Yutyrannus

MEANING: Feathered tyrant

PERIOD: Early Cretaceous

CONTINENT: Asia

Yutyrannus is the largest dinosaur yet discovered with direct evidence of feathers. It is a large basal tyrannosauroid, at about 9 m in length, and weighing around 1.5 t. Unlike more derived tyrannosaurs, Yutyrannus had long forearms with three fingers on each hand. Feathers in fossil specimens are present on various parts of the body, implying total coverage.

Yutyrannus is from the Early Cretaceous. The Cretaceous is the third and final geological period of the Mesozoic Era, with the Early Cretaceous making up roughly the first half, lasting from about 143 to 100 million years ago. The poles were ice-free, due to the relatively warm climate, and forests extended into high latitudes. The continued breakup of the continents created new coastlines and isolated landmasses, influencing the evolution of distinct dinosaur faunas.

It was a time of transition, as many groups of animals and plants began to take on more modern forms while others declined or disappeared. Pterosaurs continued to thrive, though early birds were becoming more diverse and widespread. Mammals remained small but adapted to a variety of ecological niches. In the oceans, ichthyosaurs and plesiosaurs were common, and early mosasaurs began to appear.

Dinosaurs remained the dominant land animals, with groups like iguanodontians, spinosaurids, and carcharodontosaurids rising to prominence. While sauropods declined in some regions, they remained abundant in the Southern Hemisphere. The first true ceratopsians appeared, and ankylosaurs replaced stegosaurs in their niche. Dromaeosaurs and other small theropods diversified. During this time, the first flowering plants evolved, gradually changing global ecosystems by providing new food sources for herbivores.

Yutyrannus is a proceratosaurid. Proceratosauridae is a small but interesting family of early tyrannosauroids. Living from the Middle to Late Jurassic, proceratosaurids represent some of the earliest known members of the tyrannosauroid lineage, and they already exhibited traits that would later be refined in their gigantic relatives such as elongated skulls, sharp teeth, and adaptations for a strong bite. However, unlike later tyrannosaurids, proceratosaurids were relatively small and lightly built, often measuring only a few meters in length.

Fossil remains of proceratosaurids have been found in Europe and Asia. Some examples have direct evidence of feathered integument, and this group contains the largest known feathered animals in Earth's history. Many proceratosaurids also had distinctive cranial crests that may have been used for display or communication. Their fossils provide critical insights into the early evolution of tyrannosauroids, showing that this lineage began as small, agile predators long before achieving dominance in the Late Cretaceous. Despite their modest size, proceratosaurids were efficient hunters in their ecosystems, bridging the gap between basal coelurosaurian predators and the later, more massive tyrannosaurs of the Late Cretaceous.