This video says about itself:
Evolution: Permian-Triassic Extinction
One of the most dramatic and mysterious events in the history of life, the so-called “Great Dying” of animals and plants some 250 million years ago, continues to fascinate and baffle scientists. Of the five or so mass extinctions recorded in Earth’s fossils, this one at the end of the Permian period and the start of the Triassic was the most catastrophic.
More than half of the families of living things died out, and as many as 90 to 96 percent of the planet’s marine species were lost. At the same time, perhaps 70 percent of the land’s reptile, amphibian, insect, and plants species went extinct.
From Wildlife Extra:
Fossil discovery gives clues to Xingmeng marine past
December 2013: Large numbers of bryozoan and other typical marine fossils have been discovered in the thick limestone layers and lenses of the upper part of the Linxi Formation of the Guandi section, Linxi County, eastern Inner Mongolia, according to a recent study. The discovery of marine fossils here provides the first evidence for the Xingmeng area being in a marine or mainly marine environment at the end of the later part of the late Permian.
There has been a long history of debate over the tectonic-paleogeographical environment of the Xingmeng area, much of which will be answered by the discovery of sponge spicules and crinoids and bryozoan fossils here. Most modern bryozoans are marine, and they can survive in tropical, temperate, and polar oceans. Only a very small group (the Phylactolaemata) lives in fresh water, but these do not have a mineralized skeleton and thus do not preserve as fossils. Bryozoan adaptability is very strong. They are found distributed from coastal tidal flats to the deep sea at depths of 5500 m.
Sponges are generally considered to be the most primitive and the lowest marine multicellular animal. Sponge body walls are supported by needle-shaped elements, called spicules. Sponge spicules can be preserved as fossils in ancient strata. Crinoids are a type of echinoderm, first found in Carboniferous strata. Although they are animals, they live in the sea and resemble plants, hence the name sea lily. Thus the bryozoan remains, sponge spicules and crinoids fossils in the upper Permian strata of this region are typical marine fossils.
This study provides new constraints on the final closure of the Xingmeng marine basin. It will promote changes in the way that petroleum research is undertaken in the region, especially regarding the potential for new oil and gas, and shale gas (or oil) prospects, in addition to other mineral exploration in the Upper Permian rocks in the Xingmeng region of NE China.
This paper, entitled ‘Discovery of marine fossils in the upper part of the Permian Linxi Formation in Lopingian, Xingmeng area, China’ is published in Chinese Science Bulletin, 2013, with Zhang Yongsheng (of the Institute of Mineral Resources) and Tian Shugang (of the Institute of Geology) as the corresponding authors.
See also here.
- Earth’s Greatest Killer Finally Caught (livescience.com)
- New Edmontosaurus dinosaur discovery (dearkitty1.wordpress.com)
- “The Great Dying” –MIT Insights into the Most Severe Mass Extinction in Earth’s History (dailygalaxy.com)
- Dinosaurs’ Predecessors Ready to Roar (glamadelaide.com.au)
- Fossils clarify the origins of wasps and their kin: alderfly ancestors, snakefly cousins (eurekalert.org)
- Ghosts of Gondwana: Dinosaurs of the Last Super-continents (larrycsimpson.wordpress.com)