What is the history of life on Barsoom. How did it get
to the stage it is at now? From John Carter's Barsoom, the
following data formed my core of working knowledge:
The Biology of Barsoom
in Carter's Time
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Mars has/had fish.
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Mars has/had reptiles, mostly associated with or near water. No evidence
of amphibians, so either they never found a viable niche, or they all died
off in the big crunch.
-
There are insects, but now mostly they're confined to relic populations.
-
There are birds, but again, mostly relic populations, in the swamps or
around the canals.
-
There are a couple of species of mammals, but they're small timid creatures
that apparently never amounted to much.
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Dominant life on Mars appears to be endoskeletal non-reptilian vertebrates.
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These vertebrates come in all sizes, from that of a dog or a cat, all the
way up to elephant and dino sized critters.
-
These vertebrates are distinguished in their numbers of legs. There are
four limbed, six limbed, eight limbed and ten limbed creatures.
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We don't know explicitly about all of them, but it appears that the four
limbed and six limbed specimens are definitely egg layers.
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All of these vertebrates seem to have high constant levels of activity,
and show signs of being endothermic (warm blooded), so they're definitely
not reptiles as we know them. But they're definitely not mammals either.
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As far as plants go, the dominant fauna appears to be a hardy purple moss
that grows along much of the sea bottoms, and seems to be the staple.
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There are martian trees, but they're on the way out, existing mostly in
water catchments, or along canals. They seem to be mostly the leafy broad
branched variety, rather than the evergreens.
-
I don't recall much in the way of flowering plants, although they are occasionally
mentioned. There is no mention of flower propagating species, such
as bees. Almost all plant propagation appears to be by wind.
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There are mobile carnivorous plants, a 'tree', some 'bushes' and an actual
non-sentient 'plant man' which actually more resembles a kangaroo than
a human form. The first two are rare, but generally known, the third type
is and confined to a single southern hemisphere valley.
-
Very little mention is made of crops, but by inference, they have to exist
to support the cities. I assume that trees propagate by fruits and nuts,
there may be grains, berries and bush crops. No mention that I can recall
of root or tuber crops.
So, taking this as our starting point, let us begin to work backwards.
For the canvas, we'll use the modern topographic map of Mars, showing features
which are unchanged for billions of years, and we'll assume, as speculated,
that Mars once had a vast northern ocean, as well as two great southern
seas.
Life
Begins on Barsoom, Following Earths Pattern
It is believed that life on Earth evolved on tidal flats. So too on
Mars. Although Mars did not have a moon to produced tides,
there were other factors: Seasonal water level changes
caused by the expansion and contraction of the north polar cap might have
raised and lowered the seas, and winds blowing from the Polar sea would
have pushed up vast amounts of water, creating extensive tidal zones, mud
flats and pools which provided a hospitable environment for life to emerge.
As on earth, Martian life first colonized the sea, and the earliest
plants and animals were sea borne. The sea produced corals, armoured arthropods
and eventually notochordates which evolved into fishes.
Interestingly, Barsoom does not appear to have produced mollusks, or
if it did, they are long extinct. Nowhere in Burroughs Barsoom chronicles
is there mention of shellfish, clams, mussels, oysters, snails, slugs or
cephalopods. The mollusks either never evolved or were entirely extinct
by Carter's time.
We can assume that the early evolution of vertebrates was much the same
as on Earth. We probably started off with a spinal structure which became
armoured with segmented bone or cartilage. This provided muscle anchors
to support more powerful swimming.
The early vertebrates/notochordates outdid their spineless worm and
arthropod rivals. They could easily outswim the worms, moving faster and
with more maneuverability, even able to swim against currents. They were
also far lighter than the armoured arthropods, who also had powered swimming,
and could thus swim far more efficiently. So they quickly dominated the
waters, leaving the arthropods crawling along the bottoms or confined to
tiny size ranges.
These faster moving creatures needed a more efficient respiration system.
