Skip to main content Skip to main navigation menu Skip to site footer
Responsive image
Issue: Vol. 5264 No. 4: 17 Apr. 2023
Type: Article
Published: 2023-04-17
DOI: 10.11646/zootaxa.5264.4.4
Page range: 526-544
Abstract views: 1548
PDF downloaded: 40

On the first Baryonychinae (Theropoda, Spinosauridae) teeth from South America

Pós-Graduação em Zoologia; Instituto de Ciências Biológicas; Universidade Federal de Minas Gerais; Belo Horizonte; Minas Gerais 31270-901; Brazil.
Departamento de Biologia; Centro de Ciências Biológicas e da Saúde; Universidade Federal de Sergipe; São Cristóvão; Sergipe 49100-000; Brazil.
Departamento de Biologia; Centro de Ciências Biológicas e da Saúde; Universidade Federal de Sergipe; São Cristóvão; Sergipe 49100-000; Brazil.
Campus Acopiara; Instituto Federal de Educação; Ciência e Tecnologia do Ceará; Acopiara; Ceará 63560-000; Brazil.
Departamento de Geologia; Instituto de Geociências; Universidade Federal de Minas Gerais; Belo Horizonte; Minas Gerais 31270- 901; Brazil.
Reptilia Baryonychinae Cretaceous Feliz Deserto Formation Sergipe-Alagoas Basin Spinosauridae Teeth

Abstract

We report the first occurrence in South America of spinosaurid specimens belonging to the clade Baryonychinae. The material comprises three tooth crowns recovered from the Lower Cretaceous (Berriasian–Valanginian) of the Feliz Deserto Formation, State of Sergipe, northeast Brazil. The three specimens have the typical conidont condition, displaying a fluted morphology, veined enamel texture and carinae extending to the cervix region, conditions similar to those shared among spinosaurid theropods. Furthermore, a notable feature is the presence of a serrated carinae composed of 6–7 diminutive denticles per millimetre, a key feature shared by baryonychine spinosaurids. Phylogenetic and multivariate analyses performed on dentition-based and crown-based datasets of theropod taxa confirm the relationship of the three tooth crowns described here with the well-supported spinosaurid clade. Our results retrieve the taxa which comprise the “classically” baryonychine clade as individual branches within a polytomy which includes the three tooth crowns and a subclade of spinosaurines (Spinosaurus + Angaturama/Irritator). Additionally, the discriminant and cluster analyses suggest that the materials are more similar to Suchomimus than to Baryonyx morphometrically, but clearly bearing similarities with baryonychines (sharing a similar morphospace). These new findings paleogeographically expand the occurrence of this clade to western Gondwana, and comprise one of the oldest spinosaurid records worldwide, which brings implications on hypotheses for the emergence and evolution of the clade. Furthermore, these new records indicate the presence of more than one spinosaurid taxon in the Lower Cretaceous deltaic paleoenvironment of the Feliz Deserto Formation.

 

References

  1. Allain, R., Xaisanavong, T., Richir, P. & Khentavong, B. (2012) The first definitive Asian spinosaurid (Dinosauria: Theropoda) from the early Cretaceous of Laos. Naturwissenschaften, 99 (5), 1–10. https://doi.org/10.1007/s00114-012-0911-7 DOI: https://doi.org/10.1007/s00114-012-0911-7
  2. Alonso, A. & Canudo, J.I. (2016) On the spinosaurid theropod teeth from the early Barremian (Early Cretaceous) Blesa Formation (Spain). Historical Biology, 28 (6), 823–834. https://doi.org/10.1080/08912963.2015.1036751 DOI: https://doi.org/10.1080/08912963.2015.1036751
