Abstract
We describe a new species of the basal mammaliaform Docodon, D. apoxys, sp. nov., represented by three nearly complete dentaries from the Upper Jurassic Morrison Formation of central Colorado. This species differs from other known species of Docodon in the relative heights of the principal molar cusps and in the size of the distal molars. In addition, we attribute a partial rostrum preserving much of the maxilla and most of the premaxilla, bearing a complete incisor and premolar count, to Docodon sp. These materials supply previously unknown morphology for this classic North American Jurassic taxon, and help establish a common morphology for Docodonta as a whole. While Docodon differs from the Portuguese docodont Haldanodon in the presence of only five upper incisors (none of which is entirely within the maxilla), an internarial bar is present in both taxa. The new specimens also unambiguously preserve a complete and undistorted angular process that differs conspicuously from the classical interpretation of the holotype of Docodon victor; this structure in docodonts closely resembles the angular process in australosphenidans and trechnotheres. We abandon the concept of a “pseudangular” process and we consider the angular process to be a homologous feature (where present) across Mammaliaformes.
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Allin EF (1975) Evolution of the mammalian middle ear. J Morphol 147: 403–438
Allin EF (1986) The auditory apparatus of advanced mammal-like reptiles and early mammals. In: Hotton N, MacLean PD, Roth JJ, Roth EC (eds) The Ecology and Biology of Mammal-like Reptiles. Smithsonian Institution Press, Washington D. C., pp 283-294
Archer M, Jenkins FA Jr, Hand SJ, Murray P, Godthelp H (1992) Description of the skull and non-vestigial dentition of a Miocene platypus Obdurodon dicksoni n. sp.) from Riversleigh, Australia, and the problem of monotreme origins. In: Augee ML (ed) Platypus and Echidnas. The Royal Zoological Society of New South Wales, Sydney, pp 15-27
Archer M, Murray P, Hand SJ, Godthelp H (1993) Reconsideration of monotreme relationships based on the skull and dentition of the Miocene Obdurodon dicksoni. In: Szalay FS, Novacek MJ, McKenna MC (eds) Mammal Phylogeny, Volume 1-Mesozoic Differentiation, Multituberculates, Monotremes, Early Therians, and Marsupials. Springer-Verlag, New York.
Archibald JD, Averianov AO (2003) The Late Cretaceous placental mammal Kulbeckia. J Vertebr Paleontol 23:404-419
Averianov AO, Lopatin AV (2006) Itatodon tatarinovi (Tegotheriidae, Mammalia), a docodont from the Middle Jurassic of western Siberia and phylogenetic analysis of Docodonta. Paleontol J 40: 668-677
Averianov AO, Lopatin AV, Krasnnolutskii SA, Ivantsov, SV (2010) New docodontans from the Middle Jurassic of Siberia and reanalysis of Docodonta interrelationships. Proc Zool Inst Russian Acad Sci 314: 121-148
Averianov AO, Lopatin AV, Skutchas PP, Martynovich NV, Leshchinskiy SV, Rezvyi AS, Krasnnolutskii SA, Fayngertz AV (2005) Discovery of Middle Jurassic mammals from Siberia. Acta Palaeontol Pol 50: 789-797
Averianov AO, Martin T, Lopatin AV (2013) A new phylogeny for basal Trechnotheria and Cladotheria and affinities of South American endemic Late Cretaceous mammals. Naturwissenschaften 100: 311-326
