Land mammal biostratigraphy and magnetostratigraphy of the Etadunna Formation (late Oligocene) of South Australia

Woodburne, Michael O.; MacFadden, Bruce J.; Case, Judd A.; Springer, Mark S.; Pledge, Nevile S.; Power, J. D.; Woodburne, Janice M.; Springer, Kathleen B.

doi:10.1080/02724634.1994.10011527

Cited by 144 publications

(145 citation statements)

References 14 publications

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“…The foramen innervating the dermal dorsal shield (the asterisk (*) of Zeller (1989a)) and the foramen for V 2 in Or. anatinus are larger than those of any other mammal, highlighting the extreme specialization of the platypus bill (Zeller 1988).…”

Section: (D) Foraminamentioning

confidence: 97%

“…Congeneric comparisons were made with late Oligocene (Woodburne et al 1993) Ob. insignis material from central Australia (QM F11627, left dentary fragment; SAM P18087, lower left molar (holotype)).…”

Section: Methodsmentioning

confidence: 99%

“…The Etadunna and Namba Formations (containing Ob. insignis) consist primarily of claystones and mudstones and some ¢ne-grained sandy lenses, evidence that the palaeoenvironments were dominated by £uvio-lacustrine conditions (Woodburne et al 1993), probably surrounded by cool, scrubby wet forest . The benthic substrate in these waters would probably have been silty, bordered by banks of semiconsolidated clay and mud.…”

Section: Relationships Within Monotrematamentioning

confidence: 99%

“…anatinus is proportionately larger than in any other mammal (Zeller 1988) Jollie (1962) posterior temporal canal Archer et al (1993) foramen mandibulare medium foramen mandibulare mediu Zeller (1989a) fossa mandibularis fossa mandibularis Zeller (1989a) rostrally through the maxilla carrying a large branch of V 2 (the superior alveolar nerve) to the bill in Or. anatinus, which branches at the maxillofacial foramen (Manger 1994).…”

Section: (I) Cranial Foraminamentioning

confidence: 99%

“…The elaboration of the electrical sense, however, may be a monotreme synapomorphy (Manger 1994). The trigeminal system, interestingly, is enlarged in some semi-aquatic placental mammals such as Micropotamogale to innervate the well-developed vibrissae important in underwater navigation (Stephan & Kuhn (1982), cited in Zeller (1988)). …”

Section: (D) Foraminamentioning

confidence: 99%

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New information about the skull and dentary of the Miocene platypusObdurodon dicksoni, and a discussion of ornithorhynchid relationships

Musser

Archer

1998

Phil. Trans. R. Soc. Lond. B

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A reconstruction of the skull, dentary and dentition of the middle Miocene ornithorhynchid Obdurodon dicksoni has been made possible by acquisition of nearly complete cranial and dental material. Access to new anatomical work on the living platypus, Ornithorhynchus anatinus, and the present comparative study of the cranial foramina of Ob. dicksoni and Or. anatinus have provided new insights into the evolution of the ornithorhynchid skull. The hypertrophied bill in Ob. dicksoni is seen here as possibly apomorphic, although evidence from ontogenetic studies of Or. anatinus suggests that the basic form of the bill in Ob. dicksoni (where the rostral crura meet at the midline) may be ancestral to the form of the bill in Or. anatinus (where the rostral crura meet at the midline in the embryonic platypus but diverge in the adult). Di¡erences in the relative positions of cranial structures, and in the relationships of certain cranial foramina, indicate that the cranium may have become secondarily shortened in Or. anatinus, possibly evolving from a more elongate skull type such as that of Ob. dicksoni. The plesiomorphic dentary of Ob. dicksoni, with well-developed coronoid and angular processes, contrasts with the dentary of Or. anatinus, in which the processes are almost vestigial, as well as with the dentary of the late Oligocene, congeneric Ob. insignis, in which the angular process appears to be reduced (the coronoid process is missing). In this regard the dentary of Ob. insignis seems to be morphologically closer to Or. anatinus than is the dentary of the younger Ob. dicksoni. Phylogenetic conclusions di¡er from previous analyses in viewing the northern Australian Ob. dicksoni as possibly derived in possessing a hypertrophied bill and dorsoventrally £attened skull and dentary, perhaps being a specialized branch of the Obdurodon line rather than ancestral to species of Ornithorhynchus. The presence of functional teeth and the robust, £attened skull and dentary in Ob. dicksoni argue for di¡erences in diet and lifestyle between this extinct ornithorhynchid and the living Ornithorhynchus.

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Section: (D) Foraminamentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Section: Relationships Within Monotrematamentioning

confidence: 99%

Section: (I) Cranial Foraminamentioning

confidence: 99%

Section: (D) Foraminamentioning

confidence: 99%

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