New macronarian from the Middle Jurassic of Chongqing, China: phylogenetic and biogeographic implications for neosauropod dinosaur evolution.

Macronaria is a clade of gigantic body-sized sauropod dinosaurs widely distributed from the Late Jurassic to the Late Cretaceous globally. However, its origin, early diversification, and dispersal are still controversial. Here, we report a new macronarian Yuzhoulong qurenensis gen. et sp. nov. excavated from the Middle Jurassic (Bathonian) Lower Shaximiao Formation. Yuzhoulong qurenensis bears a unique combination of features, such as two accessory fossae that exist on the posterior surface of dorsal diapophyses of anterior dorsal vertebrae. Results of phylogenetic analyses demonstrate it is one of the earliest-diverging macronarians. This new material represents a Middle Jurassic fossil record of macronarian sauropod worldwide and improves the understanding of the early diversity and dispersal of the Neosauropoda. This discovery further supports that sauropods achieved a more rapid and varied morphological diversity and palaeogeographical dispersal in the Middle Jurassic.

The oldest complete jawed vertebrates from the early Silurian of China.

Molecular studies suggest that the origin of jawed vertebrates was no later than the Late Ordovician period (around 450 million years ago (Ma))1,2. Together with disarticulated micro-remains of putative chondrichthyans from the Ordovician and early Silurian period3-8, these analyses suggest an evolutionary proliferation of jawed vertebrates before, and immediately after, the end-Ordovician mass extinction. However, until now, the earliest complete fossils of jawed fishes for which a detailed reconstruction of their morphology was possible came from late Silurian assemblages (about 425 Ma)9-13. The dearth of articulated, whole-body fossils from before the late Silurian has long rendered the earliest history of jawed vertebrates obscure. Here we report a newly discovered Konservat-Lagerstätte, which is marked by the presence of diverse, well-preserved jawed fishes with complete bodies, from the early Silurian (Telychian age, around 436 Ma) of Chongqing, South China. The dominant species, a 'placoderm' or jawed stem gnathostome, which we name Xiushanosteus mirabilis gen. et sp. nov., combines characters from major placoderm subgroups14-17 and foreshadows the transformation of the skull roof pattern from the placoderm to the osteichthyan condition10. The chondrichthyan Shenacanthus vermiformis gen. et sp. nov. exhibits extensive thoracic armour plates that were previously unknown in this lineage, and include a large median dorsal plate as in placoderms14-16, combined with a conventional chondrichthyan bauplan18,19. Together, these species reveal a previously unseen diversification of jawed vertebrates in the early Silurian, and provide detailed insights into the whole-body morphology of the jawed vertebrates of this period.

A new Silurian fish close to the common ancestor of modern gnathostomes.

The Silurian Period occupies a pivotal stage in the unfolding of key evolutionary events, including the rise of jawed vertebrates.1-4 However, the understanding of this early diversification is often hampered by the patchy nature of the Silurian fossil record,5 with the articulated specimens of jawed vertebrates only known in isolated localities, most notably Qujing, Yunnan, China.6-9 Here, we report a new Silurian maxillate placoderm, Bianchengichthys micros, from the Ludlow of Chongqing, with a near-complete dermatoskeleton preserved in articulation. Although geographically separated, the new taxon resembles the previously reported Qilinyu in possessing a unique combination of dermatoskeletal characters. However, the dermal bone of the mandible in Bianchengichthys unexpectedly differs from those in both Qilinyu and Entelognathus and displays a broad oral lamina carrying a line of tooth-like denticles, in addition to the marginal toothless flange. The external morphology of the pectoral fin is preserved and reveals an extensively scale-covered lobate part, flanked by a fringe of lepidotrichia-like aligned scales. The phylogenetic analysis reveals that Bianchengichthys is positioned immediately below Entelognathus plus modern gnathostomes. The discovery significantly widens the distribution of Silurian placoderm-grade gnathostomes in South China and provides a range of morphological disparity for the outgroup comparison to the earliest evolution of jaws, dentitions, and pectoral fins in modern gnathostomes. We also demonstrate that the previously reported Silurian placoderms from central Vietnam10 are maxillate placoderms close to Qilinyu, Silurolepis, and Bianchengichthys, corroborating the paleogeographic proximity between the Indochina and South China blocks during the Middle Paleozoic.11.

A new genus of pliopithecoid from the late Early Miocene of China and its implications for understanding the paleozoogeography of the Pliopithecoidea.

A diversity of pliopithecoids is known from Miocene localities in Europe, but until recently, this group was relatively poorly represented in China. However, new discoveries have shown that Chinese pliopithecoids were taxonomically diverse and geographically widespread. The earliest pliopithecoids in China (and Eurasia) are Dionysopithecus and Platodontopithecus from the Early Miocene of Sihong, Jiangsu (∼19-18 Ma). During the Middle Miocene (∼15-12 Ma), several species of pliopithecoids are recorded at localities in Gansu Province (Laogou), Inner Mongolia (Damiao), Xinjiang Uygur Autonomous Region (Tieersihabahe), and Ningxia Hui Autonomous Region (Tongxin). Finally, a late-surviving anapithecine crouzeliid, Laccopithecus robustus, is known from the Late Miocene (∼7 Ma) of Shihuiba in Yunnan, which postdates the extinction of pliopithecoids in Europe (during MN 10). Paleontological investigations at a late Early Miocene locality near Fanchang in Anhui Province have yielded a large sample of isolated teeth (more than one hundred) of a previously unknown species of pliopithecoid. The associated micromammals indicate an age contemporaneous with the Shanwang Formation in Shandong Province (MN 3-4, ∼18-17 Ma). All of the permanent teeth are represented except for I2. With its unique suite of dental features, the Fanchang pliopithecoid can be attributed to a new species and genus. Shared derived features of the lower molars confirm that the Fanchang pliopithecoid has its closest affinities with European crouzeliids, but a number of primitive traits indicate that it is a stem member of the clade. The evidence points to China as an important center for the early diversification of pliopithecoids. Contrary to previous zoogeographic scenarios, the occurrence of an early crouzeliid in China implies that the Pliopithecidae and Crouzeliidae may have diverged from a stem pliopithecoid in Asia during the Early Miocene before their arrival in Europe.

N,S-self-doped carbon quantum dots from fungus fibers for sensing tetracyclines and for bioimaging cancer cells.

In this work, nitrogen and sulfur dual-doped carbon quantum dots (N,S-CDs) from naturally renewable biomaterial fungus fibers were prepared by a biosynthesis and hydrothermal method. The N,S-CDs displayed good water solubility, excellent stability, high quantum yield (QY = 28.11%) as well as remarkable features for fluorescence quenching-based detection and cellular imaging of cancer cells. It was worth mentioning that the heteroatoms doped carbon quantum dots made from the fungus fibers had a satisfactory QY and could be used as a selective, efficient, and sensitive fluorescent probe to determine tetracyclines by the synergistic effects of static quenching and internal filtration effect. The probe demonstrated a wide linear range and low detection limit. For tetracycline, the linear range was 0.5 µM to 47.6 µM, and the corresponding detection limit was 15.6 nM. Significantly, the test papers prepared by using N,S-CDs could detect tetracyclines in aquiculture wastewater rapidly. The produced N,S-CDs did not affect the cell viability and showed great promises for cellular imaging.