Barghusen H (1986) On the evolutionary origin of the therian tensor veli palatini and tensor tympani muscles. In: Hotton N, MacLean PD, Roth JJ, Roth EC (eds) The Ecology and Biology of Mammal-like Reptiles. Smithsonian Institution Press, Washington, D. C., pp 253-262
Beer GR de 1937. The Development of the Vertebrate Skull. Clarendon Press, Oxford, 552 pp
Behrensmeyer AK (1982) Time resolution in fluvial vertebrate assemblages. Paleobiology 8: 211-227
Bonaparte JF (1990) New Late Cretaceous mammals from the Los Alamitos Formation, northern Patagonia. Natl Geographic Res 6: 63-93
Bonaparte JF, Martinelli AG, Schultz CL (2005) New information on Brasilodon and Brasilitherium (Cynodontia, Probainognathia) from the Late Triassic of southern Brazil. Revista Brasileira de Paleontología 8: 25-46
Bonaparte JF, Migale LA (2010) Protomamíferos y mamíferos Mesozoicos de América del Sur. Museo de Ciencias Naturales Carlos Ameghino, Mercedes, 442 pp
Butler PM (1939) The teeth of the Jurassic mammals. Proc Zool Soc London 109: 329-356
Butler PM (1997) An alternative hypothesis on the origin of docodont molar teeth. J Vertebr Paleontol 17: 435-439
Carpenter K (1998) Armor of Stegosaurus stenops, and the taphonomic history of a new specimen from Garden Park, Colorado. Mod Geol 23:127-144
Carpenter K (2013) History, sedimentology, and taphonomy of the Carnegie Quarry, Dinosaur National Monument, Utah. Ann Carnegie Mus 81: 153-232
Chow M, Rich TH (1982) Shuotherium dongi, n. gen. and sp., a therian with pseudo-tribosphenic molars from the Jurassic of Sichuan, China. Australian Mammal 5: 127-142
Chure DJ (2001) The second record of the African theropod Elaphrosaurus (Dinosauria, Ceratosauria) from the Western Hemisphere. Neues Jahrb Geol Paläontol-M 9: 565-576
Clemens WA, Lillegraven JA (1986) New Late Cretaceous, North American advanced therian mammals that fit neither the marsupial nor eutherian molds. Contrib Geol Univ Wyoming Spec Pap 3: 55-85
Crompton AW, Hylander WL (1986) Changes in mandibular function following the acquisition of a dentary-squamosal joint. In: Hotton III N, MacLean PD, Roth JJ, Roth EC (eds) The Ecology and Biology of Mammal-like Reptiles. Smithsonian Institution Press, Washington, D. C., pp 263-282
Crompton AW, Luo Z-X (1993) Relationships of the Liassic mammals Sinoconodon, Morganucodon, and Dinnetherium. In: F.S. Szalay FS, Novacek MJ, McKenna MC (eds) Mammal Phylogeny, Volume 1--Mesozoic Differentiation, Multituberculates, Monotremes, Early Therians, and Marsupials. Springer-Verlag, Inc., New York, pp 30-44
Datta PM (2005) Earliest mammal with transversely expanded upper molar from the Late Triassic (Carnian) Tiki Formation, South Rewa Gondwana Basin, India. J Vertebr Paleontol 25: 200-207
Diogo R, Abdala V, Lonergan N, Wood BA (2008) From fish to modern humans - comparative anatomy, homologies and evolution of the head and neck musculature. J Anat 213: 391-424
Edgeworth FH (1911) On the morphology of the cranial muscles in some vertebrates. Quart J Microsc Sci 56: 167-316
Freeman EF (1979) A Middle Jurassic mammal bed from Oxfordshire. Paleontology 22: 135-166
Foster J (2007) Jurassic West: Dinosaurs of the Morrison Formation and Their World. Indiana University Press, Bloomington
Gidley JW (1906) Evidence bearing on tooth-cusp development. Proc Washington Acad Sci 8: 91-106
Harris J, Carpenter K (1996) A large pterodactyloid from the Morrison Formation (Late Jurassic) of Garden Park, Colorado. Neues Jahrb Geol Paläontol-M 8: 473-484
