Honda Group, Colombia

Honda Group
Stratigraphic range: Late Oligocene-Late Miocene
typically Middle Miocene
(Laventan)
~13.8–11.8 Ma
↓

Statue of a mammal from the Honda Group in Villavieja, Huila
Type Geological group
Sub-units Villavieja Fm.
 Cerro Colorado Mb.
 Baraya Mb.
La Victoria Fm.
 Cerbatana Mb.
Underlies Gigante Group
 Neiva Fm.
Overlies Payandé Group
 Barzalosa Fm., Saldaña Fm., Santa Teresa Fm.
Thickness up to 5,000 m (16,000 ft)
Lithology
Primary Conglomerate, sandstone
Other Claystone, siltstone, volcanoclastic sediments
Location
Coordinates 5°11′31″N 74°43′21″W / 5.19194°N 74.72250°W / 5.19194; -74.72250Coordinates: 5°11′31″N 74°43′21″W / 5.19194°N 74.72250°W / 5.19194; -74.72250
Region Huila, Tolima, Cundinamarca
Middle Magdalena Basin, Upper Magdalena Basin
Central & Eastern Ranges
Andes
Country  Colombia
Extent ~250 km (160 mi)
Type section
Named for Honda
Named by Hettner
Location Honda (original)
Tatacoa Desert (redefined)
Year defined 1892
Coordinates 3°14′04″N 75°12′15″W / 3.23444°N 75.20417°W / 3.23444; -75.20417
Approximate paleocoordinates 3°06′N 72°24′W / 3.1°N 72.4°W / 3.1; -72.4
Region Tolima (original)
Huila (redefined)
Country  Colombia
Thickness at type section 3,255 m (10,679 ft)

Paleogeography of Northern South America
20 Ma, by Ron Blakey
Topographical map of Tolima Department
original type locality of the Honda Group
redefined type section in Huila

The Honda Group (Spanish: Grupo Honda, Tsh, Ngh) is a geological group of the Upper and Middle Magdalena Basin and the adjacent Central and Eastern Ranges of the Colombian Andes. The group, in older literature also defined as formation, is in its present-day type section in the Tatacoa Desert in the department of Huila subdivided into two main formations; La Victoria and Villavieja.

The group was originally defined in and named after Honda, Tolima, but has been redefined based on the many fossil finds in the Tatacoa Desert, 250 kilometres (160 mi) to the south. In the original type section of its occurrence, the 3,255 metres (10,679 ft) thick group is subdivided into three formations, from old to young; Cambrás, San Antonio and Los Limones.

The group dates to the Neogene period; in its broadest definition from the Late Oligocene to Late Miocene, and in the redefined type section restricted to the Laventan age of the South American Mammal Ages (SALMA), equivalent with the Middle Miocene Serravallian epoch.

The Honda Group is a Konzentrat-Lagerstätte at the fossiliferous La Venta site in the department of Huila and eastern Tolima and hosts one of the richest formations containing Miocene fauna worldwide.

Etymology and definitions

View of Honda, Tolima, namesake of the Honda Group

The group was first defined by Hettner in 1892 in the area of the town after which it is named; Honda, Tolima.[1] In 1942 and 1946, the group was defined as a formation by Royo and Gómez. The first author who used the name Honda for a group, was American zoologist who studied the La Venta fauna in detail, Ruben Arthur Stirton. Subdivisions of the group have been proposed by many different authors with high detail in the different beds.[2] Names as "Monkey Beds", "Fish Beds" and "Unit above Fish Beds" have been colloquially used to designate certain stratigraphic units based on their fossil content.[3][4] The most accepted definition of the group, formations and members was proposed by Villarroel et al. in 1996 to simplify the stratigraphy in a regional sense solving the excessive subdivision into 19 units by Guerrero et al. (1994).[5]

