Titanoboa

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Titanoboa
Temporal range: Mid-Late Paleocene (Peligran-Itaboraian)
~60–58  Ma
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Fossilized Titanoboa Vertebrea.jpg
Titanoboa dorsal vertebra in the José Royo y Gómez National Geological Museum, Bogotá
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Boidae
Genus:† Titanoboa
Head et al., 2009
Species:
†T. cerrejonensis
Binomial name
†Titanoboa cerrejonensis
Head et al., 2009

Titanoboa ( /ˌtaɪtənəˈboʊə/ ; lit. 'titanic boa') is an extinct genus of giant boid, the family that includes all boas and anacondas, snake that lived during the middle and late Paleocene. Titanoboa was first discovered in the early 2000s by the Smithsonian Tropical Research Institute who, along with students from the University of Florida, recovered 186 fossils of Titanoboa from La Guajira in northeastern Colombia. It was named and described in 2009 as Titanoboa cerrejonensis, the largest snake ever found. It was originally known only from thoracic vertebrae and ribs, but later expeditions collected parts of the skull and teeth. Titanoboa is in the subfamily Boinae, being most closely related to other extant boines from Madagascar and the Pacific.

Contents

They could grow up to 12.8 m (42 ft), perhaps even 14.3 m (47 ft) long and reach a body mass of 730–1,135 kg (1,610–2,500 lb). The discovery of Titanoboa cerrejonensis supplanted the previous record holder, Gigantophis garstini, which is known from the Eocene of Egypt. Titanoboa evolved following the extinction of all non-avian dinosaurs, being one of the largest reptiles to evolve after the Cretaceous-Paleogene Extinction event. Its vertebrae are very robust and wide, with a pentagonal shape in anterior view, as in other members of Boinae. Although originally thought to be an apex predator, the discovery of skull bones revealed that it was more than likely specialized in preying on fish.

History and naming

In 2002, during an expedition to the coal mines of Cerrejón in La Guajira [1] launched by the University of Florida and Smithsonian Tropical Research Institute, [2] large thoracic vertebrae and ribs were unearthed by the students Jonathon Bloch and Carlos Jaramillo. [3] [4] More fossils were unearthed over the course of the expedition, eventually totaling 186 fossils from 30 individuals. [2] The expedition lasted until 2004, during which the fossils of Titanoboa were mistakenly labeled as those of crocodiles. [5] These were found in association with other giant reptile fossils of turtles and crocodilians from the Cerrejón Formation, dating to the mid-late Paleocene epoch (around 60-58 mya), a period just after the Cretaceous–Paleogene extinction event. [2] Before this discovery, few fossils of Paleocene-epoch vertebrates had been found in ancient tropical environments of South America. [6] The fossils were then transported to the Florida Museum of Natural History, where they were studied and described by an international team of Canadian, American, and Panamanian scientists in 2009 led by Jason J. Head of the University of Toronto. [2] The snake elements were described as those of a novel, giant boid snake that they named Titanoboa cerrejonensis. The genus name derives from the Greek word "Titan" in addition to Boa, the type genus of the family Boidae. The species name is a reference to the Cerrejón region it is known from. [2]

Another expedition to Cerrejón launched in 2011 found more fossils from Titanoboa. [5] Most notably, the group returned with three disarticulated skulls of Titanoboa, making it one of the few fossil snakes with preserved cranial material. They were associated with postcranial material, cementing their referral to the species. [7] Though the skulls are undescribed, an article by the BBC in 2012 [8] and an abstract in the Society of Vertebrate Paleontology have been published. [7] A documentary on the animal titled Titanoboa: Monster Snake aired in 2012 in addition to a touring exhibit of the same name, which lasted from 2013 to 2018. [9]

Description

Size

The relative size of Titanoboa to the modern human, Palaeophis, Gigantophis, reticulated python, and green anaconda. Biggest snakes comparison chart.svg
The relative size of Titanoboa to the modern human, Palaeophis , Gigantophis , reticulated python, and green anaconda.

