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Scientists find trilobite species hidden for almost 500 million years

These 10 new species of trilobites found in a little-studied part of Thailand could be the missing pieces in an intricate puzzle of ancient world geography

Artist's rendering of a trilobite based on preserved soft body parts.(Nobu Tamura)

By Team Lounge

LAST PUBLISHED 23.11.2023  |  04:00 PM IST

Trilobites are extinct anthropods that have proven helpful for geologists in learning how the earth developed across millions of years.

Now researchers have discovered ten new species of trilobites, hidden for 490 million years in a little-studied part of Thailand, which could be the missing pieces in an intricate puzzle of ancient world geography.


Trilobites are extinct sea creatures with half-moon-shaped heads that breathed through their legs. Now a recent research monograph in the British journal Papers in Palaeontology offers more details about the new species, including one that was after Thai Royal Princess Maha Chakri Sirindhorn.

These new findings could help scientists connect Thailand with other parts of the world where similar trilobite discoveries have been made.

According to a press release from the University of California – Riverside, the trilobite fossils were trapped between layers of petrified ash in sandstone, the product of old volcanic eruptions that settled on the sea floor and formed a green layer called a tuff. Unlike some other kinds of rocks or sediment, tuffs contain crystals of zircon — a mineral that formed during an eruption and are, as the name of the rock layer containing them suggests, tough, the release explains.

Zircon is a mineral that is considered to be as tough as steel, and while other minerals in rocks erode, zircon doesn’t. According to the release, it is chemically stable as well as heat and weather resistant. “Inside these resilient zircon crystals, individual atoms of uranium gradually decay and transform into atoms of lead," the release adds.

“We can use radio isotope techniques to date when the zircon formed and thus find the age of the eruption, as well as the fossil," said Nigel Hughes, monograph co-author and UC Riverside geology professor.

It is rare to find tuffs from this particular period of time, the late Cambrian period, between 497 and 485 million years ago, the researchers add in the release. “Not many places around the world have this. It is one of the worst dated intervals of time in Earth’s history," Hughes explains.


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“The tuffs will allow us to not only determine the age of the fossils we found in Thailand, but to better understand parts of the world like China, Australia, and even North America where similar fossils have been found in rocks that cannot be dated," said Shelly Wernette, former Hughes lab geologist now at Texas State University, and first author of the monograph. “We can now connect Thailand to parts of Australia, a really exciting discovery," Wernette adds.

According to the release, the fossils were uncovered on the coast of an island called Ko Tarutao, which is about 40 minutes southwest from the mainland via high speed boat and part of an UNESCO geopark site that has encouraged international teams of scientists to work in this area.

Also read: Fish once labeled a living fossil surprises scientists again