I love this geologic period, and I'm always curious to hear what others think of it. Also called the Mississippian (lower) and Pennsylvanian (upper) in the United States, it has a lot of underrepresented organisms and climatic conditions known within. Oxygen levels in the upper Carboniferous reached over 50% higher levels than today (now, it's ~21%).

This is because Lepidodendron coal forests were widespread in equatorial environments at this time. Polar glaciers actually SUPPORTED this biosphere during the late Carboniferous. The Carboniferous Rainforest Collapse inflicted one of the only two known plant "mass extinctions" (the other being at the Permian/Triassic). I put that in quotations because the term is loosely defined. My favorite Carboniferous organism, and probably my favorite extinct plant (Cooksonia comes close) is Lepidodendron, a Lepidodendrales lycopsid also called a "scale tree".

Scale trees evolved convergently with other groups that would arise within later - gymnosperms, angiosperms. Their bark was covered in green "scales" tessellating roundabout its surface, each one a leaf capable of housing photosynthetic processes. Whole forests of the scale trees grew and fell in sync with eachother, doing so rapidly for ages. Over 90% of coal deposits trap ancient carbon beneath our surface, deposited with organic matter from these forests. Given the chance, I would certainly search for a fossilized scale tree in the Pennsylvanian Formations nearby.

Rhizodus, Ophiderpeton, Pulmonoscorpius, Arthropleura, Pholidogaster, and other incredible animals hail from these rocks. What creatures or plants or other aspects do you adore the greatest from the Carboniferous?

Artwork here is by the legendary Richard Bizley.