Based on the size of the vertebrae, Titanoboa is the largest snake in the paleontological record. In modern constrictors like boids and pythonids, increased body size is achieved through larger vertebrae rather than an increase in the number of bones making up the skeleton, allowing for length estimates based on individual bones. Based on comparison between the undistorted Titanoboa vertebrae and the skeleton of modern boas, Head and colleagues found that the analyzed specimens fit a position towards the later half of the precloacal vertebral column, approximately 60 to 65% back from the first two neck vertebrae. Using this method, initial size estimates proposed a total body length of approximately 12.82 m (42.1 ft) (± 2.18 m (7 ft 2 in)). Weight was determined by comparing Titanoboa to the extant green anaconda and the southern rock python, resulting in a weight between 652 kg (1,437 lb) and 1,819 kg (4,010 lb) (mean estimate 1,135 kg (2,502 lb)). These estimates far exceed the largest modern snakes, the green anaconda and the reticulated python, as well as the previous record holder, the madtsoid Gigantophis . The existence of eight additional specimens of similar size to the one used in these calculations implies that Titanoboa reached such massive proportions regularly. [2] The later discovery of skull material allowed for size estimates based on skull to body length proportions. Applying anaconda proportions to the 40 cm (16 in) skull of Titanoboa results in a total body length of around 14.3 m (47 ft) (± 1.28 m (4 ft 2 in)). [7] In 2016, Feldman and his colleagues estimated that a 12.8 m (42 ft) long individual would have weighed 730 kg (1,610 lb) at maximum based on their equation to estimate the body size of boids. [10]

Anatomy

Life restoration Titanoboa NT.jpg
Life restoration

Many of the fossils of Titanoboa are incomplete or undescribed, consisting primarily of thoracic vertebrae that were located before the cloaca. It possesses the same characteristics as other boids and especially Boa, such as a short, posteriorly-pointing prezygapophyseal process on these vertebrae. However, Titanoboa's are distinct due to being very robust and with a uniquely T-shaped neural spine. The neural spine also has an expanded posterior margin and a thin, blade-like anterior process. It also has much smaller foramina (small pits in bone) on its center and lateral sides, contrary to those of many other boids. [2]

The skull is only briefly described in a 2013 abstract. According to it, Titanoboa has a high amount of palatal and marginal tooth positions compared to others boids. The quadrate bone is oriented at a low angle and the articulation of both the palatine to pterygoid and pterygoid to quadrate are heavily reduced, a trait absent in its relatives. The teeth themselves are weakly ankylosed, meaning they are not strongly connected to the jawbone. [7]

Classification

Titanoboa is placed in the family Boidae, a family of snakes containing the "constrictors", that evolved during the Late Cretaceous in what is now the Americas. [11] They are a widely distributed group, with six subfamilies found on nearly every continent, [12] with Titanoboa being in the subfamily Boinae based on vertebrae morphology. All known boines are from the Americas, reaching as far north as Mexico and the Antilles [13] and south to Argentina. [14] Titanoboa is also the only extinct boine genus known; all other boine genera are still living. [15] [2]

The skull material confirmed Titanoboa's initial placement within the subfamily, now also supported by the reduced palatine choanal. The 2013 abstract recovered Titanoboa as closely related to taxa from the Pacific Islands and Madagascar, linking the Old World and New World boids and suggesting that the two lineages diverged by the Paleocene at the latest. [7] This would place Titanoboa at the stem of Boinae, a result corroborated by a study in 2015. [11]

The cladogram below follows the 2015 phylogenetic analysis: [11]

Candoia

Erycinae

Boinae

Titanoboa

Boa

Corallus

Corallus priscus

extant Corallus

Chilabothrus

Epicrates

Eunectes stirtoni

extant Eunectes

Palaeobiology

Habitat

Example of a coal mine in Cerrejon, where Titanoboa was found. Coal mining in Cerrejon.JPG
Example of a coal mine in Cerrejón, where Titanoboa was found.

Due to the warm and humid greenhouse climate of the Paleocene, the region of what is now Cerrejón was a coastal plain covered by wet tropical forests with large river systems, which were inhabited by various freshwater animals. Among the native reptiles are three different genera of dyrosaurs, crocodylomorphs that survived the KPG extinction event independently from modern crocodilians. The genera that coexisted alongside Titanoboa included the large, slender-snouted Acherontisuchus , the medium-sized but broad-headed Anthracosuchus , and the relatively small Cerrejonisuchus . [16] [17] Turtles also thrived in the tropical wetlands of Paleocene Colombia, giving rise to several species of considerable size such as Cerrejonemys [18] and Carbonemys. [19]

