Earth:Paja Formation

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Short description: Early Cretaceous geologic formation of central Colombia
Paja Formation
Stratigraphic range: Late Hauterivian-Late Aptian
~130–113 Ma
Desmatochelys padillai Colombia.jpg
Desmatochelys padillai from the Paja Formation
TypeGeological formation
Sub-unitsLutitas Negras Inferiores, Arcillolitas Abigarradas & Arcillolitas con Nódulos Huecos Members
UnderliesSan Gil Group, Simití & Tablazo Formations
OverliesRitoque & Rosablanca Formations
Area450 km (280 mi)
Thicknessup to 940 m (3,080 ft)
Lithology
PrimaryBlack shale, claystone, sandstone and limestone concretions
OtherGypsum, chalcopyrite, galena, malachite, pyrite, sphalerite
Location
Coordinates [ ⚑ ] : 5°30′N 73°30′W / 5.5°N 73.5°W / 5.5; -73.5
Paleocoordinates [ ⚑ ] 3°42′N 42°12′W / 3.7°N 42.2°W / 3.7; -42.2
RegionBolívar, Boyacá, Cundinamarca & Santander
Country Colombia
ExtentAltiplano Cundiboyacense
Eastern Ranges, Andes
Middle Magdalena Valley
Type section
Named forQuebrada La Paja
Named byWheeler
Year defined1929?
Coordinates [ ⚑ ] 7°01′33.4″N 73°19′27.8″W / 7.025944°N 73.324389°W / 7.025944; -73.324389
RegionBetulia, Santander
Thickness at type section625 m (2,051 ft)
Geologic map - outcrops of the Paja Formation and Ritoque Formation, Villa de Leyva, Colombia.jpg
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[1] 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),[2] 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.[3][4]

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

Paja Formation is located in Santander Department
Paja Formation
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).[5] 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,[6] to the Pauna Anticlinal in San Pablo de Borbur, where the formation is thrusted over the Ritoque Formation in the south.[7] In the southern extension of the exposures, the formation crops out in the north of Tununguá, near the Ibacapí Fault.[8]

Santander

In the Middle Magdalena Valley, south of Barrancabermeja, the Paja Formation in the subsurface is offset by the Casabe, Infantas and Arruga Faults.[9] 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.[10] The town center of Zapatoca rests on the formation in the synclinal named after the village.[4] 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.[11] South of there, the Paja Formation is offset by the La Corcovada and El Guineal Faults,[12] and the regional La Salina Fault.[13] Near the eponymous town, the formation is offset by the Landazurí Fault.[14]

West of Barichara, the formation underlies the corregimiento Guane, Barichara (es) and is found in the hills bordering both sides of the Suárez River.[15] In this area, the Paja Formation is offset by the Suárez Fault.[16] 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.[15] 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.[17] 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.[18] The El Carmen Fault puts the Paja Formation in contact with the Jurassic Girón Formation.[16]

Boyacá

Lua error in Module:Location_map/multi at line 27: Unable to find the specified location map definition: "Module:Location map/data/Altiplano Cundiboyacense" does not exist. 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.[18] West of Arcabuco in the Villa de Leyva Synclinal, the formation is cut by the Arcabuco River.[19] 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.[20] 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,[7] where the urban centers of Yacopí and La Palma rest on the formation.[21]

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.[7][22] Along the highway Tunja-Villa de Leyva, the formation is heavily folded and faulted along a stretch of 500 metres (1,600 ft).[23] 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,[24][25] and the Simití Formation in the northwestern Middle Magdalena Valley.[11] In the Western emerald belt, the contact with the Rosablanca Formation is concordant and abrupt.[26] The total thickness of the formation varies across its extent, but can reach up to 940 metres (3,080 ft).[27]

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.[28]
  • 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.[28]
  • 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.[27]

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.[29] Bürgl in 1954 reported beds of tuff in the Paja Formation near Villa de Leyva.[30] 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.[31]

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.[24] 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.[27] To the northeast of the extent of the formation, it correlates with the upper part of the Río Negro Formation,[32] and the lowermost Tibú-Mercedes Formation of the Catatumbo Basin.[33]

