Skip to main content

Advertisement

SpringerLink
Log in

New information about Irajatherium hernandezi Martinelli, Bonaparte, Schultz & Rubert 2005 (Eucynodontia, Tritheledontidae) from the upper triassic (Caturrita Formation, Paraná Basin) of Brazil

  • Research Paper
  • Published:
Paläontologische Zeitschrift Aims and scope Submit manuscript

Abstract

In this contribution, new specimens of the tritheledontid eucynodont Irajatherium hernandezi, from the Late Triassic (Caturrita Formation) of southern Brazil, are analyzed. The new material provides significant information about incisor count, canine size and shape, basicranial morphology, and other previously unknown aspects of skull and dentition. A cladistic analysis with inclusion of the new data supports the assignment of Irajatherium to Tritheledontidae, basal to Chalimininae and Pachygenelinae. Previously unknown characters of Irajatherium revealed by the new material include: the presence of three lower incisors; the first lower incisor is enlarged; the presence of large upper and lower canines with deep paracanine fossa on the maxilla; almost complete upper and lower postcanine tooth row with a pattern similar to that of other tritheledontids (e.g. Pachygenelus and Chaliminia); there is a conspicuous crest on the inner surface of the maxilla for the attachment of the inferred maxillary turbinates; partially confluent jugular foramen and fenestra rotunda within the jugular fossa, separated by a finger-like projection of the posterolateral wall of the opisthotic; and hypoglossal foramina located outside the jugular fossa. Irajatherium is a key taxon for understanding the early evolution of ictidosaurs, a group of cynodonts closely related to mammaliaforms, during the cynodont–mammal transition from the Late Triassic to Early Jurassic.

Kurzfassung

In dieser Arbeit werden neue Exemplare des tritheledontiden Eucynodonten Irajatherium hernandezi Martinelli et al. 2005 aus der Späten Trias (Caturrita Formation) vorgestellt. Das neue Material enthüllt wichtige Informationen zur Anzahl der Incisiven, der Grösse und Form der Canini, der Morphologie des Basicraniums und anderen Aspekte von Schädel und Bezahnung. Eine cladistische Analyse mit Berücksichtigung der neuen Daten bestätigt die Zuordnung von Irajatherium zu den Tritheledontidae, welche basal der Chalimininae und Pachygenelinae stehen. Unter den vorher unbekannten Merkmale von Irajatherium sind drei untere Incisiven mit einem vergrößerten ersten Incisivus, untere und obere Canini mit einer tiefen Paracaninus-Fossa am Maxillare; eine fast komplette obere und untere postcanine Zahnreihe mit einem Bezahnungsmuster vergleichbar mit dem anderer Tritheledontiden (z.B. Pachygenelus und Chaliminia); eine auffällige, als Ansatzfläche für die Turbinalia dienende Crista an der Innenseite of the Maxilla; partiell vereinigte Jugular-Foramina und eine Fenestra rotunda in der Jugular-fossa, welche durch einen fingerartigen Vorsprung der posterolateralen Wandung des Opistothicums voneinander getrennt werden; sowie außerhalb der Jugular-Fossa liegene hypoglossale Foramina. Irajatherium ist ein Schlüsseltaxon zum Verständnis der frühen Evolution der Ictidosauriden, eine mit den Mammaliformen nahe verwandte Cynodontier-Gruppe aus der oberen Trias und dem unteren Jura.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9

Similar content being viewed by others

Abbreviations

UFRGS PV-T:

Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil, Paleovertebrate Collection.

References

  • Abdala, F., and A.M. Ribeiro. 2003. A new traversodontid cynodont from the Santa Maria Formation (Ladinian-Carnian) of southern Brazil, with a phylogenetic analysis of Gondwanan traversodontids. Zoological Journal of the Linnean Society 139: 529–545.

    Article  Google Scholar 

  • Abdala, F., and A.M. Ribeiro. 2010. Distribution and diversity patterns of Triassic cynodonts (therapsida, Cynodontia) in Gondwana. Palaeogeography, Palaeoclimatology, Palaeoecology 286: 202–217.