Regional setting

Today, the sediments of the Honda Group are exposed in the Middle (Valle Medio del Magdalena, VMM) and Upper Magdalena Basin (Valle Superior del Magdalena, VSM) in an intermontane valley between the Central Ranges in the west and the Eastern Ranges in the east. The valley in between the two major orogenic chains is filled by the Magdalena River, the longest river of Colombia. The Upper Magdalena Valley geologically is subdivided into the Neiva Sub-basin with the Girardot Sub-basin of the southernmost Middle Magdalena Valley to the north, divided by the Natagaima Arch.[6] The Neiva Sub-basin is bound by the Chusma Fault in the west and to the east by the west-verging Garzon Fault.[7] The Tatacoa Desert, where the type section of the Honda Group has been redefined is an unusually dry region in Colombia, caused by a mountain induced rain-shadow effect. In Middle Miocene times, the geography was more comparable to the present eastern foothills of the Andes.[8]

The tectonic history of the three mountain chains of Colombia, from west to east, the Western, Central and Eastern Ranges has been studied in detail. The Western and Central Ranges were the first to be exhumed in the Paleogene, with minor uplifts in the Eastern Ranges at this age. The onset of the regional uplift of the Eastern Ranges is dated around the Middle Miocene, with an increased rate of exhumation between 12 and 3 Ma.[9] This caused a segmentation of the current Magdalena Basins and the Llanos Basin to the east, previously part of a larger foreland basin to the east of the Central Ranges.[10] The León Formation in the Llanos Basin provides the first indication of the tectonic uplift of the Eastern Ranges, isolating the Llanos Basin from the Magdalena Valley.[11]

Description

Stratigraphy

The Honda Group unconformably overlies in parts the volcanic deposits of the Prado Member,[4] Barzalosa Formation of the Payandé Group, and in other parts the Saldaña,[12] and Santa Teresa Formations.[13] The unit is overlain by the Neiva Formation of the Gigante Group.[3][14] The presence of a hiatus between the Honda Group and the Barzalosa Formation has been suggested.[15] The group is characterised by two main formations; the lower La Victoria Formation and upper Villavieja Formation. Previously, the La Dorada Formation has been named as a subdivision of the Honda Group, while other authors define that unit as a member. Other names for members and formations are Cerbatana Member, also published as Cervetana Member, named after Quebrada La Cerbatana, Las Mesitas Formation, El Líbano Formation, Baraya Volcanic Member, named after Baraya, and Cerro Colorado Red Bed Member.[16] The Perico Member of the La Dorada Formation has been made equivalent to the La Victoria Formation, as well as the El Líbano Formation.[4]

La Victoria Formation

This formation was first defined by Guerrero in his Master's thesis (1991) and further refined in his doctoral thesis in 1993. The type locality of the La Victoria Formation has been set in the La Venta area and the formation is named after the town of La Victoria, at 15 kilometres (9.3 mi) north-northeast of the urban centre of Villavieja. The formation, restricted to the Neiva Sub-basin,[17] consists mainly of sandstones, conglomeratic sandstones and conglomerates (75%) with intercalated claystones and siltstones (25%).[5]

The upper part of the La Victoria Formation, underlying the Villavieja Formation, is characterised by a 45 metres (148 ft) section of conglomerates, designated the Cerbatana Member or Cerbatana Conglomerates. The conglomerate shows trough-cross lamination and imbrication of clasts in a predominantly matrix-supported sequence, with minor clast-supported sections. The base of the conglomerate marks an erosional surface into the underlying silt and clay beds. The clasts of the conglomerate are mostly milky quartz, chert and volcanic in origin, with diameters averaging around 7 centimetres (2.8 in) with a maximum of 15 centimetres (5.9 in). Conglomeratic and medium to coarse-grained sandstone banks, with a similar grain composition as the conglomerates, up to 2 metres (79 in) thick are intercalated between the conglomeratic sections. The sandstones are cemented by calcium carbonate in hardgrounds that sometimes form rounded concretions. The claystones and siltstones that are less commonly found in the La Victoria Formations range in thickness from 1 to 11 metres (3.3 to 36.1 ft) and show reddish-brown, greenish-grey and greyish colourations.[18]

