Palaeontological evidence for the last temporal occurrence of the ancient western Amazonian river outflow into the Caribbean

Abstract

Fossil catfishes from fluvio-lacustrine facies of late Miocene Urumaco, early Pliocene Castilletes and late Pliocene San Gregorio formations provide evidence of a hydrographic connection in what is today desert regions of northern Colombia and Venezuela. New discoveries and reevaluation of existing materials leads to the recognition of two new records of the pimelodid Brachyplatystoma cf. vaillantii, and of three distinct doradid taxa: Doraops sp., Rhinodoras sp., and an unidentified third form. The presence of fossil goliath long-whiskered catfishes and thorny catfishes are indicative of the persistence of a fluvial drainage system inflow into the South Caribbean during the Pliocene/Pleistocene boundary, complementary to the previous western Amazonian hydrographic system described from the Middle Miocene Villavieja Formation in central Colombia and Late Miocene Urumaco Formation in northwestern Venezuela. The Pliocene Castilletes and San Gregorio formations potentially represent the last lithostratigraphic units related with an ancient western Amazonian fish fauna and that drainage system in the Caribbean. Alternatively, it may preserve faunas from a smaller, peripheral river basin that was cut off earlier from the Amazon-Orinoco, today found in the Maracaibo basin and the Magdalena Rivers.

Figure 1. Map of northern South America.

Marked are the locations of the outcrops containing fossil freshwater species that document the presence in Neogene times of a major drainage around what is today arid areas around the Lake Maracaibo (modified from Lundberg et al. 2010).

Figure 2. Stratigraphic sections.

A. North Corralito, Urumaco trough, Venezuela (originally from Quiroz and Jaramillo 2010, modified from Aguilera and Marceniuk 2010); B. Cocinetas Basin, Alta Guajira Peninsula, Colombia (Carlos Jaramillo unpublished, section described by Federico Moreno and drawn using SDAR, a new stratigraphic software developed by STRI); C. East San Gregorio, Urumaco trough, Venezuela (Scheyer et al. 2013).

Figure 3. Neurocrania of fossil and modern Brachyplatystoma .

A-C. Dorsal views, A. fossil † Brachyplatystoma cf. vaillantii, UNEFM-PF-500; B. line drawing of modern B . vaillantii with superimposed shaded approximation of fossil specimen, C. modern B . vaillantii . D-F. Ventral views of same. Abbreviations: ACF – anterior cranial fontanelle; BOC – basioccipital; EL – lateral ethmoid; EX – extrascapular; EXO – exoccipital; FRO – frontal; HYA – hyomandibular bone articulation site; JFSO – frontal-supraoccipital joint; JFSP – frontal-sphenotic joint; JPB – parasphenoid-basioccipital joint; JSPO – sphenotic-pterotic joint; MES – mesethmoid; OS – orbitosphenoid; OTA – articulation site of ossified transscapular ligament; OWL – otic capsule anterior wall; PSP – parasphenoid; PTO – pterotic; PTS – pterosphenoid; SPH – sphenotic; SOC – supraoccipital; SOCP – supraoccipital process; UTC – utricular chamber.

Figure 4. Neurocrania of fossil and modern Brachyplatystoma .

A, B. Left and right lateral views of fossil † Brachyplatystoma cf. vaillantii, UNEFM-PF-500; C. Left lateral view of modern B . vaillantii . D. Occipital view of fossil † Brachyplatystoma cf. vaillantii, E. Occipital view of modern B . vaillantii . Abbreviations: BOC – basioccipital; HYA – hyomandibular bone articulation site; OS – orbitosphenoid; OTA – articulation site of ossified transscapular ligament; OWL – otic capsule anterior wall; PAF – paraoccipital fossa; UTC – utricular chamber; SOCP – supraoccipital process.

Figure 5. Weberian apparatus of fossil and modern Brachyplatystoma .

Dorsal views of A. fossil † Brachyplatystoma cf. vaillantii, STRI-dbid 12959; B. modern B . vaillantii . C, D. Ventral views of same; E, F. right lateral views of same, G, H. anterior views of same. Abbreviations: AAF – aortic canal anterior foramen; AC - aortic canal; AL4 – anterior limb of fourth transverse process; CCC5 – compound centrum- fifth centrum joint; C1 - first centrum; C1CC - first centrum-compound centrum joint; C5C6 - fifth centrum- sixth centrum joint; CTP4 - crests on fourth transverse process; FTP6 – fossa and vertical wall of sixth transverse process; NA – neural arch; PAF – aortic canal posterior foramen; PL4 - posterior limb of fourth transverse process; TP5 - fifth transverse process; TP6 - sixth transverse process; TRP – tripus.