The rainforests of the Cerrejón Formation mirror modern tropical forests in regards to which families make up most of the vegetation. But unlike modern tropical forests, these Paleocene forests had fewer species. Although it is possible that this low diversity was a result of the wetland nature of the depositional environment, samples from other localities in the same time frame suggest that all of the forests that arose shortly following the Cretaceous-Paleogene mass extinction were of similar composition. This indicates that the low plant diversity of the time was a direct result of the mass extinction preceding it. [20] [21] Plants found in these Paleocene forests include the floating fern Salvinia [22] and various genera of Zingiberales and Araceae. [23]

Diet

Initially, Titanoboa was thought to have acted much like a modern anaconda based on its size and the environment it lived in, with researchers suggesting that it may have fed on the local crocodylomorph fauna. However, in the 2013 abstract, Jason Head and colleagues noted that the skull of this snake displays multiple adaptations to a piscivorous diet, including the anatomy of the palate, the tooth count, and the anatomy of the teeth themselves. These adaptations are not seen in other boids, but closely resemble those in modern caeonphidian snakes with a piscivorous diet. Such a lifestyle would be supported by the extensive rivers of Paleocene Colombia, as well as the fossil fish (lungfish and osteoglossomorphs) recovered from the formation. [7]

Climate implications

In the 2009 type description, Head and colleagues correlate the gigantism observed in Titanoboa with the climate conditions of its environment. As a poikilothermic ectotherm, Titanoboa's internal temperature and metabolism were heavily dependent on the ambient temperature, which would in turn affect the animal's size. [24] Accordingly, large ectothermic animals are typically found in the tropics and decrease in size the further one moves away from the equator. Following this correlation, the authors suggest that the mean annual temperature can be calculated by comparing the maximum body size of poikilotherm animals found in two localities. Based on the relation between temperatures in the modern Neotropics and the maximum length of anacondas, Head and colleagues calculated a mean annual temperature of at least 32–33 °C (90–91 °F) for the equatorial region of Paleocene South America. The estimates are consistent with a hot Paleocene climate as suggested by a study published in 2003 [25] and slightly higher (1–5 °C) than estimates derived from the oxygen isotopes of planktonic foraminifer. Although these estimates exceed temperatures of modern tropical forests, the paper argued that the increase in temperature was balanced out by higher amounts of rainfall. [2]

However, this conclusion was questioned by several researchers following the publication of the paper. J. M. Kale Sniderman used the same methodology as Head and colleagues on the Pleistocene monitor lizard Varanus priscus , comparing it to the extant Komodo dragon. Sniderman calculates that following this method, the modern tropics should be able to support lizards much larger than what is observed today, or in the reverse, that Varanus priscus is much larger than what would be implied by the ambient temperature of its native range. In conclusion it is argued that Paleocene rainforests may not have been any hotter than those today and that the massive size of Titanoboa and Varanus priscus may instead be the result of lacking significant mammalian competition. [26] Mark W. Denny, Brent L. Lockwood and George N. Somero also disagreed with Head's conclusion, noting that although this method is applicable to smaller poikilotherms, it is not constant across all size ranges. As thermal equilibrium is achieved through the relation between volume and surface area, they argue that the large size of Titanoboa coupled with the high temperatures proposed by Head et al. would mean that the animal would overheat easily if resting in a coiled up state. The authors conclude that several key factors influence the relationship between Titanoboa and the temperature of the area it inhabited. Varying posture could help cool down if needed, basking behavior or heat absorption through the substrate are both unknown and the potentially semi-aquatic nature of the animal creates additional factors to consider. Ultimately, Denny and colleagues argue that the nature of the giant snake renders it a poor indicator for the climate of the Paleocene and that the mean annual temperature must have been 4 to 6 °C (7 to 11 °F) cooler than the current estimate. [27]

These issues, alongside adjustments suggested by Makarieva, were addressed by Head and his team the same year, arguing that Denny and colleagues misunderstand their proposed model. They retort that the method takes into account variation caused by body size and that it's furthermore based on the largest extant snakes, making it an appropriate method. They also add that the results recovered are consistent with large extant snakes, which are also known to perform thermoregulation through behavior. Sniderman's proposal that the correlation between body size and temperature is inconsistent with modern monitor lizards is addressed twofold. For one, Head argues, Komodo dragons are a poor analogy as they are geographically restricted to the islands of Indonesia, limiting the size they could grow to while both green anacondas and Titanoboa are mainland animals. Secondly the response notes that the size estimates utilized for Varanus priscus are overestimates and unreliable, being based on secondary reports that do not match better supported estimates indicating a 2.19–4.7 m (7 ft 2 in – 15 ft 5 in) range for the monitor. [28]

