Time for a new series! Let’s get started!! In this series, I will talk about various formations, continents, geological structures and the prehistoric ecosystems they help us to reconstruct. I hope you enjoy!
Hello everyone, welcome to Stunning Strata #1. This time around we have the Candeleros Formation, a formation I have actually been studying for a while now (I’m really interested in its fauna):
The Candeleros Formation is part of the Neuquen group and outcrops in the Rio Negro, Mendoza, and Neuquen provinces of Argentina. It dates to around 99-92 million years ago. This formation was made famous (among the paleontological community, at least) through the discovery of Giganotosaurus carolinni.
The Candeleros Formation dates to the Cenomanian stage of the Cretaceous, a time when the carcharodontosaurids were the top predators on land and titanosaurids were the most diverse sauropod group. The Candeleros Formation played host to many of these animals. From the formation we have the sauropod Andesaurus, a medium sized basal titanosaurid which probably fell prey to the menagerie of predatory animals also found in the formation. Predatory dinosaurs found in the Candeleros Formation include the giganotosaurine carcharodontosaurid Giganotosaurus carolinni, the medium-sized abelisaurid Ekrixinatosaurus novasi, the small unenlagiine Buitreraptor gonzalezorum, and the large basal coelurosaurian (and possible tyrannosaurid) Bicentenaria argentina. The alvarezsaurid theropod Alnashetri cerropoliciensis is also known from the formation and was a possible omnivore.
Based on the remains of theropod lineages found in other areas of South America (i.e. Oxalaia quiliombensis from the Cenomanian of Brazil) and by comparing the Candeleros Formation to other formations of the same time period which contain similar flora and fauna, we can infer that these theropod lineages probably co-existed with the animals found in the Candeleros Formation. Therefore, the Candeleros Formation represents an ecosystem with fauna similar to the Bahariya Formation of Egypt and/or the Kem Kem Beds of Morocco. This claim is also supported by the fact that the Candeleros Formation’s habitat is similar to that of the Bahariya Formation and the Kem Kem Beds. The habitat which the Candeleros Formation represents was a braided river system which a menagerie of fish, turtle, amphibian, mammal, arthropod, and dinosaur species called home. Some dinosaur forms like Buitreraptor had adaptations specially suited for living in a river ecosystem.
B. gonzalezorum had an elongated skull similar to herons which it may have used to catch fish. The primitive snake Najash rionegrina also may have been a predator of the wetlands, slithering through the water as it searched for prey. I should also note that there is ample evidence that suggests N. rionegrina assumed a subterranean lifestyle. Other animals, it seems, were more at home surviving off the land then off the wetlands…
The Candeleros Formation played host to a number of terrestrial animals, namely dinosaurs. The first I want to mention is Bicentenaria argentina, a possible basal tyrannosaurid. I hypothesize this animal was a predator of small game, taking up a niche which would allow little (if not no) competition with the large macro-predators of the area such as Giganotosaurus. B. argentina was probably the leopard to G. carolinni’s African lion. Giganotosaurus itself is a pretty interesting animal. This highly derived carcharodontosaurid was the largest predatory animal found in the Candeleros ecosystem. Well for right now G. carolinni is, anyway. It is preposed that large carcharodontosaurid theropods (and large allosauroids in general, for that matter) were specialist hunters of sauropods. If so, G. carolinni lived in paradise. So far, 3 medium-sized sauropods have been formally described from the Candeleros Formation. These are the basal titanosaurid Andesaurus delgadoi, and the rebbechisaurids Limaysaurus tessonei and Nopcsaspondylus alarconensis. These sauropods took up a variety of herbivorous niches. The rebbechisaurids are famous for their rake-like jaws, which may have been adaptations for a grazing lifestyle. Titanosaurs had needle-like teeth, which were probably used to rip leaves off trees. All of these animals may have fallen prey to G. carolinni. Indeterminate Iguanodont tracks have also been found from the formation. I’ve heard of partial, undescribed Iguanodont skeletons gaining dust in collections which are from the Candeleros Formation, but I haven’t been able to find any articles on the subject, so if you know of any please inform me in the comment section below. Nevertheless, the Iguanodont tracks tell us that the animals were there, and I am sure they also fell prey to G. carolinni. G. carolinni wasn’t always killing. It must have co-existed peacefully with sauropods at times, just like lion prides and zebra herds do in the modern African Savannah.