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.[34]

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.[35]

Depositional environment

The thin section analysis led to the interpretation of a shoreface to lower shoreface environment,[36] in the internal parts of a carbonate platform,[37][38] where transgressions and regressions caused the variations in grain sizes and lithologies.[39] 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.[40]

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.[41] The formation contains three spikes of δ13C, with values above 1.5‰, in the lower, middle to upper and upper Paja Formation.[42] 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.[43]

Mining and petroleum geology

The Paja Formation is one of the stratigraphic units cropping out in the Western emerald belt.[44] 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.[45] In the northwestern part of Muzo, Boyacá, mineralization happened during the Early Oligocene, at 31.4 ± 0.3 Ma.[46] Previous geologic researchers considered the Paja Formation hosted emeralds,[47] 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.[48]

The Paja Formation is known for its gypsum deposits, which are mined and restricted to Santander.[49] Near Guavatá, the formation hosts sphalerite and malachite and near Otanche, pyrite and galena are found in the formation.[47] In Gámbita, the Paja Formation contains pyrite, galena and chalcopyrite.[50] Other minerals occurring in the Paja Formation, are lead and zinc, around Paime and Yacopí, Cundinamarca.[51]

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.[52][53] Vitrinite reflectance analysis on samples of the Paja Formation indicate an average value of 0.52 Ro, making the formation a marginal source rock.[54]

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,[55] 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.[56]

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.[1]

The paleontological richness of the formation led to the establishment of a center of investigation; Centro de Investigaciones Paleontológicas (es) (CIP),[57] two museums; Paleontological Museum of Villa de Leyva (es),[58] and Museo El Fósil,[59] and a dinosaur park; Gondava,[60] 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.'[61]

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
Acostasaurus pavachoquensis by duskyvel-dbys3fi.png
Callawayasaurus C. colombiensis Loma La Catalina Arcillolitas abigarradas An elasmosaurid plesiosaur, originally classified in Alzadasaurus
Callawayasaurus colombiensis.JPG
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.
Desmatochelys padillai.jpg
Monquirasaurus M. boyacensis Vereda Monquirá Arcillolitas abigarradas A large pliosaurid, initially named "Kronosaurus boyacensis"
Kronosaurus bojacens1DB.jpg
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
Leyvachelys cipadi - Paja Formation, Colombia.jpg
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
FICHA 4 VERTEBRAS.gif
