410 million years ago in Scotland!

 

410 million years in Scotland Reconstruction drawing by Steve Fayers of a spider-like trigonotarbid found in the Chert.

Dr Nigel Trewin, Dr Clive Rice, Dr Steve Fayers and Ruth Kelman.
University of Aberdeen.

A miniature tropical paradise south of the Equator and teeming with exotic life forms, hot springs and geysers - sound familiar? Yes it's Scotland! Or at least it's a part of Aberdeenshire around 410 million years ago.

In this early Scottish landscape primitive plants formed 'knee-high' forests, and marshlands were inhabited by centipedes and spider-like animals on a river flood plain from which bubbled hot springs of silica-rich water. In small pools shrimp-like crustaceans lived in association with algae, bacteria and decaying plants. Fungi decomposed organic matter and lived as parasites on plants. Our detailed knowledge of the remarkably diverse flora and fauna from this time stems from the preservative powers of the highly mineralised water.

From time to time hot silica-rich water from hot springs and geysers flooded the land surface and deposited silica in a form called amorphous opaline sinter. The sinter trapped and preserved a huge variety of early land plants and animals. Many of the fossils are preserved in perfect 3D, showing superb detail and providing a unique glimpse of an early terrestrial and freshwater ecosystem.

The sinter is now preserved as a finegrained quartz rock known as the Rhynie Chert. This rock was first discovered in 1912 as loose blocks in the fields around Rhynie near Aberdeen, and further material has been uncovered by trench digging and drilling. It has been the subject of periods of intense research involving institutions from around the world ever since, and it is now recognised as the best preserved early terrestrial ecosystem anywhere in the world.

The diversity of life recorded in the Rhynie Chert is far greater than that at any other site with a terrestrial biota of a similar age. A major surprise is the 'modern' aspect of the interactions between plants, animals and fungi found in the Early Devonian period, with complex symbiotic and parasitic relationships.

But it is the quality of the samples that makes the Rhynie Chert stand out. The fossilisation of the biota happened very quickly and incredible detail can be observed, including book lungs in arthropods, and sperm cells in plants, as well as germinating spores. The primitive plants display both sporophyte and gametophyte generations, and the fines.