  3. Andrade, M.B., Young, M.T., Desojo, J.B. & Brusatte, S.L. (2010) The evolution of extreme hypercarnivory in Metriorhynchidae (Mesoeucrocodylia: Thalattosuchia) based on evidence from microscopic denticle morphology. Journal of Vertebrate Paleontology, 30 (5), 1451–1465. https://doi.org/10.1080/02724634.2010.501442 DOI: https://doi.org/10.1080/02724634.2010.501442
  4. Arden, T.M., Klein, C.G., Zouhri, S. & Longrich, N.R. (2019) Aquatic adaptation in the skull of carnivorous dinosaurs (Theropoda: Spinosauridae) and the evolution of aquatic habits in spinosaurids. Cretaceous Research, 93, 275–284. https://doi.org/10.1016/j.cretres.2018.06.013 DOI: https://doi.org/10.1016/j.cretres.2018.06.013
  5. Aureliano, T., Ghilardi, A.M., Buck, P.V., Fabbri, M., Samathi, A., Delcourt, R., Fernandes, M.A. & Sander, M. (2018) Semi-aquatic adaptations in a spinosaur from the Lower Cretaceous of Brazil. Cretaceous Research, 90, 283–295. https://doi.org/10.1016/j.cretres.2018.04.024 DOI: https://doi.org/10.1016/j.cretres.2018.04.024
  6. Barker, C.T., Hone, D.W., Naish, D., Cau, A., Lockwood, J.A., Foster, B., Clarkin, C.E., Schneider, P. & Gostling, N.J. (2021) New spinosaurids from the Wessex Formation (Early Cretaceous, UK) and the European origins of Spinosauridae. Scientific Reports, 11, 19340. https://doi.org/10.1038/s41598-021-97870-8 DOI: https://doi.org/10.1038/s41598-021-97870-8
  7. Bertin, T. (2010) A catalogue of material and review of the Spinosauridae. PalArch’s Journal of Vertebrate Palaeontolology, 7 (4), 1–39.
  8. Bittencourt, J.S. & Kellner, A.W.A. (2004) On a sequence of sacrocaudal theropod dinosaur vertebrae from the Lower Cretaceous Santana Formation, northeastern Brazil. Arquivos do Museu Nacional, 62, 309–320.
  9. Borba, C., Paim, P.S.G. & Garcia, A.J.V. (2011) Estratigrafia dos depósitos iniciais do rifte no Campo de Furado, região de São Miguel dos Campos, Bacia de Sergipe-Alagoas. Brazilian Journal of Geology, 41, 18–36. https://doi.org/10.25249/0375-7536.20114111836 DOI: https://doi.org/10.25249/0375-7536.20114111836
  10. Brum, A.S., Pêgas, R.V., Bandeira, K.L., Souza, L.G., Campos, D.A. & Kellner, A.W. (2021) A new unenlagiine (Theropoda, Dromaeosauridae) from the Upper Cretaceous of Brazil. Papers in Palaeontolology, 7 (4), 2075–2099. https://doi.org/10.1002/spp2.1375 DOI: https://doi.org/10.1002/spp2.1375
  11. Buffetaut, E., Suteethorn, S., Suteethorn, V., Tong, H. & Wongko, K. (2019) Spinosaurid teeth from the Lower Cretaceous of Ko Kut, eastern Thailand. Annales de Paléontologie, 105 (3), 239–243. https://doi.org/10.1016/j.annpal.2019.03.006 DOI: https://doi.org/10.1016/j.annpal.2019.03.006
  12. Buffetaut, E., Suteethorn, V., Tong, H. & Amiot, R. (2008) An Early Cretaceous spinosaurid theropod from southern China. Geological Magazine, 145 (5), 745–748. https://doi.org/10.1017/S0016756808005360 DOI: https://doi.org/10.1017/S0016756808005360
  13. Canudo, J.I., Gasulla, J.M., Gómez-Fernández D., Ortega, F., Sanz, J.L & Yagüe, P. (2008) Primera evidencia de dientes aislados atribuidos a Spinosauridae (Theropoda) en el Aptiano inferior (Cretácico Inferior) de Europa: Formación Arcillas de Morella (España). Ameghiniana, 45 (4), 649–662.
  14. Carrano, M.T., Benson, R.B.J. & Sampson, S.D. (2012) The phylogeny of Tetanurae (Dinosauria: Theropoda). Journal of Systematic Palaeontology, 10 (2), 211–300. https://doi.org/10.1080/14772019.2011.630927 DOI: https://doi.org/10.1080/14772019.2011.630927
  15. Charig, A.J. & Milner, A.C. (1986) Baryonyx, a remarkable new theropod dinosaur. Nature, 324 (27), 359–361. https://doi.org/10.1038/324359a0 DOI: https://doi.org/10.1038/324359a0
  16. Charig, A.J. & Milner, A.C. (1997) Baryonyx walkeri, a fish-eating dinosaur from the Wealden of Surrey. Bulletin of the Natural History Museum: Geology Series, 53, 11–70.
