Papers by Jorge W. Moreno-Bernal
Geodiversitas, Apr 13, 2023
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En un viaje nuestro cuerpo se mueve de un lugar a otro, nuestra imaginacion se despierta al conoc... more En un viaje nuestro cuerpo se mueve de un lugar a otro, nuestra imaginacion se despierta al conocer espacios nuevos y nuestra vida cambia con cada experiencia del recorrido. Hay viajes cortos, largos, en carro, en avion, al mar, a la montana, y hay viajes que inician con un libro. Aqui te proponemos hacer un viaje con las maletas repletas de atencion y curiosidad por las imagenes y letras en cada pagina. Tus ojos, oidos e imaginacion seran las alas que te llevaran a descubrir formas, paisajes y seres vivos que vivieron en Colombia alguna vez.
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Journal of Systematic Palaeontology
The family Cynodontidae is composed of freshwater fishes inhabiting drainages east of the Andes i... more The family Cynodontidae is composed of freshwater fishes inhabiting drainages east of the Andes in South America. Its fossil record is mostly represented by isolated teeth that are difficult to identify. Here we describe fossil cranial remains of the extant species Hydrolycus scomberoides as well as isolated teeth that were identified as Hydrolycus and cf. Rhaphiodon in sediments of the late Pliocene Ware Formation in the Guajira Peninsula, west of the Andes. Novel, phylogenetically informative characters were found including the number of symphysial teeth, the plane of insertion of the leading teeth onto the dentary, the presence of accessory posterior dentigerous patches, and depressions and outline of the dentary. We performed a phylogenetic analysis combining morphological and molecular characters including both extant and extinct specimens, producing a well-resolved topology that recovers a novel sister-group relationship between the genera Hydrolycus and Cynodon, while the genus Rhaphiodon falls to the base of this clade. This contradicts earlier studies recovering Hydrolycus and Rhaphiodon as sister taxa. The phylogenetic position of Hydrolycus wallacei was found to be unstable. The occurrence of H. scomberoides in the late Pliocene of Guajira is a puzzle that could be explained by different mechanisms, including a persistent drainage connection across the Andes during the late Pliocene, and/or the result of severe drying and subsequent extinction.
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Journal of Systematic Palaeontology , 2022
The family Cynodontidae is composed of freshwater fishes inhabiting drainages east of the Andes i... more The family Cynodontidae is composed of freshwater fishes inhabiting drainages east of the Andes in South America. Its fossil record is mostly represented by isolated teeth that are difficult to identify. Here we describe fossil cranial remains of the extant species Hydrolycus scomberoides as well as isolated teeth that were identified as Hydrolycus and cf. Rhaphiodon in sediments of the late Pliocene Ware Formation in the Guajira Peninsula, west of the Andes. Novel, phylogenetically informative characters were found including the number of symphysial teeth, the plane of insertion of the leading teeth onto the dentary, the presence of accessory posterior dentigerous patches, and depressions and outline of the dentary. We performed a phylogenetic analysis combining morphological and molecular characters including both extant and extinct specimens, producing a well-resolved topology that recovers a novel sister-group relationship between the genera Hydrolycus and Cynodon, while the genus Rhaphiodon falls to the base of this clade. This contradicts earlier studies recovering Hydrolycus and Rhaphiodon as sister taxa. The phylogenetic position of Hydrolycus wallacei was found to be unstable. The occurrence of H. scomberoides in the late Pliocene of Guajira is a puzzle that could be explained by different mechanisms, including a persistent drainage connection across the Andes during the late Pliocene, and/or the result of severe drying and subsequent extinction.
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Canadian Journal of Earth Sciences
Two specimens of Borealosuchus collected from the lower facies of the Ravenscrag Formation (earli... more Two specimens of Borealosuchus collected from the lower facies of the Ravenscrag Formation (earliest Paleocene) in southern Saskatchewan are described. One largely complete individual featuring a partial skull, mandible, and postcrania can be unambiguously assigned to B. griffithi. The other specimen consisting of skull and partial postcranial fragments is referred to B. sternbergii based on diagnostic cranial features. These specimens confirm the earliest occurrence of this clade in the province of Saskatchewan and expand the known stratigraphic and geographic range of their respective species. The discovery of B. griffithi and B. sternbergii in proximity to each other within the same deposits suggest temporal and spatial range overlap in the Big Muddy area during the earliest Paleocene, hinting at possible niche partitioning or other ecological relationships between members of the same genus.
