The imagery on this page is the basis for a paper entitled The Oldest Platypus and its Bearing on Divergence Timing of the Platypus and Echidna Clades, by T. Rowe, T.H. Rich, P. Vickers-Rich, M. Springer and M.O. Woodburne (Proceedings of the National Academy of Sciences 105:1238-1242, 2008). The abstract is as follows:

       Monotremes have left a poor fossil record, and paleontology has been virtually mute during two        decades of discussion about molecular clock estimates of the timing of divergence between the        platypus and echidna clades. We describe new evidence from high-resolution X-ray computed        tomography indicating that Teinolophos, an Early Cretaceous fossil from Australia’s Flat Rocks locality        (121-112.5 Ma), lies within the crown clade Monotremata, as a basal platypus. Strict molecular clock        estimates of the divergence between platypus and echidnas range from 17-80 Ma, but Teinolophos        suggests that the two monotreme clades were already distinct in the Early Cretaceous, and that their        divergence may predate even the oldest strict molecular estimates by at least 50%. We generated        relaxed molecular clock models using three different datasets, but only one yielded a date        overlapping with the age of Teinolophos. Morphology suggests that Teinolophos is a platypus in both        phylogenetic and ecological aspects, and tends to contradict the popular view of rapid Cenozoic        monotreme diversification. Whereas the monotreme fossil record is still sparse and open to        interpretation, the new data are consistent with much slower ecological, morphological, and        taxonomic diversification rates for monotremes than in their sister taxon, the therian mammals. This        alternative view of a deep geological history for monotremes suggests that rate heterogeneities may        have affected mammalian evolution in such a way as to defeat strict molecular clock models and to        challenge even relaxed molecular clock models when applied to mammalian history at a deep temporal        scale.

This specimen, a right dentary, was collected from the Wonthaggi Formation, Bunarong Marine Park, Victoria, Australia. It was made available to The University of Texas High-Resolution X-ray CT Facility for scanning by Dr. Thomas Rich of Museum Victoria. Funding for scanning and image processing was provided by a National Science Foundation Digital Libraries Initiative grant to Dr. Timothy Rowe of The University of Texas at Austin.

This specimen was scanned by Matthew Colbert on 10 October 2005 along the coronal axis for a total of 1122 slices. Each 1024x1024 pixel slice is 0.012 mm thick, with an interslice spacing of 0.012 mm and a field of reconstruction of 11.84 mm.

