Concavenator corcovatus

Concavenator, a relatively small but fascinating theropod dinosaur that lived approximately 125 million years ago during the early Cretaceous period, is known for its distinctive, elongated neural spines along its back, which likely supported a unique, sail-like structure, and while its exact function remains debated—whether for display, thermoregulation, or mating rituals—the morphology suggests it was an important adaptation for this dinosaur, which likely inhabited what is now modern-day Spain; reaching an estimated length of about 4.5 meters and weighing around 200 kilograms, Concavenator exhibited a blend of primitive and more advanced features, such as a relatively large, slender body and a mix of carnivorous traits including sharp teeth and a partially fused, lightweight skeleton, enabling it to be a nimble predator; its forelimbs were also equipped with a notable "thumb claw," adding to its hunting versatility, possibly helping it to grasp prey, while its well-preserved fossil evidence reveals that it was part of the larger group of "carnosaurs," which includes some of the most iconic theropods like Allosaurus, further underscoring Concavenator's importance in understanding the evolutionary transition of theropod dinosaurs during the early Cretaceous, especially in terms of body plan and ecological niche.