The tardigrade specimen under a stereomicroscope, side view. Credit: Ninon Robin

Rare Tardigrade Specimen Found Trapped in 16 Million-Year-Old Amber

To study this particular fossil, scientists had to use imaging techniques commonly used in cellular and molecular biology. The size of the animal is no more than 600 micrometers which is too small to be examined under a microscope.

Scientists have described a new species of tardigrades – Paradoryphoribius chronocaribbeus: this is the only known “water bear” that lived in the Cenozoic. The tardigrade specimen is about 16 million years old and is only the third-ever fossilized representative of these tiny animals. 


Scientists found a Tardigrade specimen in 16 million-year-old amber: Everything you need to know

What is a tardigrade?

Tardigrades are microscopic invertebrates famous for their amazing ability to survive in extreme conditions, for example, even when falling to the surface of another celestial body. They separated from other lines of the invertebrate taxon from the group of Protostomes Panarthropoda in the Precambrian period.

Fossils are rare

Despite the long history of evolution and presence in both aquatic and terrestrial environments, scientists rarely got the chance to study the fossils of “water bears” and early representatives of this group – only twice.

The new Tardigrade specimen under different microscopes. Credit: Mark A. Mapalo
The new Tardigrade specimen under different microscopes. Credit: Mark A. Mapalo

Oldest Tardigrade specimen

The first was Beorn leggi, a 78 million-year-old fossil tardigrade discovered in amber from secondary sediments along Lake Cedar in the Canadian province of Manitoba and described back in 1964.

Second specimen

The second is Milnesium swolenskyi, preserved in amber from New Jersey, which was attributed to the Upper Cretaceous (that is, about 14 million years older than Beorn leggi).

Dominican amber containing Paradoryphoribius chronocaribbeus as well as three ants, a beetle and a flower, compared to a dime. Credit: Phillip Barden
Dominican amber containing Paradoryphoribius chronocaribbeus as well as three ants, a beetle, and a flower, compared to a dime. Credit: Phillip Barden

16 million-year-old Tardigrade specimen

The team of Mark Mapalo of the New Jersey Institute of Technology managed to describe the third-ever fossil of a representative of these tiny animals – from amber discovered in the Dominican Republic and dated to the Miocene era, about 16 million years ago.

New species

The tardigrade, which was attributed to the new species Paradoryphoribius chronocaribbeus, is the first fossil representative of the diverse superfamily Isohypsibioidea, and also from the Cenozoic era (began about 66 million years ago, after the Cretaceous-Paleogene extinction).

Claws of Paradoryphoribius chronocaribbeus. Credit: Phillip Barden
Claws of Paradoryphoribius chronocaribbeus. Credit: Phillip Barden

Too small to be examined under a microscope

Armed with confocal scanning microscopes, the scientists conducted a detailed analysis of the tardigrade with a body length of no more than 600 micrometers. “The difficulty was that this amber sample was too small to be examined under a microscope, so we needed special equipment to examine the fossil in detail,” explained Mapalo.

Characteristics

It was possible to visualize the tardigrade thanks to the thin and flexible cuticle that covers the body of the animal: it consists of chitin, one of the most common polysaccharides in nature. This fibrous substance acts as the main component of the cell walls of fungi and arthropod exoskeletons and also fluoresces.

Side view of the tardigrade specimen. Credit: Phillip Barden
Side view of the tardigrade specimen. Credit: Phillip Barden

Not too different from modern species

According to scientists, this ancient species does not differ from modern tardigrades at first glance. Yet, they found some distinctive features that are not seen in the most common species. Further research will help understand the evolution and changes that have occurred over millions of years.

Amber deposits

The fact that such an ancient and widespread group of multicellular organisms has a meager fossil record shows the problems associated with the study of tardigrades. According to scientists, amber deposits are the most reliable source for the search for new fossils of these amazing little “water bears”.

Research technologies

Due to their tiny size, it is not so easy to see them in a mineraloid, but new technologies should help in this. To study this particular fossil tardigrade, scientists had to use imaging techniques commonly used in cellular and molecular biology.


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Sources:

Kooser, A. (2021, October 6). ‘once in a generation’ discovery: Tardigrade fossil found in 16-million-year-old amber. CNET.
Lanese, N. (2021, October 5). Tardigrade trapped in amber is a never-before-seen species. LiveScience.
Mapalo, M. A., Robin, N., Boudinot, B. E., Ortega-Hernández, J., & Barden, P. (2021, October 6). A tardigrade in Dominican amber. Proceedings of the Royal Society B: Biological Sciences.
Starr, M. (n.d.). Incredibly ancient tardigrade from 16 million years ago is like a ghost across time. ScienceAlert.

Written by Vladislav Tchakarov

Hello, my name is Vladislav and I am glad to have you here on Curiosmos. My experience as a freelance writer began in 2018 but I have been part of the Curiosmos family since mid-2020. As a history student, I have a strong passion for history and science, and the opportunity to research and write in this field on a daily basis is a dream come true.

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