A gill system evolved, swallowing water through the mouth and passing it
out gills. The gill slits had to be supported by arches in order
to open and close and support the stresses of constant flow.
The rigid structure of the gill slits calcifies become the precursors to
ribs, their arches being doubled and redoubled along the length of the
body, adding support and strength while protecting the inner organs.
The gills and fill arches needed to be somewhat flexible, so they weren't
anchored directly to the spine. Instead, they were loosely hinged,
allowing some movement as the animal swam.
This allows the fish to grow to larger and larger sizes.
There's a limit to how big a fast moving creature can grow when its insides
are merely a squishy bag without support.
Meanwhile, the first few ribs, or gill slit arches, which are already
hinged, move forward, becoming jaws. Teeth are developed from
specialized skin scales. Fins, either lobe fin or ray-fin are
simply another development of the hinging trick done with ribs, only with
increasing amounts of muscle attached directly to them.
It's not clear if Mars went to cartilaginous fish, although that's quite
probable. Armoured fish appeared on Earth and represented a huge blind
alley of evolution, this may or may not have happened on Mars. Lighter
gravity might have made it easier on the armoured fish as far as swimming
and maneuvering went, so they may well have made an appearance.
On Earth, Lobe Finned fishes evolved, apparently contemporary with,
or even prior to Ray Finned fishes (the modern kind). This may imply that
the 'lobe finned' development was an early and natural outcome of the bone
and hinge evolution.
A protolung in the form of an air bladder also seems like a fairly natural
development, since among fish, it appears to have evolved independently
at least a couple of times. Lobe Fins, Mudskippers and Lungfish all come
to mind.
I'm assuming that equivalent air gulping Lobe Finned fish, or something
very like them, evolved on Mars.
Barsoom's
Life Diverges from the Terrestrial Pathway
Of course, on Earth, large tidal flats proved to be an environment that
Lobe Finned fish could survive and move around on. Their adaptations or
evolution allowed them to survive in the air, and make their way from one
pool to the next. Eventually, this gave rise to the four legged
amphibians, who in turn went on to dominate the planet, and give rise to
other four legged species.
But that's because Earth is a bit different from Mars. On Earth, we
had a single world ocean, and a more or less continuous supercontinent,
Gondwanaland. So, a successful evolutionary leap in one area might well
spread right along the coasts uninterupted.
Martian geography was a bit different. Okay, now yes, there's a single
polar ocean. But this ocean is configured a bit differently.
Stay with me here. Life is not going to be crawling out onto land at
arctic floes, right? Nope, the transition to landlubbers are going to happen
much further south in the temperate latitudes. And its going to stay there
for a while. Your basic lobe finned graduating up to amphibian is not going
to be going 'Arctic circle here we come!'
Now if we look at the Martian altitude map, we find that as the Martian
ocean reaches south, it divides into three isolated lobes, each separated
by two large expanses of land and highland, and a subcontinental volcanic
island plateau. The lobes are Utopia, Acidalia and Arcadia.
And each of these big lobes further give rise to isolated sheltered
bays, Valles Marinis, Isidis, and Amazonia.
Now, what this means is that on Earth, the Lobe finned fish that made
the successful transition to Amphibian could start out anywhere and gradually
colonize the whole continent.
On Mars, most likely, the Lobe finned fish that successfully colonized
the land as an Amphibian was probably stuck in a comparatively small sheltered
sea or bay. Colonizing the entire coastline would mean moving up into colder
and more inhospitable waters and lands, which would take a lot more evolving
to handle.
So, the lobe finned amphibian stayed where it was, and concentrated
on refining its act, for convenience, we'll just say its Arcadia.
Which meant that the other two ocean lobes, Acidalia and Utopia, had
miles and miles of virgin seashore, just waiting for some other breed of
local lobe finned fish to independently try the same trick.