Figure 6. Neurocranium of Doraops sp., UNEFM-PF-501, from the Urumaco Formation, Upper Member, Late Miocene.

North Corralito, northwestern Venezuela (11º 14’ 44.7” N, 70º 16’ 26.4” W). A schematic reconstruction and bones sutures (light gray: skull reference, dark gray: fossil skull); B lateral left view; C lateral right view; D posterior view; E dorsal view; F ventral view. Abbreviations: ANP – anterior nuchal plate; EPO – epioccipital; FRO – frontal; LE – lateral ethmoid; MES – mesethmoid; MNP – middle nuchal plate; PNP – posterior nuchal plate; PTO – pterotic; SCL – supracleitrum; SOC – supraoccipital; SP – dorsal-locking spine; SPH – sphenotic.

Figure 7. Neurocranium of Doraops sp., UNEFM-PF-502, from the Urumaco Formation, Upper Member, Late Miocene.

Tío Gregorio, northwestern Venezuela (11º 14’ 43.0” N, 70º 18’ 19.1” W). A schematic reconstruction and bones sutures (light gray: skull reference, dark gray: fossil skull); B lateral left view; C lateral right view; D posterior view; E dorsal view; F ventral view. Abbreviations: ANP – anterior nuchal plate; EPO – epioccipital; FRO – frontal; LE – lateral ethmoid; MES – mesethmoid; MNP – middle nuchal plate; PNP – posterior nuchal plate; PTO – pterotic; SCL – supracleitrum; SOC – supraoccipital; SP – dorsal-locking spine; SPH – sphenotic.

Figure 8. Neurocranium of Rhinodoras sp., UNEFM-PF-503, from Urumaco Formation, Upper Member, Late Miocene.

North Corralito, northwestern Venezuela (11°14’44.7″ N, 70°16’26.4″ w). A schematic reconstruction and bones sutures (light gray: skull reference, dark gray: fossil skull); B lateral left view; C lateral right view; D posterior view; E dorsal view; F ventral view. Abbreviations: ANP – anterior nuchal plate; EPO – epioccipital; FRO – frontal; LE – lateral ethmoid; MES – mesethmoid; MNP – middle nuchal plate; PNP – posterior nuchal plate; PTO – pterotic; SCL – supracleitrum; SOC – supraoccipital; SP – dorsal-locking spine; SPH – sphenotic.

Figure 9. Neurocranium of Doradidae genus and species indeterminate 1, UNEFM-PF-0157, from Urumaco Formation.

Las Huertas, northwestern Venezuela (11°14’ 00” N, 70°17’10″ W). A schematic reconstruction and bones sutures (light gray: skull reference, dark gray: fossil skull); B lateral view; C posterior view; D dorsal view; E ventral view. Abbreviations: ANP – anterior nuchal plate; EPO – epioccipital; FRO – frontal; LE – lateral ethmoid; MES – mesethmoid; MNP – middle nuchal plate; PNP – posterior nuchal plate; PTO – pterotic; SCL – supracleitrum; SOC – supraoccipital; SP – dorsal-locking spine; SPH – sphenotic.

Figure 10. Pectoral spines.

A-E. Fossil Doradidae gen. and sp. ind., STRI- dbid-16241-1/2, from Cocinetas basin, Alta Guajira Peninsula, Colombia, F-J. Recent Doradidae, Anadoras sp. MPEG-0062, Santarém, Brazil, K-M. Fossil Doradidae ind., STRI- dbid-13107, N-P. STRI- dbid-16241-2/2, Q. STRI- dbid-13114, R. STRI- dbid-390083, S. STRI- dbid-16305; T. STRI- dbid-390020, from Cocinetas basin, Alta Guajira Peninsula, Colombia. U. UNEFM-PF-508, V. UNEFM-PF-509, W. UNEFM-PF-510, from the San Gregorio Formation (Vergel Member), Early Pliocene, Northeastern of Urumaco town (11°17’53.9″ N, 70°14’33.7″ W), Venezuela. Scale bar 10 mm from A to T, 1 mm from U to W. Abbreviations: AP – axial process; CLS -cleintral surface; DLP – dorsal lateral process; IF - internal fossa; VLP – ventral lateral process.