Evolution

Tarantulas inhabit land millions of years back, probably else long before that how the dinosaurs appear. However much little is known about their prehistoric life.

Unlike vertebrates, spiders have not the internal skeleton, which traces could in different fossils. Known only single discoveries of parts of body in petrified juice of plants, amber. Else less meet the imprint the parts of body spiders themselves in sandstone. Some guesswork about evolutionary development of spiders possible to build, comparing different groups of modern representatives of Cheliceratae.

On the grounds of the whole available such sort of information possible to remove the look of fossilised spider.

Supposedly early forms there were terrestrial species, either as majority of modern Theraphosid spiders.

n later time of some group of types have abandoned their own burrows and have altered by sawing to more open lifestyle.

Hereinafter, some of them left the burrowing lifestyle and have begun to braid the web, other change in active overland hunters, but remained have saved the adherence to inhabits in burrows. At present many arachnologiests (scientist, studying arachnids) consider that mygalomorph spiders (Mygalomorphae), to which pertain modern tarantulas (Theraphosidae), most close group on its construction, exterior and lifestyle to its overland spiders-ancestors.

Discovered in Argentina petrified rock fossilised arachnid counts approximately 300 millions of years and is the oldest which discovered of such sort. This primitive organism is named Megarachne servinei. The ancient spider reaches more than fifty centimetres in legspan and thirteen centimetres of body length.*

Other fossil found in Frances, is supposedly valued the age 240 millions of years, time, when dinosaurs only have begun to go from water to overland life.

Interesting also that look of fossilised spider suffer small change with current of ages and nearly does not differ from modern tarantulas: ditto sharp division between abdomen and cephalothorax, chelicera furnishing with talon- like apical part, small feeler-like pedipalp, four pair of stilted legs and silk-producing glands on the end of abdomen.

Together with that shaping of silk-producing glands of spiders occur, obviously, in process of output on land, but possible else and in the most water since it is formed from gill-drumsticks of eleventh and tenth segments.

In prehistorically time a web was used for building an eggsacs. This function as once most developing beside tarantulas being one of the most primitively organised group of spiders.

Thereby, wholly possible that mygalomorph spider occupied land in else earlier time as stated, but at this moment the acknowledgement to this hypothesis in the manner of petrified remainders is not found.
  
   
  
According the last study of Dr. Paul Selden (Manchester University) this ancient creature do not longer belong to any arachnid but considering the most closely being a large crab.