Now, here's the interesting thing about the Coelecanth on Earth. It
doesn't just have four lobe fins, its got six. In fact, we get all kinds
of numbers of lobe fins on fossil fish, including odd numbers on fossil
lobe fins. Four wasn't a magic number.
But on Earth, what probably happened, was that it was a four limbed
lobe fin that got the jump onto others, colonized the land, and shut all
its brothers and sisters out. And that's why, ladies and gentlemen, all
Vertebrates on land are four limbed critters (setting aside a few snakes
and flightless birds).
Except on Mars, there are at least three major separated sea/seashore
biomes in the polar ocean, and quite possibly a few more minor ones. So,
somewhere a four lobed fish makes it. Somewhere else an eight lobed fish
becomes an Amphibian. Someplace else a six, and elsewhere even a ten.
Then they're all stuck. They're all in isolated biomes with no ability
to get to each other. So here evolution slows down. You have all these
relatively small, relatively isolated populations. It's not a recipe for
rapid advancement.
Basically, they're all sitting around in their amphibian cottages, watching
the sun rise, producing generation after generation, and accumulating the
evolutionary advances that will allow each of them to penetrate into dryer
country, penetrate into colder country. But apart from that, life is slow
and easy. These are the Martian salad days.
Or are they? There's huge seasonal tides along with wind tides, so there's
lots of opportunities for ambitious amphibians. Maybe they're not evolving
as slowly as we think. But one thing that's for sure, every group is facing
the same evolutionary and habitat pressures, and so springing from a common
genetic heritage of lobe finned fish, their consequent adaptations are
similar and happening at the same rate.
There isn't even really that one big habitat that would allow one line
to really get pumped up. They're all occupying ecological biomes of about
the same latitudes and the same surface areas.
Multiple
Conquests of Land, and a Permian Extinction that Didn't Happen
Martian amphibians and later Martian land animals came in four, six,
eight and ten legged varieties, each variety establishing itself in isolation
at the base of each Ocean lobe, and then expanding outwards to encounter
and evolve in competition with each other.
Of course, once they start encountering each other, then evolution starts
to take off. Fortunately, or unfortunately, its not a biological massacre,
like placental mammals in South America. Each population has had the opportunity
to develop at about the same rate, so while some lines take hits, most
survive.
Perhaps there are two legs or twelve leg lines that get wiped out. But
the 4, 6, 8 and 10 legged lines all manage to stay in the game with each
other, sure each of them loses some species to competition and extinction,
but each of them produces successful species that invade the others biomes.
The result is an explosion of adaptation as multiple lines continually
invade and reinvade biomes, and colonize and create new biomes, continually
adapting and evolving.
The amphibians are superseded by the reptiles. Colonization of dryer
and dryer lands leads to hardier and hardier forms, who then return to
the lowlands, pushing aside reptiles and amphibians. The Martians are out
there pushing into empty spaces, trying to build the better beast.
In the evolutionary terms of Earth, Mars has reached its Permian period.
On Earth, our Permian was an explosion in the seas and lands, a heady
period which saw, in succession, Amphibians, and almost immediately after,
the emergence of Reptiles, Lizards, Turtles, Crocadilians, Archosaurs,
Mammal-Like Reptiles and perhaps even Mammals. On Earth it was a brilliant
booming time that produced an amazing diversity of life and some remarkably
sophisticated animals, all dominated by the Mammal-Like Reptiles who seemed
well on the way to going places and doing things.
So what happened on Earth? Just the biggest Mass Extinction in recorded
history. A bigger Mass Extinction than the dinosaurs. Perhaps it was an
asteroid, perhaps something else. But suddenly 99% of all plants and animals
were extinct. In particular, the Mammal-Like Reptiles, who had managed
to dominate the planet and shunt off all competitors into the margins were
entirely wiped out.
Instead, after the extinction, the Dinosaurs took over. They were less
efficient than the MLR's, their brains were smaller, metabolisms creakier.
