A comparison of Barremian–early Aptian vertebrate assemblages from the Jehol Group, north-east China and the Wealden Group, southern Britain: the value of microvertebrate studies in adverse preservational settings
Vertebrates are a highly significant component of the Jehol Biota of northern Hebei, western Liaoning, and southeastern Inner Mongolia. Furthermore, Jehol vertebrate fossils from these areas are remarkable for their abundance and diversity, and for their taphonomy which has resulted in the preservation of large numbers of complete skeletons and of soft tissues including the feathers of birds and nonavian dinosaurs. In contrast, and also for taphonomic reasons, skeletons are extremely rare in the approximately coeval (Barremian–earliest Aptian) Lower Cretaceous Wealden Group of the Isle of Wight, southern England, UK. However, collection of isolated macro-remains over a period of almost 200 years has demonstrated that the Wealden Group, and in particular the Barremian Wessex Formation, contains Europe’s most diverse dinosaur assemblage. This assemblage, until the relatively recent discovery of China’s feathered nonavian dinosaurs and birds, appeared to be of comparable diversity to that of the Jehol Biota. Isolation of microvertebrate remains in an ongoing study commenced in 2002 has demonstrated that not only is the Wealden Group dinosaur assemblage more diverse than apparent from macro-remains and that it includes birds but also that it includes a high diversity of other aquatic, amphibious and terrestrial vertebrates. It is, therefore, now possible to make meaningful comparisons between the Jehol Biota and that of the Wealden Group of the Isle of Wight. Similarities and marked differences are apparent that reflect geographical separation, palaeoenvironmental factors and the remarkably small outcrop area available for the Wealden Group.