By Justin Isherwood

Our gut sense of the extinction business is this is where the screen goes dark. Not even a test pattern.

Evidence suggests five mass extinctions have punctuated our planet’s history, some more extensive than others, as an incident 250 million years ago when an estimated 96 percent of marine animals died along with 70 percent of the land animals.

These five extinctions, called the Big Five by doomsday fans are in order – the End Ordovian, Late Devonian, End Permian, End Triassic, and End Cretaceous – all within the last 540 million years, with the End Cretaceous occurring in our relative neighborhood of 65-66 million years ago.

Science, being the sport it is, some claim at least 20 extinction episodes have been part of our planetary and evolutionary history, including the Great Oxygenation of 2.45 billion years previous. When the planet’s atmosphere was converted to oxygen, the result of photosynthesis by cyanobacteria. A life form whose waste stream was oxygen, and their toxic industrial pollutant has been our heritage ever since.

The Cretaceous Extinction was a comparative comely event when a 6.8 to 50.3 mile wide asteroid plowed into the Gulf of Mexico off the Yucatan Peninsula, its ocean floor Chicxulubcrater, at 93 miles wide, 12 miles deep, was mapped in 2016. One of the more entertaining scenarios of the Cretaceous episode predicates a spectacular aftermath, when igneous material ejected by the meteor re-entered the earth’s atmosphere raining fire on the mid-latitudes, violently heating both ocean and land surfaces that burned off forest cover instantaneously, clouding the sky so completely that photosynthesis failed. Technically, this qualifies as a bad day.

So ended the domain of the Great Saurs.

Only to hook the actors, drop the curtain. Close the Book. Life on Earth, kaput.

Yet we know the End Cretaceous didn’t close the Book of Life on planet Earth. Extinction though it surely happened, was also the opportunity to reconfigure and redesign. Some of those dinosaurs survived, the ones we know yet, avian dinosaurs, more familiarly, birds. The natural question is, how come?

Ferns were not deterred. Why remains a curiosity.

The most common bird/dinosaur fossil of the Cretaceous period was tree dwelling, none of whom survived. Suggestion being, their habitat didn’t either. The birds that did survive shared certain traits, their legs for one. Ground dwelling birds have different legs than tree dwelling birds, to the end more adaptable to a landscape absent trees.

Investigation has found ground dwelling birds had a somewhat bigger brain case, presumably to fit a somewhat bigger brain. The hint here being that survival against pretty substantial odds is a brain function, and these particular birds had a survival edge in both their habitat and their brains.

New Yorker science author Elizabeth Kolbert, in her book “The Sixth Extinction: An Unnatural History,” writes that a sixth extinction event is underway, where 20-30 percent of Earth’s species are facing extinction with climate change. Oddly, the concept of mass extinction is a relatively recent innovation of science, despite Biblical hints of fire and brimstone. Charles Darwin, his holiness, Mister Evolution Himself, thought species extinction was a ridiculous notion. Charlie did not believe in wholesale cataclysm.

Enter Luis/Walter Alvarez and their breakthrough discovery of the KT layer (1981) and an asteroid impact affecting the whole planet. Cataclysm, it seems, just became a verb.

Extinction is one of those God principles, where if you are willing to think like some slightly amused spectator, extinction is not really so bad. Besides being quite entertaining. Nothing 100 million years can’t fix. At which point extinction is just an interesting plot development of every script writer.

Besides, extinction adds drama, upgrades the scenery, and gives minorities a chance to play in the major leagues. It was about here, at extinction, that certain rodent mammals got a chance at stage center, some of whose mammals ended up as humanity. Life, even in cataclysm, somehow survives; just not so cool for the actors who just get written out of the script

Watching birds comes with a certain cosmic comfort. These latter-day dinosaurs, with legs and brains enough to figure out survival. To suggest on the issue of climate change, the theme is brains.