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Biological Conservation, 2021
Abstract Biological invasions are a big concern due to their potential to impact ecosystems, as w... more Abstract Biological invasions are a big concern due to their potential to impact ecosystems, as well as local people. The hippo Hippopotamus amphibius, native to Africa, has invaded extensive areas of the Magdalena River basin (Colombia) over the past decades, and has been considered the largest invasive animal in the world. Here, we propose the use of two approaches of predictive modeling, in order to guide recommendations for the management of this biological invasion. First, we developed a population viability analysis (PVA) to simulate a hypothetical population growth under different management scenarios. Next, we explored the potential invasion area under future climate change scenarios throughout ecological niche modeling analyses. PVA models predicted that in the absence of an intense culling/hunting pressure, the population size will continue to steadily increase, which is consistent with the population growth observed during the last 20 years. Furthermore, our static and dynamic habitat suitability projections suggested that without dispersal limiting factors, potential colonization habitat for hippos may become very extensive across the landscape and can be favored by climate change in the future. Therefore, our findings show the urgent need of taking critical management decisions by the Colombian authorities, which should be focused on limiting the hippos' population growth and expansion. Ignoring cost-benefit considerations for the control of this invasive species may have unexpected and long-term social and ecological implications. However, the proposal of a course of action can become controversial when the species has a charismatic value for the society, regardless of its ecological or social impact.
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Journal of Vertebrate Paleontology, 2020
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Ameghiniana, 2019
Abstract. Fossil scales of the enigmatic teleost Acregoliath rancii Richter, collected in 1945 an... more Abstract. Fossil scales of the enigmatic teleost Acregoliath rancii Richter, collected in 1945 and 1946, are described for the first time from fine-grained sediments of the La Victoria Formation of the Honda Group in central Colombia. The specimens include one isolated but nearly complete scale from the anterior region of the body, and one isolated scale fragment. Although fragmentary, these specimens provide relevant anatomic and biogeographical information. Both specimens agree in most details with the type material of A. rancii; however, the almost complete scale differs in focus position and outline, thus suggesting topological variation. This aspect of lepidosis in A. rancii was previously unknown and could be relevant for future reassessment of the interrelationships of this taxon. The presence of A. rancii in the middle to late Miocene fossil assemblages from La Venta, Fitzcarrald, and Acre suggests a relationship between these areas during the middle Miocene. The relevance for paleodrainage evolution in northern South America is discussed in the context of these findings.
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PloS one, 2017
The late Miocene was an important time to understand the geological, climatic, and biotic evoluti... more The late Miocene was an important time to understand the geological, climatic, and biotic evolution of the ancient New World tropics and the context for the Great American Biotic Interchange (GABI). Despite this importance, upper Miocene deposits containing diverse faunas and floras and their associated geological context are rare in Central America. We present an integrated study of the geological and paleontological context and age of a new locality from Lago Alajuela in northern Panama (Caribbean side) containing late Miocene marine and terrestrial fossils (plants, invertebrates, and vertebrates) from the Alajuela Formation. These taxa indicate predominantly estuarine and shallow marine paleoenvironments, along with terrestrial influences based on the occurrence of land mammals. Sr-isotope ratio analyses of in situ scallop shells indicate an age for the Alajuela Formation of 9.77 ± 0.22 Ma, which also equates to a latest Clarendonian (Cl3) North American Land Mammal Age. Along wi...
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Journal of Systematic Palaeontology
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SireNews, 2021
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Journal of South American Earth Sciences
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PLoS ONE, 2017
The late Miocene was an important time to understand the geological, climatic, and biotic evoluti... more The late Miocene was an important time to understand the geological, climatic, and biotic evolution of the ancient New World tropics and the context for the Great American Biotic Interchange (GABI). Despite this importance, upper Miocene deposits containing diverse faunas and floras and their associated geological context are rare in Central America. We present an integrated study of the geological and paleontological context and age of a new locality from Lago Alajuela in northern Panama (Caribbean side) containing late Miocene marine and terrestrial fossils (plants, invertebrates, and vertebrates) from the Alajuela Formation. These taxa indicate predominantly estuarine and shallow marine paleoenvironments, along with terrestrial influences based on the occurrence of land mammals. Sr-isotope ratio analyses of in situ scallop shells indicate an age for the Alajuela Formation of 9.77 ± 0.22 Ma, which also equates to a latest Clarendonian (Cl3) North American Land Mammal Age. Along with the roughly contemporaneous late Miocene Gatun and Lago Bayano faunas in Panama, we now have the opportunity to reconstruct the dynamics of the Central America seaway that existed before final closure coincident with formation of the Isthmus of Panama.
