Life on terra firma began with an invasion

June 2, 2017, University of Portsmouth
Spiders, below, came from the same group as crabs, above. Credit: University of Portsmouth

Scientists are now confident animal life on solid ground started with a few short bursts of marine creatures making the leap from the oceans.

New research at the University of Portsmouth also paints a clear picture of how animals rapidly spread out and changed once they made the leap.

The research, led by Dr Nicholas Minter of the University's School of Earth and Environmental Sciences, is published in Nature Ecology and Evolution.

The first study to use trace fossils – the footprints of animal behaviour such as tracks and burrows – shows how a major evolutionary step for the Earth, the colonisation of land, took place.

The initial invasion happened across the world, from the fringes between land and oceans, followed by expansion later into floodplains, rivers, deserts and lakes.

It is the first time such a pattern has been identified using trace fossils to track the evolution of , their modes of life, and the ways in which they interacted with their new environments.

Dr Minter said: "When the first animals emerged from the oceans they had a blank canvas, there were no other animals there and so they diversified rapidly both in how they behaved and in the ecological roles, or the part they played, in the theatre of life."

This evolutionary step-change – an early burst of rapidly adapting and diversifying to new environments, followed by a long period of little change – has been seen in the shapes and sizes of animals but this is the first time it has been shown for their behaviour.

Slugs, above, came from the same group as squid, below. Credit: University of Portsmouth

The creatures which made the leap to land represent just a handful of the marine population, with spiders coming from the same group as crabs, and slugs and snails coming from the same group as squid and cuttlefish, for example.

"Not many from any one group, or Phylum, made the transition from sea to land or fresh water," said Dr Minter.

"What's surprising is the leaps in evolution follow the same pattern – an early evolutionary burst of rapid diversification and a long period of relative calm – each time animals conquered new habitats, first the margins between sea and land, then floodplains, followed by rivers, deserts and lakes.

"Each burst was an evolutionary experiment, yet the results are very similar.

"As scientists, we know experiments tend to have different outcomes if you change the parameters, but in this case, there is a consistency which suggests a fundamental constraint on the behavioural and ecological roles fulfilled by animals on land."

The exhaustive study – a seven-year-long analysis of all known trace fossil data spanning a 200 million year period of Earth history – has the potential to tell us about our future, too, he said.

"We now have a framework we can use to apply to other questions and allows us to compare ancient and living communities. This framework may help us understand if modern communities are undergoing fundamental changes, as ancient ones have in the past, for example, in response to climate change."

Trace fossils tell us a great deal about , including who was there, when and how they behaved. Although Dr Minter's research included examining reports of hundreds of trace fossils from hundreds of rock formations around the globe, the planet has not given up all its secrets.

He said: "This is not necessarily the final word. Another major step-change that took place was the evolution of social insects, such as ants and termites, which worked together to build complex structures and societies. More recently too, in the evolution of animals was the emergence of intelligent life – animals which could make and use tools, including humans and our ancestors, apes. We are yet to investigate how diversified and modified their environments during these events and how this shaped our planet."

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12 comments

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LagomorphZero
5 / 5 (2) Jun 02, 2017
Also, plants are the result of an algean invation of land from water. :)
Bart_A
1.5 / 5 (8) Jun 03, 2017
Wow. So finding footprints ("trace fossils") has proven to us that evolution is real? Bogus! Plain scientific stupidity. This does nothing to prove anything about evolution. There is so much surmising in this article as to be fit for fiction.

Question for evolutionists: How do get trace fossils?

zz5555
4.4 / 5 (7) Jun 03, 2017
Wow. So finding footprints ("trace fossils") has proven to us that evolution is real?

This study doesn't attempt to "prove" evolution. (As you're well aware, the concept of "proof" doesn't really belong in science. Only laymen with little understanding of science use it.) The overwhelming case for evolution has been well made over the last 150-200 years. (Since you're not very familiar with science, you might review some information on evolution, e.g. https://www.khana...volution or https://www.scien...tionist/ ). This article just talks about the possible history of the move from water to land.
How do get trace fossils?

https://www.ameri...otprints (This is for K-5th grade, so may help you.)
EmceeSquared
3.7 / 5 (6) Jun 03, 2017
zz5555:
This study


You're being too nice to the Creationist troll.

However, easy repudiation of Creationist trollery might be appreciated by other readers affected by troll-generated Fear, Uncertainty and Doubt. Nice assist.
EmceeSquared
4 / 5 (4) Jun 03, 2017
What is it with the war metaphors? The actual scientist used an art metaphor of creation, a canvas, but the anonymous author of this article, or maybe the anonymous website clickbait editor, sees it as a war.
Captain Stumpy
5 / 5 (1) Jun 03, 2017
What is it with the war metaphors?...sees it as a war.
@EmceeSquared
in a lot of ways evolution is a war...

but i think both metaphors work well as they can describe the dichotomy of life: situational euphoric beauty and or ghastly viciousness
TheGhostofOtto1923
5 / 5 (1) Jun 04, 2017
@EmceeSquared
in a lot of ways evolution is a war...
-and if you haven't already seen it, here is a nice compendium of opinions on how war is the thing that made us human.
http://rint.recht...rid2.htm
Da Schneib
not rated yet Jun 04, 2017
What is it with the war metaphors? The actual scientist used an art metaphor of creation, a canvas, but the anonymous author of this article, or maybe the anonymous website clickbait editor, sees it as a war.
@Emcee, clickbait as you say. My understanding is that the authors write the articles and the editor chooses the headline. I don't generally pay the headlines much attention.

On the other hand I have to point out that it has to be good enough clickbait to interest folks of a scientific frame of mind, by and large.
TheGhostofOtto1923
5 / 5 (1) Jun 04, 2017
Emcee, clickbait as you say. My understanding is that the authors write the articles and the editor chooses the headline
- And where'd you get that understanding from? If you Google the first paragraph you at least 4 sites which use the same wording verbatim.

These articles are news releases. Oh BTW

"An invasive species is a plant, fungus, or animal species that is not native to a specific location (an introduced species), and which has a tendency to spread to a degree believed to cause damage to the environment, human economy or human health."

- Is that a war reference as well?
EmceeSquared
3 / 5 (2) Jun 04, 2017
Captain Stumpy:
but i think


It's more like an infection than an invasion.

Invasion is war: Latin "invadere": "to go, come, or get into; enter violently, penetrate into as an enemy, assail, assault, make an attack on". "Violently", "enemy" and other fighting terms are not as accurate as "infect". Anthromorphizing evolution is misleading.
EmceeSquared
3 / 5 (2) Jun 04, 2017
TheGhostofOtto1923:
Is that a war reference as well?


Yes, it is. It's also misleading. These "invasions" are more like "infections" than human activity of violently attacking an enemy.
Captain Stumpy
not rated yet Jun 04, 2017
It's more like an infection than an invasion
@EmceeSquared
true that

as i consider your point i have to wonder what makes an infection so very different than an invasion
Anthromorphizing evolution is misleading
i can understand your argument but is it really anthromorphizing?

offered IMHO only:

regardless whether you view humans as parasitic, infectious or simply predatory it is still a form of combat for superiority (or existence), isn't it?

considering infection over invasion, lets take something simple: the Flu
http://micro.magn...rus.html

taking into consideration it's tactics, i would call infection (especially by something like the Flu) a violent act at their scale

maybe the host isn't reacting violently upon contact, but then again, violence is subjective
and considering the scale of the virus and it's perspective i believe it's synonymous more so than not

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