Arthropleura armata

Arthropleura was a giant relative of centipedes and millipedes that lived in Great Britain and North America during the Carboniferous period. It is the largest known land invertebrate of all time, and grew so large because of the high concentration of oxygen in Carboniferous Earth's atmosphere.

Real life
Arthropleura (name meaning "Jointed Ribs") was an arthropod genus and ancestor of modern day centipedes and millipedes, and one of the largest known land invertebrates of all time. It lived from 323 to 299 million years ago, during the upper Carboniferous period, in what is now Scotland and northeast North America. Arthropleura is thought to have been a herbivore, and it could move and swerve very quickly among its habitat's forest floor and around obstacles.

Due to the Carboniferous atmosphere's higher oxygen concentration and Arthropleura's lack of predators, it was able to grow larger than modern arthropods, being between 0.3 and 2.6 metres (1 and 8.5 feet) long. Arthropleura died out at the end of the Carboniferous period due to destruction of the Carboniferous rainforests to desertification and arid climate.

Trivia

 * Arthropleura was the first venomous creature in Primeval.

Errors

 * Arthropleura was not believed to be venomous by any means, since it presumably had no enemies and ate dead plant matter.