INTRODUCTION “Non-eutherian mammals” is obviously a paraphyletic grouping. Metatheria (Huxley, 1880: extant marsupials and their extinct relatives that fall outside of the extant crown group) and Eutheria (Gill, 1872: extant placentals and their extinct relatives that fall outside of the extant crown group) have long been considered to belong in the Theria (Parker and Haswell, 1897), exclusive of both the multituberculates and the monotremes (although see below for discussion of past and present notions of the “Marsupionta”, uniting marsupials and monotremes in a clade). MULTITUBERCULATA As discussed in Chapter 2, multituberculates have long been recognized as a distinctive group of mammals. Simpson (1945) ranked them as the subclass Allotheria (Marsh, 1880), one of three mammalian subclasses (the other two being Prototheria, or monotremes, and Theria). McKenna and Bell (1997), by comparison, recognized Allotheria as an infraclass within subclass Theriiformes; subclass Prototheria is retained, and subclass Theriiformes includes infraclasses Allotheria, Triconodonta, and Holotheria, the last including Theria as a supercohort (note that this classification differs from the one shown in Figure 1.2, below). Multituberculates are commonly known as “the rodents of the Mesozoic,” and it is probable that they filled a rodent-like niche as small omnivores and herbivores prior to the evolution of the rodents in the early Tertiary. The probable paleobiology of multituberculates, including possible reasons for their extinction, is discussed in Chapter 2, this volume. Multituberculates are usually considered as the order Multituberculata (Cope, 1884, originally proposed as a suborder of Marsupialia, now an order within the Allotheria).
|Title of host publication||Evolution of Tertiary Mammals of North America|
|Subtitle of host publication||Volume 2: Small Mammals, Xenarthrans, and Marine Mammals|
|Publisher||Cambridge University Press|
|Number of pages||12|
|State||Published - 1 Jan 2008|