The world’s largest gharialsGryposuchus: description ofG. croizati n. sp. (Crocodylia, Gavialidae) from the Upper Miocene Urumaco Formation, Venezuela

Article

Abstract

A new fossil gharialGryposuchus species is described from the Upper Miocene Urumaco Formation, Venezuela.Gryposuchus croizati new species can be distinguished from other gavialoids, includingGryposuchus colombianus andGryposuchus neogaeus by the following combination of diagnostic characters: 1) slenderness of the parietal interfenestral bar; 2) dental formula, mainly the lesser number of maxillary teeth, with four premaxillary, 19 maxillary and 22 mandibular teeth; 3) large width of palatines between the reduced palatine fenestrae; 4) medial hemicondyle of the quadrate smaller but detached and much more posteriorly elongated than the lateral one and projected ventromedially; 5) pterygoid morphology, with two posterior vacuities. The polymorphism in the contour of the external naris inGryposuchus was evaluated for taxonomic significance. The body size ofG. croizati n. sp. was estimated in 10.15 m (9.67–10.67 m) using the dorsal skull length and the estimation of the body mass was 1,745 kg (1,280–2,379 kg) based on the braincase length. These maximal values placeG. croizati n. sp. among the world’s largest gharials and even Crocodyliforms as a whole.

Keywords

Crocodylia Gavialidae Gryposuchus Urumaco Formation Miocene Venezuela 

Kurzfassung

Eine neue Gavialart vonGryposuchus wird aus der obermiozän Urumaco-Formation von Venezuela beschrieben.Gryposuchus croizati n. sp. kann von anderen Gavialoiden, einschließlichGryposuchus colombianus undGryposuchus neogaeus, anhand der folgenden diagnostischen Merkmale unterschieden werden: 1) Schlankheit des Interfenestralstabs des Parietale; 2) Zahnformel, vor allem die reduzierte Anzahl von Maxillarzähnen, mit vier Prämaxillar-, 19 Maxillar- und 22 Mandibularzähnen; 3) große Breite der Palatinae zwischen reduzierten Gaumenfenstern; 4) medialer Hemicondylus des Quadratums kleiner aber getrennt und sehr viel stärker posterior verlängert und ventromedial ausgerichtet als der laterale Hemicondylus; 5) Morphologie des Pterygoids, mit zwei posterioren Einbuchtungen. Die Polymorphismen in den Umrissen der äußeren Nasenöffnung inGryposuchus werden taxonomisch evaluiert. Die Körperlänge vonG. croizati n. sp. wurde, basierend auf der dorsalen Schädellänge, auf 10.15 m (9.67–10.67 m) geschätzt. Weiterhin wurde die Körpergröße basierend auf der Gehirnkapsellänge auf 1745 kg (1280–2379 kg) geschätzt. Anhand dieser maximalen Werte dürfteG. croizati n. sp. zu den weltweit größten Gavialen und sogar der Crocodyliformes gehört haben, die je existierten.

