Roots

I've been fascinated with the beginnings of the tetrapod invasion of various terrestrial ecosystems, and of course, you can't talk about that without talking about Ichthyeostega, famous throughout most of the 20th century as the "first amphibian", found in Fammenian rocks in eastern Greenland. For fun, here's a picture of "Ole Ichthy."

Ichthyostega isn't actually an amphibian, as it turns out, although he's a "pre-amphibian tetrapod." He was discovered in the 1930s in a famous paleontological expedition.

Some fragmentary Acanthostega material was also found, although it wasn't until the late 1980s that really good material was found on this cousin and contemporary of "Ole Ichthy." There's also some pictures of him attached:

With this new material, though, it doesn't look like "Ole Acanthy" was actually very adept at getting out of the water, and it's not believed that he did. The same is often said about Ichthyostega too. In fact, even slightly younger basal tetrapods (still not amphibians) like Hynerpeton and Tulerpeton seem to be adapted to swimming around in shallow, clogged swampways more than coming up on land. I guess that's to be expected; they've gotta handle that environment first, after all.

A couple of little guys that I wasn't aware of were discovered in the 90s that are actually even older and more primitive basal tetrapods than this crew, though, found in the Upper Frasnian in Scotland. These are Elginerpeton and the closely related Obruchevichthys. I can't find any images of the latter (and he's known from some pretty spotty skeletal remains anyway) but here's Elginerpeton for your perusal.

As you can probably see quite well just from these illustrations, these basal tetrapods are extremely primitive, and only barely removed from the sarcopterigian (lobe-finned) fishes from which they descended.

In fact, here's a sarcopterygian fish very similar to the first tetrapods for you to look at, if you're interested, weird little Tiktaalik, which frankly is as much notable for it's bizarre name as for it's position close to the ancestry of all Tetrapoda. In fact, it's so close, that cladistically, it's in a group falled Tetrapodamorpha, in which Tetrapoda is closely nested.

From these images, hopefully it's obvious how fishlike the first "amphibians"; the basal tetrapods truly are.

And that, ladies and gentlemen, is roots. The root of all land vertebrates in the entire world, which showed up in the late Devonian, 380 million years ago for the earliest examples pictured above.