    Article  Google Scholar 

  • Arantes, B.A., M.B. Soares, and C.L. Schultz. 2009. Clevosaurus brasiliensis (Lepidosauria, Sphenodontia) do Triássico Superior do Rio Grande do Sul: anatomia pós-craniana e relações filogenéticas. Revista Brasileira de Paleontologia 12(1): 43–54.

    Article  Google Scholar 

  • Araújo, D.C., and T.D. Gonzaga. 1980. Uma nova espécie de Jachaleria (Therapsida, Dicynodontia) do Triássico do Brasil. In Actas del 1 er Congreso Argentino de Paleontología y Bioestratígrafia. Buenos Aires, 159–174.

  • Bonaparte, J.F. 1980. El primer ictidosaurio (Reptilia-Therapsida) de América del Sur, Chaliminia musteloides, del Triásico Superior de La Rioja, Argentina. In Actas del 2° Congreso Argentino de Paleontología y Bioestratigrafía y 1 er Congreso Latinoamericano de Paleontología. Buenos Aires, 1:123–133.

  • Bonaparte, J.F., and M.C. Barberena. 2001. On two advanced carnivorous cynodonts from the Late Triassic of Southern Brazil. Bulletin of the Museum of Comparative Zoology 156: 59–80.

    Google Scholar 

  • Bonaparte, J.F., and H–.D. Sues. 2006. A new species of Clevosaurus (Lepidosauria: Rhynchocephalia) from the Upper Triassic of Rio Grande do Sul, Brazil. Palaeontology 49: 917–923.

    Article  Google Scholar 

  • Bonaparte, J.F., J. Ferigolo, and A.M. Ribeiro. 1999. A new early Late Triassic saurischian dinosaur from the Rio Grande do Sul State, Brazil. Proceedings of the Second Dinosaur Symposium National Sciences Museum Monographs. Tokyo 15: 89–109.

    Google Scholar 

  • Bonaparte, J.F., J. Ferigolo, and A.M. Ribeiro. 2001. A primitive Late Triassic ‘ictidosaur’ from Rio Grande do Sul, Brazil. Palaeontology 44: 623–635.

    Article  Google Scholar 

  • Bonaparte, J.F., A.G. Martinelli, and C.L. Schultz. 2005. New information on Brasilodon and Brasilitherium (Cynodontia, Probainognathia) from the Late Triassic of Southern Brazil. Revista Brasileira de Paleontologia 8: 25–46.

    Article  Google Scholar 

  • Bonaparte, J.F., G. Brea, C.L. Schultz, and A.G. Martinelli. 2007. A new specimen of Guaibasaurus candelariensis (basal Saurischia) from the Late Triassic Caturrita Formation of Southern Brazil. Historical Biology 19(1): 73–82.

    Article  Google Scholar 

  • Bonaparte, J.F., A.G. Martinelli, C.L. Schultz, and R. Rubert. 2003. The sister-group of mammals: Small cynodonts from the Late Triassic of Southern Brazil. Revista Brasileira de Paleontologia 5: 5–27.

    Google Scholar 

  • Bonaparte, J.F., C.L. Schultz, M.B. Soares, and A.G. Martinelli. 2008. Faxinal do Soturno Local Fauna of the Late Triassic of Rio Grande do Sul, Brazil. Paleontologia em Destaque Edição Especial Maio-2008:54.

  • Broom, R. 1912. On a new type of cynodont from the Stormberg. Annals of the South African Museum 7: 334–336.

    Google Scholar 

  • Cisneros, J.C., and C.L. Schultz. 2003. Soturnia caliodon n. g. n. sp., a procolophonid reptile from the Upper Triassic of Southern Brazil. Neus Jahrbuch fur Geologie und Palaeontologie Abhandlungen 227(3): 365–380.

    Google Scholar 

  • Crompton, A.W. 1958. The cranial morphology of a new genus and species of ictidosaurian. Proceedings of the Zoological Society of London 130: 183–216.

