Editing Pennsylvanian (geology) (section)

=== Invertebrates ===
The major forms of life at this time were the arthropods. Arthropods were far larger than modern ones. ''[[Arthropleura]]'', a giant [[millipede]], was a common sight and the giant [[griffinfly]] ''[[Meganeura]]'' "flew the skies".<ref>{{Cite book|title=Fossil Invertebrates|last=Paul D. Taylor|first=David N. Lewis|publisher=The Natural History Museum; First North American edition|year=2005|isbn=0565091832|pages=160}}</ref> It is commonly considered that is because of high oxygen level, however some of those large arthropod records are also known from period with relatively low oxygen, which suggest high oxygen pressure may not have been a primary reason for their gigantism.<ref>{{Cite journal |last1=Gand |first1=G. |last2=Nel |first2=A. N. |last3=Fleck |first3=G. |last4=Garrouste |first4=R. |date=2008-01-01 |title=The Odonatoptera of the Late Permian Lodève Basin (Insecta) |url=https://revistas.ucm.es/index.php/JIGE/article/view/JIGE0808120115A |journal=Journal of Iberian Geology |language=es |volume=34 |issue=1 |pages=115–122 |issn=1886-7995}}</ref><ref>{{Cite journal |last1=Davies |first1=Neil S. |last2=Garwood |first2=Russell J. |last3=McMahon |first3=William J. |last4=Schneider |first4=Joerg W. |last5=Shillito |first5=Anthony P. |date=2021-12-21 |title=The largest arthropod in Earth history: insights from newly discovered''Arthropleura''remains (Serpukhovian Stainmore Formation, Northumberland, England) |url=http://dx.doi.org/10.1144/jgs2021-115 |journal=Journal of the Geological Society |volume=179 |issue=3 |doi=10.1144/jgs2021-115 |issn=0016-7649}}</ref>