The evolution of tribospheny and the antiquity of mammalian clades

被引:168
作者
Woodburne, MO
Rich, TH
Springer, MS [1 ]
机构
[1] Univ Calif Riverside, Dept Earth Sci, Riverside, CA 92521 USA
[2] Victoria & Albert Museum, Melbourne, Vic 3000, Australia
[3] Monash Univ, Sch Geosci, Monash, VC 3800, Australia
[4] Univ Calif Riverside, Dept Biol, Riverside, CA 92521 USA
关键词
D O I
10.1016/S1055-7903(03)00113-1
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The evolution of tribosphenic molars is a key innovation in the history of Mammalia. Tribospheny allows for both shearing and grinding occlusal functions. Marsupials and placentals are advanced tribosphenic mammals (i.e., Theria) that show additional modifications of the tribosphenic dentition including loss of the distal metacristid and development of double-rank postvallum/ prevallid shear. The recent discovery of Eomaia [Nature 416 (2002) 816], regarded as the oldest eutherian mammal, implies that the marsupial-placental split is at least 125 million years old. The conventional scenario for the evolution of tribosphenic and therian mammals hypothesizes that each group evolved once, in the northern hemisphere, and is based on a predominantly Laurasian fossil record. With the recent discovery of the oldest tribosphenic mammal (Ambondro) from the Mesozoic of Gondwana, Flynn et al. [Nature 401 (1999) 57] suggested that tribospheny evolved in Gondwana rather than in Laurasia. Luo et al. [Nature 409 (2001) 53; Acta Palaeontol. Pol. 47 (2002) 1] argued for independent origins of tribospheny in northern (Boreosphenida) and southern (Australosphenida) hemisphere clades, with the latter including Ambondro, ausktribosphenids, and monotremes. Here, we present cladistic evidence for a single origin of tribosphenic molars. Further, Ambondro may be a stem eutherian, making the split between marsupials and placentals at least 167 m.y. old. To test this hypothesis, we used the relaxed molecular clock approach of Thorne/ Kishino with amino acid data sets for BRCA1 [J. Mammal. Evol. 8 (2001) 239] and the IGF2 receptor [Mammal. Genome 12 (2001) 513]. Point estimates for the marsupial-placental split were 182-190 million years based on BRCA1 and 185-187 million years based on the IGF2 receptor. These estimates are fully compatible with the results of our cladistic analyses. (C) 2003 Elsevier Science (USA). All rights reserved.
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页码:360 / 385
页数:26
相关论文
共 86 条
[1]  
AMRINEMADSEN H, 2003, IN PRESS MOL PHYLOGE
[2]  
[Anonymous], 1999, TREEROT VERSION 2
[3]   1ST MESOZOIC MAMMAL FROM AUSTRALIA - AN EARLY CRETACEOUS MONOTREME [J].
ARCHER, M ;
FLANNERY, TF ;
RITCHIE, A ;
MOLNAR, RE .
NATURE, 1985, 318 (6044) :363-366
[4]  
Archer M., 1993, PLATYPUS ECHIDNAS, P15
[5]  
ARCHER M, 1992, MAMMALIAN PHYLOGENY, V1, P75
[6]   Quantitative analysis of the timing of the origin and diversification of extant placental orders [J].
Archibald J.D. ;
Deutschman D.H. .
Journal of Mammalian Evolution, 2001, 8 (2) :107-124
[7]  
ARCHIBALD JD, 2003, IN PRESS MOL PHYLOGE
[8]   A new Eocene archaeocete (Mammalia, Cetacea) from India and the time of origin of whales [J].
Bajpai, S ;
Gingerich, PD .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1998, 95 (26) :15464-15468
[9]  
BENTON M.J., 1993, The Fossil Record
[10]  
Bonaparte J.F., 1987, 4 C LAT PAL BOL, V1, P343