Paleontology course h

INVERTEBRATE PALEONTOLOGY
2014/2015
DR. IKHLAS ALHEJOJ, UNIVERSITY OF JORDAN,

PALAEONTOLOGY
The study of fossils
Gastropod (snail) fossil
A fossil is an original material,
impression (mold), cast, or track
of any animal or plant that is
preserved in rock after the
original organic material is
transformed or removed.

PALEONTOLOGY
- Paleozoology : study of fossil animals
 a. Invertebrate paleontology - study of fossil
invertebrates (animals without a vertebral
column).
 b. Vertebrate paleontology - study of fossil
vertebrates (animals with a vertebral
column).

PALEONTOLOGY
- Paleobotany : study of fossil plants.
 Palynology : study of pollen and spores (some also
include marine one celled "plants"; i.e. acritarchs,
dinoflagellates, tasmanites, silicoflagellates, diatoms,
ebridians, calcareous nannoplankton/coccoliths).
- Micropaleontology : study of small fossils (includes
many groups mentioned under palynology and also
foraminifera, radiolaria, chitinozoa, graptolites,
pteropods (gastropods), ostracods (crustaceans),
conodonts .

Evolution and the fossil record

Age of Earth is ~4.6 billion years
Atmosphere had little free O2
Included CO2, H2O, CO, H2, N2, NH3, H2S, CH4.
Fossils range in age from the youngest at the start
of the Holocene Epoch to the oldest from
the Archaean Eon, up to 3.48 billion years old.
Evolution and the fossil record
Stromatolites 3.4 Ga from Western Australia

Types of Fossils
• Body Fossils - the actual body or body
parts of an organism, whether altered
or not.
•Trace Fossils - any evidence of past
life that is not a body fossil; examples:
tracks, trails, burrows borings,
impressions, molds, casts.

WHY STUDY FOSSILS?
Fossils give clues about organisms that
lived long ago. They help to show that
evolution has occurred.
They provide evidence about how
Earth’s surface has changed over time.
Fossils help scientists understand what
past environments may have been like.

Hard Parts: Common mineral components
Calcium carbonate CaCO3 Principal mineral components of most seashells.
Two common calcareous minerals in seashells:
Aragonite – unstable over geological time.
Aragonitic shells commonly are dissolved (preserved as moulds) or
transform to calcite (poor preservation of primary textures).
Calcite – stable over geological time. Consequently calcitic (e.g.
brachiopod) shells tends to be well-preserved.
Silica SiO2 – Usually amorphous hydrated silica (Opal A) which commonly
transforms to quartz and other silica minerals following death.
Opal may be well preserved in pelagic sediments, if deeply buried.
This is the principal “mineral” component of the skeletons of some sponges,
and micro-organisms such as diatoms and radiolarians.
Skeletons may be lost or degraded through opal dissolution and obliteration
of the original amorphous structure through quartz crystallization.
Calcium phosphate (apatite)
Ca3(F.Cl.OH)(PO4)3 –stable over geological time (tends to be well-
preserved). Principal mineral component of bones, teeth and some shells.

HOW IS A FOSSIL FORMED?
1. Sediment
An animal is buried by
sediment, such as
volcanic ash or silt,
shortly after it dies. Its
bones are protected
from rotting by the layer
of sediment.
2. Layers
More sediment layers accumulate
above the animal’s remains, and
minerals, such as silica (a
compound of silicon and oxygen),
slowly replace the calcium
phosphate in
the bones.

3. Movement
Movement of tectonic
plates, or giant rock slabs
that make up Earth’s
surface, lifts up the
sediments and pushes the
fossil closer to the surface.
4. Erosion
Erosion from rain, rivers, and wind
wears away the remaining rock layers.
Eventually, erosion or people digging
for fossils will expose the preserved
remains.

WHAT ARE THE CONDITIONS THAT ARE
FAVORABLE FOR PRESERVATION?
*Hard body parts such
as skeletal bones or
exoskeletons
*Rapid burial and/or
lack of oxygen

BODY FOSSILS
 Body Fossils are the actual body or body
parts of an organism that has been
preserved. These fossils may or may not be
altered (fossils that have gone through a
chemical change or physical change). The
two main types of body fossils are (A)
unaltered remains and (B) altered
remains…
 Unaltered remains of fossils means that
the remains have gone through little or no
chemical or physical change.