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Journal of Vertebrate Paleontology, 2016
The La Guajira Peninsula, Colombia, has a continuous vertebrate fossil record that includes both ... more The La Guajira Peninsula, Colombia, has a continuous vertebrate fossil record that includes both the late early–early middle Miocene and the Pliocene. Crocodilians from the early to early middle Miocene Jimol and Castilletes formations include gavialoids, recovered from both coastal and shallow marine deposits, and caimanines representing early records of the specialized caimanine taxa Purussaurus and Mourasuchus. Crocodyloid specimens from the Pliocene Ware Formation are assigned to Crocodylus and represent one of the oldest occurrences of the genus in the New World. Records from the La Guajira Peninsula suggest that diverse crocodilian assemblages were already established by the late early Miocene, including several widely distributed lineages that persisted for several million years. Crocodylus is a recent immigrant to South America that occupied habitats left vacant by the extinction of several crocodilian lineages.
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Journal of Vertebrate Paleontology, 2015
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Swiss Journal of Palaeontology, 2015
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Conference Presentations by Jorge W. Moreno-Bernal
Memorias del XIII congreso colombiano de Ictiología y IV encuentro de Ictiólogos suramericanos
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The shoaling and closure of the Central American Seaway (CAS) during the late Neogene had a major... more The shoaling and closure of the Central American Seaway (CAS) during the late Neogene had a major impact on local ecosystems, oceanographic currents, and global climate. Constraining the spatial and temporal context of CAS shoaling, however, is hindered by ambiguity in the stratigraphic relationships and depositional environments of marine sedimentary exposures in Panama and adjacent regions. Here, we present new information from the Alhajuela Formation (Lago Alajuela, central Panama) with implications for the presence of the CAS in the Panama Canal and Lago Alajuela Basins.
The age and stratigraphic relationships of the Alhajuela Formation are problematic due to its geographically-restricted exposures and lack of contacts with other age-constrained formations in Panama Canal Basin. Recent discoveries of a vertebrate assemblage from basal strata of the Alhajuela Formation suggest a middle-late Miocene age contemporary with the proposed onset of shoaling, yet the stratigraphy exposed in Lago Alajuela exhibits a transgressive transition from nearshore facies to shallow shelf environments. Matrix-supported conglomeratic horizons containing volcanic clasts, fossil terrestrial mammals, wood fragments, and marine vertebrates and invertebrates exhibit erosional contacts with underlying bioturbated marine sandstones with exclusively marine fossil content. Other mollusc-bearing sandstone units exhibit thin conglomeratic beds and lenses. We interpret these lithological sequences as representing conglomerate deposition in nearshore environments via subaqueous debris-flow and current-reworking processes, respectively. Higher in the stratigraphy, sediments comprise massive, carbonate-cemented, tuffaceous sandstone with exclusively marine fossil content, interpreted as shallow shelf deposits.
This transgressive sequence in the Alhajuela Formation is consistent with the overall trend in paleobathymetry recently reported for the late Miocene Gatun Formation, which is either contemporaneous or slightly younger than the Alhajuela Formation. We conclude that the Panama Canal Basin did not serve as a major conduit for the mixing of Pacific-Caribbean waters. Rather the sedimentary record in this basin records an increase in accommodation space during the middle-late Miocene.
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Society of Vertebrate Paleontology, Program and Abstracts, 2013, p. 179.
The greatest diversit... more Society of Vertebrate Paleontology, Program and Abstracts, 2013, p. 179.
The greatest diversity of Cenozoic crocodylians occurred during the Neogene in South America. However, the origin of this high diversity and its relationship to the environment are poorly understood. Most described species come from the late Miocene localities of La Venta, Urumaco, and Acre, whereas the record is sparse in the early to middle Miocene and after the latest Miocene and Pliocene. Field research in the Castilletes (Middle-Late Miocene) and Waré (Pliocene) Formations in the High Guajira Peninsula of Colombia provides new fossil data on the origin of Neotropical crocodylian diversity. The Castilletes and Waré Formations crop out most extensively in the Cocinetas Basin, and represent depositional environments consisting of deltaic and shallow marine systems in the Castilletes and predominately fluvial environments in the unconformably overlying Waré Formation. Vertebrate localities in both formations include abundant remains of sharks, rays, actinopterygians, turtles, croco...
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72nd Annual Meeting of the Society of vertebrate Paleontology. Program and Abstracts, 2012:108.
... more 72nd Annual Meeting of the Society of vertebrate Paleontology. Program and Abstracts, 2012:108.