    Article  Google Scholar 

  • Crompton, A.W. 1963a. On the lower jaw of Diarthrognathus and the origin of the mammalian lower jaw. Proceedings of the Zoological Society of London 140: 697–753.

    Article  Google Scholar 

  • Crompton, A.W. 1963b. Tooth replacement in the cynodont Thrinaxodon liorhinus Seeley. Annals of South African Museum 46: 479–521.

    Google Scholar 

  • Crompton, A.W., and Z.-X. Luo. 1993. Relationships of the Liassic mammals Sinoconodon, Morganucodon oehleri, and Dinnetherium. In Mammal Phylogeny: Mesozoic differentiation, Multituberculates, Monotremes, Early Therians and Marsupials, ed. F.S. Szalay, M.J. Novacek, and M.C. McKenna, 30–44. New York: Springer.

    Google Scholar 

  • Dias-da-Silva, S., E.V. Dias, and C.L. Schultz. 2009. First record of stereospondyls (Tetrapoda, Temnospondyli) in the Upper Triassic of Southern Brazil. Gondwana Research 15: 131–136.

    Article  Google Scholar 

  • Furin, S., N. Preto, M. Rigo, G. Roghi, P. Gianolla, J.L. Crowley, and S.A. Bowring. 2006. High-precision U-Pb zircon age from the Triassic of Italy: Implications for the Triassic time scale and the Carnian origin of calcareous nannoplankton and dinosaurs. Geology 34: 1009–1012.

    Article  Google Scholar 

  • Goloboff, P.A. 1993. “NONA”, version 2.0. Program and Documentation.

  • Gow, C.E. 1980. The dentitions of the Tritheledontidae (Therapsida: Cynodontia). Proceedings of the Royal Society of London, B 208: 461–481.

    Article  Google Scholar 

  • Gow, C.E. 1994. New find of Diathrognathus (Therapsida: Cynodontia) after seventy years. Palaeontologia Africana 31: 52–54.

    Google Scholar 

  • Gow, C.E. 2001. A partial skeleton of the tritheledontid Pachygenelus (Therapsida: Cynodontia). Palaeontologia Africana 37: 93–97.

    Google Scholar 

  • Gradstein, F.M., and J.C. Ogg. 2004. Geologic Time Scale 2004–why, how and where next. Lethaia 37: 175–181.

    Article  Google Scholar 

  • Hillenius, W.J. 1992. The evolution of nasal turbinates and mammalian endothermy. Paleobiology 18(1): 17–29.

    Google Scholar 

  • Hillenius, W.J. 1994. Turbinates in therapsids: Evidence for Late Permian origins of mammalian endothermy. Evolution 48(2): 207–229.

    Article  Google Scholar 

  • Hopson, J.A. 1990. Cladistic analysis of therapsid relationships. Journal of Vertebrate Paleontology 10(3): 28A.

    Google Scholar 

  • Hopson, J.A., and H. Barghusen. 1986. An analysis of therapsid relationships. In The ecology and biology of Mammal-like Reptiles, ed. N. Hotton III, P.D. MacLean, J.J. Roth, and E.C. Roth, 83–106. Washington DC: Smithsonian Institution Press.

    Google Scholar 

  • Hopson, J.A., and J.W. Kitching. 2001. A probainognathian cynodont from South Africa and the phylogeny of nonmammalian cynodonts. Bulletin of the Museum of Comparative Zoology 156: 5–35.

    Google Scholar 

  • Kemp, T.S. 1979. The primitive cynodont Procynosuchus: Functional anatomy of the skull and relationships. Philosophical Transactions of the Royal Society of London, B 285: 73–122.

    Article  Google Scholar 

  • Kemp, T.S. 1982. Mammal-like reptiles and the origin of mammals, 362. New York: Academic Press.

    Google Scholar 

  • Kermack, K.A., F. Mussett, and H.W. Rigney. 1981. The skull of Morganucodon. Zoological Journal of the Linnean Society 71: 1–158.