A. UNALTERED REMAINS
Original skeletal material: this means that the hard parts
of
the organism are preserved as the original material.
- Tar impregnation
- Amber Entombment
- Refrigeration
Tar impregnation: tar pits are excellent areas to preserve
life as a fossil. La Brea tar pits in California is one of the
most famous areas because of the large number of
preserved life forms found in it.

TAR IMPREGNATION
Fossilized water beetle, Hydrophilus sp., preserved in oil-
impregnated sands of a late Pleistocene (roughly 35, 000
years old) tar seep in the vicinity of the Kettleman Hills.

REFRIGERATION
 Refrigeration--During the Pleistocene
glaciations, when ice sheets cover much
of the Northern Hemisphere, some
animals (mammoths, for example) fell into
crevasses in frozen terrain or became
trapped in permanently frozen soil. Some
of these animals have been discovered
perfectly preserved.

Mammoths
They lived from
the Pliocene epoch (from
around 5 million years ago)
into the Holocene at about
4,500 years ago
Ice Age wooly mammoths
from the Pleistocene Epoch
have been found frozen in
Siberia and Alaska. Skin,
hair, and soft tissue have
been preserved in frozen
soil.

AMBER ENTOMBMENT-
- Amber-preserved fossils are organisms that
become trapped in tree resin that hardens after the
tree is buried. Small insects and other minute
organism may become trapped in this resin, which
after burial may harden into amber. Certain parts
of the Baltic Sea coast and some of the islands in
the West Indies are well known for occurrences of
insects preserved in amber

Body Fossils, Altered remains
Altered remains of fossils means that the
organisms have gone through chemical or physical
change and must be at least ten thousand years
old.The types of altered remains of fossils are…
-
Recrystallization
Replacement
Permineralization
Carbonization

PERMINERALIZATION
 Many bones, shells, and plant stems have
porous internal structures. These pores
may become filled with mineral deposits.
In the process of
permineralization,
the actual chemical
composition of the
original hard parts
of the organism may
not change
Permineralized Wood

- Carbonization
- Carbonization preserves soft tissues of plants or
animals as a thin carbon film, usually in fine-grained
sediments (shales). Fine details of the organisms
may be preserved. Plant fossils, such as ferns, in
shale generally are preserved by carbonization.
Soft-bodied animals such as jellyfish or worms may
also be preserved as carbonaceous films in black
shales
(leaf)

DISSOLUTION/REPLACEMENT
 Dissolution/Replacement -- Groundwater
(especially acidic groundwater) may act to
dissolve a hard structure in an organism trapped
in sediments and may, simultaneously deposit a
mineral in its place--molecule by molecule.
Silicification
(replacement by silica)
Fossil calcareous sponge
(originally calcitic, now siliceous)

 Depending on the chemistry of pore waters
within sediment, a number of minerals can
replace the original material. These
transformations may occur at earlier (before or
during lithification), or later (after lithification)
stages of fossilization.
 Calcareous (calcitic and aragonitic) shells are
commonly replaced by silica minerals (silicon
dioxide), pyrite (iron sulphide), or calcium
phosphate minerals.
Pyritization
(replacement by pyrite)
Pyritized brachiopod

MOLD& CAST
 Mold - impression of skeletal (or skin) remains in an
adjoining rock
 External mold = impression of outer side
 Internal mold (steinkern) = impression shows form or
markings of inner surface

 Cast - original skeletal material dissolves and cavity
(mold) fills with material

 Endocast- natural infilling of cranial cavity (may study
brain evolution in fossil mammals)

CAST
 A cast may be produced if a mold is filled
with sediment or mineral matter. A cast is a
replica of the original. Casts are relatively
uncommon. (A rubber mold of a fossil can
be filled with modelling clay to produce a
replica or artificial cast of the original
object.)

Molds
External mould
Internal mould
External mould
Internal mould
Clam Fossil clam
Fossil snailSnail
Fossil snail
2.Shell is dissolved
1. Sediment
surrounding the shell
and filling the shell
cavity hardens
2.Shell is dissolved
1. Sediment
surrounding the shell
and filling the shell
cavity hardens

A mold (below) and cast (above) of a trilobite.
.

Ichnology - study of trace fossils
(Ichnofossils = tracks, trails and burrows
of organisms).
Burrows or borings –
Spaces dug out by living things and
preserved as is or filled in
Ichnology

Trace Fossils
- Burrows: These trace fossils show how an animal such as a
worm (an annelid) moved through the soft sediment.
This worm tube
trace fossil is
hollow (the hole
goes all the way
through it).

