Prehistoric cockroaches found preserved in amber
Cockroaches are one of the most resilient creatures on the planet and may be the animal that outlives us all.
An international team of scientists have discovered a pair of 99-million-year-old cockroaches, now thought to be the oldest known animals uniquely adapted to living in caves (troglomorphic organisms).
According to a study published in the journal Gondwana Research, these cockroaches are helping to rewrite the early history of cave life.
The pair were found perfectly preserved in amber in a mine in the Hukawng Valley in Myanmar. It is understood that these creatures were the only ones able to survive living in the darkness of caves during the Cretaceous period.
Despite many examples of cave-dwelling insects available, these specimens - of two different, but related species - are the oldest animals ever found with the features that demonstrate they were cave dwellers.
The researchers explain: "Caves lack unmistakable fossils before the Cenozoic period (which began approximately 65 million years ago), meaning that this discovery is hugely important.”
The two cockroach specimens have been named Crenocticola svadba and Mulleriblattina bowangi. According to experts they have many similar characteristics to modern cave-dwelling cockroaches, including small eyes and small wings attached to equal-sized bodies.
Researchers believe that they fed on dinosaur faeces (just as modern cockroaches feed on the droppings of bats and birds).
"Cave environments are well suited for fossilisation of bones and coprolites (also known as fossilised faeces). The fossil record of cave mammals includes a plethora of rodents, ungulates, marsupials, cats, hyenas, canidae, primates and humans - no relevant fossil records from troglomorphic fauna, up until now.
These two incredibly well-preserved species are probably descendants of a common ancestor from the early Cretaceous, before the continental drift separated their homes in the supercontinent Gondwana that existed from the Neoproterozoic until the Jurassic period.
In terms of how the prehistoric creatures found themselves embedded in amber - the researchers remain unsure.
Amber fossils are common for small creatures that live near trees, because amber is fossilised tree resin. One of the theories suggests that resin could have seeped from tree roots in the caves where the cockroaches were located - meaning they were trapped there forever.
Did these species survive the mass extinction event that wiped out the dinosaurs? This is what scientists are currently attempting to find out.
Perhaps the jokes about cockroaches surviving an apocalypse are more true to life than you might have thought...
References
Hemen Sendi et al. Nocticolid cockroaches are the only known dinosaur age cave survivors, Gondwana Research (2020). DOI: 10.1016/j.gr.2020.01.002
Vršanský, P. and Bechly, G. (2015): New predatory cockroaches (Insecta: Blattaria: Manipulatoridae fam.n.) from the Upper Cretaceous Myanmar amber, Geologica Carphatica, 66(2), 133-138. doi: https://doi.org/10.1515/geoca-2015-0015