Horovitz I, Ladevèze S, Argot C, Macrini TE, Martin T, Hooker JJ, Kurz C, Muizon C de, Sánchez‐Villagra MR (2009) The anatomy of Herpetotherium cf. fugax Cope (1873) a metatherian from the Oligocene of North America. Palaeontographica Abteilung A 284: 109-141
Hu Y-M, Meng J, Clark JM (2007) A new Late Jurassic docodont (Mammalia) from northeastern Xinjiang, China. Vertebr Palasiatic 45: 173-197
Hunter JP, Jernvall J (1995) The hypocone as a key innovation in mammalian evolution. Proc Natl Acad Sci USA 92: 10718-10722
Jenkins FA Jr (1969) Occlusion in Docodon (Mammalia, Docodonta). Postilla 139: 1-24
Jenkins FA Jr, Crompton AW, Downs WR (1983) Mesozoic mammals from Arizona: new evidence on mammalian evolution. Science 222: 1233-1235
Jenkins FA Jr, Schaff CR (1988) The Early Cretaceous mammal Gobiconodon (Mammalia, Triconodonta) from the Cloverly Formation in Montana. J Vertebr Paleontol 8: 1-24
Ji Q, Luo Z-X, Yuan C-X, Tabrum AR (2006) A swimming mammaliaform from the Middle Jurassic and ecomorphological diversification of early mammals. Science 311: 1123-1127
Kemp TS (1982) Mammal-like Reptiles and the Origin of Mammals. Academic Press, London, 363 pp
Kermack KA, Kielan-Jaworowska Z (1971) Therian and non-therian mammals. In: Kermack DM, Kermack KA (eds) Early Mammals. Zool J Linn Soc, London, 103-116
Kermack KA, Lee AJ, Lees PM, Mussett F (1987) A new docodont from the Forest Marble. Zool J Linn Soc 89: 1-39
Kermack KA, Mussett F, Rigney HW (1973) The lower jaw of Morganucodon. Zool J Linn Soc 53: 87-175
Kermack KA, Mussett F, Rigney HW (1981) The skull of Morganucodon. Zool J Linn Soc 53: 87-175
Kielan-Jaworowska Z, Cifelli RL, Luo Z-X (2004) Mammals from the Age of Dinosaurs: Structure, Relationships, and Paleobiology. Columbia Univeristy Press, New York, 630 pp
Kirkland J, Carpenter K, Hunt A, Scheetz R (1998) Ankylosaur (Dinosauria) specimens from the Upper Jurassic Morrison Formation. Mod Geol 23:159-160.
Kowallis BJ, Christiansen EH, Deino AL, Peterson F, Turner CE, Kunk MJ, Obradovich JD (1998) The age of the Morrison Formation. In: Carpenter K, Chure D, Kirkland JI (eds) The Morrison Formation: An Interdisciplinary Study. Mod Geol 23: 235-260
Kirkland J, Carpenter K, Hunt A, Scheetz R (1998) Ankylosaur Dinosauria) specimens from the Upper Jurassic Morrison Formation. Mod Geol 23:159-160
Krebs B (1998) Drescheratherium acutum gen. et sp. nov., ein neuer Eupantotherier (Mammalia) aus dem Oberen Jura von Portugal. Berliner Geowissenschaftliche Abhandlungen 28: 91-111
Kretzoi M (1946) On Docodonta, a new order of Jurassic mammals. Annales Historico-Naturales Musei Nationalis Hungarici 39: 108-111
Krusat G (1980) Contribução para o conhecimento da fauna do Kimeridgiano da mina de lignito Guimarota (Leiria, Portugal). IV Parte. Haldanodon exspectatus Kuhne & Krusat 1972 (Mammalia, Docodonta). Memórias dos Serviços Geológicos de Portugal 27: 1-79
Krusat G (1991) Functional morphology of Haldanodon exspectatus (Mammalia, Docodonta) from the Upper Jurassic of Portugal. In: Kielan-Jaworowska Z, Heintz N, Nakrem HA (eds) Fifth Symposium on Mesozoic Terrestrial Ecosystems and Biota. Contributions from the Paleontological Museum, University of Oslo 363: 37-38
Kuhn H-J (1971) Die Entwicklung und Morphologie des Schädels von Tachyglossus aculeatus. Abh Senckenberg Nat Ges 528: 1-192
Lillegraven JA, Kielan-Jaworowska Z, Clemens WA (eds) (1979) Mesozoic Mammals-The First Two-thirds of Mammalian History. University of California Press, Berkeley
