,051 ft). Outcrops of the formation extend from Simití in the north, close to the border of Santander and Bolívar, where the formation is offset by the Simití Fault, to the Pauna Anticlinal in San Pablo de Borbur, where the formation is thrusted over the Ritoque Formation in the south. In the southern extension of the exposures, the formation crops out in the north of Tununguá, near the Ibacapí Fault.

Santander

In the Middle Magdalena Valley, south of Barrancabermeja, the Paja Formation in the subsurface is offset by the Casabe, Infantas and Arruga Faults. In the northeastern extent, in Río Negro, near the border with Norte de Santander, the formation is found in the subsurface, offset by the Lebríja Fault. The town center of Zapatoca rests on the formation in the synclinal named after the village. The Paja Formation also crops out in the northwestern part of the Middle Magdalena Valley, east of San Pablo, Bolívar, where in the formation underlies the Simití Formation and is offset in the subsurface by the Pozo Azul and Caña Braval Faults. South of there, the Paja Formation is offset by the La Corcovada and El Guineal Faults, and the regional La Salina Fault. Near the eponymous town, the formation is offset by the Landazurí Fault.

West of Barichara, the formation underlies the corregimiento Guane, Barichara (es) and is found in the hills bordering both sides of the Suárez River. In this area, the Paja Formation is offset by the Suárez Fault. Surrounding Jordán, Santander, the formation crops out on both sides of the Chicamocha River in the Chicamocha Canyon. The touristic town San Gil rests on the formation and the Fonce River cuts into it. East of the town center, the formation is offset by the Curití and Ocamonte Faults. The urban centers of Oiba, San Benito, Encino, Ocamonte and Charalá are built on top of the Paja Formation. In this area, the formation is offset by the Confines and Encino Faults. Further to the south, the towns of Vélez, Guavatá and Jesús María rest on the formation. West of the latter, the Paja Formation is put in a reverse faulted contact with the Cumbre Formation. The El Carmen Fault puts the Paja Formation in contact with the Jurassic Girón Formation.

Boyacá

In northeastern Boyacá, the formation underlies the urban center of Moniquirá (not to be confused with Monquirá, a vereda of nearby Villa de Leyva) and is crossed by the Moniquirá River. West of Arcabuco in the Villa de Leyva Synclinal, the formation is cut by the Arcabuco River. In the vicinity of Pauna and San Pablo de Borbur, the formation crops out in an extensive area. Here, the Paja Formation is offset by the Río Minero and Pedro Gómez Faults and occurs in the footwall of the La Venta Fault. North of Lake Fúquene, the town centers of Tinjacá and Sutamarchán are built on top of the Paja Formation. In this area, the formation extends into the northern part of Cundinamarca, where the urban centers of Yacopí and La Palma rest on the formation.

Villa de Leyva

Surrounding the touristic town of Villa de Leyva, the formation crops out in the hills in a microclimatic location, known as the La Candelaria Desert (Spanish: Desierto de La Candelaria), stretching across Villa de Leyva, Santa Sofía and Sáchica. Along the highway Tunja-Villa de Leyva, the formation is heavily folded and faulted along a stretch of 500 metres (1,600 ft). In the vicinity of Villa de Leyva, the formation has provided many fossils of marine reptiles, as well as the dinosaur Padillasaurus.

Stratigraphy

Stratigraphic column of the Paja Formation with Sachicasaurus site indicated

The Paja Formation overlies the Ritoque and Rosablanca Formations and is concordantly overlain by the San Gil Group and Tablazo Formations in the eastern extent, and the Simití Formation in the northwestern Middle Magdalena Valley. In the Western emerald belt, the contact with the Rosablanca Formation is concordant and abrupt. The total thickness of the formation varies across its extent, but can reach up to 940 metres (3,080 ft).