But nevertheless, they were ahead of the other reptilian and amphibian
forms. They shouldered aside the mammals, and took Evolution down the Mesozoic
river, a 200 million year blind alley.
On Mars, the Permian mass extinction never happened. Evolutionary pressure
pushed each of the lines to develop their own rude forms of mammal-like
reptiles, and they all just kept getting smarter and tougher and more efficient
competing with each other. There was no 200 million year blind alley.
Bigger
Bangs for the Buck, Why Ten Legs Beats Four
Of course, the different lines did find different advantages. One of
these was weight distribution. Ten legs carry weight better than four legs.
Now, the gravity is light, that's not a big deal... until you are becoming
a big deal. Suddenly, if you're getting hefty, having eight or ten legs
to distribute the weight load along becomes an advantage.
Martian ecology begins to shake out along size lines. Up around Dinosaur
size, the ten legs rule. Around Elephant size, the eight legs find that
they can go head to head with the ten legs, their advantage isn't big enough
that they can't overcome it.
Around the size of a cow, bear, buffalo, rhino or large critter like
that, the six leggers become competitive. The weight distribution advantages
of 8 to 10 legs become minimal. It's turning into a three cornered fight.
Go down another size level, to a few hundred pounds, man or deer or
mountain lion and down, then the four legs enter the fray. It's now a four
way contest, and here is where the evolutionary pressure starts to get
truly fierce.
Because that size range, is also the upper limits of where mammals,
insects and reptiles can still consider themselves somewhat competitive
on Mars.
So, on the small scale, you've got at least seven major evolutionary
lines, all fighting it out. That's going to call for some impressive competition,
a lot of speciation and specialization, a real biological laboratory of
adaptations.
So Evolution progresses swiftly. The Martian ‘Mammal-like’ reptiles
are operating very much on mammal levels as far as energy, muscle and intelligence
are concerned. Hell, they're all using everything they can grow their hands
on.
Winners and losers shake out. The big losers seem to be mammals and
reptiles, who are pushed to the margins of the ecology. In John Carter's
time, they're both still around, but fairly no-account.
The four legged critters take a pounding. There's other advantages than
weight distribution in having extra limbs. You dig faster and deeper, you
run faster and further, swim better, what have you. In fact, by John Carter's
time, just about every four legged species is extinct, the entire lineage
is mostly gone...
Except for one clever little line of fourlegs, who have out of sheer
desperation, their evolutionary back to the wall, have learned to make
and use tools.
How about that.
Ecological
Zones
On Earth in its early history, there were only two significant ecological
zones. The single land mass, Gondwanaland, and the world ocean that surrounded
it.
Gradually, plate tectonics split Gondwanaland up, creating continents,
mountain ranges, islands and isolated seas. South America, Antarctica and
Australia split off some sixty million years ago, each developing its own
unique flora and fauna. Later, Madagascar and New Zealand became separate
island ecologies. Eurasia, Africa and North America were loosely linked.
The Atlantic became a separate water body, as did the Mediterranean and
to an extent, the Caribbean. North America split from Eurasia and joined
South America. Africa, Asia and Europe were partially isolated from each
other by seas, mountain ranges and deserts.
In short, Earth in its evolutionary history began as a relatively uniform
area and then slowly divided up into a multitude of ecological zones, which
separated and then reemerged over time. And in fact, the break
of earth into different ecological zones, and the separation and unification
of those zones helped to chart the course of life and evolution on Earth.
The history of ecological zones of Martian life is much different. Without
plate tectonics, the geography was much more stable and uniform, but it
was effectively diverse in structure from the start.
Ecological zones emerged on Mars with permanent, although not insurmountable
barriers of seas and geography. This made it both easier and
harder on life. The barriers of geography were, as I said, not insurmountable.
Life forms could travel through the whole of the planet. On the other
hand, it wasn't going to be easy, and so life forms had to be adapted to
a certain degree of hardiness to overcome the geographical obstacles.
