Donglei Chen

• Doctor of Philosophy
• Researcher at Uppsala University

The teeth of gnathostomes (jawed vertebrates) show rigidly patterned, unidirectional replacement that may or may not be associated with a shedding mechanism. These mechanisms, which are critical for the maintenance of the dentition, are incongruently distributed among extant gnathostomes. Although a permanent tooth-generating dental lamina is prese...

Teeth and jaws The first vertebrates were jawless, much like a modern hagfish. There has been a lot of interest in how these forms transitioned to having jaws like most of their descendants, including humans. Much of our understanding of this process has focused on how the teeth are replaced relative to the jaw. Previous theories suggested that too...

Bone is an evolutionary novelty of vertebrates, likely to have first emerged as part of ancestral dermal armor that consisted of osteogenic and odontogenic components. Whether these early vertebrate structures arose from mesoderm or neural crest cells has been a matter of considerable debate. To examine the developmental origin of the bony part of...

The ontogenetic trajectory of a marginal jawbone of Lophosteus superbus (Late Silurian, 422 Million years old), the phylogenetically most basal stem osteichthyan, visualized by synchrotron microtomography, reveals a developmental relationship between teeth and dermal odontodes that is not evident from the adult morphology. The earliest odontodes ar...

The numerous cushion-shaped tooth-bearing plates attributed to the stem group osteichthyan Lophosteus superbus, which are argued here to represent an early form of the osteichthyan inner dental arcade, display a previously unknown and presumably primitive mode of tooth shedding by basal hard tissue resorption. They carry regularly spaced, recumbent...

New teeth are predominantly initiated lingually or postero-lingually to the old teeth in vertebrates. Osteichthyan dentitions typically consist of linear rows of shedding teeth, but internal to the marginal jawbones osteichthyans primitively have an extra dental arcade, in which teeth are sometimes spread out into a field and not organized in rows....

Computed tomography has revolutionised the study of the internal three-dimensional structure of fossils. Historically, fossils typically spent years in preparation to be freed from the enclosing rock. Now, X-ray and synchrotron tomography reveal structures that are otherwise invisible, and data acquisition can be fast. However, manual segmentation...

Computed tomography has revolutionised the study of the internal three-dimensional structure of fossils. Historically, fossils typically spent years in preparation to be freed from the enclosing rock. Now, X-ray and synchrotron tomography reveal structures that are otherwise invisible, and data acquisition can be fast. However, manual segmentation...

Computed tomography has revolutionised the study of the internal three-dimensional structure of fossils. Historically, fossils typically spent years in preparation to be freed from the enclosing rock. Now, X-ray and synchrotron tomography reveal structure that is otherwise invisible and data acquisition can be fast. However, manual segmentation of...

n-situ tooth replacement is a major innovation of osteichthyans, but how it evolved remains elusive. Classic models have attempted to analyze the regulation of the alternate tooth replacement relying on untested assumptions. The idealized models, however, cannot explain the large number of deviations of normal and abnormal dental development in the...

Ontogenetic data obtained by synchrotron microtomography of a marginal jawbone of Lophosteus superbus (Late Silurian, 422 Million years old), the phylogenetically basalmost stem osteichthyan, reveal developmental relationships between teeth and ornament that are not obvious from the adult morphology. The earliest odontodes are two longitudinal foun...

The first half of the Mississippian or Early Carboniferous (Tournaisian to mid- Viséan), an interval of about 20 million years, has become known as “Romer's Gap” because of its poor tetrapod record. Recent discoveries emphasise the differences between pre-“Gap” Devonian tetrapods, unambiguous stem-group members retaining numerous “fish” characters...

The origin of osteichthyans (bony fishes and tetrapods) dates back to the Late Silurian, but the early evolution of the group is poorly understood. Andreolepis is one of the oldest known osteichthyans, but exclusively documented by detached and fragmentary dermal microremains. A large data-set of Andreolepis scales from the Silurian of Gotland has...

Sebastiscus marmoratus larvae were exposed to waterborne polycyclic aromatic hydrocarbons (PAHs) containing 3-5 rings, benzo[a]pyrene (BaP), pyrene (Py) or phenanthrene (Phe), respectively at 0.01, 0.1 and 1 μg L⁻¹. Cumulative mortality, frequency of dorsal curvature and rate of pericardial and yolk sac edema in larvae treated for 8 days were signi...

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants, which have been known to be carcinogenic and teratogenic. However, the skeletal development toxicity of PAHs and the mechanism involved remain unclear. In fishes, the neurocranial and craniofacial skeleton develop as cartilage. The signaling molecules of hedgehog (Hh...