Related Research Articles

<span class="mw-page-title-main">Boidae</span> Family of snakes

The Boidae, commonly known as boas or boids, are a family of nonvenomous snakes primarily found in the Americas, as well as Africa, Europe, Asia, and some Pacific islands. Boas include some of the world's largest snakes, with the green anaconda of South America being the heaviest and second-longest snake known; in general, adults are medium to large in size, with females usually larger than the males. Six subfamilies comprising 15 genera and 54 species are currently recognized.

<span class="mw-page-title-main">Tropidophiidae</span> Family of snakes

The Tropidophiidae, common name dwarf boas or thunder snakes, are a family of nonvenomous snakes found from Mexico and the West Indies south to southeastern Brazil. These are small to medium-sized fossorial snakes, some with beautiful and striking color patterns. Currently, two living genera, containing 34 species, are recognized. Two other genera were once considered to be tropidophiids but are now known to be more closely related to the boids, and are classified in the subfamily Ungaliophiinae. There are a relatively large number of fossil snakes that have been described as tropidophiids, but which of these are more closely related to Tropidophis and Trachyboa and which are more closely related to Ungaliophis and Exiliboa is unknown.

Gigantophis is an extinct genus represented by its sole member Gigantophis garstini, a giant snake. Before the Paleocene constrictor genus Titanoboa was described from Colombia in 2009, Gigantophis garstini was regarded as the largest snake ever recorded. It lived about 40 million years ago during the Eocene epoch of the Paleogene Period, in the Paratethys Sea, within the northern Sahara, where Egypt and Algeria are now located.

<span class="mw-page-title-main">Erycinae</span> Subfamily of snakes

The Erycinae, also known as the Old World sand boas, are a subfamily of nonvenomous snakes in the family Boidae. Species of the subfamily Erycinae are found in Europe, Asia Minor, Africa, Arabia, central and southwestern Asia, India, Sri Lanka, and western North America. Four genera comprising 18 species are currently recognized as being valid.

<span class="mw-page-title-main">Dyrosauridae</span> Extinct family of reptiles

Dyrosauridae is a family of extinct neosuchian crocodyliforms that lived from the Campanian to the Eocene. Dyrosaurid fossils are globally distributed, having been found in Africa, Asia, Europe, North America and South America. Over a dozen species are currently known, varying greatly in overall size and cranial shape. A majority were aquatic, some terrestrial and others fully marine, with species inhabiting both freshwater and marine environments. Ocean-dwelling dyrosaurids were among the few marine reptiles to survive the Cretaceous–Paleogene extinction event.

Hyposaurus is a genus of extinct marine dyrosaurid crocodyliform. Fossils have been found in Paleocene aged rocks of the Iullemmeden Basin in West Africa, Campanian–Maastrichtian Shendi Formation of Sudan and Maastrichtian through Danian strata in New Jersey, Alabama and South Carolina. Isolated teeth comparable to Hyposaurus have also been found in Thanetian strata of Virginia. It was related to Dyrosaurus. The priority of the species H. rogersii has been debated, however there is no sound basis for the recognition of more than one species from North America. The other North American species are therefore considered nomina vanum.

The Peligran age is a period of geologic time within the Paleocene epoch of the Paleogene, used more specifically with South American land mammal ages (SALMA). It follows the Tiupampan and precedes the Riochican age.

<span class="mw-page-title-main">Itaboraian</span>

The Itaboraian age is a period within the Early Eocene geologic time epoch of the Paleogene, used more specifically with South American land mammal ages (SALMA). It follows the Riochican and precedes the Casamayoran age.

Cerrejonisuchus is an extinct genus of dyrosaurid crocodylomorph. It is known from a complete skull and mandible from the Cerrejón Formation in northeastern Colombia, which is Paleocene in age. Specimens belonging to Cerrejonisuchus and to several other dyrosaurids have been found from the Cerrejón open-pit coal mine in La Guajira. The length of the rostrum is only 54-59% of the total length of the skull, making the snout of Cerrejonisuchus the shortest of all dyrosaurids.

