The 366 daily episodes in 2014 were chronological snapshots of earth history, beginning with the Precambrian in January and on to the Cenozoic in December. You can find them all in the index in the right sidebar. In 2015, the daily episodes for each month were assembled into monthly packages, and a few new episodes were posted. Now, the blog/podcast is on an occasional schedule with diverse topics, and the Facebook Page showcases photos on Mineral Monday and Fossil Friday. Thanks for your interest!

Thursday, August 7, 2014

August 7. Permian insects



We talked about the giant insects in the Pennsylvanian coal swamps last month. Insects continued, of course, into the Permian, but the changing environments mean that the record is considerably less extensive because of poor preservation of insects. Coal swamps were great places to fossilize bugs, while more arid river systems and even deserts were not.  

One of the common ideas for the gigantic size of insects in the Pennsylvanian was the increased oxygen content at that time. There was a crash in oxygen levels toward the end of the Pennsylvanian and into the early Permian, perhaps related to the crash in the rainforest ecosystem – but gigantic insects are found in the Permian too, including one called Meganeuropsis, the largest insect known with a wingspan of 28 inches and a body length of 17 inches. So there is still research to do on the relationship between oxygen in the atmosphere and the evolution and size of insects.

The most common Permian insects are cockroaches and their relatives. The first true dragonflies probably evolved in the Permian from Pennsylvanian dragonfly-like ancestors. Until recently, the oldest known beetle was from the Permian, but in 2009 a fossil beetle was described in the Pennsylvanian Mazon Creek rocks. Beetles certainly did diversify during the Permian, and today there are at least 350,000 species of beetles.  
—Richard I. Gibson

Links:
Modern Beetles predate Dinosaurs 

The largest complete insect wing ever found

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