A living species of aquatic beetle found in 20-million-year-old sediments

A living species of aquatic beetle found in 20-million-year-old sediments
General view of the modern Helophorus sibiricus and its newly discovered Early Miocene fossil counterpart. The close-ups show the species-specific granulation of the pronotum in both the recent specimen (top) and the fossil (bottom), one of the characteristics that allowed a reliable identification of the 20-million-year-old specimen. Credit: Martin Fikáček

The fossil beetle discovered in the 16-23 million years old sediments of the Irtysh River in southern Siberia belongs to the modern species Helophorus sibiricus, a member of the water scavenger beetles (Hydrophiloidea), which is at present widely distributed in Eurasia and reaches even North America. The species was originally described in 1860 by the Russian entomologist Victor Motschulsky based on specimens collected at Lake Baikal. It is aquatic and inhabits various kinds of standing waters, predominantly the grassy temporary pools. Larvae are unknown so far, but are supposed to be terrestrial and predaceous, preying on various invertebrates, as in most other species of the genus.

The Siberian fossil provides new data for the long-lasting debate among scientists about the average duration of an . It was originally estimated to be ca. 2-3 million years based on the available , but slowly accumulating data begin to show that such an estimate is an oversimplification of the problem. Recently, evolutionary trees dated using molecular clocks suggested that some insect species are rather young, originating during the Ice Ages, but others may have been able to survive the last 10-20 million years until today. The long-living species had to survive the massive changes of the Earth's climate during the last millions of years - how they managed to do so is another question for scientists to address.

A living species of aquatic beetle found in 20-million-year-old sediments
Fossil and recent distribution of Helophorus sibiricus: the red dot indicates the locality on which the early Miocene fossil of this species was found, blue dots indicate the Pliocene and Pleistocene records based on beetle remnants found in peat bogs and permafrost. Credit: Martin Fikáček

A large missing piece for the acceptance of long-living insects as a general phenomenon and for understanding the reasons for survival of the particular species is the scarcity of the fossils of such species. The reasons seem to be rather straightforward – the majority of the fossils bear too few details to allow a detailed comparison with living species, whose taxonomy is often based on the shape of male genitalia and other details. That is why the fossil discovered by the Czech-Russian-British team is so important: it bears enough details to allow its detailed comparison with the living species. Although the genitalia are not preserved in the fossil, the scientists were lucky that Helophorus bear species-specific granulation on the pronotum which was readily seen on the fossil and allowed its reliable identification.

A life-style associated with an environment which remains stable over time, such as rotten wood, has been suggested as one of the possible ways in which long-living species may have survived from the past. The discovery of a long-living species of an aquatic beetle may indicate that temporary pools in which Helophorus sibiricus is mainly living today may be another example of such a stable environment – it is really not difficult to imagine that the conditions in a pool created in a modern grassland from the melting snow are very similar to those one would have found in such a pool 20 million years ago.

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More information: Fikáček M, Prokin A, Angus RB (2011) A long-living species of the hydrophiloid beetles: Helophorus sibiricus from the early Miocene deposits of Kartashevo (Siberia, Russia). ZooKeys 130: 239-254. doi: 10.3897/zookeys.130.1378
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Citation: A living species of aquatic beetle found in 20-million-year-old sediments (2011, October 6) retrieved 18 July 2019 from https://phys.org/news/2011-10-species-aquatic-beetle-million-year-old-sediments_1.html
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Oct 06, 2011
There are numerous million year old fossils that have names differing radically from their modern counterparts, thus making it very hard to link the two together unless one happens to have photos of both available simultaneously. What this implies is that most living species can be found in the fossil record - alongside dinosaurs. All in the same level, some even preceding those of their supposed ancestors.

Evolution remains a mythical pipe dream, and will remain so for as long as people refuse to accept the common sense that indicates quite clearly that living organisms were created [ and that in the general forms we encounter today]. It's impossible to happen by random physical processes - the specifications are simply too complex for chance.

Oct 06, 2011
kevinrtrs... what this implies is that you are pathetic...

Get away from science sites

Oct 06, 2011
kevinrtrs, no one want to read your ignorant messages here. Its a site about SCIENCE.
Please, go to conservopedia

Oct 06, 2011
What this implies is that most living species can be found in the fossil record - alongside dinosaurs. All in the same level, some even preceding those of their supposed ancestors.

Most living species? Really? Cats? Polar bears? any modern mammal or bird buried close to a dinosaur? No, not one. Not even a crockaduck. You really embarrassed yourself this time.

Oct 06, 2011
I call "shenanigans" on the headline.

Yes, I know what they meant, but still... the headline could easily be read to imply a "lungfish times a million" feat of individual longevity.

Which would have been tres cool, frankly. And a bit scary.
I figured the movie version would be next summer's big, big hit.

Oct 07, 2011
Kevin, I'm sure it will be very easy to post references supporting your argument. I'll take a lack of references as evidence that you are wrong.

Oct 07, 2011
Uh dinosaurs weren't around 1 million years ago.

The dinosaur issue is an especially tough one for Religionists. Was the ark not large enough to fit them? Were they too ugly to save? Are they still here somewhere, like the amazon or loch ness or in a vast cave under the Mediterranean, and we just haven't found them yet?

Kev seems to be implying that scientists gave allosaurs and diplodocii different names so we wouldn't confuse them with hippos and crocodiles that prefer walking on their hind quarters. Was the plesiosaur a soft-shelled turtle? The mosasaur a big barracuda? This requires some thought (or a trip to the creation museum before it goes out of business).

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