Trace Fossils
2. Trace Fossils
- Tracks: can show how an animal moved and what its
footprint looked like. These tracks can tell us a lot about the
animal that made them in the geologic past.
(trilobite)
(trilobite tracks)
(Dinosaur tracks)
Do you see the people?

Cruziana: produced by a trilobite
“plowing” along the sediment
surface.
Diplichnites: produced by a trilobite
walking over the sediment surface.

grazing
crawling
tracks resting
living
feeding
Trace fossils
Ziegler (1972)
Body
fossils

Trace fossils and water depth
Frey and Pemberton, in Walker (1884)

Hardground borings
• Condensation
• gaps, hiati
Firmground bioturbation (lower part)
• softground
• continuous sedimentation
Borings and bioturbation
Ziegler (1972)

Trace Fossils
Trace Fossils
- Coprolite: -fossil excrement of animals; may contain
undigested remains of food. usually preserved by replacement.

MORE ON TRACE FOSSILS
 Gastroliths – smooth
stones from
abdominal cavity of
dinosaurs

MORE ON TRACE FOSSILS
Tracks – impressions
of passage of living
things

Pseudofossils
Pseudofossils (meaning
“fake fossils”) many rocks and
rock structures look like
fossils, but aren't!.
(fossilized raindrops
that hit soft sediment)

PSEUDOFOSSILS
The following represent a few sedimentary features that may be
confused for fossils:
 1. Differential Weathering
- weathering of rock and mineral surfaces often yield fossil-looking
features
 2. Nodules
- formed by filling voids in the sediment and incorporation of
sedimentary materials within the sedimentary body
a. Chert Nodules
- microcrystalline quartz; typically found along bedding planes in
limestone

b. Septaria
- large nodules with radial and concentric cracks in their
centers
- Melikaria are boxwork patterns of material filling septarian
cracks; may be all that is left after weathering of the
septaria
c. Rosettes
- radiating macrocrystalline bodies of discoidal or spherical
shape, consisting essentially of one mineral (typically
pyrite, marcasite, barite, or gypsum)


 3. Concretions
- mineral growth within sediment often forms
structures that resemble bones, turtle shells,
logs, etc.
 4. Dendrites
- precipitation of manganese
- oxide along bedding planes
- creates fern-like patterns
(dendrite made by a mineral)

Different types of Trace Fossils
Do you remember what the five types of trace fossils are?
- Mold
- Cast
- Burrow
- Track
- Coprolite

 Competition - two species vie for limited
environmental resources
 Autotrophs (Producers) = manufacture their own
food; "plants"; form lowest trophic level and
constitute the base of the biomass "pyramid"
 Heterotrophs (Consumers) = feed on other
organisms; consist of "animals" (much energy is
lost cycling through higher trophic levels, and
therefore with fewer organisms)

 Herbivores = feed on producers
 Predation = effect of a predator on a prey
species
 Carnivores = feed on other consumers by
predation
 Parasites = derive nutrition from other
organisms without killing them

 Scavengers = feed on dead organisms
 Commensalism = biological association
beneficial to one but does not hurt the host
 Symbiosis = mutual benefit to both
participants

ORGANISM DISTRIBUTION (ESPECIALLY
MARINE) DEPENDS UPON THE FOLLOWING:
 a. Seawater Properties - Density and
Viscosity
 Density of aquatic organisms typically equals
water density
 Viscosity - influences shape and feeding
(there are many "filter feeders" in aquatic
environments, due to the viscosity of water
allowing food to be held in suspension)

 b. Salinity
 - usually measured in parts per thousand (0/00); average
seawater salinity is 35 0/00 but varies from 0 to 270 0/00
 - in Geochemical Studies of Paleosalinity use boron
(greater in saltwater); other trace elements; type of
organic matter; carbon and oxygen isotopes [freshwaters
depleted in heavy carbon (C-13) and heavy oxygen (0-
18)]
 - in Biological Studies use stenohaline (restricted by
salinity; organisms internal "salinities" equals surrounding
water salinity; if rapid change cells may not function)
versus euryhaline (salinity tolerant) organisms

