Dog-sized sea scorpions existed 400 million years ago, says study

Have you ever seen or heard of a scorpion that is the size of a dog? Though it may sound weird, scientists from the Nanjing Institute of Geology and Palaeontology recently unearthed a fossil of a meter-long sea scorpion that existed in the sea floors of south China.

Researchers put the existence of these 16 times longer than the average-sized scorpions to at least 400 million years ago.

The dog-sized arachnids named Terropterus Xiushanensis are considered a relative of the present-day horseshoe crab and whip spider. It is said that these scorpions had similar spiny attacking forelimbs and belonged to mixopterids, a group of eurypterids (sea scorpions) also recognised for their specialised arms used for catching prey.

"Our knowledge of mixopterids is limited to only four species in two genera, which were all based on a few fossil specimens from the Silurian Laurussia 80 years ago," the authors of the study said. The well-preserved fossils of this extinct species form new evidence to understanding the morphological diversity of mixopterids.

The dog-sized arachnids are believed to have existed during the Silurian period, somewhere between 443.8 million and 419.2 million years ago. Sea scorpions have been considered the top predators long before the evolution of barracudas or sharks.

Researchers had deduced that sea scorpions used their tails, weaponized by their serrated spiny tips, to dispatch their prey.