Villavieja Formation

Wind erosion of the Villavieja Formation in the Tatacoa Desert

The name Villavieja Formation was first proposed by Wellman in 1968 as a member of the Honda Formation. Two years later, the author elevated the rank to a formation, as part of the Honda Group. The formation takes its name from the municipality Villavieja, Huila, 35 kilometres (22 mi) to the north-northeast of the departmental capital Neiva. The type locality is situated on the right bank of the Magdalena River in the Eastern Ranges of the Colombian Andes.[19]

The contact between the Villavieja Formation and the underlying La Victoria Formation is concordant.[17] The basal part of the Villavieja Formation comprises siltstones and claystones that also form the bulk of the formation with 75 percent. The remaining quarter is composed of conglomeratic sandstones. The thickness of the siltstones and claystones can exceed 8 metres (26 ft) and have interspersed fine- to medium-grained 10 centimetres (3.9 in) thin sandstone beds. The fine sediments of the Villavieja Formation are coloured greenish, reddish-brown or bluish-grey and display weathering patterns in so-called "cauliflower erosion" structures. The light grey coarser beds, up to conglomeratic sandstone size, do not exceed 2.5 metres (8.2 ft) in thickness and commonly show a lateral transition with the silt- and claystones. The Baraya Member of the Villavieja Formation shows thin yellowish and reddish brown sandstone and siltstone levels with volcaniclastic grains.[19]

Honda area

The Honda Group extends for approximately 250 kilometres (160 mi) from the Upper to the Middle Magdalena Basin and is exposed in various locations along the right and left banks of the Magdalena River. Outcrops along the road between Girardot and Agua de Dios, Cundinamarca show a lower sequence of thick beds of greenish-yellow feldspar- and mica-rich conglomeratic sandstones, intercalated with reddish claystones and an upper level of alternating medium-to-coarse grained quartz arenites with low-angle cross stratification. These sandstones are intercalated with thick layers of fissile claystones with common calcareous sandstone concretions.[20] Sediments of the Honda Group restrict the course of the Sumapaz River to a narrow valley, close to its confluence with the Magdalena River.[21]

The majority of the municipality Prado, Tolima rests upon sediments of the Honda Group.[22] In the Middle Magdalena Basin and the eastern flank of the Central and the western flank of the Eastern Ranges, the group is subdivided into the Los Limones, San Antonio and Cambrás Formations. The total thickness of these formations in the northern original type section of the Honda Group reaches 3,255 metres (10,679 ft),[1] while a total thickness of 5,000 metres (16,000 ft) has been registered.[14]

Age

Thanks to the fossil abundance of the Honda Group at La Venta, the geological period of the sediments has received a separate name in the South American Mammal Ages (SALMA); Laventan, ranging from 13.8 to 11.8 Ma.[23] The age of the Villavieja Formation has been estimated to be between 17.0 and 12.1 Ma,[19] while the stratigraphically lower La Victoria Formation is dated at 13.82 to 12.38 Ma (Serravallian), based on fission track and volcanic analysis and paleomagnetic research.[17]

The Honda Group is laterally time equivalent with the lower part of the Real Formation in the central and northern Middle Magdalena Basin,[24] the lower part of the León Formation of the Llanos Basin,[25] the upper range of the Ciénaga de Oro Formation of the Lower Magdalena Basin,[26] and the Caja and Diablo Formations of the Llanos foothills.[27]

Depositional environment

The paleogeography of the meandering and braided river sediments of the Honda Group was characterised by a more African or Asian ecosystem than that of the Neotropics

The Honda Group has been deposited in a fluvial environment, with the lower part of the La Victoria Formation in a meandering setting, while the upper part was formed in a braided river system. The paleocurrent was from the west to the east and east-southeast.[18] The overlying predominantly finer grained Villavieja Formation was deposited in a meandering setting of a smaller size than those of the older La Victoria Formation. Paleocurrent analysis of the sediments in the Baraya and Cerro Colorado Members has revealed a similar flow direction as the La Victoria paleorivers, while the upper part of the Cerro Colorado Member shows an opposite trend to the west.[19] The volcanic clasts of the formations have as provenance the Central Range volcanism, of which the volcaniclastics in the Honda Group mark its onset.[28][29]

