Dominican Amber - Fossil Ecosystems of North America: A Guide to the Sites and their Extraordinary Biotas - page 222

Dominican
Amber

B ACKGROUND
In the last chapter we saw how the
Florissant lake sampled the plants and
animals from a wide range of habitats
both near and far from the lake site by
trapping them on the water surface.
Insects in particular are also commonly
entrapped in amber (fossilized tree resin)
to which they are attracted and by which
they become engulfed. Tree resin is a
very localized deposit and, while some
trees produce copious amounts of
exudate, it is most likely to preserve
animals and plants which are associated
with trees and forests. Rapid removal of a
carcass from a decaying environment is
the best way of preserving it, and what
could be quicker than trapping and
engulfing an insect in seemingly
impermeable resin? There is no initial
transport of the carcass, apart from some
flowage down the tree trunk and
struggling by the animal itself, although
later transport of the amber is usually
necessary for its concentration into a
sedimentary deposit.
Amber samples forest life from different
sources than a lake deposit, and its method
of preservation is far better than that of
lacustrine sediments for delicate
invertebrates such as insects, while
vertebrates are rarely preserved in amber.
Insects living on tree bark are the most
likely to be found in amber. Many insects
are attracted to tree resin, possibly sensing

the volatile oils given off by the exudate,
but whether this attraction benefits the
tree or the insects is not known. Once
attracted to the resin, insects become
trapped in it because of its adhesiveness.
Predators such as spiders are attracted to
the struggling insects and then they, too,
become trapped, in a similar manner to
the predators preserved in the tar pits of
Rancho La Brea (Chapter 14). Animals
living in bark crevices, in moss on or at the
foot of a tree, flying insects in the amber
forest, and their predators are the most
common animals preserved in amber, and
a wide range of plant material, such as
spores, pollen, seeds, leaves, and hairs are
also commonly found embedded in the
amber. Small drops of resin are unlikely to
collect many organisms, but some trees
exude vast quantities of resin from wounds;
the large masses of resin produced from
these cracks, termed 'Schlauben'
(Schlüter, 1990), flow down the tree trunk
and form ideal traps.
Resin is produced by a variety of trees
today, as in the past. A prolific producer
of resin is the araucarian (monkey-puzzle
family) Kauri pine, Agathis australis ,
which grows in northern New Zealand.
Amber deposits from this tree are known
in New Zealand from some 40 Ma.
Younger deposits of copal (resin which is
not as well fossilized as amber)
30,000-40,000 years old, also occur in
New Zealand and formed the basis of a