<span class="mw-page-title-main">Cerrejón Formation</span>

The Cerrejón Formation is a geologic formation in Colombia dating back to the Middle-Late Paleocene. It is found in the El Cerrejón sub-basin of the Cesar-Ranchería Basin of La Guajira and Cesar. The formation consists of bituminous coal fields that are an important economic resource. Coal from the Cerrejón Formation is mined extensively from the Cerrejón open-pit coal mine, one of the largest in the world. The formation also bears fossils that are the earliest record of Neotropical rainforests.

Cerrejonemys wayuunaiki is an extinct podocnemid turtle which existed in Colombia during the Paleogene period; the Middle to Late Paleocene epoch.

Acherontisuchus is an extinct genus of dyrosaurid neosuchian from Middle to Late Paleocene deposits of Colombia. The only known species is A. guajiraensis, whose name means "Acheron crocodile of the Guajira Peninsula".

<i>Carbonemys</i> Extinct genus of turtles

Carbonemys cofrinii is an extinct giant podocnemidid turtle known from the Middle Paleocene Cerrejón Formation of the Cesar-Ranchería Basin in northeastern Colombia. The formation is dated at around 60 to 57 million years ago, starting at about five million years after the KT extinction event.

<i>Anthracosuchus</i> Extinct genus of reptiles

Anthracosuchus is an extinct genus of dyrosaurid crocodyliform from the Paleocene of Colombia. Remains of Anthracosuchus balrogus, the only known species, come from the Cerrejón Formation in the Cerrejón mine, and include four fossil specimens with partial skulls. Anthracosuchus differs from other dyrosaurids in having an extremely short (brevirostrine) snout, widely spaced eye sockets with bony protuberances around them, and osteoderms that are smooth and thick. It is one of the most basal dyrosaurids along with Chenanisuchus and Cerrejonisuchus.

The "Tuffeau" de Saint-Omer is a geologic formation in northern France. The sandstones of the formation, named after Saint-Omer, preserve bird and primate fossils dating back to the middle Thanetian age of the Paleocene epoch of the Paleogene period, dating to about 58 Ma.

<i>Etayoa</i>

Etayoa is an ungulate of the family Carodniidae in the order Xenungulata that lived during the Early Eocene in northern South America.

<span class="mw-page-title-main">Bogotá Formation</span> Geological formation in Bogotá, Colombia

The Bogotá Formation (Spanish: Formación Bogotá, E1-2b, Tpb, Pgb) is a geological formation of the Eastern Hills and Bogotá savanna on the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The predominantly shale and siltstone formation, with sandstone beds intercalated, dates to the Paleogene period; Upper Paleocene to Lower Eocene epochs, with an age range of 61.66 to 52.5 Ma, spanning the Paleocene–Eocene Thermal Maximum. The thickness of the Bogotá Formation ranges from 169 metres (554 ft) near Tunja to 1,415 metres (4,642 ft) near Bogotá. Fossils of the ungulate Etayoa bacatensis have been found in the Bogotá Formation, as well as numerous reptiles, unnamed as of 2017.

<span class="mw-page-title-main">Cesar-Ranchería Basin</span> Geologic formation in Colombia

The Cesar-Ranchería Basin is a sedimentary basin in northeastern Colombia. It is located in the southern part of the department of La Guajira and northeastern portion of Cesar. The basin is bound by the Oca Fault in the northeast and the Bucaramanga-Santa Marta Fault in the west. The mountain ranges Sierra Nevada de Santa Marta and the Serranía del Perijá enclose the narrow triangular intermontane basin, that covers an area of 11,668 square kilometres (4,505 sq mi). The Cesar and Ranchería Rivers flow through the basin, bearing their names.

Titanoboa: Monster Snake is a 2012 documentary film produced by the Smithsonian Institution. The documentary treats Titanoboa, the largest snake ever found. Fossils of the snake were uncovered from the Cerrejón Formation at Cerrejón, the tenth biggest coal mine in the world in the Cesar-Ranchería Basin of La Guajira, northern Colombia, covering an area larger than Washington, D.C. The documentary premiered at the Smithsonian Channel on April 1, 2012, followed by a panel discussion from the scientists who spearheaded the research: Carlos Jaramillo from the Smithsonian Tropical Research Institute, Jonathan Bloch from the Florida Museum of Natural History and Jason Head from the University of Nebraska at Lincoln.

