They say cockroaches will be the last species standing when (fill in the apocalyptic nightmare of your choice.) Now scientists say that roaches were alive and being disgusting in the great primordial landmass of Pangaea over 300 million years ago, before the different continents even formed and split.
Ergo, the forefathers of the bug that sampled your sandwich before you did were alive and scuttling eons before the first dinosaur staggered to its scaly feet.
The conclusion resulted from a vast genomic study of existing roaches and calculation of their evolutionary clock published in Molecular Biology and Evolution by Dr. Thomas Bourguignon, now at the Okinawa Institute of Science and Technology, with an international group.
The research concluded that the roach originated at least 300 million years ago, when dry land on the planet was concentrated in a single mass called the Pangaea supercontinent.
As continental drift split Pangaea into continents, the descendants of these early roaches traveled with them, populating the newly sundered monster islands with about the same efficiency they populate our plates. And thus roaches spread to every corner of the globe, where they were fruitful and multiplied.
The cockroach supermodel
Actually, what the scientists wanted was to tap the roach as a model to test hypotheses of how new species get created through physical separation of an original population. While about it, they created new order in the cockroach families and a new timescale for the insects’ evolution, based on the genetic analysis of 119 of the thousands of existing cockroach species.
To put things into proportion, the Pangaean cockroaches would have predated the oldest-known dinosaur, Nyasasaurus parringtoni of Tanzania, which looks rather like a velociraptor, by around 50 million years.
Most species that existed 300 million years ago are long gone. So is the original cockroach. But based on their results, the scientists believe that the last common ancestor of today’s cockroaches appeared around 235 million years ago, which was before Pangaea began to break up. By the fossil record, the last common roach ancestor lived 140 million years ago.
Since Pangaea’s breakup, the various cockroach lineages diversified and evolved on their respective continents, resulting in thousands of species today, from the humble Israeli flying roach to the Madagascar hissing roach and so many, many more.
“Our results indicate that extant cockroach families evolved over periods of up to around 180 million years,” said Bourguignon. “Through reconstructions of the ancestral distribution of cockroaches using the known distributions of extant genera sampled in this study, we found evidence that continental breakup has had important impacts on cockroach biogeography.”
One wonders if roaches couldn’t have spread otherwise. The scientists point out that the things can’t fly very well or very far, ergo they would generally be confined to whatever continent was housing them (they would be “terrestrially bound”).
Given that the roach began evolving hundreds of millions of years ago, and given the existence of the many sister lineages, the scientists speculate that continental drift was key to the development and distribution of the insects we know and loathe today. And the Israeli version is large and it can fly.
Some 300 million years ago, according to a fossil found in Ohio, roaches were about 3.5 inches long. Some tropical roaches living today can reach sizes like that. Most are smaller, for which existing humans are thankful.
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