Schlüsselwörter

Crocodylia Gavialidae Gryposuchus Urumaco-Formation Miozän Venezuela 

References

  1. Aguilera, O. 2004. Tesoros paleontológicos de Venezuela: Urumaco, patrimonio natural de la humanidad. — 147 p., Caracas (Ed. Arte).Google Scholar
  2. Aguilera, O.;Riff, D. &Bocquentin-Villanueva, J. 2006. A new giantPurussaurus (Crocodyliformes, Alligatoridae) from the Upper Miocene Urumaco Formation, Venezuela. — Journal of Systematie Palaeontology4: 221–232.CrossRefGoogle Scholar
  3. Anderson, H.T. 1936. The jaw musculature of the phytosaur,Machaeroprosopus. — Journal of Morphology59: 549–573.CrossRefGoogle Scholar
  4. Benton, M. J. &Clark J.M. 1988. Archosaur phylogeny and relationships of the Crocodylia — In:Benton, M J., ed., The Phylogeny and Classification of the Tetrapods1: 295–338, Oxford (Clarendon Press).Google Scholar
  5. Bocquentin-Villanueva, J. &Buffetaut, E. 1981.Hesperogavialis cruxenti n. gen. n. sp., nouveau gavialidae (Crocodylia, Eusuchia) du Miocéne supérieur (Huayquerian) d’Urumaco (Venezuela). — Géobios14: 415–419.CrossRefGoogle Scholar
  6. Brochu, C.A. 1997. Morphology, fossils, divergence timing, and the phylogenetic relationships ofGavialis. — Systematic Biology46: 479–522.CrossRefGoogle Scholar
  7. Brochu, C.A. 1997b. A review of“Leidyosuchus” (Crocodyliformes, Eusuchia) from the Cretaceous through Eocene of North America. — Journal of Vertebrate Paleontology17: 679–697.Google Scholar
  8. Brochu, C.A. 1999. Phylogenetics, taxonomy and historical biogeography of Alligatoroidea. — In:Rowe, T.;Brochu, C.A. &Kishi, K., eds., Cranial morphology ofAlligator mississippiensis and phylogeny of Alligatoroidea. — Journal of Vertebrate Paleontology Memoir6: 9–100.CrossRefGoogle Scholar
  9. Brochu, C.A. 2004. A new gavialoid crocodylian from the Late Cretaceous of eastern North America and the phylogenetic relationships of thoracosaurs. — Journal of Vertebrate Paleontology24: 610–633.CrossRefGoogle Scholar
  10. Brochu, C.A. 2006.Eosuchus (Crocodylia, Gavialoidea) from the Lower Eocene of the Isle of Sheppey, England. — Journal of Vertebrate Paleontology26: 466–470.CrossRefGoogle Scholar
  11. Brochu, C.A. &Gingerich, P.D. 2000. New tomistomine crocodilian from the middle Eocene (Bartonian) of Wadi Hitan, Fayum Province, Egypt. — Contributions from the Museum of Paleontology, University of Michigan30: 251–268.Google Scholar
  12. Brochu, C.A. &Rincón, A.D. 2004. A gavialoid crocodylian from the Lower Miocene of Venezuela. — In:Sánchez-Villagra, M.R. &Clack, J.A., eds., Fossils of the Miocene Castillo Formation, Venezuela: Contributions on Neotropical palaeontology. — Special Papers in Palaeontology71: 61–80.Google Scholar
  13. Buffetaut, E. 1982. Systematique, origine et évolution des Gavialidae Sud-Américains. — Geobios, Memoire Special6: 127–140.CrossRefGoogle Scholar
  14. Burmeister, G. 1885. Examen crítico de los mamíferos y los reptiles denominados por Don Augusto Bravard. — Anales del Museo Público de Buenos Aires3: 95–173.Google Scholar
  15. Cozzuol, M.A. 2006. The Acre vertebrate fauna: age, diversity, and geography. — Journal of South American Earth Sciences21: 185–203.CrossRefGoogle Scholar
  16. Delfino, M.;Piras, P. &Smith, T. 2005. Anatomy and phylogeny of the gavialoidEosuchus lerichei from the Paleocene of Europe. — Acta Palaeontologica Polonica50: 565–580.Google Scholar