The depositional boundary for the Honda Group in the east is formed by the reverse Prado-Suárez and Cambrás-Salinas-Cambao Faults.[30]

Paleoclimate and vegetation

Analysis of the "Monkey Beds" of the Honda Group, provided estimates of annual precipitation levels between 1,500 and 2,000 millimetres (59 and 79 in). Today, these levels of rainfall are associated with the transition between savanna and forest environments in lowland South America. The vegetation of the La Venta fossil assemblage was diverse due to the different biomes of the depositional environment; meandering and braided river systems in a setting at lower altitudes than the present-day elevation of more than 400 metres (1,300 ft) above mean sea level. It has been suggested that the vegetational cover of the Honda Group sedimentary sequence was not a continuous canopy forest, yet a complex pattern of different flora ecosystems. The evergreen Amazonian foothill forests of today would therefore postdate the uplift of the Eastern Ranges of the Andes.[31] Based on vegetational and grazer diversity analysis of the La Venta fauna, it has been suggested the ecosystem resembled more that of Africa and Asia than of the modern Neotropics.[32] Research of the paleosols found in various levels within the Honda Group suggests the presence of arid areas in close proximity to pluvial parts.[33]

Petroleum geology

In the oil-producing Upper Magdalena Basin, the Honda Group is one of the reservoir formations, next to the more important Caballos and Monserrate Formations.[34][35] Shales of the Honda Group function as seal rock for certain oilfields in the Upper Magdalena Basin.[36] In the Tello Field in the basin, the Honda Group forms the overburden rock for the producing Monserrate reservoirs.[37]

Fossil content

A fossil species in the genus Arapaima has been described among the many fishes from the Honda Group

The Honda Group is the richest fossiliferous stratigraphic unit of Colombia, and one of the most important for the Miocene worldwide. At the La Venta site, numerous fossils of various orders have been and are found still. The site marks a unique ecosystem showing a broad range of biodiversity. La Venta is also an important site as it represents the youngest uniquely South American faunal assemblage before the Great American Biotic Interchange; the result of the uplift of the Isthmus of Panama, of which the initial phase has been dated at around 12 Ma.[38] This led to a drastic alteration of the South American former island continental fauna. The Sparassodonta formed the dominant carnivorous mammal group in South America during most of the Cenozoic. In South America, the carnivorous adaptive zone in terrestrial ecosystems was shared with other mammals, terror birds (Phorusrhacoidea), large crocodiles (Sebecidae), large snakes (Madsoiidae and Boidae), and even occasionally frogs.[39] The diversity of fossil freshwater fishes and crocodilians at La Venta is the richest assemblage of South America.[32][40] Fossilised trunks of Goupioxylon sp. have been identified in the Honda Group.[41]

The genus names Hondadelphys and Hondathentes, and the species epithets of Anadasypus hondanus and Scirrotherium hondaensis refer to the Honda Group, where the fossils have been found.