Titanoboa cerrejonensis from the Cerrejón Formation (middle to late Paleocene; 58-60 My) of Colombia, is the largest known snake. The taxon was originally diagnosed, assigned to the clade Boinae, and estimated to be approximately 12.8 m (±2.18 m) in total body length on the basis of precloacal vertebral morphology and size, but the absence of cranial remains prohibited a more precise size estimate and robust phylogenetic hypothesis. Recent fieldwork in the type locality has resulted in the recovery of several new specimens of Titanoboa including parts of the cranium and mandible (maxillae, palatine, pterygoid, quadrate, dentary, and compound elements) associated with partial axial skeletons. We estimate skull length from cranial elements to be 40 cm, corresponding to a total body length of 14.3 m (±1.28 m) based on the scaling relationship of head length to body length in the extant boine Eunectes. Phylogenetic analyses of Titanoboa and extant macrostomatan snakes using cranial and postcranial osteology, and including analyses incorporating a molecular scaffold for extant taxa, supports boine affinities of Titanoboa, based on the extreme reduction of the palatine choanal and posteromedial processes as well as vertebral anatomy. Within Boinae, Titanoboa shares a close relationship with Pacific Island-Madagascan taxa. These results are the first historical evidence linking Neotropical and Old World boines, and constrain divergence timing of the clades to no younger than 58 My. Cranial elements of Titanoboa possess unique features relative to other boids, including high palatal and marginal tooth position counts, low-angled quadrate orientation, and reduced palatine-pterygoid and pterygoid-quadrate articulations. These characters, combined with weakly ankylosed teeth in Titanoboa, are characteristic of piscivorous feeding ecology in extant caenophidian snakes. Preservation in the large-scale fluvial depositional environments of the Cerrejón Formation, combined with the recovery of associated fossils of large dipnoan and osteoglossomorph fishes, also suggests a dominantly piscivorous feeding ecology for Titanoboa, which is unique among living and fossil boids.
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Papers by Jorge W. Moreno-Bernal
Conference Presentations by Jorge W. Moreno-Bernal
The age and stratigraphic relationships of the Alhajuela Formation are problematic due to its geographically-restricted exposures and lack of contacts with other age-constrained formations in Panama Canal Basin. Recent discoveries of a vertebrate assemblage from basal strata of the Alhajuela Formation suggest a middle-late Miocene age contemporary with the proposed onset of shoaling, yet the stratigraphy exposed in Lago Alajuela exhibits a transgressive transition from nearshore facies to shallow shelf environments. Matrix-supported conglomeratic horizons containing volcanic clasts, fossil terrestrial mammals, wood fragments, and marine vertebrates and invertebrates exhibit erosional contacts with underlying bioturbated marine sandstones with exclusively marine fossil content. Other mollusc-bearing sandstone units exhibit thin conglomeratic beds and lenses. We interpret these lithological sequences as representing conglomerate deposition in nearshore environments via subaqueous debris-flow and current-reworking processes, respectively. Higher in the stratigraphy, sediments comprise massive, carbonate-cemented, tuffaceous sandstone with exclusively marine fossil content, interpreted as shallow shelf deposits.
This transgressive sequence in the Alhajuela Formation is consistent with the overall trend in paleobathymetry recently reported for the late Miocene Gatun Formation, which is either contemporaneous or slightly younger than the Alhajuela Formation. We conclude that the Panama Canal Basin did not serve as a major conduit for the mixing of Pacific-Caribbean waters. Rather the sedimentary record in this basin records an increase in accommodation space during the middle-late Miocene.
The greatest diversity of Cenozoic crocodylians occurred during the Neogene in South America. However, the origin of this high diversity and its relationship to the environment are poorly understood. Most described species come from the late Miocene localities of La Venta, Urumaco, and Acre, whereas the record is sparse in the early to middle Miocene and after the latest Miocene and Pliocene. Field research in the Castilletes (Middle-Late Miocene) and Waré (Pliocene) Formations in the High Guajira Peninsula of Colombia provides new fossil data on the origin of Neotropical crocodylian diversity. The Castilletes and Waré Formations crop out most extensively in the Cocinetas Basin, and represent depositional environments consisting of deltaic and shallow marine systems in the Castilletes and predominately fluvial environments in the unconformably overlying Waré Formation. Vertebrate localities in both formations include abundant remains of sharks, rays, actinopterygians, turtles, croco...
