Modern birds are completely toothless, yet the vast majority of their ancestors possessed teeth. As a result, the evolutionary transition from toothed jaws to edentulous beaks is often regarded as one of the most representative examples of trait loss in evolution. However, tooth evolution in Mesozoic birds was far more diverse than is often appreciated. Different groups varied considerably in the number of teeth on the premaxilla, maxilla, and dentary. Some species were compl

During the Early Cretaceous, numerous exceptionally preserved fossil localities formed around the world. In addition to skeletal remains, these deposits preserve soft tissues such as skin and muscles, providing valuable evidence for reconstructing the appearance and ecology of ancient organisms. However, most exceptionally preserved fossil sites are located in temperate or subtropical regions. Comparable records from low-latitude regions, particularly northern South America,

Sexual selection has long been regarded as one of the major drivers of evolution alongside natural selection. It primarily influences differences in morphology and behavior among species and has contributed to the remarkable diversity of biological forms. Ornamental structures found in males or females are generally considered products of sexual selection. However, sexual selection does not act independently; it often interacts with natural selection, together shaping the for

Modern non-mammalian amniotes, such as reptiles and birds, have relatively limited kidney function. As a result, species living in high-salinity environments have evolved salt glands that remove excess salt from the body. These glands can occur in different parts of the head, including the nasal cavity, orbit, and oral cavity. Sea turtles excrete excess salt through their salt glands, making them appear to be crying.（Image source：Matthias Scholz， CC BY 2.5 。） In some birds an

Most Ediacaran animals had soft bodies and lacked hard skeletons, which means that their preservation as fossils was already an unusual event. For this reason, any well-preserved fossil community of the Ediacara Biota represents a major discovery. In the lower Blueflower Formation near Sekwi Brook in the Mackenzie Mountains of the Northwest Territories, Canada, researchers have identified an Ediacaran fossil community belonging to the White Sea assemblage. Here, "assemblage"

The fossil record has long preserved a puzzling gap. The Ediacaran Period contains an array of strange organisms unlike most animals alive today, whereas the Cambrian Period suddenly reveals many forms that seem much closer to the ancestral members of modern animal groups. How these two worlds were connected has remained difficult to resolve, largely because clear body-fossil evidence from this critical interval has been scarce. The Jiangchuan Biota of eastern Yunnan, China,

In the deep sea floor of the southeastern Indian Ocean, the Diamantina Zone lies off southwestern Australia, extending for about 1,200 km along the seabed at depths ranging from 4,616 to 7,001 m. Its deepest area is close to the Dordrecht Deep in the northwestern section. In 2023, after a research team explored this region aboard the human-occupied vehicle Fendouzhe, they discovered that this stretch of sea floor preserves a remarkable deep-sea whale necropolis. Location of t

In many shallow marine environments today, the upper layers of the seafloor are shaped by the burrowing, feeding, and movement of worms, crustaceans, mollusks, and other benthic animals. These activities produce a constantly disturbed layer of surficial sediment. Before the Cambrian, however, many shallow marine seafloors were dominated by microbial mats. These layered microbial communities acted like a living net spread across the sediment surface. Microbial filaments bound

Mesozoic mammals are often imagined as small, nocturnal animals living in the shadows, doing their best to avoid becoming food for large reptiles. That picture is not without fossil support: small mammalian remains have previously been found in the gut contents of dinosaur fossils. Yet one fossil from west of Lujiatun Village, Beipiao City, Liaoning Province, China, captures a very different moment: a Psittacosaurus lujiatunensis and a Repenomamus robustus entangled with one

In modern birds, feathers are highly specialized and complex structures. In addition to providing the aerodynamic surfaces required for flight, feathers are involved in insulation, waterproofing, camouflage, courtship displays, nest building, incubation, and sensing external stimuli. It can be said that feathers are an indispensable part of birds. For a long time, scientists generally regarded feathers as a unique characteristic of birds and even considered them one of the de