First evidence for tooth-tooth occlusion in a ctenochasmatid pterosaur from the Early Cretaceous Jehol Biota

Ctenochasmatid pterosaurs flourished and diversified in the Early Cretaceous Jehol Biota. Here, a partial mandible of Forfexopterus is described based on a three-dimensional reconstruction using high-resolution X-ray Computed Tomography (CT) data. The first nine pairs of functional teeth of the rostral dentition revealed along with their replacements. The functional teeth are evenly arranged with a tooth density of 2.2 teeth/cm. The tooth crown is distinctly reduced from its base to the tip, and framed by two weak ridges, possibly as a pair of vestigial carinae. The replacement teeth are sharp and pointed, and have erupted slightly against the medial surface of the functional teeth. Surprisingly, tooth wear is observed in this specimen, the first record of tooth-tooth occlusion in ctenochasmatids. The wear facets exhibit high-angled lingual and lower-angled labial facets, implying a tooth-tooth occlusion in pterosaur clade. This discovery indicates that the Jehol ctenochasmatids possibly employed a more active feeding strategy than other filter-feeding pterosaurs (e.g. Ctenochasma, Pterodaustro, Gnathosaurus).Supplementary material at https://doi.org/10.6084/m9.figshare.c.5722060

Jehol fossils from the Jiaolai Basin of Shandong, North China: review and new perspectives

Starting in the early 1950s, paleontologists began to discover a wide range of Cretaceous terrestrial fossils in the Laiyang, Qingshan, and Wangshi groups of the Jiaolai Basin which resides in the eastern part of the Shandong Peninsula of northern China. Significant specimens from these deposits include various dinosaur eggs, footprints, and fossils including hadrosauroids, tyrannosaurids, and ankylosaurids. These expanded understanding of evolution, biodiversity, and paleoecology in East Asia. While many examples of the Jehol Biota from this area are not well constrained in terms of their stratigraphy and geochronology, previous studies have generally suggested that fossils from this region represent the second or third phase of Jehol Biota development. This paper reviews fossils, stratigraphic correlations, tectonic history, and age estimates for the less well-studied outcrops of the Shandong Peninsula that host Jehol Biota. We report three new 40Ar/39Ar ages for the Qingshang Group and discuss how these somewhat imprecise ages still constrain chronostratigraphic interpretation for the fossil-rich units.

True hopper fossils (Fulgoromorpha and Cicadomorpha) in the Jurassic to Cretaceous of eastern Asia and their evolutionary implications

True hoppers, consisting of Fulgoromorpha and Cicadomorpha, are plant feeders with very high species-level diversity. A large amount of true hopper fossils have been reported from eastern Asia, especially from the Middle to Late Jurassic Yanliao Biota, the Early Cretaceous Jehol Biota and mid-Cretaceous Kachin amber in the last two decades. Herein, true hoppers from the Jurassic and Cretaceous of eastern Asia are reviewed, and combining palaeontological data from other regions of the world and recent advances of molecular studies, the evolutionary history of true hoppers in the mid-late Mesozoic is discussed. Permocicada beipiaoensis Wang, 1987 and Archijassus plurinervis Zhang, 1985 are here excluded from Prosboloidea and Archijassidae respectively. To the end of 2020, a total of 203 species with definite systematic position have been documented in the Jurassic and Cretaceous of eastern Asia (China, Myanmar, Siberia, Mongolia, Japan and Korea), and were attributed to 116 genera in 22 families and 7 superfamilies. Available fossil data suggest that true hopper components strongly changed in the Cretaceous: primitive groups reduced and went extinct successively, and the origin and/or early diversification of most lineages (family or subfamily level) occurred, likely owing to the displacement of host-plants in the angiosperm floristic revolution.

Nuclear preservation in the cartilage of the Jehol dinosaur Caudipteryx

Previous findings on dinosaur cartilage material from the Late Cretaceous of Montana suggested that cartilage is a vertebrate tissue with unique characteristics that favor nuclear preservation. Here, we analyze additional dinosaur cartilage in Caudipteryx (STM4-3) from the Early Cretaceous Jehol biota of Northeast China. The cartilage fragment is highly diagenetically altered when observed in ground-sections but shows exquisite preservation after demineralization. It reveals transparent, alumino-silicified chondrocytes and brown, ironized chondrocytes. The histochemical stain Hematoxylin and Eosin (that stains the nucleus and cytoplasm in extant cells) was applied to both the demineralized cartilage of Caudipteryx and that of a chicken. The two specimens reacted identically, and one dinosaur chondrocyte revealed a nucleus with fossilized threads of chromatin. This is the second example of fossilized chromatin threads in a vertebrate material. These data show that some of the original nuclear biochemistry is preserved in this dinosaur cartilage material and further support the hypothesis that cartilage is very prone to nuclear fossilization and a perfect candidate to further understand DNA preservation in deep time.

Spatiotemporal evolution of the Jehol Biota: Responses to the North China craton destruction in the Early Cretaceous

The Early Cretaceous Jehol Biota is a terrestrial lagerstätte that contains exceptionally well-preserved fossils indicating the origin and early evolution of Mesozoic life, such as birds, dinosaurs, pterosaurs, mammals, insects, and flowering plants. New geochronologic studies have further constrained the ages of the fossil-bearing beds, and recent investigations on Early Cretaceous tectonic settings have provided much new information for understanding the spatiotemporal distribution of the biota and dispersal pattern of its members. Notably, the occurrence of the Jehol Biota coincides with the initial and peak stages of the North China craton destruction in the Early Cretaceous, and thus the biotic evolution is related to the North China craton destruction. However, it remains largely unknown how the tectonic activities impacted the development of the Jehol Biota in northeast China and other contemporaneous biotas in neighboring areas in East and Central Asia. It is proposed that the Early Cretaceous rift basins migrated eastward in the northern margin of the North China craton and the Great Xing’an Range, and the migration is regarded to have resulted from eastward retreat of the subducting paleo-Pacific plate. The diachronous development of the rift basins led to the lateral variations of stratigraphic sequences and depositional environments, which in turn influenced the spatiotemporal evolution of the Jehol Biota. This study represents an effort to explore the linkage between terrestrial biota evolution and regional tectonics and how plate tectonics constrained the evolution of a terrestrial biota through various surface geological processes.