  17. Dal Sasso, C., Maganuco, S., Buffetaut, E. & Mendez, M.A. (2005) New information on the skull of the enigmatic theropod Spinosaurus, with remarks on its size and affinities. Journal of Vertebrate Paleontology, 25 (4), 888–896. https://doi.org/10.1671/0272-4634(2005)025[0888:NIOTSO]2.0.CO;2 DOI: https://doi.org/10.1671/0272-4634(2005)025[0888:NIOTSO]2.0.CO;2
  18. Evers, S.W., Rauhut, O.W.M., Milner, A.C., Mcfeeters, B. & Allain, R. (2015) A reappraisal of the morphology and systematic position of the theropod dinosaur Sigilmassasaurus from the “middle” Cretaceous of Morocco. PeerJ, 3, e1323. https://doi.org/10.7717/peerj.1323 DOI: https://doi.org/10.7717/peerj.1323
  19. Fabbri, M., Navalón, G., Benson, R.B., Pol, D., O’Connor, J., Bhullar, B.A.S., Erickson, G.M., Norell, M.A., Orkney, A., Lamanna, M.C., Zouhri, S., Becker, J., Emke, A., Dal Sasso, C., Bindellini, G., Maganuco, S., Auditore, M. & Ibrahim, N. (2022) Subaqueous foraging among carnivorous dinosaurs. Nature, 603 (7903), 852–857. https://doi.org/10.1038/s41586-022-04528-0 DOI: https://doi.org/10.1038/s41586-022-04528-0
  20. Fitzinger, L. (1843) Systema reptilium. Fasciculus primus: Amblyglossae. Apud Braumüller and Seidel Bibliopolas, Vienna. [unknow pagination] https://doi.org/10.5962/bhl.title.4694 DOI: https://doi.org/10.5962/bhl.title.4694
  21. Fowler, D. (2007) Recently rediscovered baryonychine teeth (Dinosauria: Theropoda): New morphologic data, range extension & similarity to Ceratosaurus. Journal of Vertebrate Paleontology, 27 (3), 76A.
  22. França, T.C., Brilhante, N.S., Nobre, Y.O.M., Medeiros, M.A., Lindoso, R.M. & Costa, F.R. (2022) The first record of a spinosaurid pedal ungual from Brazil (Boca do Forno Ravine, Itapecuru Formation, Parnaíba Basin). Historical Biology, 34 (9), 1817–1826. https://doi.org/10.1080/08912963.2021.1981890 DOI: https://doi.org/10.1080/08912963.2021.1981890
  23. Gauthier, J. (1986) Saurischian monophyly and the origin of birds. Memoirs of the Californian Academy of Sciences, 8, 1–55.
  24. Goloboff, P.A. & Catalano, S.A. (2016) TNT version 1.5, including a full implementation of phylogenetic morphometrics. Cladistics, 32 (3), 221–238. https://doi.org/10.1111/cla.12160 DOI: https://doi.org/10.1111/cla.12160
  25. Hammer, Ø., Harper, D.A.T. & Ryan, P.D. (2001) PAST: Paleontological statistics software package for education and data analysis. Palaeontologia Electronica, 4 (1), 1–9.
  26. Hasegawa, Y., Tanaka, G., Takakuwa, Y. & Koike, S. (2010) Fine sculptures on a tooth of Spinosaurus (Dinosauria, Theropoda) from Morocco. Bulletin of Gunma Museum of Natural History, 14, 11–20.
