International audienceSpinosaurs were large theropod dinosaurs showing peculiar specializations, including somewhat crocodile-like elongate jaws and conical teeth. Their biology has been much discussed, and a piscivorous diet has been suggested on the basis of,jaw as well as tooth morphology and stomach contents. Although fish eating has been considered plausible, an aquatic or semiaquatic lifestyle has seldom been suggested because of the apparent lack of corresponding adaptations in the postcranial skeleton of spinosaurs, which on the whole is reminiscent of that of other large terrestrial theropods. On the basis of the oxygen isotopic composition of their phosphatic remains compared with those of coexisting terrestrial theropod dinosaurs and semiaquatic crocodilians and turtles, we conclude that spinosaurs had semiaquatic lifestyles, i.e., they spent a large part of their daily time in water, like extant crocodilians or hippopotamuses. This result sheds light on niche partitioning between large predatory dinosaurs, since spinosaurs coexisted with other large theropods such as carcharodontosaurids or tyrannosaurids. The likely ichlhyophagy and aquatic habits of spinosaurids may, have allowed them to coexist with other large theropods by reducing competition for food and territory

Earth and Environmental Sciences, Burnaby Building, Burnaby Road, Portsmouth, PO1 3QL, UK; James D. Gardner [james.gardner@gov.ab.ca]

No abstract

A substantially complete skull of a small crocodyliform recently found on the foreshore near Yaverland on the south-east coast of the Isle of Wight

Bulk screening of Early Cretaceous (Barremian) Wealden Group strata of the Wessex Formation exposed on the south-west and south-east coasts of the Isle of Wight, southern England, has resulted in the recovery of fragmentary remains pertaining to a new spalacolestine spalacotheriid mammal, Yaverlestes gassoni gen. et sp. nov. These represent the first European record of the Spalacolestinae. The remains comprise a dentulous incomplete dentary and isolated upper and lower molariforms, the former representing the most substantial mammal remains yet recovered from the Wealden Group. Hitherto, six species of spalacotheriid mammal were known from the Lower Cretaceous of Europe. All are referred to the genus Spalacotherium but in the case of taxa diagnosed on the basis of isolated lower teeth and other specimens where the post-canine dentition is incompletely known, it is now evident that these referrals should be treated with caution. Furthermore, the new Wessex Formation spalacotheriid and recently described spalacotheriids from the ?Barremian of Japan, and the Barremian and Aptian of China exhibit combinations of characters that suggest that spalacotheriids were more diverse and that their evolution was more complex than previously recognized. The systematic position of an isolated tooth from the basal Cretaceous Lourinhã Formation of Portugal is discussed and the tooth reassigned to the Spalacotheriidae. Together with the new Wessex Formation taxon, eight species are now known from the Lower Cretaceous of Europe. The discovery of a spalacolestine in the Barremian Wessex Formation supports the concept of faunal interchange between Europe, Asia and North America during the Early Cretaceous. It also supports derivation of North American spalacotheriids from a European or Eurasian ancestor.Key words: Asia, Britain, Cretaceous, Europe, Mammalia, North America, Spalacolestinae, Spalacotheriidae.Following discoveries made in the nineteenth Century (e.g. Buckland 1829), the vertebrate macro-fauna of the Early Cretaceous (Barremian) Wessex Formation of the Isle of Wight, southern England, has received considerable attention. Despite the fragmentary nature of much of the material, the diverse fauna recovered from the Wessex Formation is without parallel elsewhere in Europe (e.g. Benton and Spencer 1995; Martill and Naish 2001, and references therein; Naish and Martill 2002; Hutt and Newbery 2004; Naish et al. 2004; Sweetman 2004; Steel et al. 2005) and is of international importance. In contrast, until recently the microvertebrate fauna was largely unknown despite efforts by a number of workers to investigate it (Butler and Ford 1975; Freeman 1975; Buffetaut and Ford 1979; Evans et al. 2004). The discovery of two multituberculate teeth in the Wessex Formation (Butler and Ford 1975) and the earlier discovery of mammal teeth in the Wealden of the Weald (Clemens 1963; Kermack et al. 1965; Clemens and Lees 1971; Gill 2004) indicated that a comprehensive search of Wessex Formation strata might yield more mammal...