Titanoboa cerrejonensis from the Cerrejón Formation (middle to late Paleocene; 58-60 My) of Colombia, is the largest known snake. The taxon was originally diagnosed, assigned to the clade Boinae, and estimated to be approximately 12.8 m (±2.18 m) in total body length on the basis of precloacal vertebral morphology and size, but the absence of cranial remains prohibited a more precise size estimate and robust phylogenetic hypothesis. Recent fieldwork in the type locality has resulted in the recovery of several new specimens of Titanoboa including parts of the cranium and mandible (maxillae, palatine, pterygoid, quadrate, dentary, and compound elements) associated with partial axial skeletons. We estimate skull length from cranial elements to be 40 cm, corresponding to a total body length of 14.3 m (±1.28 m) based on the scaling relationship of head length to body length in the extant boine Eunectes. Phylogenetic analyses of Titanoboa and extant macrostomatan snakes using cranial and postcranial osteology, and including analyses incorporating a molecular scaffold for extant taxa, supports boine affinities of Titanoboa, based on the extreme reduction of the palatine choanal and posteromedial processes as well as vertebral anatomy. Within Boinae, Titanoboa shares a close relationship with Pacific Island-Madagascan taxa. These results are the first historical evidence linking Neotropical and Old World boines, and constrain divergence timing of the clades to no younger than 58 My. Cranial elements of Titanoboa possess unique features relative to other boids, including high palatal and marginal tooth position counts, low-angled quadrate orientation, and reduced palatine-pterygoid and pterygoid-quadrate articulations. These characters, combined with weakly ankylosed teeth in Titanoboa, are characteristic of piscivorous feeding ecology in extant caenophidian snakes. Preservation in the large-scale fluvial depositional environments of the Cerrejón Formation, combined with the recovery of associated fossils of large dipnoan and osteoglossomorph fishes, also suggests a dominantly piscivorous feeding ecology for Titanoboa, which is unique among living and fossil boids.
The age and stratigraphic relationships of the Alhajuela Formation are problematic due to its geographically-restricted exposures and lack of contacts with other age-constrained formations in Panama Canal Basin. Recent discoveries of a vertebrate assemblage from basal strata of the Alhajuela Formation suggest a middle-late Miocene age contemporary with the proposed onset of shoaling, yet the stratigraphy exposed in Lago Alajuela exhibits a transgressive transition from nearshore facies to shallow shelf environments. Matrix-supported conglomeratic horizons containing volcanic clasts, fossil terrestrial mammals, wood fragments, and marine vertebrates and invertebrates exhibit erosional contacts with underlying bioturbated marine sandstones with exclusively marine fossil content. Other mollusc-bearing sandstone units exhibit thin conglomeratic beds and lenses. We interpret these lithological sequences as representing conglomerate deposition in nearshore environments via subaqueous debris-flow and current-reworking processes, respectively. Higher in the stratigraphy, sediments comprise massive, carbonate-cemented, tuffaceous sandstone with exclusively marine fossil content, interpreted as shallow shelf deposits.
This transgressive sequence in the Alhajuela Formation is consistent with the overall trend in paleobathymetry recently reported for the late Miocene Gatun Formation, which is either contemporaneous or slightly younger than the Alhajuela Formation. We conclude that the Panama Canal Basin did not serve as a major conduit for the mixing of Pacific-Caribbean waters. Rather the sedimentary record in this basin records an increase in accommodation space during the middle-late Miocene.
The greatest diversity of Cenozoic crocodylians occurred during the Neogene in South America. However, the origin of this high diversity and its relationship to the environment are poorly understood. Most described species come from the late Miocene localities of La Venta, Urumaco, and Acre, whereas the record is sparse in the early to middle Miocene and after the latest Miocene and Pliocene. Field research in the Castilletes (Middle-Late Miocene) and Waré (Pliocene) Formations in the High Guajira Peninsula of Colombia provides new fossil data on the origin of Neotropical crocodylian diversity. The Castilletes and Waré Formations crop out most extensively in the Cocinetas Basin, and represent depositional environments consisting of deltaic and shallow marine systems in the Castilletes and predominately fluvial environments in the unconformably overlying Waré Formation. Vertebrate localities in both formations include abundant remains of sharks, rays, actinopterygians, turtles, croco...
