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rhabdosome

Rhabdosome is a term used in paleontology and protozoology to describe a rod-like skeletal framework found in certain shelled protists, particularly some radiolarians and related fossil groups. The word derives from Greek rhabdos meaning rod and soma meaning body. In these organisms, the rhabdosome refers to an internal skeleton composed of slender, rod-shaped elements that connect to form an axial spine or lattice that supports the outer test or cell body. The arrangement can be linear, branching, or mesh-like, and may be integrated with, or distinct from, the external silica-based test that is commonly preserved in fossils.

Function and significance: The rhabdosome provides mechanical support, contributes to buoyancy, and influences the overall form

Occurrence: The term is most often used in descriptions of radiolarian skeletons and some related protists

See also: Radiolaria, Foraminifera, Skeletal microstructures, Radiolarian skeleton.

and
rigidity
of
the
organism.
In
the
fossil
record,
rhabdosomes
aid
in
species
identification
and
help
illuminate
the
morphological
evolution
of
early
protists.
The
study
of
rhabdosomes,
typically
through
light
and
electron
microscopy
of
preserved
microfossils,
informs
on
patterns
of
biomineralization
and
can
contribute
to
reconstructions
of
ancient
environments.
from
Paleozoic
to
Mesozoic
strata;
usage
varies
among
authors,
and
older
literature
may
employ
the
term
with
somewhat
different
definitions.