Tardigrades are a diverse group of microinvertebrates widely known for their remarkable ability to survive. Molecular clocks suggest that tardigrades diverged from other panarthropods (arthropods, tardigrades, velvet worms, and lobopods) before the Cambrian, but the fossil record is extremely poor. Now, paleontologists have described a new species of tardigrade and redescribed previously known species. readBoth are from Canadian Cretaceous amber.
Artistic Restoration read (Top) and Aerobius dactylus (Bottom) A hypothetical fossilization environment. Image courtesy of Franz Anthony.
First discovered in 1773, tardigrades are a diverse group of microscopic invertebrates best known for their ability to survive in extreme environments.
Also known as tardigrades or moss pigs, these creatures can live up to 60 years and grow to a size of up to 0.5mm. They are best seen under a microscope.
They can survive up to 30 years without food or water, and can survive temperatures as low as -272°C and as high as 150°C for a few minutes, and as low as -20°C for decades.
Tardigrades can withstand pressures ranging from nearly zero atmospheres in outer space to 1,200 atmospheres at the bottom of the Mariana Trench, and can also tolerate radiation levels of up to 5,000-6,200 Gy.
They survive by entering a state of suspended animation called biostasis, using proteins that form a gel inside the cells and slow down vital processes.
“Tardigrades are microscopic invertebrates characterized by a compact body shape with lobopod legs with four pairs of claws, and are closely related to the clawed pterygota and euarthropods. Panarthropods“Harvard doctoral student Mark Mapalo and his colleagues said:
“Tardigrades are widely known for having several species with cryptobiotic capabilities that allow them to survive extreme conditions such as the vacuum of space, ionizing radiation and freezing temperatures. Tardigrades are also found in marine, freshwater and terrestrial habitats around the world.”
“Despite their ubiquity in the modern biosphere, tardigrades have a notoriously poor fossil record, and research into their macroevolution, such as the origin of their body shape, the timing of their terrestrialization, and the acquisition of their cryptic abilities, is limited.”
“Currently, only four fossil crown-group tardigrades are known, all preserved as amber inclusions, but only two of these have an established taxonomic position relative to extant tardigrades.”
Aerobius dactylusImages/Photos: Mapalo others., doi: 10.1038/s42003-024-06643-2.
For the study, the authors looked at a piece of amber containing a tardigrade fossil that was discovered in Canada in the 1960s. read and what was presumed to be another tardigrade, which was virtually unexplained at the time.
Using confocal laser scanning microscopy, a technique commonly used to study cell biology, the researchers were able to examine the microscopic structure of the tardigrade fossils in astonishing detail.
This study read It has been identified as a new species in the Tardigrade family tree, Aerobius dactylus.
“Both were found in the same Cretaceous amber, which means that these tardigrades coexisted with dinosaurs,” said Dr Javier Ortega-Hernández of Harvard University.
” read The seven claws are well preserved, and those that curve towards the body are smaller than those that curve away from it, a pattern seen in modern tardigrades.”
“The second, previously unidentified specimen had claws of equal length on each of the first three pairs of legs, but the outer claws on the fourth leg were longer.”
Both species serve as important calibration points for an analysis called a molecular clock analysis, which helps scientists estimate important evolutionary timing.
For example, new research suggests that modern tardigrades likely branched off during the Cambrian period, more than 500 million years ago.
The study also sheds light on the origins of tardigrades' remarkable ability to survive extreme environments by entering a state of torpor.
“This study estimates that this survival mechanism likely evolved during the middle to late Palaeozoic and may have played a key role in helping tardigrades survive the end-Permian mass extinction, one of the most severe extinction events in Earth's history,” Dr Ortega-Hernández said.
of result Published in a journal Communication Biology.
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MA Mapalo others2024. Inclusions in Cretaceous amber shed light on evolutionary origins of tardigrades. Communication Violet 7, 953; doi: 10.1038/s42003-024-06643-2
Source: www.sci.news