Members

The Paja Formation is subdivided into three members, from oldest to youngest:

• Lutitas Negras Inferiores (Lower Black Shales) – a sequence of 340 metres (1,120 ft) of black shales and sandy shales with a segment containing calcareous nodules. The age of this member is estimated at late Hauterivian, based on ammonites analyzed by Fernando Etayo.
• Arcillolitas Abigarradas (Mottled Claystones) – a series of multicolored claystones with abundant calcareous fossiliferous nodules, reaching a thickness of 480 metres (1,570 ft). In the upper 235 metres (771 ft) of this member, intercalations of gypsum occur. The age of the middle member of the Paja Formation is estimated at early Barremian to late Aptian on the basis of ammonites described by Fernando Etayo.
• Arcillolitas con Nódulos Huecos (Claystones with Hollow Nodules) – the upper member of the formation of approximately 174 metres (571 ft) thick consists of yellowish and grey claystones containing hollow nodules. Ammonite analysis has led to an estimated late Aptian age for the member.

In the northern part of the Middle Magdalena Valley, the Paja Formation comprises dark grey to blueish shales, intercalated with grey to yellowish fine-grained sandstones and fossiliferous limestones, locally with a sandy component. Bürgl in 1954 reported beds of tuff in the Paja Formation near Villa de Leyva. Thin section analysis of samples of the Paja Formation has provided insight in the micritic components of the sediments, where three microfacies were recognized; biomicritic wackestones, foraminiferous packstones and sandy biomicritic floatstones containing fragments of echinoderms, bivalves, crinoids and gastropods cemented by hematite.

The Paja Formation correlates with the Tibasosa Formation to the east on the northern Altiplano Cundiboyacense in Boyacá and with the El Peñón Formation pertaining to the Villeta Group to the south in the Eastern Ranges. The formation is laterally equivalent with the black shales of the Fómeque Formation in the eastern part of the Eastern Ranges and the sandstones of Las Juntas Formation in the Sierra Nevada del Cocuy. In the Middle Magdalena Valley to the west, the formation partly overlies and partly is laterally equivalent to the limestones of the Rosablanca Formation. The Paja Formation is diachronous with the Ritoque and Rosablanca Formations. To the northeast of the extent of the formation, it correlates with the upper part of the Río Negro Formation, and the lowermost Tibú-Mercedes Formation of the Catatumbo Basin.

Paleogeography

Paleogeography of northern South America during the Barremian and early Aptian

During deposition of the Paja Formation, the paleo coastline was oriented west-east.

From the late Aptian to early Albian, the area was covered by an extensive carbonate platform, in the extent of the Paja Formation represented by the San Gil Group, Tablazo Formation and Villeta Group.

Depositional environment

The thin section analysis led to the interpretation of a shoreface to lower shoreface environment, in the internal parts of a carbonate platform, where transgressions and regressions caused the variations in grain sizes and lithologies. The Barremian to Aptian sequence shows evidence of an overall relative sea level fall with open marine sedimentation in the lowest member and tidal deposits in the upper part of the formation.

One of the longest anoxic intervals of geologic history occurred during the Cretaceous, from about 125 to 80 Ma (early Aptian to early Campanian). During this Oceanic Anoxic Event, there were two spikes, the Selli event, dating to the early Aptian (approximately 120 Ma) was active during deposition of the black shales of the Paja Formation. The formation contains three spikes of δ¹³C, with values above 1.5‰, in the lower, middle to upper and upper Paja Formation. These spikes indicate a global change in the carbon cycle and the preservation of organic matter due to poor oxygenation of sea waters. The cause of these elevated δ¹³C levels may have been a global increase in volcanic activity.

Mining and petroleum geology

The Paja Formation is one of the stratigraphic units cropping out in the Western emerald belt. Mineralization in the formation has been dated on the basis of ⁴⁰Ar/³⁹Ar analysis of muscovite minerals. In western San Pablo de Borbur, Boyacá, the mineralization dates to the Late Eocene at 36.4 ± 0.1 and 37.3 ± 0.1 Ma. In the northwestern part of Muzo, Boyacá, mineralization happened during the Early Oligocene, at 31.4 ± 0.3 Ma. Previous geologic researchers considered the Paja Formation hosted emeralds, and later definition of the stratigraphy of Colombia separated one of the main emerald formations of Colombia as the contemporaneous Barremian Muzo Formation, providing emeralds in the La Pita mine and important Coscuéz mine.