Mammals

Order Fossils Image Notes
Primates Aotus dindensis, Cebupithecia sarmientoi, Lagonimico conclucatus, Micodon kiotensis, Micoureus laventicus, Miocallicebus villaviejai, Mohanamico hershkovitzi, Neosaimiri annectens (syn. Laventiana annectens), Neosaimiri fieldsi, Nuciruptor rubricae, Patasola magdalenae, Stirtonia tatacoensis (syn. Kondous laventicus), Stirtonia victoriae
Astrapotheria Hilarcotherium castanedaii
Granastrapotherium snorki
Xenastrapotherium kraglievichi
Anteaters and sloths Hapalops sp.
Brievabradys laventensis, Glossotheriopsis pascuali, Huilabradys magdaleniensis, Neonematherium flabellatum, Neotamandua borealis, Pseudoprepotherium confusum, Megalonychidae sp., Megatheriinae sp., Nothrotheriinae sp.
Armadillos Anadasypus hondanus, Boreostemma acostae (syn. Asterostemma), Boreostemma gigantea (syn. Asterostemma), Nanoastegotherium prostatum, Neoglyptatelus originalis, Pedrolypeutes praecursor, Scirrotherium hondaensis, Dasypodidae sp.
Litopterna Theosodon sp.
Megadolodus molariformis, Pericotoxodon platignathus, Prolicaphrium sanalfolsensis, Prothoatherium colombianus, Villarroelia totoyoi, Proterotheriidae indet.
Notoungulata Huilatherium pluriplicatum
Cochilius sp., Miocochilius anomopodus, Leontiniidae sp., Toxodontidae sp.
Sparassodonta Anachlysictis gracilis
Dukecynus magnus
Lycopsis longirostrus
Hondadelphys fieldsi
Microbiotheria marsupials Pachybiotherium minor
Opossums Thylamys colombianus, Thylamys minutus
Shrew opossums Hondathentes cazador, Pithiculites chenche
Rodents Acarechimys minutissimus, Eodolichotis elachys, E. maddeni, Microscleromys cribiphilus, M. paradoxalis, Microsteiromys jacobsi, Neoreomys huilensis, Olenopsis sp., Prodolichotis guerreroi, P. pridiana, Rhodanodolichotis antepridiana, R. vucetichae, Ricardomys longidens, Scleromys colombianus, S. schurmanni, ?Steiromys sp., Dolichotinae sp., ?Echimyidae sp.
Bats Diclidurus sp., Eumops sp., Kiotomops lopezi, Mormopterus colombiensis, Notonycteris magdalenensis, N. sucharadeus, Palynephyllum antimaster, Potamops mascahehenes, Tonatia sp. or Lophostoma sp.
lesser bulldog bat (Noctilio albiventris), LaVal's disk-winged bat (Thyroptera lavali), Spix's disk-winged bat (Thyroptera tricolor), Thyroptera robusta
Sea cows Potamosiren magdalenensis

Birds

Order Fossils Notes
Gruiformes Aramus paludigrus
Piciformes Galbula hylochoreutes
Opisthocomiformes Hoazinoides magdalenae

Reptiles and amphibians

Order Fossils Image Notes
Crocodiles Gryposuchus colombianus
Langstonia huilensis
Purussaurus neivensis
Balanerodus logimus, Charactosuchus fieldsi, Eocaiman sp., Gavialis sp., Mourasuchus atopus, Sebecus sp., Alligatoridae indet.
Turtles Chelus colombiana, Geochelone hesterna, Podocnemis medemi
Snakes Colombophis portai, ?Eunectes stirtoni
Lizards Dracaena colombiana (syn. Paradracaena colombiana)
Frogs cane toad (Bufo marinus)

Fish and crustaceans

Order Fossils Notes
Fish Colossoma macropomum, Lepidosiren paradoxa, cf. Acanthicus, Arapaima sp., Brachyplatystoma cf. B. vaillanti, Brachyplatystoma promagdalena, cf. Corydoras sp., Hoplias sp., cf. Hoplosternum, Hydrolycus sp., Phractocephalus hemiliopterus, Serrasalmus sp., Pygocentrus sp., or Pristobrycon sp. (cf. Myletes sp.), Ariidae gen. et. sp. Incertae sedis, Characidae cf. Tetragonopterinae gen. et. sp., Cichlidae gen. et. sp. Incertae sedis, Doradidae gen. et. sp. Incertae sedis 1-3, Loricariidae gen. et. sp. Incertae sedis 1 & 2, Potamotrygonidae
Crabs Sylviocarcinus piriformis

Panorama

Panorama of the Tatacoa Desert, reassigned type section of the Honda Group

See also

Geology of the Eastern Hills
Geology of the Ocetá Páramo
Geology of the Altiplano Cundiboyacense
Bogotá, Cerrejón, Floresta, Paja Formations