There were no free rides brought about by continental plates joining up.
The principle ecological zone was the Polar Ocean that dominated the
Northern Hemisphere. The Ocean extended into three lobes which provided
some diversity in local fish and plant populations.
The three lobes of the Polar Ocean also meant that there would be three,
loosely connected and interrelated lowland equatorial areas each with slightly
different conditions, which may have contributed to the proliferation of
vertebrate life forms.
Each equatorial lowland seemed to develop in its own way, but overland
and coastal transmission meant that as they each expanded, they encountered
and began to influence each other. As many species are common to all three
or two out of three as are particular to only one. Of the three, the most
unique, geologically, and biologically is Marinis Valles.
Around the sea, ecological zones emerged based on altitude above sea
level, thus seasonal tidelands emerged near the seas, rain forests above
the maximum sea levels, grasslands above the rain forests and finally deserts
in the highlands.
Elysium and Hecates, geographically separated from the mainland evolved
radically on its own. In the southern hemisphere, vast deserts of Tharsis
and Syrtis acted as geographical barriers, slowing the spread of life and
isolating it. Life did not originate independently in the Oceans of the
Southern hemisphere, but travelled there as primitive or hardy forms from
the north, who swiftly adapted to the relative prosperity of the Hellas
and Argyre regions.
The
Birthplace of Barsoom, the Polar Sea
For ancient Barsoom, the polar ocean was the planet's engine. Due to
greater distance from the sun, the martian environment was proportionally
colder and less energetic than the terrestrial. This is moderated somewhat
by the shallow northern polar ocean which maintains a high level of biological
activity, equivalent to sub-arctic and sub temperate ocean areas. The cooler
temperatures meant that the waters were saturated with oxygen and the lower
gravity dramatically increased the nutrient content of the oceans and seas
in terms of suspended sediments or dissolved constituents.
The great polar sea and its tributaries were biologically intensely
active, teeming with multitudes of fish. In the shallows, lobe finned fish
predominated. On sea floors a variety of arthropods devoured the slowly
drifting vestiges of the biological feast above them. Barsoom produced
a variety of fish, including analogues of sharks, rays, eels and whales.
The Polar Ocean was a single continuous body, so there would be a degree
of commonality to its species, particularly for fish or arthropod species
that were adapted for northern waters, or could survive passage through
northern waters.
But moving south, the Ocean divided into three lobes. For southern adapted
fish and arthropods, the northern reaches formed a subtle barrier, allowing
species to diversify and specialize. Each southern lobe offered its own
mix of hospitable shorelines, bays, coves, harbours, valleys and lowlands,
and so we can imagine a lively and diverse series of coastal fisheries.
Likely or most of the early permanent communities of Barsoomian hominids
were based on fisheries rather than agriculture. The sea, once again, was
the mother, this time to Barsoomian civilization.
The
Martian Mediterranean, Marinis
The Marinis Valles canyon system, a huge gouge that stretches across
3600 miles of modern Mars with trenches up to ten miles deep is flooded
and is an adjunct to the Acidalia lobe of the Polar sea.
Hydrologically, it does not behave like the rest of the ocean. The deep
canyon trenches and high ridge walls provide a degree of climactic and
environmental stability that is unique. Marinis has the most stable and
consistently warm climate on the planet, even the seasonal fluctuations
in water level are reduced here.
The
Madagascar of Mars, Elysium
The shield volcano that created the Elysium Montes platform was never
part of the Martian mainlands, and never connected by any kind of land
bridge. Accordingly, like Madagascar or New Zealand, life evolved in its
own directions.
The Elysium Montes area constituted a central land mass, with an equally
large hinterland of seasonal tidal lands, and a large network of islands,
many of which were isolated from surrounding lands, or submerged completely,
during the summer high waters.
Geographically separated for all of its history, life took some different
turns here. Lobe fins and amphibians colonized the tidal lands, as had
been done on the mainland. Even the primitive seagoing reptiles made it
over, as did many species of wind borne or water borne plants.