The Paja Formation is known for its gypsum deposits, which are mined and restricted to Santander. Near Guavatá, the formation hosts sphalerite and malachite and near Otanche, pyrite and galena are found in the formation. In Gámbita, the Paja Formation contains pyrite, galena and chalcopyrite. Other minerals occurring in the Paja Formation, are lead and zinc, around Paime and Yacopí, Cundinamarca.

The Paja Formation is considered a minor source rock in the Eastern Cordillera Basin and the Middle Magdalena Valley, with seal capacity for the underlying Rosablanca Formation reservoir in the latter basin. Vitrinite reflectance analysis on samples of the Paja Formation indicate an average value of 0.52 Ro, making the formation a marginal source rock.

Paleontological significance

Gondava Dinosaur Park

The Paja Formation is the richest Mesozoic fossiliferous formation of Colombia. Fauna of dinosaurs, Padillasaurus, and various marine reptiles, among which plesiosaurs, ichthyosaurs, pliosaurs and turtles make up the vertebrate assemblage. Furthermore, many ammonites, the foraminifer Epistomina, decapods, flora and fossil fish have been recovered from the formation. Paja ammonites have been used in the walls and floor of the Convento del Santo Ecce Homo (es) near Villa de Leyva.

In 2019, turtle expert Edwin Cadena described a fossil of Desmatochelys padillai who was found with her eggs still inside her.

Within the Arcillolitas Abigarradas Member of the Paja Formation, some horizons preserve abundant wood, which is frequently bored by pseudoplanktonic pholadoid bivalves, commonly referred to as "shipworms" or "piddocks". The presence of wood boring bivalves in Paja Formation seas indicates the continued presence of xylic substrates, and long residence time of floating wood.

The paleontological richness of the formation led to the establishment of a center of investigation; Centro de Investigaciones Paleontológicas (es) (CIP), two museums; Paleontological Museum of Villa de Leyva (es), and Museo El Fósil, and a dinosaur park; Gondava, near Villa de Leyva.

IUGS geological heritage site

In respect of the 'world's most complete record of Lower Cretaceous marine reptiles and associated fauna', the International Union of Geological Sciences (IUGS) included the 'Marine Reptile Lagerstätte from the Lower Cretaceous of the Ricaurte Alto' in its assemblage of 100 'geological heritage sites' around the world in a listing published in October 2022. The organisation defines an IUGS Geological Heritage Site as 'a key place with geological elements and/or processes of international scientific relevance, used as a reference, and/or with a substantial contribution to the development of geological sciences through history.'

Fossil content

Reptiles

Reptiles of the Paja Formation
Genus	Species	Location	Member	Description	Notes	Image
Acostasaurus	A. pavachoquensis		Arcillolitas abigarradas	A pliosaurid with short snout, likely not a brachauchenine
Callawayasaurus	C. colombiensis	Loma La Catalina	Arcillolitas abigarradas	An elasmosaurid plesiosaur, originally classified in Alzadasaurus
Desmatochelys	D. padillai	Loma de Monsalve Loma La Catalina	Arcillolitas abigarradas	A species of the genus Desmatochelys, sea turtles that belongs to the extinct family Protostegidae. Is the oldest known sea turtle, and a specimen was found with eggs still inside her.
Monquirasaurus	M. boyacensis	Vereda Monquirá	Arcillolitas abigarradas	A large pliosaurid, initially named "Kronosaurus boyacensis"
Leyvachelys	L. cipadi	Loma La Catalina	Arcillolitas abigarradas	A durophagous turtle member of the Sandownidae; is the first record for this group in South America. This species occurs too in the Glen Rose Formation in USA
Leivanectes	L. bernadoi		Arcillolitas abigarradas	An elasmosaurid plesiosaur
Muiscasaurus	M. catheti	Vereda Llanitos	Arcillolitas abigarradas	An ophthalmosaurid ichthyosaur, that it seems have occupied a different ecological niche respect to P. sachicarum
Padillasaurus	P. leivaensis	La Tordolla	Arcillolitas abigarradas	A brachiosaurid dinosaur, that makes the first record of a terrestrial animal in the area, and the first Cretaceous brachiosaurid known outside from North America
Kyhytysuka	K. sachicarum	Sáchica	Arcillolitas abigarradas	A platypterygiine ichthyosaur, relative of P. americanum
Sachicasaurus	S. vitae	Sáchica	Arcillolitas abigarradas	A 10 metres (33 ft) subadult pliosaur
Stenorhynchosaurus	S. munozi	Loma La Cabrera	Arcillolitas abigarradas	A small pliosaurid, over 3 meters in length. Formerly considered as a close relative of Brachauchenius lucasi from North America
Teleosauroidea gen. indet.	species indet.		Arcillolitas abigarradas Mb.	Fossils of a member of Teleosauroidea with an estimated body length of 9.6 m, representing the most recent definitive record of Teleosauroidea reported

