Pterygotus buffaloensis   scale in cms CLASS - Merostomata ORDER - Eurypterida FAMILY - Pterygotidae GENUS/SPECIES - Pterygotus buffaloensis ROCK UNIT - Bertie Group AGE - Upper Silurian (410 million years old) LOCALITY - Buffalo, Erie Co., New York The broad leaf-like tail (telson) of Pterygotus is quite different from the spike-like tail that most eurypterids possess. A single raised ridge runs down the middle of the tail and forms a structure similar to the tail fins on a small airplane. It undoubtably aided the sea scorpion in swimming and navigating. PRI 42411