Saltriovenator zanellai - right mcII and phII-1

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Articulation of the right second metacarpal and first phalanx of the right second manual digit of Saltriovenator zanellai stands out as a remarkable discovery from the Saltrio Formation, Saltrio (Varese), Italy. This early Sinemurian find, dating back to 199-198 million years ago, marks the oldest known ceratosaurian in the Dinosauria: Theropoda lineage. According to Dal Sasso et al., the manual elements of Saltriovenator exhibit a more robust structure than those found in coelophysoid-grade theropods. This adaptation allows for sustained mechanical loads during predation, making it a more efficient predator. Diagnostic features of the second metacarpal bone and first phalanx of the second digit include a hypertrophied semicircular extensor lip on mcII and a deep and narrow flexor palmar groove on phII-1. The specimen is carefully preserved at the Museo di Storia Naturale di Milano. A recent study by Dal Sasso C, Maganuco S, and Cau A sheds light on the evolution of the three-fingered hand of birds through this groundbreaking discovery in the Lower Jurassic period of Italy.