    Article  Google Scholar 

  • Kischlat, E.-E., and S.G. Lucas. 2003. A phytosaur from the Upper Triassic of Brazil. Journal of Vertebrate Paleontology 23(2): 464–467.

    Article  Google Scholar 

  • Knoll, F. 2004. Review of the tetrapod fauna of the “Lower Stormberg Group” of the main Karoo Basin (southern Africa): Implications for the age of the Lower Elliot Formation. Bulletin de la Societe Géologique de France 175: 73–83.

    Article  Google Scholar 

  • Knoll, F., and B. Battail. 2001. New ornithischian remains from the Upper Elliot Formation (Lower Jurassic) of Lesotho and stratigraphical distribution of southern African fabrosaurids. Geobios 34: 415–421.

    Article  Google Scholar 

  • Lehrmann, D.J., J. Ramezani, S.A. Bowring, M.W. Martin, P. Montgomery, P. Enos, J.L. Payne, M.J. Orchard, W. Hongmei, and W. Jiayong. 2006. Timing of recovering from the end-Permian extinction: Geochronology and biostratigraphic constraints from South China. Geology 34: 1053–1056.

    Article  Google Scholar 

  • Lillegraven, J.A., and G. Krusat. 1991. Craniomandibular anatomy of Haldanodon excpectatus (Docodonta; Mammalia) from the Late Jurassic of Portugal and its implications to the evolution of mammalian characters. University of Wyoming Contributions to Geology 28: 39–138.

    Google Scholar 

  • Liu, J., and P. Olsen. 2010. The phylogenetic relationships of Eucynodontia (Amniota: Synapsida). Journal of Mammalian Evolution. doi: 10.1007/s10914-010-9136-8.

  • Luo, Z.-X. 1994. Sister-group relationships of mammals and transformations of diagnostic mammalian characters. In In the shadow of the dinosaurs: Early Mesozoic tetrapods, ed. N.C. Fraser, and H.-D. Sues, 98–128. Cambridge: Cambridge University Press.

    Google Scholar 

  • Luo, Z.-X. 2007. Transformation and diversification in early mammal evolution. Nature 450: 1011–1019.

    Article  Google Scholar 

  • Luo, Z.-X., and A.W. Crompton. 1994. Transformation of the quadrate (incus) through the transition from non-mammalian cynodonts to mammals. Journal of Vertebrate Paleontology 14: 341–374.

    Article  Google Scholar 

  • Luo, Z.-X., A.W. Crompton, and S.G. Lucas. 1995. Evolutionary origins of the mammalian promontorium and cochlea. Journal of Vertebrate Paleontology 15: 113–121.

    Article  Google Scholar 

  • Luo, Z–.X., Z. Kielan-Jaworowska, and R.L. Cifelli. 2002. In quest for a phylogeny of Mesozoic mammals. Acta Palaeontologica Polonica 47: 1–78.

    Google Scholar 

  • Luo, Z–.X., Z. Kielan-Jaworowska, and R.L. Cifelli. 2004. Evolution of dental replacement in mammals. Bulletin of Carnegie Museum of Natural History 36: 159–175.

    Article  Google Scholar 

  • Martinelli, A.G., and J.F. Bonaparte. 2008. Postcanine replacement in Brasilodon and Brasilitherium (Cynodontia, Probainognathia) and its bearing in cynodont evolution. In Libro de Resúmenes del 3 er Congreso Latinoamericano de Paleontología de Vertebrados. Neuquén, 151.

  • Martinelli, A.G., and G.W. Rougier. 2007. On Chaliminia musteloides Bonaparte (Cynodontia, Tritheledontidae) and the phylogeny of the Ictidosauria. Journal of Vertebrate Paleontology 27(2): 442–460.

    Article  Google Scholar 

  • Martinelli, A.G., J.F. Bonaparte, C.L. Schultz, and R. Rubert. 2005. A new tritheledontid (Therapsida, Eucynodontia) from the Late Triassic of Rio Grande do Sul (Brazil) and its phylogenetic relationships among carnivorous non-mammalian eucynodonts. Ameghiniana 42(1): 191–208.

