We talked about early plants on April 11, and last month I mentioned that there are some fossil spores from the Ordovician that indicate there were some primitive plants on land that long ago. But really, even though there are some early to middle Silurian land plants known, there still wasn’t much, even towards the end of the Silurian, coming up at about 416 million years ago.
Most of the land surface was bare rock or the kind of soil that forms from the physical weathering of rock. Plants seem to have mostly lived mostly along sea coasts, in wetlands, and it’s reasonable to suppose they might have grown along some rivers. But even with that limited range, they were still pretty much worldwide – from what is now Greenland to Siberia to Australia – all areas that were within the temperate or tropical zones during the Silurian.
Cooksonia didn’t have leaves, or flowers, or a root system. William Lang, who described the first specimens, named it for Isabel Cookson, an Australian botanist and paleobotanist who worked with him in Britain. Her work on Silurian and Devonian plants was important in establishing theories of the evolution of land plants.
So, we’re getting there – the land isn’t just bare rock any more. Short stalked plants, mosses, and a millipede here and there to eat the dead plant detritus, and that’s about it. But it was a start.
—Richard I. Gibson
Drawing by Smith609 via Wikipedia, under Creative Commons license