For 490 million years, ten little-known species of trilobites have remained hidden in a barely mapped part of Thailand. These may be the missing pieces of our planet’s complex geographic puzzle.
Trilobites are fascinating creatures. They have dominated ecosystems at the bottom of the world’s oceans for more than 250 million years, and managed to survive two major mass extinctions. This means that they lasted much longer than dinosaurs, for example. What’s special is that they breathe through their legs. There are more than 20,000 known species and you have undoubtedly seen fossils of these animals.
Hidden in tuff
Now ten new species have been found. The fossils were trapped between layers of fossilized ash in the sandstone, the result of very ancient volcanic eruptions on the sea floor, which formed a layer of tuff. Tuff contains zircon crystals. Zircon is a rocky mineral that forms during a volcanic eruption and is resistant to heat and water. This continues while the other minerals in the rocks have long since been destroyed. Zircon is interesting because it contains radioactive isotopes. Eventually, uranium decays into lead. By determining the ratio between the amount of uranium and lead, geologists can determine the age of the rock in which the zircon was found.
“We can use radioisotope techniques to find out when the volcanic eruption occurred and how old the fossils are,” explains geology professor Nigel Hughes from the University of California. University of California Riverside Outside. Tufa from the Late Cambrian, between 497 and 485 million years ago, is rare. “There aren’t many places in the world where this happens. It’s one of the worst documented periods in Earth’s history,” Hughes said.
“Tuff not only helps us determine the age of fossils recovered from Thailand, but also leads to a better understanding of other parts of the world, such as China, Australia and even North America where similar fossils have been found in otherwise undetectable rocks.” says lead researcher Shelley Wernett.
Animate the 3D puzzle
Trilobite fossils have been found on the coast of Ko Tarutau Island, a UNESCO geopark where research is encouraged. “The most exciting discovery is dozens of species of trilobites that have been found in other parts of the world, but have never before been found in Thailand. We can now connect Thailand to parts of Australia, which is a very special discovery.”
When the trilobites lived, this part of Thailand was located on the outer edges of Gondwana, the ancient supercontinent that included Africa, India, Australia, South America and Antarctica. “Because continents change, part of our work was to figure out where this Thai region stood compared to the rest of Gondwana,” Hughes says. “It’s a moving, shape-shifting 3D puzzle that we’re trying to solve. This discovery helps with that.”
A good example of this is tsynania Sirindornai, The trilobite, named after Princess Sirindhorn, is due to its commitment to advancing science in Thailand. “I also thought this type had a regal quality, with a wide headdress and clean, flowing lines,” says Wernett.
If researchers can extract a date from the tuff containing a fossil of a royal trilobite and determine when the species lived, they can conclude that the closely related species of Tsinania, found in northern and southern China, is roughly the same age.
In this way, the map of the ancient world is slowly filled in with information hidden in fossils. “What we have here is a record of the evolutionary changes that involved extinction. “Earth wrote this document for us and fortunately we found it,” says Hughes. “The more we learn from this, the better prepared we will be to meet the challenges our planet faces today.”
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