    Google Scholar 

  • Martinez, R.N., C.L. May, and C.A. Forster. 1996. A new carnivorous cynodont from the Ischigualasto Formation (Late Triassic, Argentina), with comments on eucynodont phylogeny. Journal of Vertebrate Paleontology 16: 271–284.

    Article  Google Scholar 

  • Muttoni, G., D.V. Kent, P.E. Olsen, P. Di Stefano, W. Lowrie, S.M. Bernasconi, and F.M. Hernández. 2004. Tethyan magnetostratigraphy from Pizzo Mondello (Sicily) and correlation to the Late Triassic Newark astrochronological polarity time scale. Geological Society of America Bulletin 116: 1043–1058.

    Article  Google Scholar 

  • Nixon, K.C. 1999. Winclada (BETA) 0.9.9. New York: Ithaca.

    Google Scholar 

  • Oliveira, E.V. 2006. Reevaluation of Therioherpeton cargnini Bonaparte & Barberena, 1975 (Probainognathia, Therioherpetidae) from the Upper Triassic of Brazil. Geobios 28: 447–465.

    Google Scholar 

  • Oliveira, T.V., and C.L. Schultz. 2007. La predominancia de Exaeretodon Cabrera 1943 en una sección Triásica de Brasil y su probable correlación con el mismo evento en la porción mediana superior de la Formación Ischigualasto (Triásico de Argentina). Ameghiniana 44(4-Suplemento): 14R.

  • Oliveira, T.V., M.B. Soares and A.G. Martinelli. 2008. New data on the Late Brazilian Triassic tritheledontid cynodont Irajatherium hernandezi Martinelli, Bonaparte, Schultz and Rubert, 2005. In Libro de Resúmenes del 3 er Congreso Latinoamericano de Paleontología de Vertebrados. Neuquén, 186.

  • Ovtcharova, M., H. Bucher, U. Schaltegger, T. Galfetti, A. Brayard, and J. Guex. 2006. New Early to Middle Triassic U-Pb ages from South China: Calibration with ammonoid biochronozones and implications for the timing of Triassic biotic recovery. Earth and Planetary Sciences Letters 243: 463–475.

    Article  Google Scholar 

  • Owen, R. 1861. Palaeontology, or a systematic summary of extinct animals and their geological relations, 463. Edinburgh: Adam and Charles Black.

    Google Scholar 

  • Rodrigues, P.G. 2005. Endotermia em cinodontes não-mamalianos: a busca por evidências osteológicas. Unpublished M.Sc. thesis, Universidade Federal do Rio Grande do Sul, 133.

  • Rogers, R.R., C.C. Swisher III, P.C. Sereno, A.M. Monetta, C.A. Forster, and R.N. Martínez. 1993. The Ischigualasto tetrapod assemblage (Late Triassic, Argentina) and 40Ar/39Ar dating of dinosaur origins. Science 260: 794–797.

    Article  Google Scholar 

  • Rougier, G.W., J.R. Wible, and J.A. Hopson. 1992. Reconstruction of cranial vessels in the Early Cretaceous mammal Vincelestes neuquenianus: Implications for the evolution of the mammalian cranial vascular system. Journal of Vertebrate Paleontology 12: 188–216.

    Article  Google Scholar 

  • Rowe, T. 1988. Definition, diagnosis, and origin of Mammalia. Journal of Vertebrate Paleontology 8: 241–264.

    Article  Google Scholar 

  • Schultz, C.L., and M.B. Soares. 2006. Proposta de nova denominação para a Cenozona de Ictidosauria, do Triássico Superior (Formação Caturrita) do Rio Grande do Sul. In Boletim de Resumos do 5° Simpósio Brasileiro de Paleontologia de Vertebrados. Santa Maria, 41.

