Brontoscorpio anglicus

Brontoscorpio was a species of large scorpion from the Silurian period.

Characteristics
Brontoscorpio was a carnivorous predator, which would attack victims with its stinger to incapacitate them with its venom, then would drag the attacked prey's body away to suck out and consume their internal organs after the venom killed them. (Sea Scorpions) It would seem that Brontoscorpio preferred to attack prey who were alone or off-guard, although it would engage an organised group of other animals in a direct fight if it had to. Brontoscorpio displayed some similar caution and attack strategy to some modern day scorpions; approaching prey tensed and cautiously, and momentarily backing away slightly at movement, resistance and aggression from the victim.

Venom
Brontoscorpio made their home in caves and burrows, and they also made use of hidden sinkholes across the land in their territory as sandtraps to trap unaware other animals for the Brontoscorpio to come for.

The symptoms of Brontoscorpio poisoning and the speed at which the venom took effect depended very much upon the dosage injected: a direct sting such as a stab would bring the victim down instantly and kill it within seconds, whereas an indirect sting such as a shallow scratch would gradually weaken, numb and then kill the stung victim over the course of a matter of hours.

Real life
Brontoscorpio was a species of large, presumably aquatic scorpion, which lived sometime during the Late Silurian period. It is believed to have been a carnivore which probably fed on worms, fish and even other arthropods. Brontoscorpio is only known from a single fossilized pedipalp limb found in Trimpley, Worcestershire. It is estimated that Brontoscorpio was at least 90 centimetres (35 inches) long. 'Brontos' is the Ancient Greek for 'thunder', hence the episode title.

Trivia

 * However, that is unlikely, as the Silurian Scorpion more closely resembled a whip scorpion and lacked a stinger, while Brontoscorpio was a true scorpion and had a stinger. The Silurian Scorpion was more likely an eurypterid (commonly known as a "sea scorpion") instead of a true scorpion like Brontoscorpio.

Errors

 * Fans have suggested that the Brontoscorpio in the show may have been an unusually large specimen, or that the real-life fossilised Brontoscorpio was actually a juvenile in the Primeverse.
 * The Brontoscorpio had very large and thick pincers, like scorpions that crush their prey rather than sting them to death.
 * It is unlikely that Brontoscorpio's venom would have been effective against mammals such as humans, as there were no mammals or even reptiles or amphibians in the Silurian; Brontoscorpio's venom would have probably only worked against other arthropods.