Kyhytysuka K. sachicarum Sáchica Arcillolitas abigarradas A platypterygiine ichthyosaur, relative of P. americanum
Platypterygius sachicarum.jpg
Sachicasaurus S. vitae Sáchica Arcillolitas abigarradas A 10 metres (33 ft) subadult pliosaur
Sachicasaurus vitae - holotype - Paja Formation, Colombia.jpg
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
Acanthoptychoceras trumpyi - Paja Formation, Colombia.jpg
[77]
Ancycloceras vandenheckii
Ancyloceras vandenheckii velezianum (2) & Ancyloceras vandenheckii (3) - Paja Formation, Colombia.jpg
[78]
Ancycloceras vandenheckii velezianum [79]
Buergliceras buerglii
Buergliceras buerglii - Paja Formation, Colombia.jpg
[77][80]
Colchidites breistrofferi
Colchidites breistrofferi - Paja Formation, Colombia.jpg
[81][82]
Crioceratites emerici
Crioceratites emerici - Paja Formation, Colombia.jpg
[83]
Crioceratites leivaensis
Crioceratites leivaensis - Paja Formation, Colombia.jpg
[84]
Crioceratites tener
Crioceratites tener - Paja Formation, Colombia.jpg
[85]
Hamiticeras chipatai
Hamiticeras chipatai - Paja Formation, Colombia.jpg
[86]
Hamiticeras pilsbryi
Hamiticeras pilsbryi - Paja Formation, Colombia.jpg
[87]
Hamulinites munieri
Hamulinites munieri - Paja Formation, Colombia.jpg
[88]
Karsteniceras beyrichi
Karsteniceras beyrichi - Paja Formation, Colombia.jpg
[89][90]
Karsteniceras multicostatum
Karsteniceras multicostatum - Paja Formation, Colombia.jpg
[91]
Monsalveiceras monsalvense
Monsalveiceras monsalvense - Paja Formation, Colombia.jpg
[92]
Nicklesia pulcella
Nicklesia pulcella - Paja Formation, Colombia.jpg
[77][82]
Pariacrioceras barremense
Paracrioceras barremense - Paja Formation, Colombia.jpg
[78]
Pedioceras asymmetricum
Pedioceras asymmetricum - Paja Formation, Colombia.jpg
[93]
Pedioceras caquesense
Pedioceras caquesense - Paja Formation, Colombia.jpg
[94]
Protanisoceras creutzbergi
Protanisoceras creutzbergi - Paja Formation, Colombia.jpg
[95]
Pseudoaustraliceras columbiae
Pseudoaustraliceras columbiae - Paja Formation, Colombia.jpg
[96]
Pseudoaustraliceras pavlowi
Pseudoaustraliceras pavlowi - Paja Formation, Colombia.jpg
[97]
Pseudoaustraliceras ramososeptatum
Pseudoaustraliceras ramososeptatum - Paja Formation, Colombia.jpg
[98]
Pseudocrioceras anthulai
Pseudocrioceras anthulai - Paja Formation, Colombia.jpg
[96]
Ptychoceras puzosianum
Ptychoceras puzosianum - Paja Formation, Colombia.jpg
[81]
Tonohamites koeneni
Tonohamites koeneni - Paja Formation, Colombia.jpg
[99]
Criceratites sp.
Criceratites sp. - Paja Formation, Colombia.jpg
[77]
Pedioceras sp.
Pedioceras sp. - Paja Formation, Colombia.jpg
[77]
Acanthohoplites [100]
Acrioceras julivertii [101]
Colchidites apolinarii [102]
Crioceratites portarum [103]
Favrella colombiana [104]
Heinzia (Gerhardtia) veleziensis [82]
Nicklesia didayana didayana [105]
Nicklesia didayana multifida [105]
Nicklesia dumasiana [105]
Nicklesia nolani [105]
Olcostephanus boussingaultii [106]
Parasaynoceras horridum [107]
Pseudohaploceras incertum [105]
Psilotissotia colombiana [108]
Pulchellia galeata [82]
Dufrenoyia sp. [109]
Valdedorsella sp. [105]