  • Shubin, N.H., A.W. Crompton, H–.D. Sues, and P.E. Olsen. 1991. New fossil evidence on the sister-group of mammals and early Mesozoic faunal distributions. Science 251: 1063–1065.

    Article  Google Scholar 

  • Sidor, C.A., and P.J. Hancox. 2006. Elliotherium kersteni, a new tritheledontid from the Lower Elliot Formation (Upper Triassic) of South Africa. Journal of Paleontology 80(2): 333–342.

    Article  Google Scholar 

  • Soares, M.B. 2004. Novos materiais de Riograndia guaibensis (Cynodontia, Tritheledontidae) do Triássico Superior do Rio Grande do Sul, Brasil: análise osteológica e implicações filogenéticas. Unpublished Ph.D. thesis, Universidade Federal do Rio Grande do Sul, 347.

  • Soares, M.B., J.F. Bonaparte, and C.L. Schultz. 2005. New material of Riograndia guaibensis (Eucynodontia, Tritheledontidae) from the Caturita Formation, Upper Triassic of Southern Brazil: Anatomical study and phylogenetic implications. In Boletim de Resumos do II Congresso Latino-americano de Paleontologia de Vertebrados. Rio de Janeiro, 250–251.

  • Soares, M.B., and J.E.F. Dornelles. 2009. Cinodontes, a chave para a origem dos mamíferos. In Vertebrados fósseis de Santa Maria e Região, org. 153–208, ed. A.A.S. Da-Rosa. Santa Maria: Pallotti.

    Google Scholar 

  • Watson, D.M.S. 1913. On a new cynodont from the Stormberg. Geological Magazine 10: 145–148.

    Article  Google Scholar 

  • Wible, J.R. 1991. Origin of Mammalia: The craniodental evidence reexamined. Journal of Vertebrate Paleontology 11: 1–28.

    Article  Google Scholar 

  • Wible, J.R., and J.A. Hopson. 1993. Basicranial evidence for early mammal phylogeny. In Mammal Phylogeny: Mesozoic differentiation, Multituberculates, Monotremes, Early Therians and Marsupials, ed. F.S. Szalay, M.J. Novacek, and M.C. McKenna, 45–62. New York: Springer.

    Google Scholar 

  • Wu, X.-C. 1994. Late Triassic-Early Jurassic sphenodontians from China and the phylogeny of the Sphenodontia. In In the shadow of the dinosaurs: Early Mesozoic tetrapods, ed. N.C. Fraser, and H–.D. Sues, 38–69. Cambridge: Cambridge University Press.

    Google Scholar 

  • Zerfass, H., E.L. Lavina, C.L. Schultz, A.J.V. Garcia, U.F. Faccini, and F. Chemale Jr. 2003. Sequence stratigraphy of continental Triassic strata of Southernmost Brazil: A contribution to Southwestern Gondwana palaeogeography and palaeoclimate. Sedimentary Geology 161: 85–105.

    Article  Google Scholar 

Download references

Acknowledgments

We thank Luiz Flávio Lopes for the photographs of several specimens and CNPq for financial support (TVO). The suggestions of the reviewers Fernando Abdala and Zhe-Xi Luo and the editor Oliver Rauhut improved the quality of this paper.

Author information

Authors and Affiliations

  1. Departamento de Paleontologia e Estratigrafia, Universidade Federal do Rio Grande do Sul, Instituto de Geociências, Campus do Vale. Avenida Bento Gonçalves, 9500, Bairro Agronomia, Caixa Postal 15001, CEP 91501-970, Porto Alegre, RS, Brazil

    Téo Veiga de Oliveira & Marina Bento Soares

  2. Centro de Pesquisas Paleontológicas Llewellyn Ivor Price, BR-262, Km 784, Peirópolis, Uberaba, MG, Brazil

    Agustín G. Martinelli

Authors
  1. Téo Veiga de Oliveira
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Agustín G. Martinelli
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Marina Bento Soares
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Téo Veiga de Oliveira.