C. TEMPERATURE
 - water moderates temperature
 - in cold-blooded organisms, an increase in temperature of 10°C often
causes metabolic activity to double
 - in warm-blooded organisms there is little metabolic change with
temperature change
 - temperature influences reproductive cycles
 - in Geochemical Studies of Paleotemperature use 18O/16O (less with
greater temperature; most important for determining paleotemperatures);
boron and bromine greater if greater temperature; Calcium/Magnesium
and Calcium/Strontium ratios are less if the temperature is increased
 - in Biological studies of paleotemperature use stenothermal
(temperature intolerant) versus eurythermal (temperature tolerant)
organisms; also may look at species diversity (greater in warmer
environments) or morphology (body form reflects environmental factors)

 d. Dissolved Gases
 - concentrations depend on atmospheric concentration;
solubility of gas; water temperature and salinity

 d1. Nitrogen (N) - most abundant dissolved gas;
required by plants in ionic form

 d2. Oxygen (O) - enters sea by photosynthesis, river
water, atmosphere; all organisms use oxygen during
respiration; oxygen at maximum near surface, minimum
at about 700-1,000m Oxygen; approximately 6 to 10 ppm;
warmer, saltier or organic debris-rich water with less
oxygen

 d3. Carbon Dioxide (CO2) - enters sea from organism respiration,
atmosphere and rivers; removed by plants for photosynthesis and used
by organisms to make shells; increases to approximately 1,000m;
increased CO2 leads to Greenhouse Effect (increase temperature)

 d4. Hydrogen Sulfide (H2S) - produced by anaerobic bacteria

 e. Light
 - Photic zone = zone of light penetration
 Euphotic zone = upper illuminated layers of water in the photic zone;
receive sufficient light to support photosynthesis; usually 10-60 meters
but clear tropical waters may be greater than 100 meters
 - Aphotic zone = zone in which light does not penetrate


 f. Pressure
 - pressure increases approximately 1 atmosphere per 10 meters
 - affects vertical migration of organisms, bacterial decomposition, production of
shells (CCD = carbonate compensation depth)

 g. Depth
 - deep water stores carbon, nitrate, phosphate

 Paleobathymetry - the ancient water depth may be determined by type of body
fossils and trace fossils present

 h. Water energy, turbidity and sedimentation rates
 - affects distribution of food and nutrients; types and morphology of organisms
present
 - amount of suspended sediment especially affects filter-feeders
 - nature of substrate affects type of infauna (live in substrate) or epifauna (live on
substrate; sessile or vagile benthonic) present

 Biostratigraphy ("Stratigraphic Paleontology")

 1. Biostratigraphic distributions are controlled
by:

 a. Evolution
 b. Paleoecology - no organism inhabits all
environments
 b1. Facies-controlled organisms = restricted
to particular sedimentary environments (often
with slow evolutionary change)

 b2. Biofacies = facies distinguished on the basis of their fossils (Ex. = reef
biofacies - may have corals, coralline algae, stromatoporoids, rudist bivalves)
 2. Biostratigraphic Units
- body of rocks delimited from adjacent rocks by their fossil content
- often use fossils for Correlation (matching stratigraphic sections of the same age)
 a. First appearances of fossils may be due to 1) evolutionary first occurrence
2) immigration
FAD = First appearance datum FOD = First occurrence datum
b. Last appearance of fossils may be due to 1) extinction event 2) emigration
LAD = Last appearance datum LOD = Last occurrence datum

Biozone
 - basic unit of biostratigraphic classification
 - based on the distribution of Index Fossils
(fossils characteristic of key formations;
should have short time span, wide
geographic range, independent as possible
of facies, abundant, rapidly changing and
with distinctive morphology)


Biological Classification of Fossils
As fossils clearly represent the the remains of ancient biological organisms, it
only makes sense that they should also be classified in the same manner as
living organisms.
The fundamental unit of biological classification is the species. Members of a
species are able to interbreed and give rise to fertile offspring.
Palaeontologists, lacking evidence of reproductive isolation of ancient
“species”, focus on morphological definitions of species. Above the species
level are increasingly more inclusive groups which are defined by certain
characteristics possessed by all their members. These various groupings are
as follows:
Kingdom: (e.g. Animalia)
Phylum: (e.g. Chordata)
Class: (e.g. Mammalia)
Order: (e.g. Primates)
Family: (e.g. Hominidae)
Genus (e.g. Homo)
Species: (e.g. Homo sapiens)
This classification heirarchy applies mainly to body fossils. As you will see,
trace fossils classification is more limited in this respect.