Crustaceans

Crustaceans of the Paja Formation
Species Image Notes
Bellcarcinus aptiensis
Bellcarcinus aptiensis - Paja Formation, Colombia.jpg
[110]
Colombicarcinus laevis [111]
Notopocorystes kerri [112]
Planocarcinus olssoni [113]
Telamonocarcinus antiquus [114]

Flora

Flora of the Paja Formation
Species Image Notes
Frenelopsis cf. ramosissima
Frenelopsis cf. Ramosissima - Paja Formation, Colombia.jpg
[115]
Pseudofrenelopsis sp.
Pseudofrenelopsis sp. - Paja Formation, Colombia.jpg
[116]

Fish

Ichnofossils

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

Notes

References

  1. 1.0 1.1 Noé et al., 2018
  2. Morales, 1958
  3. Reyes et al., 2006, p.33
  4. 4.0 4.1 Plancha 120, 2010
  5. Patarroyo & Moreno, 1997, p.30
  6. Plancha 85, 2006
  7. 7.0 7.1 7.2 Plancha 190, 1998
  8. Reyes et al., 2006, p.32
  9. Plancha 119, 2008
  10. Plancha 97, 2009
  11. 11.0 11.1 Plancha 96, 2006
  12. Plancha 149, 2008
  13. Plancha 134, 2008
  14. Plancha 150, 2008
  15. 15.0 15.1 Plancha 135, 2009
  16. 16.0 16.1 Royero & Clavijo, 2001, p.53
  17. Plancha 151, 2009
  18. 18.0 18.1 Plancha 170, 2009
  19. Plancha 171, 2009
  20. Reyes et al., 2006, p.83
  21. Plancha 189, 2005
  22. Plancha 191, 1998
  23. Moreno & Hincapié, 2010, p.44
  24. 24.0 24.1 Villamil, 2012, p.168
  25. Royero & Clavijo, 2001, p.31
  26. Reyes et al., 2006, p.26
  27. 27.0 27.1 27.2 Moreno & Hincapié, 2010, p.26
  28. 28.0 28.1 Moreno & Hincapié, 2010, p.25
  29. Sarmiento et al., 2015, p.65
  30. Sarmiento Rojas, 2002, p.56
  31. Espinel & Hurtado, 2010, p.70
  32. Royero & Clavijo, 2001, p.29
  33. Royero & Clavijo, 2001, p.32
  34. Rivera et al., 2018, p.30
  35. Villamil, 2012, p.164
  36. Gaona Narváez et al., 2013
  37. Espinel & Hurtado, 2010, p.73
  38. Espinel & Hurtado, 2010, p.89
  39. Galvis & Valencia, 2009, p.79
  40. Galvis & Valencia, 2009, p.81
  41. Moreno & Hincapié, 2010, p.48
  42. Moreno & Hincapié, 2010, p.63
  43. Moreno & Hincapié, 2010, p.64
  44. Reyes et al., 2006, p.82
  45. Gómez Tapias et al., 2015, p.214
  46. Gómez Tapias et al., 2015, p.208
  47. 47.0 47.1 Sarmiento Rojas, 2002, p.65
  48. Reyes et al., 2006, p.106
  49. Royero & Clavijo, 2001, p.60
  50. Sarmiento Rojas, 2002, p.66
  51. Acosta & Ulloa, 2002, p.75
  52. Mojica et al., 2009, p.22
  53. Mojica et al., 2009, p.39
  54. Moreno & Hincapié, 2010, p.74
  55. Patarroyo Camargo et al., 2009
  56. 56.0 56.1 En Colombia encuentran el primer fósil de una tortuga marina, ¡embarazada! – Universidad del Rosario
  57. (in Spanish) Centro de Investigaciones Paleontológicas
  58. (in Spanish) Museo Paleontológico de Villa de Leyva
  59. (in Spanish) Museo El Fósil
  60. (in Spanish) Parque Gondava
  61. "The First 100 IUGS Geological Heritage Sites". IUGS. https://iugs-geoheritage.org/videos-pdfs/iugs_first_100_book_v2.pdf. 
  62. Gómez Pérez & Noè, 2017
  63. Welles, 1962
  64. Carpenter, 1999
  65. 65.0 65.1 Cadena & Parham, 2015a
  66. Acosta et al., 1979
  67. Hampe, 1992
  68. Cadena, 2015b
  69. Páramo Fonseca et al., 2019
  70. Maxwell et al., 2015
  71. Carballido et al., 2015
  72. Páramo, 1997
  73. Páramo Fonseca et al., 2018, p.226
  74. Hampe, 2005
  75. Páramo et al., 2016
  76. Cortés et al., 2019
  77. 77.0 77.1 77.2 77.3 77.4 Patarroyo, 2009, p.19
  78. 78.0 78.1 Kabakadze & Hoedemaeker, 1997, p.66
  79. Kabakadze & Hoedemaeker, 1997, p.67
  80. Etayo, 1968b, p.63
  81. 81.0 81.1 Kabakadze & Hoedemaeker, 1997, p.81
  82. 82.0 82.1 82.2 82.3 Patarroyo, 2000, p.154
  83. Kabakadze & Hoedemaeker, 1997, p.62
  84. Kabakadze & Hoedemaeker, 1997, p.59
  85. Kabakadze & Hoedemaeker, 1997, p.61
  86. Kabakadze & Hoedemaeker, 1997, p.77
  87. Kabakadze & Hoedemaeker, 1997, p.75
  88. Kabakadze & Hoedemaeker, 1997, p.80
  89. Etayo, 1968b, p.54
  90. Kabakadze & Hoedemaeker, 1997, p.71
  91. Kabakadze & Hoedemaeker, 1997, p.72
  92. Kabakadze & Hoedemaeker, 1997, p.74
  93. Kabakadze & Hoedemaeker, 1997, p.64
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