Lillegraven JA, Krusat G (1991) Cranio-mandibular anatomy of Haldanodon exspectatus (Docodonta: Mammalia) from the Late Jurassic of Portugal and its implications to the evolution of mammalian characters. Contrib Geol Univ Wyoming 28: 39–138
Lopatin AV, Averianov AO (2005) A new docodont (Docodonta, Mammalia) from the Middle Jurassic of Siberia. Doklady Biol Sci 405: 434–436
Lopatin AV, Averianov AO, Maschenko EN, Leshchinskiy SV (2009) Early Cretaceous Mammals of Western Siberia: 2. Tegotheriidae. Paleontol J 43: 453-462
Luo Z-X, Crompton AW, Sun A-L (2001) A new mammaliaform from the Early Jurassic and evolution of mammalian characteristics. Science 292: 1535-1540
Luo Z-X, Ji Q, Yuan C-X (2007) Convergent dental adaptations in pseudo-tribosphenic and tribosphenic mammals. Nature 450: 93-97
Luo Z-X, Martin T (2007) Analysis of molar structure and phylogeny of docodont genera. Bull Carnegie Mus Nat Hist 39: 27-47
Luo Z-X, Wible JR (2005) A Late Jurassic digging mammal and early mammalian diversification. Science 308: 103-107
Luo Z-X, Yuan C-X, Ji Q (2011) A Jurassic eutherian mammal and divergence of marsupials and placentals. Nature 476: 442-445
Marsh OC (1878) Fossil mammal from the Jurassic of the Rocky Mountains. Am J Sci 15: 459
Marsh OC (1880) Notice on Jurassic mammals representing two new orders. Am J Sci 20: 235-239
Marsh OC (1881) Notice of new Jurassic mammals. Am J Sci 21: 511-513
Martin T (2005) Postcranial anatomy of Haldanodon exspectatus (Mammalia, Docodonta) from the Late Jurassic (Kimmeridgian) of Portugal and its bearing for mammalian evolution. Zool J Linn Soc 145: 219-248
Martin T, Averianov AO (2004) A new docodont (Mammalia) from the Middle Jurassic of Kyrgyzstan, Central Asia. J Vertebr Paleontol 24: 195-201
Martin T, Averianov AO, Pfretzschner H-U (2010) Mammals from the Late Jurassic Qigu Formation in the southern Junggar Basin, Xinjiang, Northwest China. Palaeobiodiv Palaeoenvironm 90: 295-319
Martin T, Nowotny M (2000) The docodont Haldanodon from the Guimarota Mine. In: Martin T, Krebs B (eds) Guimarota: A Jurassic Ecosystem. Verlag Dr. Friedrich Pfeil, Munich, pp 91-96
Martinelli AG, Rougier GW (2007) On Chaliminia musteloides (Eucynodontia: Triltheledontidae) from the Late Triassic of Argentina, and a phylogeny of Ictidosauria. J Vertebr Paleontol 27: 442-460
Maschenko EN, Lopatin AV, Voronkevich AV (2002) A new genus of the tegotheriid docodonts (Docodonta, Tegotheriidae) from the Early Cretaceous of West Siberia. Russ J Theriol 1: 75–81
McWhinney L, Carpenter K, Rothschild B (2001) Dinosaurian humeral periostitis: a case of a juxtacortical lesion in the fossil record. In: Tanke D, Carpenter K, Skrepnick MW (eds) Mesozoic Vertebrate Life. Indiana University Press, Bloomington, pp 364-377
Miao D (1988) Skull morphology of Lambdopsalis bulla (Mammalia, Multituberculata). Contrib Geol Uni Wyoming Spec Pap 4: 1-104
Moore WJ (1981) The Mammalian Skull. Cambridge University Press, Cambridge, 369 pp
Musser AM, Archer M (1998) New information about the skull and dentary of the Miocene platypus Obdurodon dicksoni, and a discussion of ornithorhynchid relationships. Phil Trans R Soc Lond Biol Sci ser B 353: 1063-1079
Novacek MJ, Rougier GW, Wible JR, McKenna MC, Dashzeveg D, Horovitz I (1997) Epipubic bones in eutherian mammals from the Late Cretaceous of Mongolia. Nature 389: 483-486