Ammonites

Ammonites of the Paja Formation in the floor of Convento del Santo Ecce Homo

Centro de Investigaciones Paleontológicas

Ammonite in concretion in the Museo Paleontológico de Villa de Leyva

Septarian concretions in the museum

Ammonites of the Paja Formation
Species	Images	Notes
Acanthoptychoceras trumpyi
Ancycloceras vandenheckii
Ancycloceras vandenheckii velezianum
Buergliceras buerglii
Colchidites breistrofferi
Crioceratites emerici
Crioceratites leivaensis
Crioceratites tener
Hamiticeras chipatai
Hamiticeras pilsbryi
Hamulinites munieri
Karsteniceras beyrichi
Karsteniceras multicostatum
Monsalveiceras monsalvense
Nicklesia pulcella
Pariacrioceras barremense
Pedioceras asymmetricum
Pedioceras caquesense
Protanisoceras creutzbergi
Pseudoaustraliceras columbiae
Pseudoaustraliceras pavlowi
Pseudoaustraliceras ramososeptatum
Pseudocrioceras anthulai
Ptychoceras puzosianum
Tonohamites koeneni
Criceratites sp.
Pedioceras sp.
Acanthohoplites
Acrioceras julivertii
Colchidites apolinarii
Crioceratites portarum
Favrella colombiana
Heinzia (Gerhardtia) veleziensis
Nicklesia didayana didayana
Nicklesia didayana multifida
Nicklesia dumasiana
Nicklesia nolani
Olcostephanus boussingaultii
Parasaynoceras horridum
Pseudohaploceras incertum
Psilotissotia colombiana
Pulchellia galeata
Dufrenoyia sp.
Valdedorsella sp.

Crustaceans

Crustaceans of the Paja Formation
Species	Image	Notes
Bellcarcinus aptiensis
Colombicarcinus laevis
Notopocorystes kerri
Planocarcinus olssoni
Telamonocarcinus antiquus

Flora

Flora of the Paja Formation
Species	Image	Notes
Frenelopsis cf. ramosissima
Pseudofrenelopsis sp.

Fish

• Protolamna ricaurtei
• Vinctifer sp.
• Ichthyodectidae

Ichnofossils

• Teredolites clavatus

Regional correlations

Panorama

Panorama of the Chicamocha Canyon, from bottom to top; Jurassic Jordán and Girón Formations, and the Cretaceous Rosablanca and Paja Formations

See also

• Plesiosaur stratigraphic distribution
• Floresta Formation, Devonian fossiliferous formation of the Altiplano Cundiboyacense
• Cerrejón Formation, Paleocene fossiliferous formation of northeastern Colombia
• Honda Group, Miocene Lagerstätte of the Upper Magdalena Valley
• La Amarga Formation, contemporaneous fossiliferous formation of the Neuquén Basin in Argentina
• Cerro Barcino Formation, contemporaneous fossiliferous formation of the Cañadón Asfalto Basin in Argentina
• Río Belgrano Formation, contemporaneous fossiliferous formation of the Austral Basin in Argentina
• Camarillas Formation, contemporaneous fossiliferous formation of the Galve Basin in Spain

