EARLY CAMBRIAN PERIOD to
LATE
PERMIAN PERIOD: 570
million - 230
million years ago
Trilobites
are hard-shelled, segmented creatures
that lived hundreds of millions of years ago in the Earth's ancient seas.
They are considered to be one of our planet's earliest complex
life-forms and are one of the key
signature creatures of the Paleozoic Era. Trilobites went extinct before dinosaurs even
existed. The name 'TRILOBITE' means 'three lobed" and is
derived from the fact these animals had bodies featuring three longitudinal
lobes, not lateral (head, body, tail) as is often thought. The
lateral division of three parts is shared by many arthropods, not just
trilobites.
Next
to dinosaur fossils, trilobites command a dedicated and passionate
following amongst both scientists and fossil collectors, alike. In
a relatively short time-frame (scientifically speaking, of course), we
have the emergence and subsequent extinction of these fascinating
creatures. Still most baffling is the incredible diversity of
sizes and features that made up the trilobite group. Many bizarre
species co-existed with highly specialized body parts that defy the
theories of evolution in their "sudden" emergence and
diversity during the Early Cambrian Period in what is known as the
'Cambrian Explosion'.
Trilobites
were among the world's first arthropods, a phylum of hard-shelled
creatures with multiple body segments and jointed legs (although the
legs, antennae and other finer structures of trilobites only very rarely
are
preserved). They constitute an extinct class of arthropods, Trilobita, that is comprised of over 15,000 known species. It has been
reported that every year, four to five new species are discovered in the
Atlas and Anti-Atlas Mountain regions in Morocco, alone! This
desolate northern fringe of the Sahara Desert was once covered by a
prehistoric ocean and its fossil deposits can be considered amongst the world's
richest and most diverse source of these ancient sea creatures.
Trilobites
are the single most diverse group of extinct organisms that ever
existed, period! The smallest known trilobite is just three
millimeters long, while the largest type grew to a length of 70
centimeters (over two feet long!).
The most
common fossil of trilobites is the mineralized dorsal exoskeleton of the
creature. This is found in partial form from molting (shedding the
shell as it grows) or in complete form when the animal was buried and
died intact. The soft parts of the underside are rarely
preserved. Trilobite fossils are collected by locating a
fossil-bearing layer in rock and then breaking boulder or splitting rock
sheet to reveal a cross-section of the preserved trilobite carapace in
the break or to reveal an imprint in the sheet. Once the fossil is
located, the pieces are then reassembled and delicate preparation then
ensues to remove the surrounding rock above and around the trilobite to
expose the fossil.
Much of
what we hypothesize about trilobites comes from our knowledge of modern
arthropods and marine crustaceans. Scientists believe they
reproduced sexually, molted and underwent a series of life stages.
We know trilobites lived in a variety of marine environments over the
course of their existence on our planet. Feeding habits are
believed to have been varied including predators, scavengers,
filter-feeders and parasites, depending on both type of trilobite and
life stage. The majority are believed to have been predator /
scavengers due to the presence of a calcified mouthpart called a 'hypostome'.
Rare fossils of trilobites showing detailed preserved anatomy under the
carapace indicates they had a series of jointed legs and gill
structures.
Considerable
study has been done on trilobites as a whole organism. Even more
fascinating though, is the research done on a microscopic level with
regards to trilobite morphology. Radiographs have
captured incredible detail of complete and fully articulated antennae
and underparts like legs and gills, preserved in the host rock of some
fossilized specimens. Perhaps the most impressive and classic
feature of trilobites that comes to mind is the eyes. Microscopic
studies of trilobite eye structures have also revealed marvelous
adaptation and very high degrees of specialization in
vision.
It seems
that the more we learn about trilobites, the unfolding of their mystery
is stranger than fiction. Certainly we gain a greater appreciation
with each new discovery of these strange and highly advanced but now
extinct 'butterflies of the ancient seas'.
Unfortunately,
fakes plague the fossil market and both ignorance and dishonesty on the
supply side continues to facilitate the increasing appearance of fakes in
the fossil market and especially, the trilobite market. Education and vigilance is
needed. To learn more about this topic, we urge you to spend some
time in the fossil
INFORMATION
section, as well as
FAKE
FOSSIL
section. A dedicated educational section on fake trilobites can be
accessed by clicking on the button below.
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