  17. Díaz De Gamero, M.L. 1996. The changing course of the Orinoco River during the Neogene: a review. — Palaeogeography, Palaeoclimatology, Palaeoecology123: 385–402.CrossRefGoogle Scholar
  18. Díaz De Gamero, M.L. &Linares, O.J. 1989. Estratigrafía y paleontología de la Formación Urumaco, del Mioceno tardío de Falcón Noroccidental. — VII. Congreso Geológico Venezolano, Memorias1: 419–438.Google Scholar
  19. Erickson, G.M. &Brochu, C.A. 1999. How the ‘terror crocodile’ grew so big. — Nature398: 205–206.CrossRefGoogle Scholar
  20. Felsenstein, J. 1978. Cases in which parsimony or compatibility methods will be positively misleading. — Systematic Zoology27: 401–410.CrossRefGoogle Scholar
  21. Gasparini, Z.B. 1968. Nuevos restos deRhamphostomopsis neogaeus (Burm.)Rusconi 1933 (Reptilia, Crocodilia) del Mesopotamiense (Plioceno mediosuperior) de Argentina. — Ameghiniana5: 299–311.Google Scholar
  22. Gasparini, Z.B. 1996. Biogeographic evolution of the South American Crocodilians. — Münchner Geowissenschaftliche Abhandlungen30 (A): 159–184.Google Scholar
  23. Gatesy, J.;Amato, G.;Norell, M.;Desalle, R. &Hayashi, C. 2003. Combined support for wholesale taxic atavism in gavialine crocodylians. — Systematic Biology52: 403–422.CrossRefGoogle Scholar
  24. Gmelin, J. 1789. Linnei Systema Naturae. — 1057 p., Leipzig (G.E. Beer).Google Scholar
  25. Goloboff, P.A. 1993. NONA Version 1.9. — San Miguel de Tucuman, Argentina (Program and documentation distributed by the author).Google Scholar
  26. Goloboff, P.A. 1993b. Estimating character weights during tree search. — Ciadistics9: 83–91.CrossRefGoogle Scholar
  27. Graybeal, A. 1998. Is it better to add taxa or characters to a difficult phylogenetic problem? — Systematic Biology47: 9–17.CrossRefGoogle Scholar
  28. Gürich, G. 1912.Gryposuchus jessei, ein neues schmalschnauziges Krokodil aus den jüngeren Ablagerungen des oberen Amazonas-Gebietes. — Mitteilungen des Mineralogischen, Geologischen Instituts Hamburg4: 59–71.Google Scholar
  29. Hay, O. P. 1930. Second bibliography and catalogue of the fossil vertebrata of North America. — Carnegie Institute of Washington Publication390 (2): 1–1074.Google Scholar
  30. Head, J.J. 2001. Systematics and body size of the gigantic, enigmatic crocodyloidRhamphosuchus crassidens, and the faunal history of Siwalik Group (Miocene) crocodylians. — Journal of Vertebrate Paleontology, Abstracts31: 59A.Google Scholar
  31. Hua, S. &Jouve S. 2004. A primitive gavialoid from the Paleocene Morocco. — Journal of Vertebrate Paleontology24: 341–350.CrossRefGoogle Scholar
  32. Hurlburt, G.R.;Heckert, A.B. &Farlow, J.O. 2003. Body mass estimates of phytosaurs (Archosauria: Crurotarsi) from the Petrified Forest Formation (Chinle Group: Revueltian: early-mid Norian) based on skull and limb bone measurements. — In:Zeigler, K.E.;Heckert, A.B. &Lucas, S.G., eds., Paleontology and geology of the Upper Triassic (Revueltian) Snyder quarry, New Mexico. — New Mexico Museum of Natural History and Science Bulletin24: 105–113.Google Scholar
  33. Iordansky, N.N. 1973. The skull of the Crocodilia. — In:Gans, C. &Parsons, T.S., eds., Biology of the Reptilia4: 201–264, London (Academic Press).Google Scholar
  34. Kälin, J.A. 1933. Beiträge zur vergleichenden Osteologie des Crocodilidenschädels. — Zoologisches Jahrbuch.57: 535–714.Google Scholar
  35. Kraus, R. 1998. The cranium ofPiscogavialis jugaliperforatus n. gen., n. sp. (Gavialidae, Crocodylia) from the Miocene of Peru. — Paläontologische Zeitschrift72: 389–406.Google Scholar
