 Numerous complete or partial specimens of "M. bassanni" housed at PIMUZ (Paläontologisches Institut und Museum der Universität Zürich) include A III/208, T 1534, T 2470, T 2472, T 2474 through T 2477, T 2809, T 2812 through T 2816, T 4822, and T 4355.The smallest specimen of this species is MSNM BES SC111, which is believed to be a juvenile about 30 centimeters long.The largest specimens were about 90 centimeters long.