Eutherian (placental) mammals are the dominant group of modern mammals, with very good Cenozoic and reasonable complete Late Cretaceous fossil record. However, the earliest, Early Cretaceous history of this important group is still inadequately known. Until recently, the only undisputed Early Cretaceous eutherian was Prokennalestes Kielan-Jaworowska & Dashzeveg, 1989, represented by two species from the Aptian-Albian of Mongolia (see also Beliajeva et al. 1974 and Sigogneau-Russell et al. 1992). Recent discoveries both in North America (Cifelli 1999) and Asia (Averianov & Skutschas l999,2000a, b) demonstrate greater diversity of earliest eutherians, or their closest relatives, than previously recognized. We describe here a new taxon, Murtoilestes gen. n., from the Early Cretaceous of Siberia. Murtoilestes gen. n. presents an unusual combination of primitive and derived characters compared with Prokennalestes and North American Montanalestes Cifelli, 1999, which indicate that the early evolutionary history of eutherian mammals was complex and is poorly understood.

Alexander 0. Averianov [sasha@AA1923.spb.edu ] and Pavel P. Skutschas [skutchas@mail.ru ], Zoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, 199034 Saint Petersburg, Russia