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Taphonomy
This research line focuses on the factors
that control the formation of the amber
deposits and their paleobiological content,
which is a necessary step before attempting
to reconstruct the paleocommunities and
paleoenvironments. In order to accomplish
this, the taphonomy of amber and the
organisms preserved within, chiefly
arthropods and plants, is being studied. |
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A group of objectives comprises the
comparison of taphonomical biases in amber
with those in modern resins and copal.
Actualistic experiments are comparing
tropical leguminous forests (Hymenaea spp.,
Copaifera spp.) with temperate
araucariaceans forests (Agathis australis).
During the last years, the fauna in modern
resins and Pleistocene copal from Agathis
was collected in New Zealand. These data are
being compared with those from modern resins
and copal from Hymenaea in Madagascar and
Mexico, which were recently collected.
Taphonomical analysis of amber and copal
inclusions is based on differences between
the trapping methods used in the tropical
forest fieldwork. Due to the likely paucity
in the diversity of arthropods collected in
the field, we only use data on the most
abundant groups (including the best
represented groups in Cretaceous ambers),
such as arachnids, hymenopterans, dipterans,
and coleopterans. Numerous studies show that
the arthropods preserved in resins do not
accurately reflect their populations living
around resiniferous trees, i.e., there are
significant taphonomical and paleoecological
biases. The presence of certain groups of
arthropods in amber depends, among other
factors, on the original viscosity of the
resin, as fluid resin favoured the inclusion
of small-sized individuals, which are unable
to escape by amputation.
We also study the taphonomic factors that
control the preservation of resin and its
transformation in amber. In that regard,
thanks to the morphological study of some
amber pieces we have inferred that the resin
that originated the Spanish amber was
secreted in the proximity of its burial
place. Another topic that we have been
addressing is the preservation of soft body
parts in amber inclusions, chiefly using X-ray
synchrotron imaging in order to find
preserved structures like muscles, digestive
tracks, or sexual organs in the studied
arthropods so we can compare their
morphology with that of Recent fauna.
The taphonomic study of the amber-bearing
deposits have demonstrated that the
production of resin in the Cretaceous
forests from Spain was, in part, influenced
by abundant paleofires associated with the
high CO2 and O2 levels in the atmosphere at
that time; charcoalized wood and plant
remains in the sediment, as well as
charcoalized vegetal fibres as amber
inclusions, are common.
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