The abelisaurid Ekrixinatosaurus novasi was also a resident of the Candeleros Formation ecosystem. E. novasi may have competed with Giganotosaurus for prey, but was way smaller compared to the giant carcharodontosaurid. At an estimated 26 feet long, a fully-grown Ekrixinatosaurus would be easily overpowered by a full grown 45 foot long, 8 ton Giganotosaurus carolinni.
We should also look at the smaller animals which make up the prehistoric fauna of the Candeleros Formation. These include reptiles, turtles, fish, and amphibians (specifically frogs). Two species of the turtle Prochelidella have been found within the Candeleros Formation, as well as a variety of frogs, fish and mammals. The running crocodylomorph Araripesuchus patagonicus is known from the formation. It may have been a small predator of the wetlands, preying on the various animals which called the wetlands home. Alnashetri was a small alvarezsaurid that most liekly led an omnivorous lifestyle. It is only known from its hind limbs, making it very hard to classify it among other coelurosaurs. The presence of the possible alvarezsaurid Alnashetri greatly increases the diversity of coelurosaurs in the Candeleros Formation.
Overall, the Candeleros Formation represents a very bio-diverse braided river ecosystem, and I hope more studies will be conducted on this formation. Thanks for reading!
1. F. Ortega, Z. Gasparini, A.D Buscaloni and J. O. Calvo. 2000. “A new species of Araripesuchus (Crocodylomorpha, Mesoeucrocodylia) from the Lower Cretaceous of Patagonia (Argentina).” Journal of Vertabrate Paleontology 20(1): 57-76.
2. Baez, Ana M. , Muzzopappa, Paula, and Nicoli, Laura. 2007. “Anurans from the Candeleros Formation (?Cenomanian-Turonian) of west-central Argentina: new evidence for pipoid evolution.” Cretaceous Research 28 (2007): 1005-1016.
3. Sánchez, Maria Lidia; Heredia, Susana & Calvo, Jorge O. 2006. “Paleoambientes sedimentarios del Cretácico Superior de la Formación Plottier (Grupo Neuquén), Departamento Confluencia, Neuquén.” Revista de la Asociación Geológica Argentina 61(1): 3-18.
4. Wichmann, R. 1929. “Los Estratos con Dinosaurios y su techo en el este del Territorio del Neuquén.” Dirección General de Geología, Minería e Hidrogeología Publicación 32: 1-9.
5. Apesteguía, Sebastián; Hussam Zaher. 2006. “A Cretaceous terrestrial snake with robust hindlimbs and a sacrum”. Nature 440 (7087): 1037–1040.
6. Calvo, J. O. and Salgado, L. 1995. “Rebbachisaurus tessonei sp. nov. A new sauropod from the Albian-Cenomanian of Argentina; new evidence on the origin of the Diplodocidae.” Gaia, 11: 13-33.
7. Salgado, L., Garrido, A., Cocca, S. E., and Cocca, J. R. 2004. “Lower Cretaceous rebbachisaurid sauropods from Cerro Aguada Del León, Neuquén Province, northwestern Patagonia, Argentina.” Journal of Vertebrate Paleontology, 24(4): 903-912.
8. Apesteguía, Sebastián. 2007. “The sauropod diversity of the La Amarga Formation (Barremian), Neuquén (Argentina)”.Gondwana Research 12 (4): 533–546.
10. Calvo, J.O. & Bonaparte, J.F. 1991. “Andesaurus delgadoi n. g. n. sp. (Saurischia, Sauropoda) a titanosaurid dinosaur from the Río Limay Formation (Albian-Cenomanian), Neuquén, Argentina.” Ameghiniana. 28: 303-310.
11. Mannion, P. D. and Calvo, J. O. ” Anatomy of the basal titanosaur (Dinosauria, Sauropoda) Andesaurus delgadoi from the mid-Cretaceous (Albian–early Cenomanian) Río Limay Formation, Neuquén Province, Argentina: implications for titanosaur systematics.” Zoological Journal of the Linnean Society, 163 (2011): 155-181.
12. Novas, F.E., Salgado, L., Calvo, J.O., & Agnolin, F. 2005. “Giant titanosaur (Dinosauria, Sauropoda) from the Late Cretaceous of Patagonia. ” Revista del Museum Argentino de Ciencias Naturales 7(1): 37-41.
13. Jorge Calvo, David Rubilar-Rogers and Karen Moreno .2004. “A new Abelisauridae (Dinosauria: Theropoda) from northwest Patagonia”. Ameghiniana 41 (4): 555–563.
14. Leanza, H.A.; Apesteguia, S.; Novas, F.E. & de la Fuente, M.S. 2004. “Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages.” Cretaceous Research 25(1): 61-87.
