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SPEC'S LATE MAASTRICHTIAN (c.66,000,000 - 62,000,000 b.p.)
= Home-Earth K-T Boundary
Across the globe, the Earth was a grand stage for fantastic tectonic activity. Great mountain ranges were being
pushed upwards while the continental plates were sliding about like hockey pucks. The grandest tectonic spectacle
took place on the Gondwanan fragment of India, as this sizable subcontinent dashed itself against the Asian plate.
Erupting in their full glory were the volcanoes that would create the Deccan Traps, leaving
an area of 1.5 million square kilometers buried under 2 kilometers of flow basalt.
The India fiasco was not the only upheaval facing the
world. Across the globe, the oceans had been in retreat for the past few
million years, exposing vast tracts of shallow seafloor. Great Britain rose
from its watery prison and the two halves of North America united as the Western
Interior Seaway shrunk to a fraction of its former glory.
Life on Spec was under pressure. Great clouds
of volcanic ash screened the sunlight. The retreat of inland seas stranded entire continental
shelf communities. Once lush coastal paradises were faced with continental
climates that brought extremes of temperature and erratic rainfall.
The late Maastrichtian was a very bad time for tropical marine
life. Oceanic cooling and the draining of inland seas led to a
drastic reduction of tropical reef ecosystems. Many once-diverse families
were eliminated or reduced to a few cosmopolitan forms. Cool-water species
from the higher latitudes flocked towards the equator. The ancient coiled
ammonites maintained their overall
numbers, but at a greatly reduced diversity.
On the seafloor, once vast beds of giant inoceramid clams dwindled then
vanished, while their cousins, the rudists, were reduced to a handful of
species. Although rudists as a group would survive up until the present
day, their time as the dominant reef-builders was over. As for the giant
marine reptiles, the sea turtles and serpentine mosasaurs appeared to
be holding their own. The graceful plesiosaurs were poorly,
while, up in the sky, the once diverse pterosaurs were reduced to a single
cosmopolitan family of giants, Azdarchidae.
The situation of life on land was less clear. Most dinosaur lineages of the Late Cretaceous survived, but suffered
a marked drop in species diversity. Many survivors tended to be considerably larger than their immediate
ancestors, possibly an evolutionary response to the rise of extreme continental climates. Falling sea-levels
united previously isolated landmasses, allowing populations of dinosaurs to travel unhindered between the
continents. These environmental changes probably put a further strain on dinosaur populations via the spread of
disease and the arrival of new competitors.
About 64.5 million years ago, few of the animals would have noticed the new star that had appeared in the heavens. As
the weeks progressed it gradually grew in size, trailing a shimmering gossamer train in its wake. Bigger and
brighter it became until it was clearly visible in the daylight. Then on one night the wanderer seemed to
lose its resolve and grew almost imperceptibly dimmer. As the nights passed it continued to wane, smaller and
smaller, until it was lost amongst the myriad of stars. The world had arrived at a crossroads and taken one path at
the expense of another. The dinosaurs lived on, entirely oblivious to the grim fate that had just been averted.
TRL END OF SPEC'S CRETACEOUS PERIOD (c.62,000,000 - 55,000,000 b.p.)
= Home-Earth Early Paleocene Epoch
Depleted ecosystems around the world were
regaining their lost biodiversity as conditions improved. Areas once
laid barren by volcanic eruptions now burst into life. The equatorial
seas teemed with new species of plankton allowing marine food chains to
reestablish themselves. Insects filled the skies, greedily pursued by
birds and early bats. Mammals and lizards scurried in the undergrowth.
With regards to the larger animals, the picture was almost identical to that of the Maastrichtian.
Great mosasaurs and predatory sharks terrorised the seas, although the swan-necked plesiosaurs
were much rarer than before. A final handful of pterosaur species still cast
their great shadows over the earth.
Worldwide, it appeared that just about all
the major dinosaur families of the Maastrichtian had survived. The dominant
large herbivores were the hadrosaurs, with great herds of duckbills roaming
across every continent. The giant long-necked sauropods were widespread
and common in the southern hemisphere with a few species scattered around
the north. Great numbers of small ceratopsians and bone-headed
pachycephalosaurs plucked at the low-foliage. Stalking the herds were the great tyrannosaurs,
including the genus Tyrannosaurus, itself. Smaller theropods included
the sickle-clawed dromaeosaurs and the ostrich-like ornithomimosaurs. All
in all, the vertebrate fauna represented a steady progression from the
preceding Maastrichtian with no big evolutionary surprises.
