One of the world’s most important fossil deposits has been found in Wales, according to experts.
A large number of extraordinary new fossils, including many soft-bodied creatures, have been discovered near Llandrindod Wells in Powys.
Amgueddfa Cymru – Museum Wales researchers found the fossils in rocks which were laid down under the sea over 460 million years ago at a time when what is now mid-Wales was covered by an ocean.
Over 170 species were discovered in 2020 during the Covid-19 lockdown at a secret location on private land known as Castle Bank by researchers and Llandrindod residents Dr Joseph Botting and Dr Lucy Muir.
They said it was one of the very rare sites where soft tissues and complete organisms are preserved, rather than just hard parts like shells and bones.
Almost all the previous examples are from the Cambrian Period but Castle Bank dates from the Middle Ordovician, some 50 million years later.
Dr Muir said the discovery was important because it gives a new insight into how life was evolving at this time.
“It coincides with the ‘Great Ordovician Biodiversification Event’, when animals with hard skeletons were evolving rapidly,” she said.
“For the first time, we will be able to see what the rest of the ecosystem was doing as well.”
Fossils of many different kinds of animals were found at Castle Bank and most were small – between 1mm to 5mm – and many were either completely soft-bodied when alive or had a tough skin or exoskeleton.
Places where such soft-bodied fossils are found are extremely rare, and only one other Ordovician site in the world, the Fezouata Biota of Morocco, preserves close to this level of detail.
The Castle Bank fossils include the youngest known examples of some unusual groups of animals, including opabiniids with their vacuum cleaner-like proboscis, and wiwaxiids, strange oval-shaped molluscs with a soft underbelly and a back covered with rows of leaf-shaped scales and long spines.
At the same time, the site includes the oldest examples of more modern-looking animals, including a creature that looks almost like an insect and may be distantly related to them.
The new fossils also include many different types of worms, sponges, barnacles, starfish and a primitive horseshoe crab.
Very fine details can be seen on many of the fossils under the microscope, including eyes and possible primitive brain in the head of an unknown arthropod, gut traces in trilobites and other animals, and worm tentacles and jaws.
Researchers in Sweden also dissolved some of the rock in hydrofluoric acid, and extracted minute fragments of organic remains that show cellular-level detail.
Dr Botting and Dr Muir are not employed as academics and had to crowd-fund to purchase microscope equipment to aid their work.
“In some ways this is a real community effort to reveal this fauna, because it wouldn’t have been possible for us to do it without the support of a large number of people,” said Dr Botting.
“Even most universities do not have the equipment that we were ultimately able to buy.”
Collecting such tiny fossils is also challenging, and can only be done in good light, knowing exactly how to split and examine the right layers in order to reveal them.
Dr Botting and Dr Muir have spent over 100 days in the field collecting the fossils and are working with colleagues in Cardiff, Cambridge, Sweden and China to examine the finds.
“There are some very important early Ordovician fossil sites but those are from much earlier, and entirely soft-bodied animals are rare even there,” said Dr Botting.
“Here, it seems, we’ve got everything. Despite the extraordinary range of fossils already discovered, work has barely begun.
“Every time we go back, we find something new, and sometimes it’s something truly extraordinary.
“There are a lot of unanswered questions, and this site is going to keep producing new discoveries for decades.
“This is just the beginning, and we’re excited to see what comes next.”
– The findings have been published in a paper, A Middle Ordovician Burgess Shale-type Fauna From Castle Bank, Wales (UK), in the journal Nature Ecology And Evolution.