Titanoboa cerrejonensis from the Cerrejón Formation (middle to late Paleocene; 58-60 My) of Colombia, is the largest known snake. The taxon was originally diagnosed, assigned to the clade Boinae, and estimated to be approximately 12.8 m (±2.18 m) in total body length on the basis of precloacal vertebral morphology and size, but the absence of cranial remains prohibited a more precise size estimate and robust phylogenetic hypothesis. Recent fieldwork in the type locality has resulted in the recovery of several new specimens of Titanoboa including parts of the cranium and mandible (maxillae, palatine, pterygoid, quadrate, dentary, and compound elements) associated with partial axial skeletons. We estimate skull length from cranial elements to be 40 cm, corresponding to a total body length of 14.3 m (±1.28 m) based on the scaling relationship of head length to body length in the extant boine Eunectes. Phylogenetic analyses of Titanoboa and extant macrostomatan snakes using cranial and postcranial osteology, and including analyses incorporating a molecular scaffold for extant taxa, supports boine affinities of Titanoboa, based on the extreme reduction of the palatine choanal and posteromedial processes as well as vertebral anatomy. Within Boinae, Titanoboa shares a close relationship with Pacific Island-Madagascan taxa. These results are the first historical evidence linking Neotropical and Old World boines, and constrain divergence timing of the clades to no younger than 58 My. Cranial elements of Titanoboa possess unique features relative to other boids, including high palatal and marginal tooth position counts, low-angled quadrate orientation, and reduced palatine-pterygoid and pterygoid-quadrate articulations. These characters, combined with weakly ankylosed teeth in Titanoboa, are characteristic of piscivorous feeding ecology in extant caenophidian snakes. Preservation in the large-scale fluvial depositional environments of the Cerrejón Formation, combined with the recovery of associated fossils of large dipnoan and osteoglossomorph fishes, also suggests a dominantly piscivorous feeding ecology for Titanoboa, which is unique among living and fossil boids.
In 2010 and 2011 we undertook an initial exploratory survey of the late Miocene-early Pliocene Castilletes Formation (Eastern Guajira Peninsula, Colombia). The Castilletes is composed of deltaic and shallow marine deposits, with an abundant continental fauna in some intervals. These new findings will contribute to a better understanding of the neotropical vertebrate communities and paleoenvironments during a time of high tectonic activity and global climate change. The fauna includes sharks (Carchariniformes), rays (Myliobatiformes), catfish (Siluriformes), dogtooth tetras (Cynodontidae), fresh water turtles (Podocnemidae), and one of the oldest records of Crocodylus in the Americas. The mammal assemblage comprises five orders and ten families. Xenarthrans include megatheriid and nothrotheriid sloths and the cingulates Boreostemma pliocena (Glyptodontinae), Neoglyptatelus sp. (Glyptatelinae), cf. Holmesina and cf. Pampatherium (Pampatheriidae). Rodents are represented by Chapalmatherium (Hydrochoeridae), cf. Neoepiblema (Neoepiblemidae) and Paramyocastor sp. (Echymidae). Indigenous South American ungulates include horse-like protherotheriids (Litopterna), rhino-like toxodonts (Notoungulata), and astrapotheres (Astrapotheria). Associated fossil wood is found in some localities. Overall, the Castilletes fauna and flora indicates the presence of extensive water bodies, in a delta complex with moderate to high rates of rainfall during the late Miocene-early Pliocene. Considering that today the Guajira peninsula is characterized by a very dry climate with xerophitic vegetation, the inferred paleoenvironment for the Castilletes Formation indicates that the region has suffered a drastic climatic change over the last 4 million years.
The modern northern Neotropics possesses some of the highest diversity among extant squamates, but the sparse fossil record from this region has previously limited the ability to reconstruct their evolutionary histories. New discoveries from the early Paleogene of northern South America reveal biogeographic patterns and paleoecology of modern clades. Squamates have been recovered as components of vertebrate faunas from the late Paleocene Cerrejón Formation and late Paleocene- early Eocene Bogotá Formation of Colombia. The Cerrejón Formation represents large-scale fluvial deposits with associated rainforest flora and herpetofauna. The squamate record consists of snakes, including multiple individuals of the giant aquatic boid Titanoboa cerrejonensis and a single, poorly preserved precloacal vertebra assigned to Anilioidea on the basis of extreme reduction of the neural spine, broadly concave dorsal margin of the neural arch and comparatively narrow zygosphene. The presence of a fossorial to leaf-litter specialist provides the first the first terrestrial component to the reptile record and indicates geographic proximity of the aquatic record to rainforest habitats within the Cerrejón Formation. The Muchelo Creek locality in the Bogotá Formation is dated to just before the Early Eocene Climatic Optimum (EECO). It represents smaller scale fluvial deposition, and preserves a diverse squamate fauna consisting of iguanians, including the fossil record of hoplocercines, and boine, caenophidian, and ungaliophiine snakes. Modern members of these clades include arboreal taxa, and the Bogotá squamate record represents a forest herpetofauna. Extant tropical forest squamates undergo thermal stress at high ambient temperatures, and inferred thermal tolerances of the Bogotá squamate record may constrain temperature estimates at the beginning of the equatorial EECO.
