Ancient fish often get credit for being the first animals to walk on land but is that reputation deserved?
The Fake News
Google “what was the first animal to walk on land?” and you’ll be greeted with the word Acanthostega…which is so wrong, I can’t even be arsed to address it in this article (long-story short, it never even left the water). However, dig beyond Google’s algorithms and you’ll probably find a myriad of pictures and stories about something that looks like one of these two goofballs:
That’s Tiktaalik and Ichthyostega, a lobed-finned fish and an early amphibian respectively. Tiktaalik holds the record for being the earliest known vertebrate that could move and breathe out of water. Its four fleshy fins were supported with bones and its swim-bladder, an organ most fish use for buoyancy, had evolved into a primitive lung. Ichthyostega is one of the first tetrapods, or animals with four limbs. Something like these creatures would eventually give rise to all amphibians, reptiles, mammals and birds.
However, they were the first animals to walk on land in the same way Columbus was the first person to set foot in the Americas, Magellan was the first person the circumnavigate the globe, or Edison was the first person to do anything except steal all the patents. In that they weren’t even close to being first, history just gave them all the credit. Why? Well, it’s a giant conspiracy by ‘Big Paleo’ (probably) to sell more fossils to gullible science cultists or promote four-limbed supremacy or something. So, prepare to swallow the prehistoric red pill, as I unpack THE HIDDEN TRUTH THEY DON’T WANT YOU TO KNOW about terrestrial locomotion.
What is Walking?
When answering “what was the first animal to walk on land?”, we must start by invoking the spirit of Jordan Peterson and say to ourselves: “Well, it depends on what you mean by ‘walk’…bucko”. Now I know what you’re thinking: “Is this just going to be an obfuscating game of semantics?” And yes, it sort of is about semantics. However, it’s an important word to define, because it’s highly unlikely either that amphibious fish or that fishy amphibian had a gait one would describe as ‘walking’.
Think of any animal that walks, be it a spider, a centipede, a horse, or a human and they share two common traits: they have legs and those legs can support the animal’s weight as it moves on land. Even under these simple metrics, our adventurous ancestors start running into some problems. Ichthyostega may have had four legs but the rear ones were about as useful out of water as Theresa May is at negotiating Brexit…and Tiktaalik? Well, it didn’t even have legs, so, much like yours truly, it couldn’t fully support itself.
True walkers also use an ‘inverted pendulum’ gait, where the body vaults over a stiff limb(s) with each step. Tiktaalik and Ichthyostega, on the other hand, probably used a method of locomotion similar to “crutching”, the way mudskippers and seals get around on land today. Using their front limbs in unison, like a human on crutches, to lift and propel their bodies forward. Skipping along on their bellies, like that drunk girl at Uni who thought she could do ‘the worm’.
Who Really Conquered the Land?
Now, some of you might, quite reasonably be scoffing at this and saying: “Sod your semantics man, who gives a damn if all they could do was flob around? Them fishy-amphibious things were goddamn pioneers! They were still the first animals to drag their sorry asses out the sea and get shit done. How have you aided the evolution of life on earth by writing cynical articles from your bedroom?”
To which I’d say: “I’ve taken up permanent camp in the living room, actually, and no one’s been stupid enough to have children with me (yet), so my evolutionary value is undetermined.”
But also: “Were they really the first animals to walk on land? I mean really?”
The answer is no, not by a long shot. (This is the part where my Columbus/Magellan/Edison analogy from earlier starts to actually make sense). You see, Tiktaalik and Ichthyostega can only claim to be the ‘first’ out of water if you ignore an entire phylum of animals that had been on the land for millions of years. A group, that in terms of sheer numbers and biomass, has dominated the planet ever since. I am talking about the arthropods, creatures with segmented bodies and exoskeletons, such as, insects, spiders, scorpions, centipedes, millipedes and crustaceans. Yep, all that nasty shit. If it makes your skin crawl, there’s a good chance it was crawling on Earth’s skin long before Tiktaalik laboured up the shoreline.
Myriapods, the group that includes centipedes and millipedes, have the best claim for being the first to conquer the land. Given that the oldest fossilised land animal we know of, the 414 million-year-old* Pneumodesmus, is a myriapod. However, insects don’t preserve very well as fossils and our earliest record of one, Rhyniognatha, might be a winged creature. Meaning there’s a possibility insects had been on land a while as well, at least in their adult forms. Yet, these creatures were just the first to make the land their home full-time. We must go back even further if we want to find the true hero to our story.
A 414 million year old myriapod, apparently (Pneumodesmus). 
Obviously, a 400 million year old insect (Rhyniognatha).
And the Winner Is?
How far back must we go? Well, in the US and Canada, there is some rock dating to the Cambrian, about 500mya, that yielded some tantalising fossils in the 19th century. They were recognised, correctly, by Sir Richard Owen, as the fossilised footprints of the first animal to walk on land. Made in intertidal mud, not that long, in evolutionary terms, after complex life had first got going in the ocean.
These fossils, named Protichnites, are believed to have been made by animals called Euthycarcinoids, which we may or may not have to thank for things like myriapods, crustaceans and insects existing. So, there’s going to be some mixed-feelings here for a lot of us, I’m not going to lie. On the one hand, only 100 million years or so after the first animals came into existence, one was spending part of its time out the water and on land. How amazing is that? On the other, if there was one lineage you wouldn’t have minded all those extinction events down the years wiping out…
Now we have our suspects, the unassuming Euthycarcinoids, all we need is our motive. So, why did these early arthropods first venture out the ocean and onto the shore?
The prevailing theory was that it was a safer environment for them to lay their eggs, away from hungry predators; and this is probably true. However, one of these Protichnite fossils has, under closer research, revealed another reason why they may have wandered onto the land. This study believes some of these ancient footprints were made by animals in ‘amplexus‘. Students of Latin will know that means ’embrace’, students of innuendo will know that means they were banging.
So yeah, turns out the first animals to walk on land did so because they had the same misguided fantasies about sex on the beach that we do! Who knew?
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Do Your Own Damn Research!
Further reading on the first land animals, tetrapods and arthropods alike, we don’t discriminate here (except against Trav, obviously):
https://evolution.berkeley.edu/evolibrary/article/evograms_04
http://www-news.uchicago.edu/releases/06/060405.tiktaalik.shtml
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4339279/
https://academic.oup.com/icb/article/53/2/192/806098
http://www.sicb.org/students/jonesk.php
https://www.pnas.org/content/111/3/893
https://books.google.co.uk/books?redir_esc=y&id=yMaN9pk8QJAC&dq=biomechanics+biewener&q=inverted+pendulum#v=snippet&q=inverted%20pendulum&f=false
https://news.nationalgeographic.com/news/2012/05/120523-tetrapod-walk-flopped-nature-science-ichthyostega/
http://jeb.biologists.org/content/212/14/2279
https://www.researchgate.net/publication/282875991_An_analysis_of_multiple_trackways_of_Protichnites_Owen_1852_from_the_Potsdam_Sandstone_Late_Cambrian_St_Lawrence_Valley_NY
https://evolution-institute.org/a-new-look-at-the-first-footprints-on-land/
https://www.jstor.org/stable/41480207?seq=1#page_scan_tab_contents
*The age of Pneumodesmus and whether it was the first air-breathing land animal has recently come under dispute, see here. This is why I use 414mya as an age for the fossil and not 428mya, like most sources, which were created before this study. Although it is younger than previously thought, it is still the oldest fossilised land animal as far as I could tell. So that article’s title seems misleading when it says it has ‘lost’ this claim to fame.
Do the Damn Research! 