The story
About 305 million years ago, at the end of the Carboniferous, the tropical coal forests of Euramerica collapsed. Giant club-moss trees such as Lepidodendron and Sigillaria, up to about 30 metres high, vanished across much of the equator, along with their associated swamp communities. Tree ferns and seed plants such as conifers survived, and the wet, uniform forest became a patchwork of smaller, drier habitats.
The cause was a shift to a drier climate. Ice sheets in Gondwana, part of the Late Paleozoic Ice Age, grew and shrank, altering rainfall, and the Pangaean continents were joining. The study that named this event in 2010, by Sarda Sahney, Michael Benton and Howard Falcon-Lang, argues the broken habitats split animal populations and reduced amphibians, which depended on wet places, while reptiles and other amniotes, with eggs that do not need water, thrived. This is a real example of how climate change can restructure life on land, though some scientists see the shift as gradual rather than sudden.
Why it mattered
- The collapse ended the great coal-swamp forests and, with them, much coal formation.
- It favoured the amniotes over the amphibians, shaping the rise of reptiles and synapsids.
- It is a case study of habitat fragmentation driving evolution on land.
Sources
- Rainforest collapse triggered Carboniferous tetrapod diversification in Euramerica Royal Holloway, University of London
- Collapse of tropical rainforests gave early reptiles their big break (news release) University of Bristol
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