References

  1. ↑ Rodríguez García, Gabriel, and Ana Cristina Londoño. 2002. Mapa geológico del departamento de La Guajira , 1–259. INGEOMINAS. Accessed 2017-05-22.
  2. 1 2 3 4 5 6 7 8 9 Head, J.J.; Bloch, J.I.; Hastings, A.K.; Bourque, J.R.; Cadena, E.A.; Herrera, F.A.; Polly, P.D.; Jaramillo, C.A. (2009). "Giant boid snake from the Paleocene neotropics reveals hotter past equatorial temperatures". Nature . 457 (7230): 715–717. Bibcode:2009Natur.457..715H. doi:10.1038/nature07671. PMID   19194448. S2CID   4381423.
  3. ↑ Kwok, R. (4 February 2009). "Scientists find world's biggest snake". Nature News . doi: 10.1038/news.2009.80 .
  4. ↑ "At 2,500 Pounds And 43 Feet, Prehistoric Snake Is Largest On Record". Science Daily . 4 February 2009. Retrieved 6 February 2009.
  5. 1 2 "How Titanoboa, the 40-Foot-Long Snake, Was Found". Smithsonian Magazine. Retrieved 7 June 2023.
  6. ↑ Maugh II, T.H. (4 February 2009). "Fossil of 43-foot super snake Titanoboa found in Colombia". Los Angeles Times . Retrieved 4 February 2009.
  7. 1 2 3 4 5 6 Head, Jason; Jonathan Bloch; Jorge Moreno Bernal; Aldo Fernando Rincón Burbano, and Jason Bourque. 2013. Cranial osteology, body size, systematics, and ecology of the giant Paleocene snake Titanoboa cerrejonensis , 140–141. Society of Vertebrate Paleontology. Accessed 2017-05-22.
  8. ↑ O'Brien, Jane (2 April 2012). "The giant snake that stalked the Earth". BBC News. Retrieved 22 May 2017.
  9. ↑ "Titanoboa: Monster Snake". Smithsonian. 2012. Retrieved 10 June 2023.
  10. ↑ Feldman, A.; Sabath, N.; Pyron, R.A.; Mayrose, I.; Meiri, S. (2016). "Body sizes and diversification rates of lizards, snakes, amphisbaenians and the tuatara". Global Ecology and Biogeography. 25 (2): 187–197. doi:10.1111/geb.12398. S2CID   25049185.
  11. 1 2 3 Head, JJ (2015). "Fossil calibration dates for molecular phylogenetic analysis of snakes 1: Serpentes, Alethinophidia, Boidae, Pythonidae". Palaeontologia Electronica. doi: 10.26879/487 . ISSN   1094-8074.
  12. ↑ McDiarmid, R.W.; Campbell, J.A.; Touré. T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference Vol. 1. Herpetologists' League. 511 pp. ISBN   1-893777-00-6 (series). ISBN   1-893777-01-4 (volume).
  13. ↑ IUCN (20 August 2018). "Boa imperator: Montgomery, C.E. & da Cunha, O.: The IUCN Red List of Threatened Species 2018: e.T203879A2771951". doi: 10.2305/iucn.uk.2018-2.rlts.t203879a2771951.en . S2CID   240344156.{{cite journal}}: Cite journal requires |journal= (help)
  14. ↑ "ITIS - Report: Epicrates cenchria". www.itis.gov. Retrieved 9 June 2023.
  15. ↑ Lotte, Jose; Lotte, Ben (1996). "Taxonomy and Description of Boa Constrictor". Litteratura Serpentium. 16 (3): 78–81.
  16. ↑ Hastings, Alexander K.; Bloch, Jonathan I.; Jaramillo, Carlos A. (17 November 2015). "A new blunt-snouted dyrosaurid, Anthracosuchus balrogus gen. et sp. nov. (Crocodylomorpha, Mesoeucrocodylia), from the Palaeocene of Colombia". Historical Biology. 27 (8): 998–1020. doi:10.1080/08912963.2014.918968. ISSN   0891-2963.
  17. ↑ Hastings, Alexander K.; Bloch, Jonathan I.; Jaramillo, Carlos A. (2011). "A new longirostrine dyrosaurid (Crocodylomorpha, Mesoeucrocodylia) from the Paleocene of north-eastern Colombia: biogeographic and behavioural implications for New-World Dyrosauridae: SECOND NEW DYROSAURID FROM COLOMBIA". Palaeontology. 54 (5): 1095–1116. doi:10.1111/j.1475-4983.2011.01092.x.