  27. Hassler, A., Martin, J.E., Amiot, R., Tacail, T., Godet, F.A., Allain, R. & Balter, V. (2018) Calcium isotopes offer clues on resource partitioning among Cretaceous predatory dinosaurs. Proceedings of the Royal Society B: Biological Sciences, 285 (1876), 20180197. https://doi.org/10.1098/rspb.2018.0197 DOI: https://doi.org/10.1098/rspb.2018.0197
  28. Hendrickx, C. & Mateus, O. (2014) Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth. Zootaxa, 3759 (1), 1–74. https://doi.org/10.11646/zootaxa.3759.1.1 DOI: https://doi.org/10.11646/zootaxa.3759.1.1
  29. Hendrickx, C., Mateus, O. & Araújo, R. (2015a) A proposed terminology of theropod teeth (Dinosauria, Saurischia). Journal of Vertebrate Paleontology, 35 (5), e982797. https://doi.org/10.1080/02724634.2015.982797 DOI: https://doi.org/10.1080/02724634.2015.982797
  30. Hendrickx, C., Mateus, O. & Araújo, R. (2015b) The dentition of megalosaurid theropods. Acta Palaeontologica Polonica, 60 (3), 627–642. https://doi.org/10.4202/app.00056.2013 DOI: https://doi.org/10.4202/app.00056.2013
  31. Hendrickx, C., Mateus, O. & Araújo, R. (2019) The distribution of dental features in non-avian theropod dinosaurs: taxonomic potential, degree of homoplasy, and major evolutionary trends. Palaeontologia Electronica, 22 (3), 1–10. https://doi.org/10.26879/820 DOI: https://doi.org/10.26879/820
  32. Hendrickx, C., Tschopp, E. & Ezcurra, M.D. (2020) Taxonomic identification of isolated theropod teeth: the case of the shed tooth crown associated with Aerosteon (Theropoda: Megaraptora) and the dentition of Abelisauridae. Cretaceous Research, 108, 104312. https://doi.org/10.1016/j.cretres.2019.104312 DOI: https://doi.org/10.1016/j.cretres.2019.104312
  33. Holtz Jr, T. R., Molnar, R. E., & Currie, P. J. (2004). 4. Basal Tetanurae. In: Weishampel, D.B., Dodson, P. & Osmólska, H. (Eds.), The Dinosauria. 2nd Edition. University of California Press, Berkeley, Florida, pp. 71–110. DOI: https://doi.org/10.1525/california/9780520242098.003.0006
  34. Hone, D.W.E. & Holtz Jr, T.R. (2017) A Century of Spinosaurs—A Review and Revision of the Spinosauridae with Comments on Their Ecology. Acta Geologica Sinica, 91 (3), 1120–1132. https://doi.org/10.1111/1755-6724.13328 DOI: https://doi.org/10.1111/1755-6724.13328
  35. Hone, D.W.E. & Holtz Jr., T.R. (2019) Comment on: Aquatic adaptation in the skull of carnivorous dinosaurs (Theropoda: Spinosauridae) and the evolution of aquatic habits in spinosaurids. 93: 275–284. Cretaceous Research, 134, 104152. https://doi.org/10.1016/j.cretres.2019.05.010 DOI: https://doi.org/10.1016/j.cretres.2019.05.010
  36. Hone, D.W.E., Xu, X. & Wang, D.Y. (2010) A probable baryonychine (Theropoda: Spinosauridae) tooth from the Upper Cretaceous of Henan Province, China. Vertebrata PalAsiatica, 48 (1), 19–26.