O’Leary MA, Bloch JI, Flynn JJ, Gaudin TJ, Giallombardo A, Giannini NP, Goldberg SL, Kraatz BP, Luo Z-X, Meng J, Ni X, Novacek MJ, Perini FA, Randall ZS, Rougier GW, Sargis EJ, Silcox MT, Simmons NB, Spaulding M, Velazco PM, Weksler M, Wible JR, Cirranello AL (2013) The placental mammal ancestor and the post–K-Pg radiation of placentals. Science 339: 662-667
Osborn HF (1888) On the structure and classification of the Mesozoic Mammalia. J Acad Nat Sci Philadelphia 9: 186-264
Ostrom JH, McIntosh JS (1966) Marsh’s Dinosaurs- the Collections from Como Bluff. Yale University Press, New Haven, 338 pp
Pascual R, Goin FJ, González P, Ardolino A, Puerta P (2000) A highly derived docodont from the Patagonian Late Cretaceous: evolutionary implications for Gondwanan mammals. Geodiversitas 22: 395-414
Patterson B (1956) Early Cretaceous mammals and the evolution of mammalian molar teeth. Fieldiana: Geol 13: 1-105
Patterson B (1958) Affinities of the Patagonian fossil mammal Necrolestes. Breviora Mus Comp Zool 94: 1-14
Pfretzschner H-U, Martin T, Maisch MW, Matzke AT, Sun G (2005) A new docodont mammal from the Late Jurassic of the Junggar Basin in Northwest China. Acta Palaeontol Pol 50: 799-808
Polly PD, Le Comber SC, Burland TM (2005) On the occlusal fit of tribosphenic molars: are we underestimating species diversity in the Mesozoic? J Mammal Evol 12: 283-299
Prasad GVR, Manhas BK (2007) A new docodont mammal from the Jurassic Kota Formation of India. Paleontol Electronica 10: 1-11
Presley R (1984) The tympanic cavity of Mesozoic mammals. In: Reif WE, Westphal F (eds) Third Symposium on Mesozoic Terrestrial Ecosystems, Tübingen. Attempto Verlag, Tübingen, pp 187-192
Prothero DR (1981) New Jurassic mammals from Como Bluff, Wyoming, and the interrelationships of non-tribosphenic Theria. Bull Am Mus Nat Hist 167: 277-326
Rich TH, Vickers-Rich P, Trusler P, Flannery TF, Cifelli RL, Constantine A, Kool L, van Klaveren N (2001) Monotreme nature of the Australian Early Cretaceous mammal Teinolophos. Acta Palaeontol Pol 46: 113-118
Rougier GW, Apesteguía S, Gaetano L (2011) Highly specialized mammalian skulls from the Late Cretaceous of South America. Nature 479: 98-102
Rougier GW, Martinelli AG, Forasiepi AM, Novacek MJ (2007) New Jurassic mammals from Patagonia, Argentina: a reappraisal of australosphenidan morphology and interrelationships. Am Mus Novitates 3566: 1-54
Rougier GW, Wible JR, Beck RMD, Apesteguía S (2012) The Miocene mammal Necrolestes demonstrates the survival of a Mesozoic non-therian lineage into the late Cenozoic of South America. Proc Natl Acad Sci USA 109: 20053–20058
Rougier GW, Wible JR, Novacek MJ (1998) Implications of Deltatheridium specimens for early marsupial history. Nature 396: 459-463
Rowe TB (1996) Coevolution of the mammalian middle ear and neocortex. Science 273: 651-654
Rowe TB, Macrini TE, Luo Z-X (2011) Fossil evidence on origin of the mammalian brain. Science 332: 955-957.
Ruf I, Luo Z-X, Martin T (2013) Reinvestigation of the basicranium of Haldanodon exspectatus (Mammaliaformes, Docodonta). J Vertebr Paleontol 33: 382-400
Saban R (1971) Particularités musculaires des Monotrémes: musculature de la tête. In: Grassé P-P (ed) Traité de Zoologie, XVI: 3 (Mammifères). Masson et Cie, Paris, pp 681-732
Sigogneau-Russell D (1998) Discovery of a Late Jurassic Chinese mammal in the upper Bathonian of England. C R Acad Sci 327: 571-576.
