For decades, many palaeontologists have regarded several small-bodied, gracile tyrannosaur-like specimens—such as CMNH 7541, BMRP 2002.4.1, and KUVP 156375—as juvenile individuals of Tyrannosaurus rex . Under this interpretation, T. rex  would have undergone extreme ontogenetic transformations, shifting from a slender, cursorial juvenile form to a massive apex predator in adulthood. However, a recent study re-examines this hypothesis using exceptionally complete skeletal mate

From the Cambrian to the Ordovician, many animal phyla first appeared and diversified rapidly, and the phylum Echinodermata eventually became one of the major groups of marine animals that continues to thrive today. The ancestors of modern echinoderms—such as sea stars, sea urchins, and sea cucumbers—can largely be traced back to the early Paleozoic. During that time, echinoderms evolved at a remarkable pace. Within only a few tens of millions of years, they underwent extensi

（Stocktrek Images via Getty Images） In 1955, an American amateur fossil collector, Francis Tully, obtained a peculiar fossil from the Mazon Creek fossil beds in Illinois. Intrigued by its unusual form, he brought the specimen to the Field Museum of Natural History for identification. The paleontologists there were immediately puzzled. The fossil preserved an organism with a cigar-shaped body, a triangular tail fin, and a pair of eyes mounted on a long horizontal stalk. Most b

Anyone who has watched Game of Thrones  will remember the enormous wolf-like animals raised by members of House Stark. These creatures, known as “direwolves” in the story, were inspired by a real prehistoric animal: the dire wolf. Ecological reconstruction of the habitat where dire wolves lived, with the dire wolf shown in the lower left（圖片來源： National Park Service ， CC0 1.0  公共領域。） Like the fictional ice wolves, dire wolves were noticeably larger than the modern grey wolf. Y

Reconstruction of Scleromochlus taylori （感謝Gabriel Ugueto提供） Pterosaurs were the first vertebrates to take to the skies. From the Late Triassic until the end of the Cretaceous, they occupied the air for more than 150 million years. Anyone fascinated by prehistoric life is familiar with these flying reptiles, yet the earliest stages of their evolution have long remained obscure. The fossil record reveals a considerable anatomical and temporal gap between fully developed pteros

Fossil locality of Ajnabia Geological age of Ajnabia （白稜製作） During the Late Cretaceous, dinosaur faunas in the northern hemisphere (Laurasia) and the southern hemisphere (Gondwana) differed markedly. In Laurasia, herbivorous dinosaurs were dominated by ornithischians such as hadrosaurids and ceratopsians, while tyrannosaurids served as the apex predators. In contrast, Gondwanan ecosystems were characterized by titanosaurian sauropods as the primary herbivores and abelisaurids

Model of the tail based on Apatosaurus  specimens used in this study（手手蟲/呂淳濤提供） Sauropod dinosaurs are famous for their enormous body size and their remarkably long necks and tails. Among them, diplodocids possessed some of the most extreme tail elongation known in vertebrate animals, a feature that has long intrigued researchers and prompted numerous hypotheses about the function of these tails. The diplodocid tail consisted of roughly eighty caudal vertebrae. Their morpholo

Illustration of Saichania  and Pinacosaurus （圖片來源：ABelov2014，採用  CC BY 3.0  授權） When people imagine the sound of dinosaurs, the thunderous roars popularized by films such as Jurassic Park  often come to mind. However, a recent study focusing on an ornithischian dinosaur suggests that this image may not reflect reality. Instead of roaring like giant reptiles, some dinosaurs may have produced sounds more reminiscent of bird calls.

Reconstruction of Yuanchuavis kompsosoura （圖片來源：Luxquine，採用  CC BY-SA 4.0  授權） Many birds display bright colors or exaggerated ornamental features that appear to offer little advantage for survival. Vivid plumage can make individuals easier for predators to detect, and elongated feathers may hinder rapid escape. Yet such traits are widespread among modern birds. At first glance, one might expect natural selection to eliminate these seemingly disadvantageous characteristics, b

Hupehsuchus filter-feeding reconstruction（感謝Shunyi Shu & Long Cheng, Wuhan Center of China Geological Survey提供） Among modern marine giants, several animals obtain food by filtering tiny organisms from seawater. Baleen whales and whale sharks are two well-known examples, yet they rely on very different anatomical solutions. Baleen whales possess baleen plates derived from specialized skin tissues of the upper jaw. These structures are made of keratin, the same material that fo