  37. Ibrahim, N., Maganuco, S., Dal Sasso, C., Fabbri, M., Auditore, M., Bindellini, G., Martill, D.M., Zouhri, S., Mattarelli, D.A., Unwin, D.M., Wiemann, J., Bonadonna, D., Amane, A., Jakubczak, J., Joger, U., Lauder, G.V. & Pierce, S.E. (2020) Tail-propelled aquatic locomotion in a theropod dinosaur. Nature, 581 (7806), 67–70. https://doi.org/10.1038/s41586-020-2190-3 DOI: https://doi.org/10.1038/s41586-020-2190-3
  38. Isasmendi, E., Sáez-Benito, P., Torices, A., Navarro-Lorbés, P. & Pereda-Suberbiola, X. (2020) New insights about theropod palaeobiodiversity in the Iberian Peninsula and Europe: spinosaurid teeth (Theropoda, Megalosauroidea) from the Lower Cretaceous of La Rioja (Spain). Cretaceous Research, 116, 104600. https://doi.org/10.1016/j.cretres.2020.104600 DOI: https://doi.org/10.1016/j.cretres.2020.104600
  39. Kellner, A.W.A., Azevedo, S.A.K., Machado, E.B., Carvalho, L.B. & Henriques, D.D.R. (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. https://doi.org/10.1590/S0001-37652011000100006 DOI: https://doi.org/10.1590/S0001-37652011000100006
  40. Kellner, A.W.A. & Campos, D.A. (1996) First Early Cretaceous theropod dinosaur from Brazil with comments on Spinosauridae. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 199 (2), 151–166. https://doi.org/10.1127/njgpa/199/1996/151 DOI: https://doi.org/10.1127/njgpa/199/1996/151
  41. Kifumbi, C., Scherer, C.M.S., Jones, F.H. & Kuchle, J. (2017) High resolution stratigraphy of initial stages of rifiting, Sergipe-Alagoas Basin, Brazil. Brazilian Journal of Geology, 47 (4), 657–671. https://doi.org/10.1590/2317-4889201720170003 DOI: https://doi.org/10.1590/2317-4889201720170003
  42. Lacerda, M.B.S., de Andrade, M.B., Sales, M.A.F., Aragão, P.R.L., Vieira, F.S., Bittencourt, J.S. & Liparini, A. (2023) The vertebrate fossil record from the Feliz Deserto Formation (Lower Cretaceous), Sergipe, NE Brazil: paleoecological, taphonomic, and paleobiogeographic implications. Cretaceous Research, 147, 105463. https://doi.org/10.1016/j.cretres.2022.105463 DOI: https://doi.org/10.1016/j.cretres.2022.105463
  43. Lacerda, M.B.S., Grillo, O.N. & Romano, P.S.R. (2022) Rostral morphology of Spinosauridae (Theropoda, Megalosauroidea): premaxilla shape variation and a new phylogenetic inference. Historical Biology, 34 (11), 2089–2109. https://doi.org/10.1080/08912963.2021.2000974 DOI: https://doi.org/10.1080/08912963.2021.2000974
  44. Malafaia, E., Gasulla, J.M., Escaso, F., Narvaéz, I., Sanz, J.L. & Ortega, F. (2020) A new spinosaurid theropod (Dinosauria: Megalosauroidea) from the upper Barremian of Vallibona, Spain: implications for spinosaurid diversity in the Early Cretaceous of the Iberian Peninsula. Cretaceous Research, 106, 104221. https://doi.org/10.1016/j.cretres.2019.104221 DOI: https://doi.org/10.1016/j.cretres.2019.104221
  45. Marsh, O.C. (1881) Principal characters of American Jurassic dinosaurs. Part V. American Journal of Science, Series 3, 21, 417–423. https://doi.org/10.2475/ajs.s3-21.125.417 DOI: https://doi.org/10.2475/ajs.s3-21.125.417
  46. Mateus, O. & Estraviz-López, D. (2022) A new theropod dinosaur from the early Cretaceous (Barremian) of Cabo Espichel, Portugal: Implications for spinosaurid evolution. PloS One, 17 (2), e0262614. https://doi.org/10.1371/journal.pone.0262614 DOI: https://doi.org/10.1371/journal.pone.0262614
  47. Medeiros, M.A. (2006) Large theropod teeth from the Eocenomanian of northeastern Brazil and the occurrence of Spinosauridae. Revista Brasileira de Paleontologia, 9 (3), 333–338. https://doi.org/10.4072/rbp.2006.3.08 DOI: https://doi.org/10.4072/rbp.2006.3.08
  48. Medeiros, M.A. & Schultz, C.L. (2002) A fauna Dinossauriana da “Laje do Coringa”, Cretáceo Médio do Nordeste do Brasil. Arquivos do Museu Nacional, 60 (3), 155–162.
  49. Meso, J.G., Hendrickx, C., Baiano, M.A., Canale, J.I., Salgado, L. & Díaz-Martínez, I. (2021) Isolated theropod teeth associated with a sauropod skeleton from the Late Cretaceous Allen Formation of Río Negro, Patagonia, Argentina. Acta Palaeontologica Polonica, 66 (2), 409–423. https://doi.org/10.4202/app.00847.2020 DOI: https://doi.org/10.4202/app.00847.2020
  50. Milner, A.C. (2003) Fish-eating theropods: a short review of the systematics, biology and palaeobiology of spinosaurs. Jornadas Internacionales sobre Paleontol de Dinosaurios y su Entoro, 2, 129–139.
