How did life respond to Earth’s greatest mass extinction? This is the subject of a new study in Science.
First some background. It has long seemed that the Early Triassic was a relatively boring time in the history of life, dominated by those “weedy” species that made it through the end-Permian catastrophe. A popular model of ecosystem recovery imagined a gradual refilling of the trophic “bucket,” beginning with the lowest levels and proceeding to higher and higher ones. The matter has remained obscure, though, in virtue of the death of lagerstätten from the earliest Triassic. (Lagerstätten provide privileged windows into the structure of past ecosystems. So, the dearth of lagerstätten from the earliest Triassic makes it difficult to assess the extent of trophic diversity during the first three million years of this period.)
But ask and you shall receive—or at least that’s how it seems to work in the rocks of South China. Back in 2015, paleontologist Xu Dai discovered the oldest Mesozoic lagerstätte in a succession of rocks near Guiyang. It dates to about a million years after the end-Permian extinction, and bursts with fish, shrimp, lobsters, ammonoids, sponges, conodonts and forams. This is a genuine treasure trove, which suggests a more rapid recovery from the end-Permian extinction than has previously been entertained. Maybe it was the case that more occupants of high trophic levels dodged the Permian extinction than we thought. Or maybe important elements of the modern marine fauna radiated quickly, despite inhospitable conditions in the earliest Triassic. At any rate, it seems that notions of a slow and stepwise recovery are no longer adequate. The story of earth’s greatest extinction just got more interesting, again.
For those interested in a quicker read, here’s a write-up from the news team at Nature (also, sadly, paywalled).