Literature

Archer M, Flannery TF, Ritchie A, Molnar RE (1985) Nature 318:363-366.
Augee ML, Gooden BA (1992) in Platypus and Echidna, ed Augee ML (Roy Zool Soc New South Wales,    Sydney), pp. 211-215.
Belov K, Hellman L (2003) Austral Mammal 25:87-94.
Bech C, Nicol S, Andersen NA (1992) in Platypus and Echidna, ed Augee ML (Roy Zool Soc New South Wales,    Sydney) pp. 134-139.
Bever GS, Rowe T, Ekdale EG, Macrini TE, Colbert MW, Balanoff AM (2005) Science 309:1492a.
Bininda-Emonds ORP, Cardillo M, Jones KE, MacPhee RDE, Beck RMD, Grenyer R, Price SA, Rutger AV,    Gittleman JL, Purvis A (2007) Nature 446:507-512.
Bohringer RC (1992) in Platypus and Echidna, ed Augee ML (Roy Zool Soc New South Wales, Sydney), pp.    194-203.
Burrell H (1927) The Platypus (Angus & Robertson Ltd, Sydney).
Cao Y, Janke A, Waddell PJ, Westerman M, Takenaka O, Murata S, Okada N, Pääbo S, Hasegawa M (1998)    J Mol Evol 47:307-322.
Carlson WD, Rowe T, Ketcham RA, Colbert MW, (2003) in Applications of X-ray Computed Tomography in the    Geosciences, eds. Mees F, Swennen R, Van Geet M, Jacobs P, (Geol Soc London 215) pp. 7-22.
Clemens WA, Richardson BJ, Baverstock PR (1989) in Faunas of Australia: Biogeography and Phylogeny of the    Metatheria, eds Walton DW, Richardson BJ, (Austr Gov Publ Serv, Canberra), pp. 527-548.
Flannery T, Archer M, Rich T. H, Jones R (1995) Nature 377:418-420.
Gemmell NJ, Westerman MJ (1994) J Mamm Evol 2:3-23.
Gregory WK (1910) Bull Amer Mus Nat Hist 27:1-524.
Gregory WK (1947) Bull Amer Mus Nat Hist 88:1-52.
Grützner F, Deakin J, Rens W, El-Mogharbel N, Graves JAM (2003) Comp Biochem Physiol A 136:867-881.
Hope RM, Cooper S, Wainwright B, (1989) Austral J Zool 37:289-313.
Hopson JA, Crompton AW (1969) Evol Biol 3:15-72.
Iggo A, Gregory JE, Proske U (1992) J Physiol 447:449-465.
Janke A, Xu X, Arnason U (1997) Proc Natl Acad Sci USA 94:1276-1281.
Janke A, Magnell O, Wieczorek G, Westerman M, Arnason U, (2002) J Mol Evol 54:71-80.
Ji Q, Luo Z-X, Yuan C-X, Wible JR, Zhang JP, Georgi JA (2002) Nature 416:816-822.
Ji Q, Luo Z-X, Yuan C-X, Tabrum AR (2006) Science 311:1123-1127.
Kermack KA, Kielan-Jaworowska Z (1971) in Early Mammals, eds Kermack DM, Kermack KA, (Zool J Linn Soc,    vol 50 suppl 1) pp. 103-115.
Kielan-Jaworowska Z, Cifelli RL, Luo Z-X (2004) Mammals from the Age of Dinosaurs (Columbia University    Press, New York).
Kishino H, Thorne JL, Bruno WJ (2001) Mol Biol Evol 18:352-361.
Kirsch JAW, Mayer GC (1998) Phil Trans Roy Soc B, 353:1221-1237.
Kumanzawa Y, Nishida M (1999) Mol Biol Evol 16:784-792.
Luo Z-X, Wible J (2005) Science 308:103-107.
Luo Z-X, Cifelli RL, Kielan-Jaworowska Z (2001) Nature 409:53-56.
Luo Z-X, Cifelli RL, Kielan-Jaworowska Z (2002) Acta Palaeont Polon 47:1-78.
Luo Z-X, Crompton AW, Sun A-L (2003) Science 292:1535-1540.
Macrini TE, Rowe T, Archer M (2006) J Morph 267:1000-1015.
Manger PR, Pewttigrew JD (1996) Brain Behav Evol 48:27-54.
Martin T, Luo Z-X (2005) Science 307:861-862.
McKenna MC, Bell SO (1997) Classification of Mammals Above the Species Level (Columbia University Press,    New York).
Meng J, Hu Y, Wang Y, Wang X, Li C (2006) Nature 444:889-893.
Messer M, Weiss A, Shaw D, Westerman M (1998) J Mamm Evol 5:95-105.
Müller J, Reisz RR (2005) BioEssays 27:1069-1075.
Murphy WJ, et al. (2001) Science 294:2348-2351.
Musser AM (2003) Comp Biochem Physiol 136:927-942.
Nilsson MA, Arnason U, Spencer PB, Janke A (2004) Gene 340:189-196.
Nowak MA, Parra ZE, Hellman L, Miller RD (2004) Immunogen 56:555-563.