References

Bibliography

Geology

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• Gaona Narváez, T.; J.M.M. Florentin, and F. Etayo Serna. 2013. Geochemistry, palaeoenvironments and timing of Aptian organic-rich beds of the Paja Formation (Curití, Eastern Cordillera, Colombia). Geological Society, London, Special Publications 382. 31–48. Accessed 2019-03-12.
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Paleontology

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• Noé, Leslie; Paula Ordóñez Pérez; Luisa Rengifo Cajias, and Marcela Gómez Pérez. 2018. Lower Cretaceous marine boring bivalves, from the Paja Formation Lagerstätte of central Colombia, northern South America, 1. 5th International Palaeontological Congress, Paris. Accessed 2019-03-29.
• Páramo Fonseca, María Euridice; Cristian David Benavides Cabra, and Ingry Esmirna Gutiérrez. 2018. A new late Aptian elasmosaurid from the Paja Formation, Villa de Leiva, Colombia. Earth Sciences Research Journal 22. 223–238. Accessed 2019-10-12.
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• Chaparro Vargas, León F.; Oscar M. León Sánchez, and Arley de J. Gómez Cruz. 2015. Ocurrencia de Teredolites clavatus (Leymerie, 1842) en la Formación Paja (Aptiano) de Colombia, 1–2. Colonia del Sacramento, Uruguay, III Simposio Latinoamericano de Icnología. Accessed 2019-03-12.
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• Luque, Javier. 2014. A new genus and species of raninoidian crab (Decapoda, Brachyura) from the Lower Cretaceous of Colombia, South America. Scripta Geologica 147. 27–34. Accessed 2019-03-12.
• Luque, Javier; Rodney M. Feldmann; Carrie E. Schweitzer; Carlos Jaramillo, and Christopher B. Cameron. 2012. The oldest frog crabs (Decapoda: Brachyura: Raninoida) from the Aptian of northern South America. Journal of Crustacean Biology 32. 405–420. Accessed 2019-03-12.
• Patarroyo Camargo, Germán David; Pedro Patarroyo, and Carlos Alberto Sánchez Quiñónez. 2009. Foraminíferos bentónicos en el Barremiano inferior de la Formación Paja (Boyacá-Santander, Colombia): Evidencias preliminares de un posible bioevento – Lower Barremian benthic foraminifera on the Paja Formation (BoyacáSantander, Colombia): Preliminary evidences from a possible bioevent. Geología Colombiana 34. 111–122. Accessed 2019-03-12.
• Patarroyo, Pedro. 2009. Amonitas de un nivel de alta energía del Barremiano inferior en la Formación Paja de los sectores de Villa de Leyva (Boyacá) y Vélez (Santander). Boletín de Geología 31. 15–21. Accessed 2019-03-12.
• Moreno Sánchez, M.; A. de J. Gómez Cruz, and H. Castillo González. 2007. Frenelopsis y Pseudofrenelopsis (Coniferales: Cheirolepidiaceae) en el Cretácico temprano de Colombia. Boletín de Geología 29. 13–19. Accessed 2019-03-12.
• Hampe, Oliver. 2005. Considerations on a Brachauchenius skeleton (Pliosauroidea) from the lower Paja Formation (late Barremian) of Villa de Leyva area (Colombia). Mitteilungen aus dem Museum für Naturkunde in Berlin, Geowissenschaftliche Reihe 8. 37–51. Accessed 2019-03-12.
• Patarroyo, Pedro. 2000. Distribución de Amonitas del Barremiano de la Formación Paja en el Sector de Villa de Leyva (Boyacá, Colombia). Bioestratigrafía. Geología Colombiana 25. 149–162. Accessed 2019-03-12.
• Páramo, María E. 1998. Platypterygius sachicarum (Reptilia, Ichthyosauria) nueva especie del Cretácico de Colombia. Revista INGEOMINAS 6. 1–12.
• Kakabadze, Mikheil V., and Philip J. Hoedemaeker. 1997. New and less known Barremian-Albian ammonites from Colombia. Scripta Geologica 114. 57–117. Accessed 2019-03-12.
• Hampe, O. 1992. Ein großwüchsiger Pliosauride (Reptilia:Plesiosauria) aus der Unterkreide (oberes Aptium) von Kolumbien. Courier Forschungsinstitut Senckenberg 145. 1–32.
• Acosta, C.E.; G. Huertas, and P.M. Ruiz. 1979. Noticia preliminar sobre el hallazgo de un presunto Kronosaurus (Reptilia: Dolichorhynchopidae) en el Aptiano superior de Villa de Leiva, Colombia. Lozania (Acta Zoologica Colombiana) 28. 1–7.
• Etayo Serna, Fernando. 1968a. El Sistema Cretáceo en la región de Villa de Leiva y zonas próximas. Geología Colombiana 5. 5–74. Accessed 2019-03-12.
• Etayo Serna, Fernando. 1968b. Apuntaciones acerca de algunas amonitas interesantes del Hauteriviano y del Barremiano de la region de Villa de Leiva (Boyaca, Colombia, S.A.) – Hauterivian and Barremian ammonites from the Villa de Leiva region (Boyaca, Colombia, South America). Boletín de Geología 24. 51–70. Accessed 2019-03-12.
• Welles, S.P. 1962. A new species of elasmosaur from the Aptian of Colombia and a review of the Cretaceous plesiosaurs. University of California Publications in Geological Sciences 44. 1–96.

