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The history of Spec as a timeline distinct from our native stream ("Home-Earth" or "Real-Life" - henceforth referred to as RL) begins roughly 65 million years ago. On RL, this point in time
corresponds with the end of the Mesozoic Era and the dawn of the Cenozoic
- the so called Cretaceous-Tertiary (K-T) boundary, although many workers
now prefer to divide the Tertiary into the Paleogene (Paleocene-Oligocene)
and Neogene (everything else before the Quaternary).
Specworld fossils dating from before the K-T boundary
most often belong to organisms described in our native timeline's
fossil record, indeed some famous pre-Cenozoic RL fossil sites, such as the
Dinosaur National Monument and the Burgess Shales have identical Specworld
counterparts and have actually produced matching specimens. A few Mesozoic Spec fossils (most
notably Mirabilotheridium, a monotreme from Cretaceous South
America and Lepelara, an early angiosperm) represent new taxa.
All these novel finds fit comfortably within the accepted theories of
our home-Earth's Mesozoic history.In all likelihood, these taxa
simply represent fossils of creatures that once existed on RL but have
yet to be found.
Above the sediments laid down at the same time
as Home-Earth's K-T boundary, Spec's fossil record diverges radically
from the natural history of our native timeline. The most obvious feature
is the fact that the great dinosaurs did not go extinct, and nor did the
host of other organisms that vanished in RL. Secondly, a great variety of
animals that appeared in the early Cenozoic of RL (particularly large
mammals) are missing - without the catastrophic K-T extinction event to
clear out the competition, these forms never had the opportunity to evolve
on Spec.
Most Spec-researchers continue to use a stratigraphic
system based on the one developed and calibrated for Home-Earth sedimentary
formations. This system is workable in the contexts of either timeline, as the broad geological and climatic
histories of our two worlds - with the exception of the K-T boundary - appear to be
identical. For example, the timing of the appearance and disappearance of
the index fossils (various marine planktonic forms) that help to demarcate
the different stages of the Cenozoic show a strong degree of
correspondance between the two timelines. It should be noted that the actual makeup of
the Cenozoic planktonic floras of Spec and RL are very different, however
the arrival and extinction of stratigraphically useful taxa happens at about
the same time.
There remains one glaring geological difference
that separates Spec from RL - 65 million year old sedimentary deposits
on Spec show no sign of a large impact event or the subsequent
mass-extinctions. In fact, discounting the long-term decline of certain lineages
and a drop in marine tropical diversity, there appear to be no abrupt
changes in the global biota between about 71 million to 63 million years
ago. This low-level extinction roughly corresponds on the RL chronological sequence with the
start of the Maastrichtian Age (the final stage of the Late Cretaceous)
to several million years into the Paleocene Epoch (the first Epoch of the
Cenozoic Era). Especially noticeable is the continued formation of chalk
deposits in Spec during this time whereas, in RL, all chalk production suddenly ceases after the K-T boundary,
due to the sudden disappearance of radiolarians (chalk-producing planktonic
organisms). Just as striking is the complete absence on Spec of the famous band
of iridium-rich deposits, the ominous global signature of the K-T impact.
Largely for reasons of convenience, many Spec-based
research publications continue to use Home-Earth K-T stratigraphy and
chronology (ie. the Cretaceous Period ends 65 million years ago) for describing the
corresponding sections of sediment and past-time on Spec even though the
physical geological boundaries do not exist (ie. there is nothing in the 65
million year old sediments of Spec that would warrant the termination of
the Mesozoic Era and the start of the Cenozoic Era). As a result of this
anomaly, some researchers have proposed a number of amendments to the stratigraphic
table of Specworld to account for these striking differences:
1. The end of the Cretaceous Period (and thus the Mesozoic
Era as well) on Spec is pulled forwards from c.65 million years ago to
c.55 million years ago, corresponding to the end of the Paleocene Epoch
in RL.
2. The period of time on Specworld corresponding to the first
3 million years of the Paleocene on RL is now incorporated into the
Maastrichtian Age of the Cretaceous. Thus the Maastrichtian, which extends from 72-65
million years ago in RL, extends from 72-62 million years ago on Spec.
3. The remainder of Spec's Paleocene, (extending from 62-55
million years ago) is retained as a distinct unit owing to changes in planktonic
assemblages. It is however, considered to be the final age of the Cretaceous
Period rather than a part of the Cenozoic Era. A large extinction event
(albeit less drastic than RL's K-T event) at the end of this age marks the
end of the Mesozoic Era and the dawn of the Cenozoic Era on Spec.
4. From after 55 million years ago, the stratigraphic units of Spec once
again conform with those ofRL save for the fact that the Eocene is now considered to be the first
Epoch of the Paleogene/Cenozoic.
However, these amendments have yet to be widely accepted and, rather than risk confusion to the reader in this
introductory publication, we will henceforth continue to use the Home-Earth chronostratigraphic system.
FROM 65,000,000 YEARS AGO TO THE PRESENT DAY.
The following account is based on our current understanding of the natural history of Specworld from the what would
have been the end of the Cretaceous on RL, up to the present day. The reader should note that many facets of Spec's
fascinating past are poorly understood, and the subject of intense scientific debate.
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