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A pair of 99 - million - twelvemonth - old cockroaches are rewriting the early story of the underworld .
The ancient roaches , find preserve in gold in Myanmar , are the oldest - have it off examples of " troglomorphic " organism — creatures that conform to the eldritch , dark surround of cave . And they ’re the only such dark - adapted creatures known from theCretaceous period , having scurried around in the world ’s shaded crevices even asTyrannosaurus rexwalked theEarth . Nowadays , biologist haveplenty of instance of cockroachesand of cave - dwelling insects with small eyes and wing , pallid body , and foresightful arms and feeler . But these specimens , from two decided , related mintage , are the old animate being ever found with those traits .
One of the ancient cockroaches is pictured preserved in its amber grave.
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" cave lack definitive fossils before theCenozoic , " the researchers wrote in a newspaper publisher describing their breakthrough , come to to a later period after the mass experimental extinction ( known as the K / Pg boundary ) when dinosaurs died and mammals rose to their current gibbosity .
And even cave fossil from after the extinguishing lean to be of animate being that spent only some of their meter in caves , using them as shelter in between expedition into the sunstruck world .
" Cave environments are well suitable for fossilization of castanets and coprolite [ or fossilized feces ] and the fogey record of cave mammal include rodents , ungulates , marsupials , ursids , felid , hyaenids , canine , order Primates and humans , " they wrote — all species with mint of castanets and poop . They add that " there is no relevant fossil record of any troglomorphic fauna before K / Pg with the exception of the present uncovering . "
Until now , the history of cave - dwelling cockroaches was be intimate to go back to theCenozoic era , which lead off about 65 million old age ago . But investigator had long suspected that cave - lie in roach might date stamp back to the dinosaur eld , the researchers wrote , based on transmitted analysis . But there had never before been firm evidence .
These two " exquisitely preserved " species , they say , according toa news article on Phys.org , were probable descendant of a plebeian root from earlier in the Cretaceous , before continental drift differentiate their homes on the supercontinent Gondwana .
It ’s not clear , the researchers note , how the roaches ended up so well preserved . Amber fogey are common forsmall creatures that live near tree , because amber is fossilized tree resin . It ’s possible , the researchers suggested , that ancient rosin dripped from tree diagram root word into the cockroaches ' caves and then harden around the paleo - arthropods .
The study researchers , hailing from several institutions in Slovakia , China , Russia and Thailand , detail their discovery online Feb. 11 in the journalGondwana Research .
Originally published onLive Science .
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