Digging into planet’s history reaps rewards
News of a marvel took me to the palaeontology labs of the University of Kansas recently. There I found myself looking at the fossilised bones of an ancient paddlefish.
What had me thunderstruck were the tiny beads of glass caught in its gill rakers, which suggest that the creature perished while gasping for air as fire rained from the sky.
The composition of those beads, or tektites, further suggests that they were formed when a massive asteroid slammed into the Earth with the force of 10 billion Hiroshimas and ended the Cretaceous period.
In other words, I was looking at a recording in rock of the moment when life nearly ended on Earth, arguably the biggest single event in our planet’s living history.
This fish is one of a trove of fossils discovered by University of Kansas graduate student Robert DePalma at a site in North Dakota. Should the site prove to contain all that DePalma claims, it is among the most important finds in history.
DePalma’s thesis adviser, David Burnham, showed me the fish and other artefacts entombed in the fallout from the so-called Tanis site. A decorated veteran of the academic battlefield, Burnham appeared unworried that some scientists have expressed doubts about the extravagant claims.
‘‘We will be making the case in a number of papers over the next few years, and people will see what we’ve found,’’ said Burnham.
It’s all there, he assured me: evidence of catastrophic flooding unleashed by seismic waves, of pulverised bedrock falling like hail, of forests burning in a worldwide conflagration, of early mammals huddling in their burrows as dinosaurs died aboveground. He reiterated that
scientists will be unpacking the treasures of Tanis for a halfcentury.
One of the astonishments of these times is just how large a half-century has become. A young palaeontologist working the same sparse land 50 years ago could have unearthed this fossil bed without the knowledge necessary to read its amazing story.
The Apollo missions to the moon had just awakened the scientific community to the idea of space as a sort of shooting gallery in which the Earth was the target of frequent incoming shots.
The father-and-son team of Luis and Walter Alvarez had not yet argued that a band of ash heavy in iridium, a rare metal found in space debris, had coated the Earth roughly 65 million years ago (science would later narrow the date to about 66 million years ago).
Alan Hildebrand and William Boynton had not yet pinpointed the Chicxulub crater in what is now the Yucatan Peninsula as the impact site of a giant asteroid or comet.
Indeed, only in 2010 did a panel of scientists weigh in to say, based on core samples of the crater, that an impact some
66 million years ago sent shock waves through the planet, raining fire and coating the Earth in ash. This catastrophe marked the end of the age of dinosaurs, extinguishing some
95 per cent of all species and clearing the way for the rise of mammals.
It’s all part of the advance of science, which has accelerated from a march to a gallop. Technology and globalisation may rattle economies and inflame politics, but they are astonishing accelerators of discovery. I could see this in Burnham’s face as he described the dinosaur plumage unearthed at Tanis – feathers made readily comprehensible thanks to the discovery in the 1990s of exquisite feathered fossils at Liaoning, China.
Within a short time, he said, scanning electron microscopes will access traces in the fossils that reveal the precise colours of those long-dead ancestors of today’s birds.
Scientists will be unpacking the treasures of Tanis for a half-century.
A tangled mass of fish from the deposit in North Dakota’s Hell Creek formation.