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.
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.
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).
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.
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).
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.
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.
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.
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”.
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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• 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.