Then, towards the very end of the Paleocene, something drastic happened, signalling the end of
the Mesozoic Era and the dawn of the Cenozoic on Specworld. Global
temperatures were already very warm, but 55 million years ago they suddenly skyrocketed,
raising the mean annual temperature by over 10 degrees C. The probable
source of this dramatic climatic shift was just as disturbing as the
effects - the Earth was suffering from a chronic and lethal case of flatulence.
SPEC'S END-OF-CRETACEOUS EXTINCTION EVENT (c. 55,000,000 b.p.)
= Home-Earth Paleocene-Eocene Boundary
In the cool seafloors of the world, immense quantities of methane are concentrated as a frozen
substance known as methane clathrate. When the temperature of
the ocean rises above a certain level, it begins to warm this methane
clathrate which ultimately triggers off a huge release of gas from the seabed.
Such an outgassing event seems to have occured on a massive scale 55 million years ago, probably
initiated by a shift in ocean currents or possibly even an extraterrestrial
impact. Once released, the methane gas soon broke down into its constituent
elements of carbon and hydrogen. The carbon combined with oxygen in the
air to form vast quantities of carbon dioxide. With such a dramatic increase
of this greenhouse gas in the atmosphere, global temperatures soared and,
for tens of millennia, the Earth was a sweltering hothouse.
Surprisingly, an identical event occured at about the same time on RL, but it seems to have had a
fairly minor impact on the level of planetary biodiversity. The most likely
explanation is that the preceding catastrophe at the end of the Cretaceous
had already wiped out everything that could have been adversely affected
by the methane eruption. The K-T extinction event had left behind an impoverished world biota
of resilient and adaptable organisms that were well able to handle yet
another sudden change in climate. In effect, the K-T impact had vaccinated
the biosphere against the outgassing event of the Late Paleocene.
On the Specworld, however, the Eocene extinction was far more severe. As
the oceanic currents on Spec went haywire, the seas witnessed a catastrophic
extinction event only a little less devastating than the aftermath of RL's K-T impact.
The oceans at the equator became too hot for all but the most hardy of organisms.
Corpses of coolwater marine creatures which had been left unscathed by the tectonic
mayhem of the Maastrichtian now littered the seafloor in their billions. As the tiny
radiolarians perished, chalk production ground to a halt and marked the abrupt end
of the Cretaceous Period.
This was the final nail in the coffin for the oceanic plesiosaurs and the flying pterosaurs.
Exclusively tropical members of both groups had been wiped out at the
close of the Maastrichtian. The survivors must all have been high-latitude
forms which, despite having spread to the equator, still returned to
the milder, richer polar waters to feed and breed. The methane-induced
temperature spike hit the marine food-chains in these areas particularly
hard, and sealed the fate of these two ancient reptilian lineages. The
great pterosaurs, pioneers of vertebrate aviation, had at last surrendered
the skies to the birds and the recently-evolved mammalian bats.
Alas, neither of these groups would ever produce a flier that would come
even close to rivalling the sheer majesty of the largest pterosaurs.
On land at this time, the effects of the outgassing soon became apparent. Dense forests and crocodile-infested
swamps suddenly appeared at both poles. A number of dinosaur taxa died out, but the
pattern of extinction is confusing with different families suffering to
different degrees. Duckbills, ceratopsians and tyrannosaurs seemed to maintain
their overall diversity, although they lost most of their larger
representatives. Sauropods survived in the south, but vanished in the north. Amongst the
ankylosaurs, the club-tailed ankylosaurids disappeared, while the once
very rare spiny nodosaurids actually seem to have increased their numbers.
The ornithomimosaurs and pachycephalosaurs, once among the most common
dinosaurs in the northern hemisphere, died out completely. In general, northern
populations of dinosaurs were hit harder than the south, probably because the polar
continent of Antarctica acted as a large refuge away for the searing lower
latitudes.
Precisely how this seemingly random pattern of extinction occured is still a mystery, but it seems likely that
different parts of the world experienced different kinds of detrimental effects.
Weather patterns altered radically, the vegetation changed, new competitors appeared from elsewhere. It is
also possible the elevated temperatures affected the sex-ratios of dinosaur hatchlings, producing an imbalance
of males over females or vice versa.
As Specworld's Late Cretaceous drew to a close, the Eocene Epoch dawned, as did Specworld's Cenozoic Era.
The excessive greenhouse effect gradually lifted, leaving a stable, though still sweltering, global climate. Despite their losses, dinosaurs as a whole were just as common as ever before. Their empire had recently
been through hard times but the great beasts survived, maintaining their
reign on the planet. The Age of the Dinosaurs goes on...
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