Pascual R, Archer M, Jaureguizar EO (1992) in Platypus and Echidna, ed Augee ML (Roy Zool Soc New South    Wales, Sydney), pp. 1-14.
Pascual, R, Archer M, Jaureguizar EO, Prado JL, Godthelp H, and Hand SJ (1992) in Platypus and Echidna,    eds Augee ML, (Roy Zool Soc New South Wales, Sydney), pp. 1-14.
Penny D, Hasegawa M (1997) Nature 387:549-550.
Penny D, Hasegawa M, Wadell PJ, Hendy MD (1999) Syst Biol 48:76-93.
Pettigrew JD (1999) J Exp Biol 202:1447-1454.
Phillips MJ, Penny D (2003) Mol Phylo Evol 28:171-185.
Pridmore PA, Rich TH, Vickers-Rich P, Gambaryan P (2005) J Mamm Evol 12:359-378.
Proske U, Gregory JE, Iggo A (1992) in Platypus and Echidna, ed Augee ML (Roy Zool Soc New South Wales,    Sydney), pp. 204-210.
Rauhut OWM., Martin T, Ortiz-Jaureguizar E, Puerta P (2002) Nature 416:165-168.
Reisz RR., Müller J (2004) Trends Genetics 20:237-241.
Retief JD, Winkfein RJ, Dixon GH (1993) Euro J Biochem 218:457-461.
Reyes A, Gissi C, Catzeflis F, Nevo E, Pesole G, Sacconell C (2004) Mol Biol Evol 21:397-403.
Rich TH, Vickers-Rich P, Constantine A, Flannery TF, Kool L, van Klaveren N (1999) Rec Queen Victoria Mus    106:1-29.
Rich TH, Vickers-Rich P, Trusler P, Flannery TF, Cifelli R, Constantine A, Kool L, van Klaveren N (2001) Acta    Palaeont Polon 46:113-118.
Rich TH, Flannery TF, Trusler P, Kool L, van Klaveren NA, Vickers-Rich (2002) J Vert Paleo 22:466-469.
Rich TH, Hopson JA, Musser AM, Flannery TF, Vickers-Rich P (2005) Science 307:910-914.
Rougier GW, Wible JR, Hopson JA (1996) Amer Mus Novitates 3138:1-38.
Rougier GW, Forasiepi AM, Martinelli AG (2005) Science 309:1492.
Rowe MJ, Bohringer RC (1992) in Platypus and Echidna, ed Augee ML (Roy Zool Soc New South Wales,    Sydney) pp. 177-193.
Rowe T (1988) J Vert Paleo 8:241-264.
Rowe T (1996) Science 273:651-654.
Rowe T (1996) in New Perspectives on the History of Life, eds Ghiselin M, Pinna G (Calif. Acad. Sci. Memoir    20) pp. 71-96.
Rowe T (1993) in Mammalian Phylogeny, eds Szalay FS, Novacek MJ, McKenna MC (Springer-Verlag, New    York,) pp. 129-145.
Rowe T, Kappelman J, Carlson WD, Ketcham R A, Denison C (1997) Geotimes 42:23-27.
Taylor NG, Manger PR, Pettigrew JD, Hall LS (1992) in Platypus and Echidna, ed Augee ML (Roy Zool Soc    New South Wales, Sydney), pp. 216-224.
Thorne JL, Kishino H (2002) Syst Biol 51:689-702.
Thorne JL, Kishino H, Painter IS (1998) Mol Biol Evol 15:1647-1657.
Toyosawa S, O’hUigin C, Figueroa F, Tichy H, Klein J (1998) Proc Natl Acad Sci USA 95:13056-13061.
van Rheede T, Bastiaans T, Boone DN, Hedges SB, de Jong WW, Madsen O (2006) Mol Biol Evol 23:587-597.
Vernesson M, Aveskogh M, Munday B, Hellman L (2002) Eur J Immunol 32:2145-2155.
Westerman M, Edwards D (1992) in platypus and echidna, eds Augee ML, (Roy Zool Soc New South Wales,    Sydney), pp. 28-34.
Wilson DE, Reeder DM, eds (2005) Mammal Species of the World (Johns Hopkins University Press, Baltimore).
Woodburne MO (2003) J Mamm Evol 10:195-248.
Woodburne MO, Tedford RH, (1975) Amer Mus Novitates 2588:1-11.
Woodburne MO, Macfadden BJ, Case JA, Springer MS, Pledge NS, Power JD (1993) J Vert Paleo 13:483-515.
Woodburne MO, Tedford RH, Archer A, Turnbull WD, Plane MD, Lundelius EL (1985) Spec Pub S Austral Dept    Mines Energy 5:347-363.
Woodburne MO, Rich TH, Springer MS (2003) Mol Phylo Evol 28:360-385.
Zardoya R, Meyer A, (1998) Proc Natl Acad Sci USA 95:14226-14231.
Zeller U (1989) U Abh Senckenberg Naturforsch Gesell 545:1-188.

None available.