  51. Novas, F.E., Agnolín, F.L., Ezcurra, M.D., Porfiri, J. & Canale, J.I. (2013) Evolution of the carnivorous dinosaurs during the Cretaceous: The evidence from Patagonia. Cretaceous Research, 45, 174–215. https://doi.org/10.1016/j.cretres.2013.04.001 DOI: https://doi.org/10.1016/j.cretres.2013.04.001
  52. Riff, D. & Kellner, A.W.A. (2001) On the dentition of Baurusuchus pachecoi price (Crocodyliformes, Metasuchia) from the Upper Cretaceous of Brazil. Boletim do Museu Nacional, 59, 1–15.
  53. Sales, M.A.F., Liparini, A., Andrade, M.B., Aragão, P.L.R. & Schultz, C.L. (2017) The oldest South American occurrence of Spinosauridae (Dinosauria, Theropoda). Journal of South American Earth Sciences, 74, 83–88. https://doi.org/10.1016/j.jsames.2016.10.005 DOI: https://doi.org/10.1016/j.jsames.2016.10.005
  54. Sales, M.A.F. & Schultz, C.L. (2017) Spinosaur taxonomy and evolution of craniodental features: evidence from Brazil. PloS One, 12 (11), e0187070. https://doi.org/10.1371/journal.pone.0187070 DOI: https://doi.org/10.1371/journal.pone.0187070
  55. Sánchez-Hernández, B., Benton, M.J. & Naish, D. (2007) Dinosaurs and other fossil vertebrates from the Late Jurassic and Early Cretaceous of the Galve area, NE Spain. Palaeogeography, Palaeoclimatology, Palaeoecology, 249, 180–215. https://doi.org/10.1016/j.palaeo.2007.01.009 DOI: https://doi.org/10.1016/j.palaeo.2007.01.009
  56. Sereno, P.C., Beck, A.L., Dutheil, D.B., Gado, B., Larsson, H.C.E., Lyon, G.H., Marcot, J.D., Rauhut, O.W.M., Sadleir, R.W., Sidor, C.A., Varricchio, D.D., Wilson, G.P. & Wilson, J.A. (1998) A long-snouted predatory dinosaur from Africa and the evolution of spinosaurids. Science, 282 (5392), 1298–1302. https://doi.org/10.1126/science.282.5392.1298 DOI: https://doi.org/10.1126/science.282.5392.1298
  57. Sereno, P.C., Myhrvold, N., Henderson, D.M., Fish, F.E., Vidal, D., Baumgart, S.L., Keillor, T.M., Formoso, K.K. & Conroy, L.L. (2022) Spinosaurus is not an aquatic dinosaur. eLife, 11, e80092. https://doi.org/10.7554/eLife.80092 DOI: https://doi.org/10.7554/eLife.80092
  58. Smith, J.B. & Dodson, P. (2003) A proposal for a standard terminology of anatomical notation and orientation in fossil vertebrate dentitions. Journal of Vertebrate Paleontology, 23, 1–12. https://doi.org/10.1671/0272-4634(2003)23[1:APFAST]2.0.CO;2 DOI: https://doi.org/10.1671/0272-4634(2003)23[1:APFAST]2.0.CO;2
  59. Stromer, E. (1915) Ergebnisse der Forschugsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltier-Reste der Baharîje-Stufe (untertes Cenoman). III. Das Original des Theropoden Spinosaurus aegyptiacus nov. gen., nov. spec. Abhandlungen der Königlich Bayerischen Akademie der Wissenschaften, Mathematisch-physikalische Klasse, 22, 1–79.
  60. Sues, H.-D., Frey, E., Martill, D.M. & Scott, D.M. (2002) Irritator challengeri, a spinosaurid (Dinosauria: Theropoda) from the Lower Cretaceous of Brazil. Journal of Vertebrate Paleontology, 22 (3), 535–547. https://doi.org/10.1671/0272-4634(2002)022[0535:ICASDT]2.0.CO;2 DOI: https://doi.org/10.1671/0272-4634(2002)022[0535:ICASDT]2.0.CO;2