Sigogneau-Russell D (2003) Docodonts from the British Mesozoic. Acta Palaeontol Pol 48: 357-374
Sigogneau-Russell D, Godefroit P (1997) A primitive docodont (Mammalia) from the Upper Triassic of France and the possible therian affinities of the order. C R Acad Sci 324: 135-140
Sigogneau-Russell D, Hahn G (1995) Reassessment of the Late Triassic symmetrodont mammal Woutersia. Acta Palaeontol Pol 40: 245-260
Simpson GG (1928) A Catalogue of the Mesozoic Mammalia in the Geological Department of the British Museum. Trustees of the British Museum, London, 215 pp
Simpson GG (1929) American Mesozoic Mammalia. Mem Peabody Mus 3: 1-235
Small BJ, Carpenter K (1997) Upper Jurassic microvertebrates from the “Small Quarry,” Garden Park, Colorado. J Vertebr Paleontol 17, supplement to no 3: 76-77A
Trujillo KC (2006) Clay mineralogy of the Morrison Formation (Upper Jurassic-?Lower Cretaceous), and its use in long distance correlation and paleoenvironmental analysis. In: Foster JR, Lucas SG (eds) Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Mus Nat Hist Sci Bull 36: 17-23
Trujillo KC, Chamberlain KR, Strickland A (2006) Oxfordian U/Pb ages from SHRIMP analysis for the Upper Jurassic Morrison Formation of southeastern Wyoming with implications for biostratigraphic correlations. Geol Soc Am Abstracts with Programs 38: 7
Turner CE, Peterson F (1999) Biostratigraphy of dinosaurs in the Upper Jurassic Morrison Formation of the Western Interior, U.S.A. In: Gillette DD (ed) Vertebrate Paleontology in Utah. Utah Geol Survey Misc Publ 99-1: 77-114
Turner CE, Peterson F (2004) Reconstruction of the Upper Jurassic Morrison Formation extinct ecosystem—a synthesis. Sedimentary Geol 167: 309-355
Weishampel DB, Barrett PM, Coria RA, Le Loeuff J, Xing X, Xijin Z, Sahni A, Gomani EM, Noto CR (2004) Dinosaur distribution. In: Weishampel DB, Dodson P, Osmólska H (eds) The Dinosauria, Second Edition. University of California Press, Berkeley, pp 517-606
Wible JR (2008) On the cranial osteology of the Hispaniolan solenodon, Solenodon paradoxus Brandt, 1833 (Mammalia, Lipotyphla, Solenodontidae). Ann Carnegie Mus 77: 321-402
Wible JR, Novacek MJ, Rougier GW (2004) New data on the skull and dentition of the Mongolian Late Cretaceous eutherian mammal Zalambdalestes. Bull Am Mus Nat Hist 281: 1-144
Wible JR, Rougier GW, Novacek MJ, Asher RJ (2009) The eutherian mammal Maelestes gobiensis from the Late Cretaceous of Mongolia and the phylogeny of Cretaceous Eutheria. Bull Am Mus Nat Hist 327: 1-123
Wilkinson M (1995) Coping with abundant missing entries in phylogenetic inference using parsimony. Syst Biol 44: 501-514
Zeller U (1989) Die Entwicklung und Morphologie des Schädels von Ornithorhynchus anatinus (Mammalia: Prototheria: Monotremata). Abh Senckenberg Nat Ges 545: 1-188
Acknowledgements
We would like to thank Richard Stucky (Denver Museum of Nature and Science) for access to the docodont material central to this study. Michael Eisenback assisted with imaging, and Jade Bilyeu assisted with illustrations (both University of Louisville). Zhe-Xi Luo and an anonymous reviewer provided helpful comments on the manuscript. This study was supported by NSF grants DEB 0946430 and DEB 1068089 to GWR.
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Rougier, G.W., Sheth, A.S., Carpenter, K. et al. A New Species of Docodon (Mammaliaformes: Docodonta) from the Upper Jurassic Morrison Formation and a Reassessment of Selected Craniodental Characters in Basal Mammaliaforms. J Mammal Evol 22, 1–16 (2015). https://doi.org/10.1007/s10914-014-9263-8
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DOI: https://doi.org/10.1007/s10914-014-9263-8