Geologists Search for Clues to Dinosaurs’ Extinction
DUHOK—Many unanswered questions swirl around the extinction of dinosaurs. One of the most significant is: How did life bounce back? Researchers are studying rocks in Northern Iraq in hopes of finding out.
“I’m interested in the line between when dinosaurs existed and when they didn’t,” says Abdulrahman Bamerni, an assistant lecturer in the department of applied geosciences at the University of Duhok.
Specifically, he’s looking for a perfect cross section of rock with uninterrupted layers stacked on top of each other from both the Cretaceous and Tertiary periods. Between these prehistoric time stamps, about 65 million years ago, a mass extinction event occurred.
Dinosaurs lived just about everywhere in the world, including the Middle East and North Africa, but the mass extinction event wiped out millions of species regardless of their size or habitat. (See a related article, “Egyptian Team’s Dinosaur Find Is a Long-Sought Link.”)
Land dinosaurs became extinct and so too did sea creatures. Even plankton, tiny organisms at the bottom of the oceanic food chain, perished in large numbers. Approximately 75 percent of plant and animal species on Earth were lost, and it spelled the end of the dinosaurs.
Bamerni hopes to find a rocky cross section to further our understanding of what happened.
“The line should be continuous between the two periods because I’m interested in how life came back again and flourished,” he says.
Bamerni has recently returned from Urbino University in Italy where he was testing the age range of a cross section of rock he discovered near Duhok, close to the Turkish frontier in Iraqi Kurdistan.
“I couldn’t do it in Iraq because I don’t have the tools,” he says. “We don’t have electron-scanning microscopes here in Duhok.”
In Italy, Bamerni also measures the mass of atoms within the rock—in a process known as isotope analysis—to provide a highly accurate time stamp.
Bamerni has developed an eye for a good rock sample.
“I consider myself a rock ‘reader,’” he says.
Within the rock there are certain index fossil species that he looks for that can help to roughly gauge the age of a sample. “It’s enough to sort through potential samples for a good candidate,” says Bamerni. But it’s not until he gets the rock to Italy for a comprehensive analysis that he can be sure.
He had been hopeful that his latest cross section was a contender to bridge the two periods before he left for in Italy.
Unfortunately, the sample turned out to be lacking, but Bamerni is undeterred because other scientists have found complete samples in nearby Iran and Turkey.
“I will eventually find a complete cross section,” he says.
The Perfect Cross Section
It takes time and perseverance to find the perfect cross section, says Rund Hammoudi, a professor in the department of applied geosciences at the University of Duhok.
“It’s difficult because you need a fresh sample with no soil contamination and with uninterrupted layers of rock from sub-ages with the Cretaceous and Tertiary periods,” she says. “Kurdistan is the best place in Iraq to study this because the cross sections are above ground.”
While some unbroken cross sections of rock connecting the two periods have already been discovered in various locations, more are needed to offer definitive answers—especially if they come from different parts of the world.
The best example of a Cretaceous-Tertiary (K-T) boundary cross section is in northwestern Tunisia, close to the Algerian border. Known as the El Kef section, it is 55 centimeters thick and has a continuous layering of rock sediments from the correct time periods with a well-preserved stock of microfossils within them.
Named after the town close to the discovery site, the El Kef section was designated by an assembly of international geologists in 1989 as the standard by which other K-T boundary samples are judged.
Geologists and paleontologists are debating how life could rebound after the extinction event. There is also a question of whether the extinction was caused by a gradual environmental change or a catastrophic event such as a meteorite—although many now believe it was the latter.
It’s important to answer these questions not just for academic curiosity, says Hammoudi. “What happened and when matters because it contributes to mineral and oil investigations,” she says. “It could have economic implications.”
Some scientists believe that the earth could be headed for another mass extinction, possibly caused by climate change, human overcrowding and habitat destruction. “What happened then could happen now,” says Hammoudi.
The more we know about previous extinction events, the better equipped we will be to save species in the future.