After that, things went off in their own direction. The relatively small
land mass, large tidal flats and multitude of islands gave a permanent
advantage to semi-aquatic forms. Land based life had trouble getting started.
Arthropods were likely the first to successfully colonize Elysium, and
a variety of gigantic insects and spiders flourished on the permanently
dry land, many using the power of flight to reach the lands and propagate
themselves, reaching the absolute limits of size under the square cube
rule.
Lizards and reptiles tended to dominate along the shores and swamps.
Developing into titanic serpents and huge dinosaur like foragers.
Birds were a relatively late addition to the environment of Elysium
Montes, and fought a protracted war with flying insects for a foothold.
Elysium probably had a variety of winged and flightless birds, including
some of the largest species on the planet.
The regular varieties of land animals, whether four legged, six, eight
or ten, would find it difficult to reach Elysium, forever out of reach
across the sea. Only the aquatic or semi-aquatic types would
be able to reach it, and they might find little incentive to colonize the
land. The local lobe fins might evolve into ‘legged’
animals, but there would be a very good chance that these creatures were
poorly adapted and more primitive than their mainland cousins.
The only mainland animal that could truly colonize Elysium was a sailing
species: Man
Click
for larger image
Martian
Wasteland - The Tharsis Bulge
The extreme highlands of the Tharsis Bulge, the home of most of the
Martian Volcanoes and a huge volcanic shield plateau amounted to some of
the coldest, most inhospitable zones on the planet.
Arid and nearly devoid of moisture, by reason of its extreme altitude
the bulge frequently sported thin air, blistering hot and cold temperatures
and savage storms.
Life on the Tharsis Bulge was likely to be hard, brutish and short.
Many conventional Martian plant and animal species probably colonized the
bulge, but tended to evolve rapidly to suit the harsh conditions. Martian
trees and plants grew stunted, with withered leaves designed to conserve
moisture and thick root systems.
The animals which survived up there tended to become Dwarf versions
of the originals. Thus, there was a probably omnivorous Dwarf Thoat, Dwarf
White Ape, etc. Life evolving for Tharsis did poorly in the more generous
lower latitudes.
All around the Tharsis bulge, in the shadow of great volcanoes, we would
expect volcanic vents, steam vents, geysers and small deep canyons. Essentially
a series of microclimates of extreme conditions, perhaps some of the hottest
and moistest habitats on Mars. It would be fascinating to see what colonizes
these inhospitable regions, and how they adapt to their new homes.
The
Desert Barrier, Syrtis and the Ring Around Hellas and Argyre
Syrtis is an arid desert area, roughly boomerang shaped, which separates
Hellas from the Polar Ocean and lowlands in the north, to Korus in the
west. The Syrtis desert comprises a wide variety of biomes from harsh sterile
desert at its core, to tundra, moderate or mild desert and scrub lands
towards its periphery.
Syrtis was probably the area closest to modern Barsoom, and likely it
was the birthplace of many of the surviving species of John Carter's time.
Syrtis is not so much an ecological zone as a barrier to ecological
zones. The life at its edges is often most influenced by its immediate
neighbors. Only a handful of plant and animal species, such as the White
Ape are both native and range widely.
Hellas,
A Lost World in the Southern Hemisphere
The northern hemisphere and the polar ocean and its shores were the
origins of life on Mars. But in the southern hemisphere, two large seas,
Hellas and Argyre were isolated bodies of water, separated by several thousand
miles from each other and from the northern water complexes.
On Earth, the oceans interconnect, and isolate islands and continents.
Australia, New Zealand, Madagascar were all isolated areas which allowed
life to evolve differently. On Mars, the Tharsis bulge and Martian desert
highlands formed massive barriers which isolated and created ecological
‘island continents around Hellas and Argyre.
