archeology

Via The Earth Story:

The cave has already been used in research on Saharan dust transport across the Atlantic since its depths make an ideal sediment trap, and now new work has confirmed the inference from other sources that the Maya civilisation fell after a series of long droughts. They used a series of sediment samples from the epoch of their demise (around 800-1000 CE) and compared the changing ratios of aluminium and titanium, which reveal periods of heavy rainfall from tropical cyclones (the source of most of the water that kept the Mayans alive).

These indicated several long periods of drought at the time of their slow downfall that eked out over two centuries as the inter tropical convergence zone shifted north and south, taking the rain giving cyclones with it. The science is simple, in times of greater rain, more of the volcanic rocks in the area are weathered, and the water flows into the sea dumping its sediment and accompanying titanium with it. Analysing through the core allows the shifting rainfall densities to be tracked over time.

The wingspan of Pelagornis sandersi dwarfs that of today's biggest flier, the royal albatross, whose span measures a "mere" 11.5 feet (3.5 meters). And it rivals that of the largest flying bird on record: Argentavis magnificens—a South American condor with a 23-foot (7-meter) wingspan that glided among the mountaintops of the Andes six million years ago.

"Pelagornis was certainly much lighter and a better 'flier'" than the vanished giant condor, says paleontologist Antoine Louchart of France's Institute of Functional Genomics in Lyon, who was not involved with the study.

...The new fossil, which the team has named Aurornis xui ( Aurornis meaning "dawn bird," and xui in honor of Xing Xu's contributions to bird origins), was found in Liaoning province's Tiaojishan Formation, in sediments dated about 160 million years ago, according to the Nature report. That's around the time that dinosaurs are believed to have started evolving into birds...