References

  1. 1 2 Acosta & Ulloa, 2002, p.34
  2. ↑ Villarroel et al., 1996, p.47
  3. 1 2 Villarroel et al., 1996, p.48
  4. 1 2 3 Villarroel et al., 1996, p.50
  5. 1 2 Villarroel et al., 1996, p.51
  6. ↑ López Quintero, 2007, p.1
  7. ↑ Jiménez et al., 2012, p.186
  8. ↑ Kay & Madden, 1997, p.163
  9. ↑ Sánchez et al., 2012, p.1
  10. ↑ Parra, 2008, p.41
  11. ↑ Villegas et al., 1994, p.1849
  12. ↑ Carrera Ortíz, 2015, p.24
  13. ↑ Álvarez et al., 2017, p.142
  14. 1 2 García et al., 2009. p.85
  15. ↑ López Quintero, 2007, p.16
  16. ↑ Villarroel et al., 1996, p.49
  17. 1 2 3 Villarroel, 1996, p.53
  18. 1 2 Villarroel et al., 1996, p.52
  19. 1 2 3 4 Villarroel et al., 1996, p.54
  20. ↑ ANi & Infracon, 2015, p.33
  21. ↑ ANi & Infracon, 2015, p.45
  22. ↑ N.N., s.a., p.182
  23. ↑ Laventan at Fossilworks.org
  24. ↑ Sánchez et al., 2012, p.3
  25. ↑ García et al., 2009. p.60
  26. ↑ Torres et al., 2012, p.2
  27. ↑ Acosta & Ulloa, 2002, p.22
  28. ↑ Gónzalez, 2001, p.81
  29. ↑ Kroonenberg et al., 1982, p.21
  30. ↑ Triviño, 1993, p.29
  31. ↑ Kay & Madden, 1997, p.186
  32. 1 2 Kay & Madden, 1997, p.183
  33. ↑ Flórez et al., 2013, p.243
  34. ↑ Barrero et al., 2007, p.85
  35. ↑ Carrera Ortíz, 2015, p.25
  36. ↑ Carrera Ortíz, 2015, p.26
  37. ↑ Ramón et al., 2001, p.63
  38. ↑ De Porta, 2003, p.191
  39. ↑ Súarez, 2015, p.03
  40. 1 2 3 (in Spanish) Fauna de La Venta - flora, cangrejos y peces
  41. ↑ The Villavieja Formation, Colombia - Berkeley University
  42. 1 2 3 4 5 6 7 8 9 Croft, 2007, p.299
  43. 1 2 Croft, 2007, p.301
  44. ↑ Meldrum & Kay, 1997
  45. ↑ Organ & Lemelin, 2011
  46. ↑ Rosenberger et al., 1991
  47. ↑ Setoguchi & Rosenberger, 1988
  48. ↑ Setoguchi, 1985
  49. ↑ Takai et al., 2001
  50. ↑ Tejedor, 2013, p.22
  51. ↑ Defler, 2004, p.32
  52. ↑ Cebupithecia sarmientoi at Fossilworks.org
  53. ↑ Miocallicebus villaviejai at Fossilworks.org
  54. ↑ Neosaimiri annectens at Fossilworks.org
  55. ↑ Stirtonia tatacoensis at Fossilworks.org
  56. ↑ Stirtonia victoriae at Fossilworks.org
  57. ↑ Vallejo Pareja et al., 2015
  58. 1 2 3 4 5 6 Croft, 2007, p.302
  59. ↑ Pardo Jaramillo, 2010
  60. 1 2 Granastrapotherium snorki, Sebecus sp. at Fossilworks.org
  61. 1 2 3 4 Croft, 2007, p.300
  62. ↑ Villarroel, 2000, p.118
  63. ↑ Kay & Madden, 1997, p.171
  64. ↑ Brievabradys laventensis at Fossilworks.org
  65. ↑ Huilabradys magdaleniensis at Fossilworks.org
  66. ↑ Neonematherium flabellatum at Fossilworks.org
  67. ↑ Neotamandua borealis at Fossilworks.org
  68. ↑ Pseudoprepotherium confusum at Fossilworks.org