Sea life and river life was effectively cut off from the southern hemisphere
water bodies. But wind was a major vector for transmission of seeds and
spores from land and shore plants. Soon, the empty seas were surrounded
by plant ecologies which had blown south, and began to evolve radically
on their own. Wind based colonization was impeded by the fact that the
southern hemisphere was cooler than the northern one, and thus winds tended
to blow strongly north to south.
This meant that while wind seeded plants might find a southern-going
wind, these tended to be the lightest and often the most basic and widespread
plants. Many plant species with heavier seeds or travelling at lower altitudes
never got out of the northbound winds and failed to make it south.
The southern hemisphere started with substantially less biodiversity
than the north. This meant that the few life forms that did make it down
found empty ecological niches literally on every side, and swiftly began
to proliferate to take advantage of these new opportunities.
Animal life, travelling overland, eventually made it to the empty seas
of Hellas, where over millions of years, many forms returned to the sea,
taking advantage of lack of competition from water breathers. The Hellas
sea was populated by equivalents of Martian dolphins, seals, otters, sea
cows, crocodiles, turtles and perhaps even mermaids. On the shores of Hellas,
other specialized variations of primitive Martian animals evolved, creating
an ecological biome as unique as Australia.
Hellas became the dominant biome of the southern hemisphere. Plants
and amphibian and desert animals evolving around Hellas spread to the multitudes
of empty crater lakes in the southern hemisphere. A variety of animals
spread out from Hellas, adapted for cold weather, erratic moisture and
harsh conditions.
The Lost
Sea of Korus
Argyre is Mars smallest ocean or sea. Argyre, was directly south of
the Valles Marinis biological zone, in primeval times, it was loosely connected
by a winding series of lowlands and oasis known as the Iss Corridor. The
Iss Corridor allowed early Martian plants, but not animals to colonize
the Korus sea complex.
The Iss Corridor was a precarious series of valleys and oasis which
formed a barrier to fish and to most of the primeval Martian land and insect
life. Instead, prehistoric martian plants were able to propagate themselves
in stepping stones through the corridor, during freakish wet periods that
may have lasted only a few years or even months over millennia or millions
of years, before finally establishing themselves in Argyre.
The plant life of Argyre has many resemblances to some of the earliest
prehistoric plant life of the polar ocean lands, back before animals had
truly learned to dominate the surface. Without animals for competition,
plant life in Argyre evolved and diversified in strange ways. Separated
from winds by the high ridge walls, many found alternate means of propagation.
Some eventually evolving mobile and semi-mobile forms, becoming animal
like, in replacement of missing animals.
Meanwhile the shallow valleys of the Iss Corridor were desicated by
their proximity to the Syrtis and Tharsis highlands. The oasis dried up
for millions of years. A partial warm humid spell, millions upon millions
of years later allowed a second invasion of small northern hemisphere plants
and animals, mostly reptiles. But by this time, the native plants had evolved
so far and were so well established, and the invading plants and animals
were so small and weak in comparison, that they were simply incorporated
into the ecology and local mobile plants became carnivorous to prey upon
these new sources of food.
The ultimate result of Argyre unique evolution were the feared Plant
men of the Dor Valley, and a variety of man eating plants, including a
semi-mobile tree that, although fixed, could seize prey. Some of the exotic
and motile plant forms were transplanted by homo ares into small pockets
in the northern hemisphere, where they survived to John Carter's time.
Animal life remained marginal. Reptiles returned to the water and gave
rise to a unique range of eel like creatures known as silurians.
Argyre has had some ecological influence on its surrounding biomes,
although not as much as Hellas. The crater lakes closest to the pole and
adjacent to Argyre contain primitive but hardy plant life closely related
to Argyre forms. However, due to harsh conditions, much of it is fairly
primitive. There are many crater lakes where Argyre and Hellas plant life
are found, but Hellas invariably dominates.
The motile plants are not seen in any of the crater lakes and are unique
to Argyre Korus regions.
