Laophis crotaloides measured between 10 and 13 feet (3 and 4 meters) long and weighed a whopping 57 lbs. (26 kilograms). Today's longest venomous snakes, king cobras (Ophiophagus hannah), can grow to be about 18 feet (5.5 m) long. But at typical weights between 15 and 20 lbs. (6.8 to 9 kg), king cobras are scrawny compared to Laophis.

What makes Laophis even stranger was that it achieved this bulk not in the tropics, where most large reptiles live today, but in seasonal grasslands where winters were cool.