Maps

• Bernal Vargas, Luis Enrique, and Luis Carlos Mantilla Figueroa. 2006. Plancha 85 – Simití – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Bernal Vargas, Luis Enrique, and Luis Carlos Mantilla Figueroa. 2006. Plancha 96 – Bocas del Rosario – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Vargas, Rodrigo, and Alfonso Arias. 2009. Plancha 97 – Cáchira – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Beltrán, Alejandro, and Claudia I. Quintero. 2008. Plancha 119 – Barrancabermeja – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Ward, Dwight E.; Richard Goldsmith; Andrés Jimeno; Jaime Cruz; Hernán Restrepo, and Eduardo Gómez. 2010. Plancha 120 – Bucaramanga – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Beltrán, Alejandro; José Alfredo Lancheros; Carolina López; Claudia Chaquea; Alejandro Patiño; Angela Guerra; Julio C. Cabrera; Claudia I. Quintero, and Simón Emilio Molano. 2008. Plancha 134 – Puerto Parra – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Angarita, Leonidas; Víctor Carrillo; Alfonso Castro; Rommel Daconte; Mario Niño; Orlando G. Pulido; J. Antonio Rodríguez; José María Royero, and Rosalba Salinas, Carlos Ulloa and Rodrigo Vargas. 2009. Plancha 135 – San Gil – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Beltrán, Alejandro; José Alfredo Lancheros; Carolina López; Claudia Chaquea; Alejandro Patiño; Angela Guerra; Julio C. Cabrera; Claudia I. Quintero, and Simón Emilio Molano. 2008. Plancha 149 – Puerto Serviez – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Beltrán, Alejandro; José Alfredo Lancheros; Carolina López; Claudia Chaquea; Alejandro Patiño; Angela Guerra; Julio C. Cabrera; Claudia I. Quintero, and Simón Emilio Molano. 2008. Plancha 150 – Cimitarra – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Pulido González, Orlando. 2009. Plancha 151 – Charalá – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Ulloa, Carlos E, and Erasmo Rodríguez. 2009. Plancha 170 – Vélez – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Renzoni, Giancarlo, and Humberto Rosas. 2009. Plancha 171 – Duitama – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Fuquen M., Jaime A, and José F. Osorno M. 2009. Plancha 190 – Chiquinquirá – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Renzoni, Giancarlo; Humberto Rosas, and Fernando Etayo Serna. 1998. Plancha 191 – Tunja – 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.

External links

• (in Spanish) Leyvachelys cipadi, una nueva especie de tortuga sandownidae del Cretácico inferior de Colombia
• (in Spanish) Brachauchenius, un superpredador de los mares cretácicos