Ten newly discovered trilobites, which have been hidden for 490 million years in a remote part of Thailand, could be the missing pieces in an intricate puzzle of ancient world geography.
Trilobites are extinct sea creatures with half-moon-shaped heads and legs that breathed through. A 100-page monograph in the British journal provides extensive information on the new species, including one named after Thai Royal Princess Maha Chakri Sirindhorn.
The trilobite fossils were discovered between layers of petrified ash in sandstone, which was formed by old volcanic eruptions that settled on the sea floor and formed a green layer known as tuff. Tuffs, unlike some other types of rocks or sediment, contain crystals of zircon, a mineral that formed during an eruption and is tough, as the name of the rock layer containing it suggests.
The tuffs will allow us not only to determine the age of the fossils we discovered in Thailand, but also 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.
Shelly Wernette
Zircon is chemically stable and resistant to heat and weather. It is as hard as steel and does not erode when minerals in other types of rocks do. Individual uranium atoms gradually decay and transform into lead atoms inside these tough zircon crystals.
“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.
Tuffs from this time period, the late Cambrian period, between 497 and 485 million years ago, are extremely rare. “This is not found in many places around the world. “It’s one of the worst-dated periods in Earth’s history,” Hughes said.
“The tuffs will allow us not only to determine the age of the fossils we discovered in Thailand, but also 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, a former Hughes lab geologist now at Texas State University and the monograph’s first author.
The fossils were uncovered on the coast of an island called Ko Tarutao. It is about 40 minutes southwest from the mainland via high speed boat and is part of an UNESCO geopark site that has encouraged international teams of scientists to work in this area.
The most intriguing discovery for Wernette was the discovery of 12 different types of trilobites that had never been seen before in Thailand. “We can now connect Thailand to parts of Australia, a really exciting discovery.”
This region was on the outskirts of Gondwanaland, an ancient supercontinent that included Africa, India, Australia, South America, and Antarctica at the time of the trilobites.
“Because continents shift over time, part of our job has been to work out where this region of Thailand was in relation to the rest of Gondwanaland,” Hughes went on to say. “We’re attempting to put together a moving, shape-shifting, 3D jigsaw puzzle.” This discovery will assist us in doing so.”
Consider the species named after Royal Princess Sirindhorn. The species was named in honor of the princess for her unwavering commitment to the advancement of science in Thailand. “I also thought this species was regal.” Wernette described it as having “a broad headdress and clean sweeping lines.”
Researchers will be able to say that closely related Tsinania species found in northern and southern China are roughly the same age if they can get a date from the tuffs containing her namesake species, Tsinania sirindhornae, and determine when they lived.
Finally, the researchers believe that the images of the ancient world hidden in the fossils they discovered contain invaluable information for the modern world.
