Paleontology Laboratory
PROTISTA, EUBACTERIA,
ARCHEOCYATHIDS, PORIFERA
& CONULARIDS
• Fossil organisms within the Kingdom
Protista represent the earliest life forms
known.
• These organisms are characterized by a
single-celled body plan
• Kingdom Eubacteria (green and blue-green
algae) have no nucleus.
• The protist phyla Foraminifera and Diatoms
have mineralized skeletons and an extensive
fossil record.
• Because of their wide-spread distribution
and rapid evolutionary rates, many of the
protists are excellent index fossils used in
biostratigraphic studies.
FORAMINIFERA
• Foraminifera are the most common and geologically
most important of the fossil protozoans.
• Today, nearly all forams live in marine environments
and are either bottom dwellers (benthic) or float in
the water column (planktic).
• Forams are characterized by multi-chambered tests
which are built by addition of new chambers during
life. Chambers are separated by partitions called
septa (singular = septum), whose exterior
expressions are termed sutures.
• Composition of the tests are either calcite (CaCO3) or
agglutinated (cemented foreign particles, e.g., sand
or silt grains).
• The classification of Foraminifera is based on
– (i) test microstructure,
– (ii) test symmetry, and
– (iii) aperture type.
BENTHIC FORAM
PLANKTIC FORAM
FUSILINID
NUMMULITES
Radiolarians and Diatoms
• Radiolarians are heterotroph protozoans which
thrive in the upper layers of the seas.
• The protoplasm of radiolarians is surrounded by a
test commonly composed of an intricate lattice work
of opaline silica
• The tests of radiolarians exhibit great morphologic
diversity, but they are typically characterized by
radial or spherical symmetry.
• Diatoms are a kind of microscopic golden-brown
algae that secrete siliceous tests (sometimes called
frustules) consisting of two overlapping halves or
valves that fit together.
• The walls of the tests are ornamented by pores,
grooves, and ridges.
RADIOLARIAN
DIATOM
EUBACTERIA
• Stromatolites are organically produced
sedimentary structures and are amongst the
oldest fossils known on Earth
• They are made by cyanobacteria (often
erroneously called “blue-green algae”, however,
because the cells are prokaryotic, they should
not be confused with true algae which are
eukaryotes.
• Stomatolites are without skeletons (they are
layers of sediment), and differ from some
similar-looking sponges that have a mineralized
skelton.
Archeocyathids
• Archeocyathids have been assigned by
paleontologists to many different animal
groups, primarily the corals and
Pleosponges.
• Many researchers even referred to them to a
distinct, separate Phylum, Archeocyatha.
• Recent investigations have proved pretty
conclusively that archeocyathids were an
early experiment in the Phylum Porifera--they
are now generally considered an extinct type
of calcareous sponge.
Archaeocyathids
• Archaeocyathids were sessile, marine
organisms of shallow, tropical and
subtropical waters that lived during the
early Cambrian period about 550 million
years ago. T
• hey were widespread in Cambrian seas
throughout the world and were the first
major reef-builders before the true corals
PHYLUM PORIFERA (sponges)
• Porifera means "pore-bearing". Exterior covered by tiny
pores.
Globular, cylindrical, conical or irregular shape.
• Interior may be hollow or filled with branching canals.
• Solitary or colonial.
• Skeletal elements are called spicules, and they may be
separate or joined.
• Composition may be calcareous, siliceous or organic
material called spongin.
• Geologic range: Cambrian to Recent.
• Mode of life: Attached to the sea floor. Most are marine.
SPONGES
• Sponges have an asymmetric body with no true tissues,
or organs.
• They have two layers of cells.
• Flattened cells cover the exterior. Collar cells line the
interior chambers. Collar cells move large volumes of
water through body pores by their beating flagella.
• They also trap suspended food particles in their microvilli
collars.
• Between the two layers of cells there is a semifluid
matrix with needlelike structures for support.
• Sponges reproduce sexually and have a free-living larval
stage. They also reproduce asexually by fragmentation
or gemmules.
PORIFERA
SPONGE SPICULES
GLASS SPONGE
DEVONIAN
GLASS SPONGE
CONULARIDS
• CONULARIDS- Although there is some
controversy in regards to the systematic position
of the conularids, most workers today place
them with the scyphozoan cnidarians.
• The exoskeleton of conularids is composed of
chitin and in outline is pyramidal with four sides.
• The exterior surfaces of conularids normally
have finely spaced longitudinal ribs.
• The interior of conularids may have thickenings
or septa developed.
• In life, conularids lived attached apical end down
to the substrate.
Conularid