The Colombian squamate record indicates that the continental-scale biogeographic zonation of the modern northern Neotropics was established no later than the middle Eocene. Both the Bogotá and Cerrejón formations include representatives of extant clades that are either endemic or predominately South America (“anilioids”) or whose Central American distributions are limited or represent more recent immigration from South America (hoplocercines, boines). These records additionally indicate that the biogeographic events that initially assembled Neotropical squamate faunas, including New World immigration of iguanians and first occurrence of South American boines, were likely late Mesozoic in age.
Una campaña de Ingeominas en el año 2001 colectó un ejemplar fósil de astrapoterio en la quebrada Malnombre, vereda Hilarco, municipio de Purificación, departamento del Tolima, Colombia. El ejemplar está depositado en la colección del Museo Geológico Nacional José Royo y Gómez (JACR28112001-1). Los restos incluyen un cráneo parcial sin los huesos de la bóveda y la región posterior del arco cigomático derecho; la mandíbula con dentarios derecho e izquierdo fusionados, pero con pérdida de la porción posterior del ramo izquierdo; el húmero izquierdo completo y la región proximal de una costilla. Estos restos fueron excavados en intercalaciones de arcillas, limolitas y limos arenosos con lentes de arena del Grupo Honda, correspondientes a la Formación La Victoria, cuya localidad tipo fue descrita en el Desierto de la Tatacoa (al sur de la zona del hallazgo). El ejemplar presenta todas las sinapomorfías dentales de la Subfamilia Uruguaytheriinae, y representa un nuevo género y especie. El género se diagnostica por la combinación de los siguientes rasgos: fórmula dental 0/3, 1/1, 1/1, 3/3, caninos inferiores con implantación levemente extrovertida (diagonal) con sección transversal subtriangular en la base e hipocono en el tercer molar superior. La estimación del tamaño corporal utilizando correlaciones con mediciones dentales y del húmero indican que el espécimen habría pesado entre 1100 y 1400kg, en un rango de tamaño comparable al de Astrapotherium magnum Owen y Xenastrapotherium kraglievichi Cabrera, pero claramente menor comparado con Granastrapotherium snorki Johnson y Madden, reportado también para el Mioceno medio de Colombia en sedimentitas del Grupo Honda. Un análisis filogenético preliminar utilizando 46 caracteres dentales, que incluye doce especies de astrapoterios, sugiere que el ejemplar corresponde a uno de los linajes más recientes de astrapoterios, siendo taxón hermano de G. snorki.
This work is intended to provide body length and mass estimates for the Tropical South American Miocene crocodiles Purussaurus (Alligatoroidea) and Gryposuchus (Gavialoidea). Size estimates were done from skull and femoral measurements, using regressions published for extant crocodile species. Most Purussaurus specimens were estimated at lengths between 7-8 meters, with body masses between 1.7-2.7 metric tones. A P. brasiliensis specimen was estimated in a maximum of 10 meters and 5 tones. Gryposuchus length was between 7 and 10 meters, without accurate body mass estimates, due to the lack of proper studies in longirostral forms such as Gavialis and Tomistoma. Purussaurus and Gryposuchus are longer and heavier than the biggest extant Crocodylia (with maximum sizes of 6 meters and 1 ton), and close to giant Cretaceous forms such as Deinosuchus or Sarcosuchus. Comparisons between skull-based and femur-based estimates suggests that while in Purussaurus femur size, relative to body size, is as expected in crocodilians, Gryposuchus has reduced femora, suggestive of more aquatic habits. Robustness of Purussaurus limbs can be related to the foraging of big terrestrial prey on the shores of water bodies. Gigantism in crocodilians implies higher and more stable body temperatures, with a risk of overheating, and reduced basking habits. Huge nares seen in giant fossil Crocodiliformes such as Sarcosuchus, Mourasuchus amazonensis and Purussaurus could have been related with a heat exchange mechanism. This study was possible thanks to the collaboration of the Smithsonian Tropical Research Institute.