  36. Langston, W. 1965. Fossil Crocodilians from Colombia and the Cenozoic history of the Crocodilia in South America. — University of California Publications in Geological Sciences52: 1–157.Google Scholar
  37. Langston, W. &Gasparini, Z.B. 1997. Crocodilians,Gryposuchus, and the South Americans gavials. — In:Kay, R.F.;Madden, R.L;Ciffelli, R.L. &Flynn, J.J., eds., Vertebrate paleontology in the Neotropics: The Miocene fauna of La Venta, Colombia: 113–154, Washington, DC (Smithsonian Institution Press).Google Scholar
  38. Lydekker, R. 1886. Indian Tertiary and post-Tertiary Vertebrata. Siwalik Crocodilia, Lacertilia and Ophidia. — Memoir of the Geological Survey of India, Palaeontologica Indica10 (3): 209–240.Google Scholar
  39. Martin, B.G.H &Bellairs, A.D’A. 1977. The narial excrescence and pterygoid bulla of the gharial,Gavialis gangeticus (Crocodilia). — Journal of Zoology182: 541–558.CrossRefGoogle Scholar
  40. Ministerio de Energía y Minas. 1997. Léxico estratigráfico de Venezuela (Tercera Edición). — Boletín de Geología12: 1–828.Google Scholar
  41. Mook, C. 1921. The dermo-supraoccipital bone in the Crocodilia. — Bulletin of the American Museum of Natural History44: 101–103.Google Scholar
  42. Müller, K. 2004. PRAP — computation of Bremer support for large data sets. — Molecular Phylogenetics and Evolution31: 780–782.CrossRefGoogle Scholar
  43. Nixon, K.C. 1999. The parsimony ratchet, a new method for rapid parsimony analysis. — Ciadistics15: 407–414.CrossRefGoogle Scholar
  44. Rogers, J.V. 2003.Pachycheilosuchus trinquei, a new procoelous crocodyliform from the Lower Cretaceous (Albian) Glen Rose Formation of Texas. — Journal of Vertebrate Paleontology23: 128–145.CrossRefGoogle Scholar
  45. Sánchez-Villagra, M.R.;Aguilera, O. &Horovitz, I. 2003. The anatomy of the world’s largest extinct rodent. — Science301: 1678–1679.CrossRefGoogle Scholar
  46. Sánchez-Villagra, M.R. &Aguilera, O. 2006. Neogene vertebrates from Urumaco, Falcón State, Venezuela: diversity and significance. — Journal of Systematic Palaeontology4: 213–220.CrossRefGoogle Scholar
  47. Sanderson M.J. &Shaffer H.B. 2002. Troubleshooting molecular phylogenetic analyses. — Annual Review of Ecology and Systematics33: 49–72.CrossRefGoogle Scholar
  48. Sereno, P.C.;Larsson, H.C.E.;Sidor, C.A. &Gado, B. 2001. The giant crocodyliformSarcosuchus from the Cretaceous of Africa. — Science294: 1516–1519.CrossRefGoogle Scholar
  49. Sill, W. 1970. Nota preliminar sobre un nuevo gavial del Plioceno de Venezuela y una discusíon de los gaviales Sudamericanos. — Ameghiniana7: 151–159.Google Scholar
  50. Souza Filho, J.P. 1998. Novas formas fósseis de Crocodylia (Alligatoridae e Gavialidae) da Formação Solimões, Cenozóico do Estado do Acre-Brasil, representadas por materiais cranianos e mandibulares. — PhD Thesis, Universidade Federal do Rio Grande do Sul. — 124 p., Rio Grande do Sul (unpublished).Google Scholar
  51. Swofford, D.L. 1998. PAUP. Phylogenetic Analysis Using Parsimony (and other methods). Version 4. Sunderland, MA (Sinauer Associetes).Google Scholar

Copyright information

© E. Schweizerbart’sche Verlagsbuchhandlung 2008

Authors and Affiliations

  1. 1.Departamento de Ciências NaturaisUniversidade Estadual do Sudoeste da BahiaVitória da Conquista-BABrasil
  2. 2.Centro de Investigaciones en Ciencias BásicasUniversidad Nacional Experimental Francisco de MirandaEstado FalcónVenezuela

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