caa a22 4500 445326158 CHVBK 20180317142721.0 cr unu---uuuuu 170323e20111201xx s 000 0 eng 10.1007/s10914-011-9168-8 doi (NATIONALLICENCE)springer-10.1007/s10914-011-9168-8 Davis Brian Sam Noble Oklahoma Museum of Natural History and Department of Zoology, University of Oklahoma, 2401 Chautauqua Ave., 73072, Norman, OK, USA aut Evolution of the Tribosphenic Molar Pattern in Early Mammals, with Comments on the "Dual-Origin” Hypothesis [Elektronische Daten] [Brian Davis] Development of the tribosphenic molar was a fundamental event that likely influenced the rise of modern mammals. This multi-functional complex combined shearing and grinding in a single chewing stroke, and provided the base morphology for the later evolution of the myriad dental morphologies employed by mammals today. Here a series of morphotypes are presented that represent stepwise acquisition of characters of the molar crown, in an effort to clarify homologies and functional analogies among molars of tribosphenic and tribosphenic-like mammals, as well as their putative sister groups. This is accomplished by evaluation of wear features, which provide direct evidence of occlusal function, and mapping these features on molars of the various morphotypes demonstrates their utility in determining homology. The original singular lower molar talonid cusp is homologous with the hypoconid, and upper molar cusp C in early mammals is homologous with the metacone (cusp "C” is a neomorph with variable occurrence). The lingual translation of the metacone to a position more directly distal to the paracone (as in Peramus) creates an embrasure for the lower molar hypoconid, and is accompanied by the development of the hypoconulid and a new shearing surface. Lastly, the Gondwanan radiation of tribosphenic-like mammals, the Australosphenida (including monotremes), is determined to be functionally non-tribosphenic. The Tribosphenida are restricted to Laurasian taxa, with an origin at or just prior to the Jurassic-Cretaceous boundary. Springer Science+Business Media, LLC, 2011 Mammalia nationallicence Tribosphenida nationallicence Australosphenida nationallicence Mesozoic nationallicence Molar occlusion nationallicence Homology nationallicence Journal of Mammalian Evolution Springer US; http://www.springer-ny.com 18/4(2011-12-01), 227-244 1064-7554 18:4<227 2011 18 10914 https://doi.org/10.1007/s10914-011-9168-8 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10914-011-9168-8 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Davis Brian Sam Noble Oklahoma Museum of Natural History and Department of Zoology, University of Oklahoma, 2401 Chautauqua Ave., 73072, Norman, OK, USA aut NATIONALLICENCE 773 0- Journal of Mammalian Evolution Springer US; http://www.springer-ny.com 18/4(2011-12-01), 227-244 1064-7554 18:4<227 2011 18 10914 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer