On Friday I gave you a palaeontological mystery object and asked you to choose what you thought it was from a poll:

As it turns out, you did pretty well, with 60% of you selecting the correct category (with a couple of you making comments which went into greater detail). The object in indeed a piece of fossil plant, Lepidodendron acerosus from the Late Cambrian period (approx 300 million years ago). This piece is probably from coal deposits around Radstock in Somerset where specimens with this kind of detail of preservation are well known.

Lepidodendron is an apt name for this, since it’s a Greek word meaning “scale tree”; and although these plants were more closely related to the primitive club-mosses and quillworts than to the trees we see today, they could reach heights of 30 metres. The “scales” are actually leaf cushions, little chlorophyll filled bumps that would have been used in photosynthesis for most of the plant’s life, because they didn’t branch until late in their life cycle (which was fairly short for something so big – maybe 20 years or so). Image a swamp full of giant green scaly poles and you’re pretty much there.

The high density of Lepidodendrons in a given area of swamp, their rapid rate of growth, the anoxic conditions present in stagnant water and the lack of specialist wood-eating detritivores in the Carboniferous has meant that Lepidodendrons are incredibly common as fossils and they comprise a huge amount of the coal which fuelled the industrial revolution and is still being burned for electricity. All that carbon was buried for 300 million years and is now being dug up and burned at the rate of over 6 billion tonnes a year. So, it’s not a big surprise that CO2 levels have increased and seems pretty unlikely that natural conditions will ever be suited to the reburial of all that carbon, but perhaps BECCS will be able to step up to the challenge? Perhaps.