15. J.O. Calvo .1990. “Un gigantesco theropodo del Miembro Candeleros (Albiano–Cenomaniano) del la Formación Río Limay, Patagonia, Argentina”, VII Jornadas Argentinas de Paleontología de Vertebrados. Ameghiniana 26(3-4): 241
16. Calvo, J.O. and Coria, R.A. 1998. “New specimen of Giganotosaurus carolinii (Coria & Salgado, 1995), supports it as the largest theropod ever found.” Gaia, 15: 117–122.
17. Coria, R.A. & Salgado, L. 1995. “A new giant carnivorous dinosaur from the Cretaceous of Patagonia.” Nature 377: 225-226.
18. Coria, R. & Salgado, L. .1996. “Dinosaurios carnívoros de Sudamérica”, Investigación Sciencia, 237: 39-40.
19. Matthew T. Carrano, Roger B. J. Benson & Scott D. Sampson .2012. “The phylogeny of Tetanurae (Dinosauria: Theropoda)”, Journal of Systematic Palaeontology, 10(2): 233.
20. J.O. Calvo .1999. “Dinosaurs and other vertebrates of the Lake Ezequiel Ramos Mexía area, Neuquén-Patagonia, Argentina”. In Y. Tomida, T. H. Rich, and P. Vickers-Rich, Proceedings of the Second Gondwanan Dinosaur Symposium, National Science Museum Monographs 15: 13-45.
21. Seebacher, F. 2001. “A new method to calculate allometric length-mass relationships of dinosaurs”. Journal of Vertebrate Paleontology 21 (1): 51–60.
22. Therrien, F.; Henderson, D.M. 2007. “My theropod is bigger than yours…or not: estimating body size from skull length in theropods”. Journal of Vertebrate Paleontology 27 (1): 108–115.
23. Gianechini, F.A.; Apesteguía, S.; Makovicky, P.J .2009. “The unusual dentiton of Buitreraptor gonzalezorum (Theropoda: Dromaeosauridae), from Patagonia, Argentina: new insights on the unenlagine teeth”. Ameghiniana 46 (4): 29R.
24. Makovicky, Peter J.; Apesteguía, Sebastián; Agnolín, Federico L. 2005. “The earliest dromaeosaurid theropod from South America”. Nature 437: 1007–1011.
25. Makovicky, P. J.; Apesteguía, S. N.; Gianechini, F. A. .2012. “A New Coelurosaurian Theropod from the La Buitrera Fossil Locality of Río Negro, Argentina”. Fieldiana Life and Earth Sciences 5: 90.
26. Novas, F.E., Ezcurra, M.D., Agnolín, F.L., Pol, D. and Ortíz, R. .2012. “New Patagonian Cretaceous theropod sheds light about the early radiation of Coelurosauria.” Revista del Museo Argentino de Ciencias Naturales, nueva serie, 14: 57–81.
27. Kellner, Alexander W.A.; Sergio A.K. Azevedeo, Elaine B. Machado, Luciana B. Carvalho and Deise D.R. Henriques. 2011.”A new dinosaur (Theropoda, Spinosauridae) from the Cretaceous (Cenomanian) Alcântara Formation, Cajual Island, Brazil”.Anais da Academia Brasileira de Ciências 83 (1): 99–108.
28. Medeiros, M.A. .2006. “Large theropod teeth from the Eocenomanian of northeastern Brazil and the occurrence of Spinosauridae”. Revista Brasileira de Paleontologia 9: 333–338.
29. Catuneanu O., Khalifa M.A. & Wanas H.A. .2006. “Sequence stratigraphy of the Lower Cenomanian Bahariya Formation, Bahariya Oasis, Western Desert, Egypt”. Sedimentary Geology 190 (1-4): 121–137. 29.
30. Weishampel, David B; et al .2004. “Dinosaur distribution (Late Cretaceous, Africa).” In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 604.
31. Khalifa M.A. & Catuneanu O. .2008. “Sedimentology of the fluvial and fluvio-marine facies of the Bahariya Formation (Early Cenomanian), Bahariya Oasis, Western Desert, Egypt”. Journal of African Earth Sciences 51 (2): 89–103.
32. Tanner L.H. & Khalifa M.A. .2010.”Origin of ferricretes in fluvial-marine deposits of the Lower Cenomanian Bahariya Formation, Bahariya Oasis, Western Desert, Egypt”. Journal of African Earth Sciences 56 (4-5): 179–189.32.
33. Weishampel, David B; et al. .2004. “Dinosaur distribution (Late Cretaceous, Africa).” In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 604-605.