Las faunas miocénicas de Suramérica intertropical proporcionan asociaciones bien conocidas de Crocodylia fósiles. Estas asociaciones son ricas en especies, ocupando un espectro ecológico muy amplio. Varios restos de cocodrilos fueron recuperados en campañas dirigidas por INGEOMINAS en Pubenza, Cundinamarca. La asociación incluye restos de tortugas dulceacuícolas y piezas de mamíferos, entre las que destacan molares bunodontos posiblemente pertenecientes a un Megadolodinae. Los elementos aparecen impregnados de gipsita, lo que dificulta su preparación y observación. Con base en particularidades craneales y dentales se reconocen formas pertenecientes a las familias Alligatoridae y Gavialidae. Un cráneo de gran tamaño presenta características (extrema longitud rostral, festoneado lateral del rostro, orbitas y fenestras supratemporales de tamaño similar) que indican afinidades con Ikanogavialis, mientras que un fragmento de maxilar y varios dientes de gran tamaño sugieren la posible presencia de Purussaurus. También han sido recuperadas varias vértebras pertenecientes a cocodrilos de gran tamaño. La Formación Barzalosa, de donde proceden estos restos, ha sido datada tentativamente como Mioceno Inferior en base a polen. De confirmarse, estos restos corresponderían a los registros más antiguos para estos géneros. La persistencia de formas similares de Crocodylia a lo largo del Mioceno indicaría así un periodo prolongado de estabilidad ambiental.
Oenocarpus sp., es un género de Arecaceae, pantropical y subtropical con mesocarpo y semilla ricos en aceites, fibra y proteínas. Estudios sobre su ecología de dispersión identificaron roedores, ungulados, primates y aves como dispersores/depredadores implicados en germinación y supervivencia de plántulas. Se evaluó la depredación pre-dispersión/pos dispersión en frutos y semillas de Oenocarpus sp. en un bosque de galería, en el Centro de Investigación Carimagua, departamento del Meta. En pre dispersión se tomaron aleatoriamente cuatro racimos, haciéndose conteo y caracterización de daño de frutos totales; para pos-dispersión se colectaron aleatoriamente frutos y semillas a tres distancias con respecto al fuste de la palma. Los daños se clasificaron en siete tipos según tamaño, forma de perforación y posible depredador. En pre-dispersión predominaron los daños tipo A (fruto) y D (semilla) por insectos. En pos-dispersión predominaron daños tipo D, B y C (frutos) posiblemente provocados por aves, primates y roedores. Un ANOVA a dos vías arrojo diferencias significativas entre los tipos de daño. Análisis Cluster arrojaron agrupamiento diferenciado de frutos y semillas por distancia respecto al fuste. Se observó consumo de frutos caídos y en racimo por grupos de Amazona ochrocephala, Coragyps atratus, Cathartes aura, Polyborus plancus, Aotus sp. y Cebus apella.
Siete especies de Crocodylomorpha han sido halladas en la parte inferior del Miembro Baraya de la Formación Villavieja. Los mecanismos que permitieron la coexistencia dentro de esta comunidad son poco comprendidos. Las diferencias en parámetros morfológicos del rostro (longitud rostral / longitud craneal; diámetro lateromedial del rostro / diámetro dorsoventral del rostro) muestran adaptaciones tróficas divergentes. Los gavialidos Gryposuchus colombianus y Charactosuchus fieldsi poseen rostros largos y tubulares; en los alligatóridos Eocaiman sp, Caiman sp, y Purussaurus neivensis el rostro es mas corto y amplio, en P. neivensis el diámetro dorsoventral es inusualmente alto. En Mourasuchus atopus el rostro es inusualmente largo, plano y mucho mas amplio comparado al de los gavialidos. Sebecus huilensis difiere en su morfología de los Crocodylia al tener un cráneo oreinirostro (alto y estrecho), y una diferente morfología dental. La comparación con análogos modernos indica que la estrategia trófica variaba entre los diferentes taxa, siendo los gavialidos especialistas en presas relativamente pequeñas, principalmente peces, los alligatóridos de rostros cortos y anchos con una dieta mas variada, consumidores de presas relativamente más grandes. Las adaptaciones craneales y dentales de P. neivensis sugieren una especialización para el consumo de presas grandes y de huesos duros. La morfología inusual de M. atopus sugiere una estrategia trófica desconocida entre los Crocodylia actuales. Sebecus huilensis posee un conjunto de adaptaciones similares a las vistas en grandes lagartos depredadores terrestres y dinosaurios terópodos. Las diferencias de tamaño entre los Crocodylia, en términos de máxima longitud craneal, se analizaron utilizando las tasas de Hutchinson (especie más grande / especie inmediatamente más pequeña). Las diferencias de tamaño resultaron mayores dentro de los crocodylia con morfologías rostrales más similares. En el caso de Eocaiman sp y Caiman sp, de tamaño y morfología similar, la separación de nicho puede haber estado definida por desplazamiento de caracteres o diferencias de microhabitat. La riqueza de especies de crocodylomorpha de la parte inferior del Miembro Baraya sugiere una mayor heterogeneidad de hábitats y una mayor estabilidad, típicas de un estado avanzado de sucesión en el ecosistema.