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Researchers describe a new tardigrade fossil found in Domincan amber 16 million years ago

An artistic reconstruction of Paradoryphoribius chronocaribbeusgen. etsp. In November moss.Credits: Original art created by Holly Sullivan

Tardigrades, also known as tardigrades, are a diverse group of charismatic microscopic invertebrates, best known for their ability to withstand extreme conditions. A famous example was the 2007 space travel, in which tardigrades were exposed to space vacuum and harmful ionized solar radiation and were able to survive and regenerate after returning to Earth. Tardigrades are found on all continents of the world in a variety of environments, including marine, freshwater, and terrestrial.


Tardigrades survived all five Phanerozoic mass extinction events, but the earliest modern tardigrades are known only from the Cretaceous, about 80 million years ago. Despite their long evolutionary history and global distribution Tardigrade The fossil record is very sparse. Due to their microscopic size and non-biomineralized bodies, tardigrades are unlikely to fossilize.

In a treatise published on October 6th Bulletin of the Royal Society B Researchers describe new tardigrade fossils that represent new genera and new species. In this study, a confocal laser scanning microscope was used to obtain high-resolution images of important anatomical properties useful for phylogenetic analysis to establish the taxonomic arrangement of fossils.

New fossil Paradoryphoribius chronocaribbeus The third tardigrade amber fossil has been fully described and officially named so far.The other two fully described modern tardigrade fossils Milnesium swolenskyi When Beorn leggi, Both are known from the Cretaceous amber of North America. Paradrifolibius Is the first fossil embedded in the Miocene (about 16 million years ago) and the first fossil to represent the tardigrade superfamily Isohypsibioidea.

Phillip Barden, co-author of the New Jersey Institute of Technology, introduced the fossils to lead author Dr. Mark A. Maparo. Professor Javier Ortega Hernandez, a candidate and senior author of the Department of Bioevolutionary Biology at Harvard University. Baden’s lab discovered the fossil and worked with Ortega Hernandez and Maparo to analyze the fossil in detail. Maparo, who specializes in bear beetles, led the analysis of fossils using a confocal microscope at Harvard University’s Center for Biological Imaging.

“The difficulty with handling this amber specimen is that it’s too small to dissect the microscope. We needed a special microscope to see the fossils completely,” said Maparo. In general, the light transmitted by an anatomical microscope works well to reveal the morphology of larger inclusion bodies such as amber insects and spiders. Paradoryphoribius, However, the total length of the body is only 559 micrometers, or just over 0.5 millimeters. On such a small scale, anatomical microscopes can only reveal the external morphology of fossils.

Researchers describe a new tardigrade fossil found in Domincan amber 16 million years ago

Left) Side view of Paradoryphoribius chronocaribbeusgen. etsp. November Viewed under a stromo microscope with transmitted light (top) and under a confocal laser microscope with autofluorescence (bottom). Right) Ventral view of Paradoryphoribius chronocaribbeusgen. etsp. November Viewed under a stromo microscope with transmitted light (top) and under a confocal laser microscope with autofluorescence (bottom). Credit: Marc A. Mapalo

Fortunately, the cuticle of the bear beetle is made of chitin, a fibrous glucose substance that is the main component of the fungal cell wall and arthropod exoskeleton. Chitin is fluorescent and easily excited by a laser, so confocal laser scanning microscopes can be used to fully visualize fossils of Kumamushi. Using a confocal laser scanning microscope instead of transmitted light, study the degree of fluorescence produced by the fossil, allowing a clearer view of the internal morphology. In this way, Maparo was able to fully visualize two very important features of fossils, the claw and oral apparatus, or the animal’s foregut, also made of cuticles.

“It looked like a modern tardigrade on the outside, but with a confocal laser scanning microscope, it has this unique foregut tissue, New genus Within this extant tardigrade superfamily group, “Maparo said.Paradrifolibius It is the only genus in the superfamily Isohypsibioidea that has this particular unique character arrangement. “

“Tardigrade fossils are rare,” said Ortega-Hernández. “In our new study, the complete tally includes only four specimens, only three of which are formally described and named. Paradrifolibius.. This treatise basically covers one-third of the known tardigrade fossil records. Moreover, Paradrifolibius The entire fossil record provides the only data on the tardigrade oral device. “

The authors state that amber tardigrade fossils have a strong conservation bias. Small size And habitat preferences. Therefore, amber deposits provide the most reliable source of information for finding new tardigrade fossils, but that does not mean that finding them is an easy task. The discovery of fossils of Kumamushi in Dominica’s amber suggests that fossils of Kumamushi may also be lurking in other frequently sampled areas, such as Burmese and Baltic amber deposits. I am. Historically, small inclusions as small as tardigrades are hard to see and require very good observation skills and expertise, so amber tends to have large inclusions.

“Scientists know where the tardigrade fits widely in the tree of life, is related to arthropods, and has a deep origin during the Cambrian explosion. The problem is the name. There is this very lonely gate with only three fossils with “Hmm,” said Ortega-Hernández.

“If you look at the external morphology of the tardigrade, you might think that there was no change inside the tardigrade, but if you use a confocal laser scanning microscope to visualize the internal morphology, it’s a range of species. Observed in fossils, this helps to understand what changes have occurred in the body over millions of years, even if the tardigrades are the same externally. It suggests that some changes are happening internally. “

Mapalo and Ortega-Hernández continue to study other amber-colored Kumamushi using confocal laser microscopy technology in the hope of expanding the fossil record of Kumamushi.


New tardigrade Macrobiotus shonaicus sp. November Specified in Japan


For more information:
Dominican amber tardigrade, Bulletin of the Royal Society B (2021). rspb.royalsocietypublishing.or… .1098 / rspb.2021.1760

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Harvard University

Quote: Researchers are 16 million years old Domincan Amber (2021) obtained from https://phys.org/news/2021-10-tardigrade-fossil-million-year-domincan.html on October 5, 2021. Explains the new tardigrade fossils found in (October 5, 2014)

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Researchers describe a new tardigrade fossil found in Domincan amber 16 million years ago

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