Appendices

Appendix 1: Score for Irajatherium hernandezi in the data matrix of Martinelli & Rougier (2007)

  • Irajatherium

  • ?11?1?1002110?????100011101210???0110?????0????1???????????????????1000??1?1?????0????0111???

Changes in the score for Irajatherium hernandezi presented in this paper compared with the data matrix of Martinelli & Rougier (2007):

  • Character 2. Lower incisor number: from ? to 1 (three incisors).

  • Character 3. Some incisor enlarged: from ? to 1 (present).

  • Character 24. Sectorial postcanines with the major axis anteromedial-posterolaterally oriented, passing the distal portion of an anterior tooth medial to the mesial portion of the next tooth: from 0 to 1 (present).

  • Character 35. Mandibular symphysis: from ? to 1 (unfused).

  • Character 36. Postdentary bones: from ? to 1 (reduced to narrow rod lying in postdentary trough).

  • Character 68. Trigeminal nerve (V2 and V3) exit: from ? to 1 (foramen located entirely on the prootic, or on the anterior lamina of the petrosal).

  • Character 69. Prootic and ophistotic: from ? to 0 (unfused).

  • Character 70. Petrosal promontorium: from ? to 0 (absent).

  • Character 71. Fenestra ovalis: from ? to 0 (with thickened ring).

  • Character 74. Perilymphatic foramen separation from jugular foramen: from ? to 1 (partially separated by finger-like projection from postero-lateral wall of jugular foramen).

  • Character 76. Hypoglossal foramen: from ? to 1 (separated from the jugular fossa).

Appendix 2: Diagnoses of clades (numbered as in Fig. 9; some clades are not diagnosed here). An asterisk (*) indicates ambiguous character-states

  • Clade 4. Ictidosauria (sensu Martinelli & Rougier, 2007): presence of some enlarged incisors (Ch. 3), upper incisor 2 large and the others small (Ch. 4), lower incisor 1 large and the other small (Ch. 5), premaxilla forming the posterior border of incisive foramen (Ch. 39)*, length of palatine longer relative to maxilla in secondary palate (Ch. 47).

  • Clade 5: Tritheledontidae (sensu Martinelli & Rougier, 2007): dominant central bulbous main cusp on upper postcanines (Ch. 11), upper posterior postcanines with cusp B and C buccally displaced and bulbous, prominent cusp A (Ch. 12), lower middle and posterior postcanines with four cusps aligned decreasing in size posteriorly (Ch. 19), posterior portion of secondary palate almost at the level of the tip of upper postcanine teeth, forming a deep groove between hard palate and tooth row (Ch. 48).

  • Unnamed clade. Pachygenelinae (Clade 6) plus Chalimininae (Clade 7): single roots of postcanines (Ch. 25), tooth row parallel to sub-parallel from the axial plane of the cranium (Ch. 30), maxillary buccal shelf overhanging tooth row (Ch. 43).

  • Clade 6. Pachygenelinae (sensu Martinelli & Rougier, 2007): upper postcanines with buccal cingulum (Ch. 9)*, narrow upper postcanines with lingual cingulum (Ch. 10)*.

  • Clade 7. Chalimininae (sensu Martinelli & Rougier, 2007): more than 11 upper postcanine teeth in adult (Ch. 8)*, absence of imbrincated sectorial postcanines (Ch. 24)*.

  • Tritheledon plus Diarthrognathus: absence of upper posterior postcanines with cusp B and C buccally displaced and bulbous, prominent cusp A (Ch. 12)*.

Rights and permissions

Reprints and permissions

About this article

Cite this article

de Oliveira, T.V., Martinelli, A.G. & Soares, M.B. New information about Irajatherium hernandezi Martinelli, Bonaparte, Schultz & Rubert 2005 (Eucynodontia, Tritheledontidae) from the upper triassic (Caturrita Formation, Paraná Basin) of Brazil. Paläontol Z 85, 67–82 (2011). https://doi.org/10.1007/s12542-010-0078-5

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s12542-010-0078-5

Keywords

Schlüsselwörter

Search

Navigation