Lycoptera

Abstract: The Late Mesozoic strata in the Daohugou area of Ningcheng,Inner Mongolia are well developed with rich fossils, which are composed of tuffaceous mudstones and siltstones and interbedded with volcanic rocks. Regionally, in the Xitaizi area are distributed Early Cretaceous beds of Yixian Formation, yielding rich fossils of Jehol Biota, such as Lycoptera davidi, Peipiaosteus pani, Yanosteus longidorsalis, Protopsephurus liui (fishes) and Confuciusornis sanctus (birds). In the Daohugou area, however, are distributed Middle—Late Jurassic strata of Tiaojishan Formation, yielding very rich fossils of Daohugou Biota, such as Jeholotriton paradoxus and Chunerpeton tianyiensis (salamanders), Jeholopterus ningchengensis and Pterorhynchus wellnhoferi (pterosaurs), Scansoriopteryx heilmanni and (?) Pedopenna daohugouensis (Maniraptora, theropods), Mesobaetis sibirica, Mesoneta antiqua, Rhipidoblattina (Canaliblatta) hebeiensis, Brunneus haifanggouensis, Palaeontinodes haifanggouensis and others (insects), Euestheria ziliujingensis, E. haifanggouensis, E. jingyuanensis and E. luanpingensis (conchostracans), Cladophlebis (Osmunda ?) sp., Anomozamites angulatus, A. (Trymia ?) sp., Cycadolepis sp., Ginkgoites sp., Pityospermus sp., Pityocladussp., Zamites gigas, Yanliaoia sinensis and Coniopteris burejensis (plants). According to our current study, Daohugou Biota is surely considered to be of an age of Middle—Late Jurassic (Callovian—Oxfordian), rather than Early Cretaceous.

Abstract: The Lower Cretaceous Sinuiju Series of the Jasong Supergroup (=Jasong System of Pak and Kim, 1996) developed in the Amnok River Basin, North Korea, has yielded a potentially important vertebrate fauna, the taxonomic components of which are closely similar to those of the Jehol Biota best known from the Yixian and Chiufotang (=Jiufotang) formations in western Liaoning province, China (Chang et al., 2003; Zhou et al., 2003). The fossil-bearing beds of the Sinuiju Series consist of lacustrine fine-grained sandstones, mudstones, tuffaceous shales and andesites with a total thickness of over 2500 meters (Pak and Kim, 1996). Stratigraphically, the Sinuiju Series rests unconformably on top of Paleo-proterozoic metamorphic rocks, and underlies the Cretaceous Taebo Supergroup and Palaeogene strata. The age of the Sinuiju Series was thought to be Late Jurassic (Pak and Kim, 1996), but the strata contain the characteristic Eosestheria-Ephemeropsis-Lycoptera complex of the Jehol Biota, supporting an Early Cretaceous age of the Series (see also Lee et al., 2001). Accordingly, the Sinuiju fauna signifies the geographic extension of the Jehol Biota from northeast China into the Korean Peninsula. Vertebrate fossils were found at a road-cut approximately six kilometers south of the city of Sinuiju (Figure 1). The fossil specimens already excavated from this site include Lycoptera and sturgeon fishes, anuran amphibians, several birds, possible theropod dinosaurs, and pterosaurs; none of these have been described in scientific publication, and the taxonomic status has remained uncertain ever since their discovery. Most of the fossils are preserved as dorso-ventral compressions as commonly seen in the Liaoning beds, but occur in dark shales that denote a slightly different depositional environment than the Yixian and Chiufotang formations in western Liaoning, China.

Abstract: Several specimens of a fossil fish recently collected from Cretaceous deposits near Changma, Gansu Province, China, are here described as a new genus and species of osteoglossomorph, Shuleichthys brachypteryx. This fish is a stem osteoglossomorph that cannot be included in either the Hiodontiformes or Osteoglossiformes without making either order polyphyletic. The fossils from the Changma locality are exceptionally well preserved, and allow many details of the anatomy of the new fish to be described, including the presence of a postpelvic bone, which was previously only known to be present in the living Hiodon. The relationships of the osteoglossomorph fishes are still not well resolved, and the addition of the new species to previous phylogenetic analyses causes even less resolution to be found. However, the new species appears to be more derived than Lycoptera and Paralycoptera, two other well-known stem osteoglossomorphs.

Abstract: Recent fieldwork has extended the distribution of the Daohugou Bed deposits from the Daohugou Village to its several neighboring areas. The fossil-bearing Daohugou deposits uncomformably overlie complex bedrocks, and comprise three major parts. The red shales in the lower part were misidentified as belonging to the Tuchengzi Formation. Field excavation has indicated that the shales of upper part of the bed are the major fossil-bearing horizon. Due to strong tectonic activities, sediments were often folded with the se- quences inverted in the region. Some newly recognized con- tacts between the Daohugou Bed and the volcanic rocks showed that the ignimbrite of the Tiaojishan Formation (159―164 Ma) underlies the Daohugou deposits, rather than overlying the latter as previously proposed. Thus, the age of the Daohugou deposits should be younger than the age of the ignimbrite, and thus it was incorrect to correlate the Dao- hugou Bed with the Middle Jurassic Jiulongshan Formation. Although biostratigraphic studies based on conchostracans and insects support a Middle Jurassic-early Late Jurassic age for the Daohugou deposits, vertebrate fossils such as Liaoxitriton, Jeholopterus and feathered maniraptorans show much resemblance to those of the Yixian Formation. In other words, despite the absence of Lycoptera, a typical fish of the Jehol Biota, the Daohugou vertebrate assemblage is closer to that of the Early Cretaceous Jehol Biota than to any other biota. We propose that the Daohugou fossil assemblage probably represents the earliest evolutionary stage of the Jehol Biota based on both vertebrate biostratigraphy and the sedimentological and volcanic features which suggest the Daohugou deposit belongs to the same cycle of volcanism and sedimentation as the Yixian Formation of the Jehol Group.