water-to land-based animals

**Manco** · December 08, 2008, 08:26 AM

I was wondering, do all land-based animals come from the same group of animals who developed abilities to survive on land. Or were there several different parallel evolutions of land-based animals?

In essence, is the the first land-based animal a common ancestor of all land-based animals?

**Lucifer Sam** · December 08, 2008, 11:43 AM

well if dawins theory of evoloution is completely correct, then we all came from one cell.

i would imagine that all mammals, reptiles birds and most amphibians did, maybe a few different ancestorss for amphibians, loads (of different ancestors) for lungfish and with hundreds (of different ancestors) of others for invertibrates.

also some of these would now be extinct.

invertibrates definately came from a different ancestor though.

**Playfishpaste** · December 08, 2008, 08:58 PM

Originally Posted by Lucifer Sam

well if dawins theory of evoloution is completely correct, then we all came from one cell.

i would imagine that all mammals, reptiles birds and most amphibians did, maybe a few different ancestorss for amphibians, loads (of different ancestors) for lungfish and with hundreds (of different ancestors) of others for invertibrates.

also some of these would now be extinct.

invertibrates definately came from a different ancestor though.

Actually, we could have come from multiple organisms.

EDIT: According to the modern theory of evolution. Darwin postulated this in his revisions as well.

**chamaeleo** · December 08, 2008, 02:47 PM

Several colonizations, at different times in Earth's history. Most land-vertebrates share a common ancestor of one (or more?) amphibious Devonian fish. I think inverts colonized later (Pennsylvanian?) in multiple waves. Some critters even went back: whales, seals, otters, and hippos (in reverse order of specialization), many birds, sea-snakes, diving-bell spiders, various insects, etc...

Despite its prehistoric appearance, mudskippers evolved relatively recently (18Mya?) from gobies. It is a fish, but if it were forced to submerged for too long you'd drown it. Who knows how many other organisms have evolved new mechanisms, to cope with the land-water interface?

LS: I don't think Darwin ever postulated that all life originated with a single cell. What's more, the evolution of that single cell strongly challenges our very definition of life.

**IndianPrince** · December 09, 2008, 07:58 AM

Originally Posted by chamaeleo

LS: I don't think Darwin ever postulated that all life originated with a single cell. What's more, the evolution of that single cell strongly challenges our very definition of life.

How does evolution from a single cell strongly challenge our very definition of life :hmmm: ?

Plus, I dont think the single-cell theory existed in Darwin's time. And even if it did, it wasn't scientifically proven untill Pasteur. So, can't really blame him.

Prince

**chamaeleo** · December 09, 2008, 11:01 AM

Originally Posted by IndianPrince

How does evolution from a single cell strongly challenge our very definition of life :hmmm: ?

Plus, I dont think the single-cell theory existed in Darwin's time. And even if it did, it wasn't scientifically proven untill Pasteur. So, can't really blame him.

Prince

You misunderstand.

I said "evolution of that single cell", referring to that fortuitous meeting of organic compounds, minerals, water and whatever other conditions & ingredients created the universe's best (yet) defense mechanism against entropy: LIFE! We cannot even agree whether viruses are "alive", what with all our anthropocentric hang-ups. Maybe our definition of Life needs some tweaking.

Leeuwenhoek (sp?) described the first single-cell organism (algae: Spirogyra) in the 17th century. Darwin was most definitely aware of single cell critters. Even if he did believe that we'd all evolved from such an extremely simple origin, he was religious and probably felt it was too big a bite for his contemporaries to swallow. He habitually avoided controversy (believe it!) and only published the Origin of Species after 20 years of editing, much cajoling from supporters, and the prospect of getting scooped.

Louis didn't get cracking on his vaccines until late 19th century.

**IndianPrince** · December 09, 2008, 07:56 AM

The mudskippers might've been one example of land-based colonization. Another is that amphibians evolved legs in the water itself, and because they provided them with another route of escape from the giant bony fish of the devonian - LAND ... they were selected for.

They looked something like this:

Prince

**Manco** · December 09, 2008, 11:04 AM

So as I suspected there were several different populations that made the jump from water to land based, and some species till make the jump these days.

**chamaeleo** · December 09, 2008, 11:46 AM

Originally Posted by Maraud

So as I suspected there were several different populations that made the jump from water to land based, and some species till make the jump these days.

Don't forget all those critters whose juvenile stage is aquatic, and adult stage is terrestrial...in this case, did they really "make a jump"? Many (such as mayflies) spend 99% of their lives in the water and spend but a single day or two as adults...lacking the ability to even eat! From this perspective, the adult stage is purely reproductive and you could argue that adults are merely the vehicle to allow the migration of juvenile nymphs. Science is so cool...

**MrMofo** · December 09, 2008, 02:44 PM

It's quite a complex process. In fact, whales are believed to have gone to the oceans FROM the land. Ancient fossils of some whales have vestigial legs.

**chamaeleo** · December 09, 2008, 04:46 PM

Originally Posted by MrMofo

It's quite a complex process. In fact, whales are believed to have gone to the oceans FROM the land. Ancient fossils of some whales have vestigial legs.

True indeed.

Originally Posted by Copperknickers

As a general rule, yes, all land vertebrates are descended from the first fish(pl) that ventured onto land. It went from amphibious fish to amphibian, then reptile, then mammals and birds split off from reptiles during the late mesozoic era.

Generally, yes, but who's to say that the first Devonian air-breathing fish and modern mudskippers are the only examples of this in the fossil record? How many evolutionary dead ends are not yet represented? It could've happened any number of times over the past 500 My. I'm sure more examples will present themselves in the future.

**IndianPrince** · December 09, 2008, 04:49 PM

Originally Posted by MrMofo

It's quite a complex process. In fact, whales are believed to have gone to the oceans FROM the land. Ancient fossils of some whales have vestigial legs.

So cool !

Just boggles the mind what kind of ancient forces have been @ work to create a creature so beautiful from something like a pigmy hippo. Oh evolution, how fascinating are thee.

Prince

**Copperknickers II** · December 09, 2008, 03:22 PM

Originally Posted by Maraud

I was wondering, do all land-based animals come from the same group of animals who developed abilities to survive on land. Or were there several different parallel evolutions of land-based animals?

In essence, is the the first land-based animal a common ancestor of all land-based animals?

As a general rule, yes, all land vertebrates are descended from the first fish(pl) that ventured onto land. It went from amphibious fish to amphibian, then reptile, then mammals and birds split off from reptiles during the late mesozoic era.