It was getting late and the team of paleontologists excavating a previously unexplored outcrop of the Burgess Shale was ready to call it a day. A camera crew filming the dig in Kootenay National Park had already packed it in.

Then one of the team members split open a large plate of shale.

B次元官网网址淚 just remember the gasps all around,B次元官网网址� said Joe Moysiuk of the Royal Ontario Museum.

B次元官网网址淓veryone was running to come and see what had been found. It was clearly a new animal.B次元官网网址�

What that 2018 dig revealed was something that stood out even in the bizarre world of the Burgess Shale, an outcrop of 500-million-year-old rocks in the Canadian Rockies of British Columbia that is chock-a-block with fossils from the earliest days of complex life on Earth.

Most of those fossils are little-finger size. Not this one.

B次元官网网址淲e uncovered this huge carapace,B次元官网网址� Moysiuk recalled.

B次元官网网址淭he whole animal must be at least 50 centimetres long. This is definitely one of the largest animals that we know of from the Cambrian period.B次元官网网址�

Titanokorys gainesi hails from a time that predated life on land, when the seas were a giant laboratory for evolution to work out answers that plants and animals still use today. Spinal chords, eyes, exoskeletons B次元官网网址� they all first appear in the Cambrian.

B次元官网网址淎ll of the major animal body plans first evolved then,B次元官网网址� Moysiuk said.

B次元官网网址淲e see the first representatives of things that looked like fish, things that looked like insects and crabs. Any other animal you might dream up, it most likely had some relative from the Cambrian period.B次元官网网址�

Not that Titanokorys would look remotely familiar.

B次元官网网址淭hese things are very alien-looking,B次元官网网址� said Moysiuk.

The whole beastie was flattish and oblong, with gill slits toward the back, a horseshoe-shaped plate protecting its head and armoured plates underneath. Its eyes, halfway back along the body, would probably have been on stalks. It had claws out front with rake-like outgrowths.

A predator, it probably cruised the sea bottom looking for whatever tasty bits it could sweep into its mouth.

B次元官网网址淭he mouth itself is really cool,B次元官网网址� Moysiuk said. B次元官网网址淚t looks like a pineapple slice thatB次元官网网址檚 lined with these sharp, inward-pointing teeth.B次元官网网址�

Burgess Shale fossils are renowned not only for their age, but for their preservation. Soft body parts such as eyes are often visible. A critterB次元官网网址檚 last meal is sometimes preserved in the rock.

Even for the Burgess, Titanokorys is well-preserved.

B次元官网网址淲e have relatively complete remains,B次元官网网址� said Moysiuk. B次元官网网址淭hese fossils are very rare.B次元官网网址�

The fossil, he said, will allow paleontologists to study some of evolutionB次元官网网址檚 most basic questions. Why, for example, do some animals get big and others donB次元官网网址檛?

B次元官网网址淚t seems to be related to this evolutionary arms race that was happening during the Cambrian where you have bigger and bigger animals that are trying to outdo each other in size,B次元官网网址� Moysiuk said. B次元官网网址淎s a predator, it benefits you to be pretty big.B次元官网网址�

But whatever eventually comes from the study of Titanokorys, Moysiuk said nothing will match the thrill of seeing its fossil emerge after hundreds of millions of years from the dark shale of the Burgess.

B次元官网网址淚t was one of those moments IB次元官网网址檒l never forget.B次元官网网址�

B次元官网网址擝ob Weber, The Canadian Press