Lagerstätte are geological areas that have exceptionally preserved fossils. These fossils even have preserved soft tissue and biomolecules, such as DNA.
It was the summer of 1909. Charles Doolittle Wolcott and his family had returned to the Canadian Rockies in search of fossils. Wolcott was a prodigious, self-taught paleontologist and that year he returned to explore the fossils of strange animals from the Cambrian period 500 million years ago.
High up in these mountains, thin flaky rocks called shale held the vague markings of prehistoric life. Two years earlier, Wolcott had found shale with impressions of an oval, segmented, and scaly creature with numerous skittering legs – the trilobite, and he was here to find more of them.
The journey wasn’t easy. Wolcott writes in his journal, “The best way to make a collection from the ‘fossil bed’ is to ride up the trail on a pony to about 2000 feet [about 600 m] above the railroad, collect specimens, securely wrap them in paper, place them in a bag, tie the bag to the saddle, and lead the pony down the mountain.”
Wolcott made an early start on his search on August 30, 1909. He found trilobites stuck in stone, much like he’d expected. But as the day went on, his pile of fossils continued to grow. He had never encountered such a wealth of natural history before; it was like stumbling on the key to a library with untold literary riches.
Over the next 5 days, Wolcott and his family collected a “large number of specimens”, as he modestly notes in his journal. Many of these specimens are unknown, the vague outlines of animals that once were.
Wolcott understood the importance of his findings and dashed off a letter to his friend and colleague, William Arthur Parks, writing that he had found “some very interesting things”. These “interesting things” would lead him back to the cliffs of the Canadian Rockies in search for more Cambrian puzzles for the next two decades.
The treasure trove of the Earth’s past, shielded in the Canadian Rockies, is called the Burgess Shale and was the first Lagerstätte to be discovered.
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What is a Lagerstätte?
The credit for the word ‘Lagerstätte’ (la-ger-shta-t) goes, not to Wolcott, but to another prodigious paleontologist, Adolf ‘Dolf’ Seilacher in the 1970s.
‘Lagerstätte’ in German originally means a part of the Earth rich in mining metal ore, and was a word usually used by miners. Seilacher coopted that word for paleontology to mean a part of the Earth with a rich and extremely well-conserved deposits of fossils.
There are two types of Lagerstätten – konservat, pronouned as (conservation) and konzentrat (concentration).
Konservat lagerstätten have exceptionally preserved fossils—soft tissue, proteins and sometimes even DNA that manages to survive.
The Burgess Shale Lagerstätte that Wolcott found was a Konservat Lagerstätte with exceptionally preserved fossils of animal life, such as trilobites, but also plant life, which is harder to preserve, as plants don’t have scales or other hard and degradation-resistant exoskeletons.
Another famous Konservat Lagerstätte is the Solnhofen Lagerstätte in Germany, where the famous Archeopteryx fossils were found; that is why we know that dinosaurs had feathers and that birds are their relatives (among other evidence, of course).
Konzentrat Lagerstätten have an abundance of fossils from a time period, but they aren’t as well persevered as those found in konservat Lagerstatte. These haven’t gained the attention, fame and glory that konservat Lagerstätte have, but they do provide valuable information on many different species of life and from a wider time frame.
How do Lagerstätte create fossils?
Lagerstätte aren’t a specific type of geological feature. It is any place that has managed to conserve fossils in large numbers or exceptional preservation. The Lagerstätte discovered so far display a wide range of geological conditions that provide the perfect conditions to preserve living matter.
When a living thing dies, its body begins to degrade. Individual cells and tissues begin to shrivel and die because they can no longer produce the energy to live, while scavengers like insects, and decomposers, such as bacteria and fungi, consume the body. In warm conditions with plenty of oxygen, life can degrade very quickly.
Hostile conditions like lakes fuming with sulphide or extreme saltiness are effective preservers of organic matter. Both these conditions make it difficult for flesh-eating insects and decomposing microorganisms like bacteria and fungi to survive. This is why salted foods like pickles have such a long shelf life, as extremely few bacteria can survive such saltiness. High salt concentration is a reason for the excellent preservation of the Solnhofen Lagerstätte.
A partial or complete lack of oxygen in an environment also halts degradation. These anoxic conditions might happen at the bottom of lakes and oceans, where sediments depositing rapidly can cut off any oxygen supply. Floodplains also create similar oxygen-deprived areas.
As more earth deposits over the remains, it causes the soft sediment to harden into rock. This process is called diagenesis. Rock formation is what makes the fossils we know today. Depending on the conditions and how much degradation occurred, we can find impressions of animals, or, as konservat Lagerstätte offer us, feathers, teeth, scales, and the all-important soft tissue!
However, fossils in rocks aren’t the only sources of well-preserved specimens. Insects and other small creatures are caught in tree resin and then fossilized into amber. A small dinosaur skull was discovered preserved in Amber in a mine in Myanmar, a find that was reported on and published in 2020.
Some famous Lagerstätte
Wolcott collected about 65,000 fossils from his quarry at Burgess Shale. His work there was followed by several paleontologists that went on to fossilize their names in the history books for making some of the most valuable discoveries in the field. Yet, at the time, Wolcott’s work languished in a corner, largely unheeded. It was 40 years before two paleontologists, Alberto Simonetta and Laura Delle Cave, reconstructed several of his arthropod fossils.
In the 1960s, modern science was still coming of age, maturing with new discoveries related to DNA, genetics, and theories of evolution to tie all this burgeoning cellular and molecular study together. Paleontology was also benefitting from these advances. As more individuals, labs, and organizations began exploring fossils, more lagerstätte were discovered.
Today, new lagerstätte found all over the world are helping to fill in the puzzle pieces of prehistoric life. A Burgess Shale-like lagerstätte in China, the Qingjiang biota, is providing new evidence of life from the Early Cambrian, about 500 million years ago.
The Ediacara Hills in Australia have offered us glimpses of life on Earth from the Precambrian period, 1000 to 850 mya. Precambian life has been particularly difficult to sketch out, since life before the Cambrian didn’t have hard exoskeletons to create viable fossils. The evidence that the Ediacara Hills offers towards the evolution of life is extremely valuable.
Lagerstätte all over the world have provided glimpses into periods as late as 1000 million years ago to as recently as 20 million years ago (which is basically yesterday in geological time).
Wolcott didn’t believe that the Burgess Shale had anything more to offer, which he recorded in his journal in 1912. No one had come upon such a rich hoard of fossils all in one place, and understandably, it sounded too good to be true.
However, if Wolcott were still alive today, he would become giddy at the wealth of fossils at Burgess Shale. The Lagerstätte is still giving scientists and explorers with treasures since Wolcott’s pony ride to a remote mountain one fine summer morning.