  69. ↑ Anadasypus hondanus at Fossilworks.org
  70. ↑ Boreostemma acostae at Fossilworks.org
  71. ↑ Boreostemma gigantea at Fossilworks.org
  72. ↑ Neoglyptatelus originalis at Fossilworks.org
  73. ↑ Pedrolypeutes praecursor at Fossilworks.org
  74. ↑ Scirrotherium hondaensis at Fossilworks.org
  75. ↑ Prolicaphrium sanalfolsensis at Fossilworks.org
  76. ↑ Prothoatherium colombianus at Fossilworks.org
  77. ↑ Duke Locality 33 at Fossilworks.org
  78. ↑ Villarroelia totoyoi at Fossilworks.org
  79. ↑ Villarroel, 1997
  80. ↑ Villarroel et al., 1996, p.63
  81. ↑ Hoffstetter, 1971, p.40
  82. ↑ Suárez et al., 2015
  83. ↑ Marshall, 1976
  84. ↑ Hondadelphys fieldsi at Fossilworks.org
  85. ↑ Pachybiotherium minor at Fossilworks.org
  86. ↑ Thylamys colombianus at Fossilworks.org
  87. ↑ Thylamys minutus at Fossilworks.org
  88. ↑ Hondathentes cazador at Fossilworks.org
  89. ↑ Pithiculites chenche at Fossilworks.org
  90. ↑ Neoreomys huilensis at Fossilworks.org
  91. ↑ Rhodanodolichotis antepridiana at Fossilworks.org
  92. ↑ Scleromys colombianus at Fossilworks.org
  93. ↑ Scleromys schurmanni at Fossilworks.org
  94. ↑ Prodolichotis guerreroi at Fossilworks.org
  95. ↑ UCMP V4936 at Fossilworks.org
  96. ↑ Eodolichotis elachys at Fossilworks.org
  97. ↑ Eodolichotis maddeni at Fossilworks.org
  98. ↑ Rhodanodolichotis vucetichae at Fossilworks.org
  99. 1 2 Czaplewski et al., 2003, p.278
  100. ↑ Takai et al., 1991
  101. ↑ Kiotomops lopezi at Fossilworks.org
  102. ↑ Potamops mascahehenes at Fossilworks.org
  103. ↑ Thyroptera robusta at Fossilworks.org
  104. ↑ Croft, 2007, p.303
  105. 1 2 3 Rasmussen, 1997
  106. ↑ Miller, 1953
  107. ↑ Gryposuchus colombianus at Fossilworks.org
  108. ↑ Sebecus huiensis at Fossilworks.org
  109. ↑ Purussaurus neivensis at Fossilworks.org
  110. ↑ Charactosuchus fieldsi at Fossilworks.org
  111. ↑ Mourasuchus atopus at Fossilworks.org
  112. ↑ UCMP Locality V4524 at Fossilworks.org
  113. ↑ Balanerodus logimus at Fossilworks.org
  114. ↑ Eocaiman at Fossilworks.org
  115. ↑ Cadena et al., 2008, p.1206
  116. ↑ De la Fuente et al., 2013, p.102
  117. ↑ Geochelone hesterna at Fossilworks.org
  118. ↑ Hsiou et al., 2010
  119. ↑ (in Spanish) Fauna de La Venta - serpientes
  120. ↑ Dracaena colombiana at Fossilworks.org
  121. ↑ Estes & Wassersug, 1963
  122. ↑ Kay & Madden, 1997, p.185
  123. ↑ Lundberg & Chernoff, 1992, p.5
  124. ↑ Brachyplatystoma promagdalena at Fossilworks.org

Bibliography

Regional geology

Local geology

Paleontology

Maps

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