  18. ↑ Cadena, Edwin A.; Jonathan I. Bloch, and Carlos A. Jaramillo. 2010. New Podocnemidid Turtle (Testudines: Pleurodira) from the Middle-Upper Paleocene of South America. Journal of Vertebrate Paleontology 30. 367–382. Accessed 2017-05-22.
  19. ↑ Cadena, Edwin A.; Daniel T. Ksepka; Carlos A. Jaramillo, and Jonathan I. Bloch. 2012a. New pelomedusoid turtles from the late Palaeocene Cerrejon Formation of Colombia and their implications for phylogeny and body size evolution. Journal of Systematic Palaeontology 10. 313–331. Accessed 2017-05-22.
  20. ↑ Wing, Scott L.; Fabiany Herrera; Carlos A. Jaramillo; Carolina Gómez Navarro; Peter Wilf, and Conrad C. Labandeira. 2009. Late Paleocene fossils from the Cerrejón Formation, Colombia, are the earliest record of Neotropical rainforest. Proceedings of the National Academy of Sciences 106. 18627–18632. Accessed 2017-05-22.
  21. ↑ Woodburne, Michael O; Francisco J. Goin; Mariano Bond; Alfredo A. Carlini; Javier N. Gelfo; Guillermo M. López; A. Iglesias, and Ana N. Zimicz. 2014. Paleogene Land Mammal Faunas of South America; a Response to Global Climatic Changes and Indigenous Floral Diversity. Journal of Mammalian Evolution 21. 1–73. .
  22. ↑ Pérez Consuegra, Nicolás; Cuervo Gómez, Aura; Martínez, Camila; Montes, Camilo; Herrera, Fabiany; Madriñán, Santiago; Jaramillo, Carlos (2017). "Paleogene Salvinia (Salviniaceae) from Colombia and their paleobiogeographic implications". Review of Palaeobotany and Palynology . 246: 85–108. Bibcode:2017RPaPa.246...85P. doi:10.1016/j.revpalbo.2017.06.003.
  23. ↑ Herrera, Fabiany A.; Jaramillo, Carlos A.; Dilcher, David L.; Wing, Scott L.; Gómez N., Carolina (2008). "Fossil Araceae from a Paleocene neotropical rainforest in Colombia". American Journal of Botany . 95 (12): 1569–1583. doi:10.3732/ajb.0800172. PMID   21628164.
  24. ↑ Makarieva, Anastassia M.; Gorshkov, Victor G.; Li, Bai-Lian (2005). "Gigantism, temperature and metabolic rate in terrestrial poikilotherms". Proceedings of the Royal Society B . 272 (1578): 2325–2328. doi:10.1098/rspb.2005.3223. PMC   1560189 . PMID   16191647.
  25. ↑ Shellito, C.J.; Sloan, L.C.; Huber, M. (2003). "Climate model sensitivity to atmospheric CO2 levels in the Early–Middle Paleogene". Palaeogeography, Palaeoclimatology, Palaeoecology . 193 (1): 113–123. Bibcode:2003PPP...193..113S. doi:10.1016/S0031-0182(02)00718-6.
  26. ↑ Sniderman, J.M.K (2009). "Biased reptilian palaeothermometer?". Nature . 460 (7255): E1–E2. Bibcode:2009Natur.460....1S. doi:10.1038/nature08222. S2CID   4322274.
  27. ↑ Denny, Mark W.; Lockwood, Brent L.; Somero, George (2009). "Can the giant snake predict palaeoclimate?". Nature . 460 (7255): E3–E4. Bibcode:2009Natur.460....3D. doi:10.1038/nature08224. S2CID   41962223.
  28. ↑ Head, J.J.; Bloch, J.I.; Hastings, A.K.; Bourque, J.R.; Cadena, E.A.; Herrera, F.A.; Polly, P.D.; Jaramillo, C.A. (2009). "Head et al. reply". Nature . 460 (7255): E4–E5. Bibcode:2009Natur.460....4H. doi:10.1038/nature08225. S2CID   4420868.
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