INVERTEBRATE GROUPS
 Sponges (Phylum Porifera)
 Cnidarians (Phylum Cnidaria)
 Phylum Brachiopoda: (both articulates and
inarticulates)
Bryozoans
 Mollusks (Phylum Mollusca):
- Class Bivalvia
-Class Cephalopoda (Subclass Nautiloidea)
-Class Gastropoda
-Class Monoplacophora

INVERTEBRATE GROUPS
 Arthropods (Phylum Arthropoda):
-Class Crustacea (Subclass Ostracoda)
-Class Trilobita
 Echinoderms (Phylum Echinodermata)
-Starfish
-Echinoids (sea urchins sand dollars, and sea
biscuits)

Phylum Mollusca (Kingdom Animalia

PHYLUM MOLLUSCA
 The molluscs include bivalves (or pelecypods,
Lamellibranchia), gastropods (snails),
cephalopods (ammonoids, belemnoids,
squids, etc.), and a few other groups.
 Molluscs diversified following the Permian
extinctions, and became more diverse than in
the Paleozoic. During the Mesozoic, the
molluscs surpassed the brachiopods (which
had dominated the Paleozoic seafloor).
Class. Cephalopoda
Class. Gastropoda
Class. Bivalvia

The body of mollusca
are divided into:
Head
Hard Body : Shell
Mantel
Foot

MOLLUSCA: CLASS CEPHALOPODS
 Cephalopods
The cephalopods include the ammonoids, nautiloids,
belemnoids, and squids. Most were nektonic
(swimmers). the cephalopods extinct groups are
ammonites and belemnites).
- Environments: Marine (Shallow and deep)
 Predatory animals
 Geological age : Cambrian to present
-

MORPHOLOGY OF FOSSIL CEPHALOPOD SHELLS
 The structure secreted by the mantle of cephalopods for protection or neutral buoyancy is
called the Shell or Conch (except octopus). The complete shell is basically a hollow
cone with two major parts, the Body Chamber, or Living Chamber, and
thePhragmocone. The opening on the large end is called the Aperture, and the Apex is
at the tip of the small end. The shell orTest that forms the cone is called the Shell Wall.
 Orientation : Lateral is between ventral and dorsal. Longitudinal is in an anterior to
posterior direction, and Transverse is in a dorsal to ventral direction.
 Body Chamber:
- Chambers
- Septa
- Siphuncle: extended from the mantel to apex
-About 8-10 tentacles
-Funnel
-The edge of the aperture is the Peristome.


Two lateral views of the shell of Nautilus, external on the left and internal on the right

Drawings of an imaginary coiled cephalopod
shell

 Phragmocone
As the animal grew, it occasionally moved forward in the body chamber
and secreted a Septum at the back of the mantle. This created a series
of Chambers, or Camerae, called the Phragmocone. Some septa are
deposited a short distance along the shell wall, this part is called
the Mural Part. The Free Part of the septum is between the mural part
and the septal neck.
Parts of a Septal Suture line.

Septal Suture line types
 The septum is attached to the shell wall along a Suture,
seen as a series of simple to complex lines on internal
molds. Parts of the suture line directed adorally are
termed Saddles, and those directed adapically are
termed Lobes.
 Orthoceratitic Sutures are relatively simple having shallow
lobes and saddles.
 Agoniatitic Sutures have broad lobes and saddles with a
narrow mid ventral lobe.
 Goniatitic Sutures have strong, mostly angular lobes and
angular to rounded saddles.
 Ceratitic Sutures have strong rounded saddles and
serrated lobes.
 Ammonitic Sutures have complex lobes and saddles

SHELL SHAPE
 Nautiloid shells can be Planispirally Coiled (coiled in one
plane) or straight, curved, open spiral etc., ammonoids not
Planispirally coiled or have an open spiral are
termed Heteromorphs.
 Curved or coiled shells are Exogastric if the ventral side,
or Venter, is convex and on the outer side,
and Endogastric if the dorsal side, or Dorsum, is convex
and on the outer side.

 The cross sectional shape, or Whorl
Section,
canbe Round, Oval, Square, Rectangular,
Triangular, Lanceolate(shaped like a lance
point), Fastigate (tapering towards the
venter), Tabulate (with a flattened venter) or
some variation of each.
 Compressed shells are shorter laterally,
and Depressed shells are shorter ventro-
dorsally.

 A Whorl is one complete volution of a coiled shell. The
space enclosed on both sides by the last whorl is termed
the Umbilicus.
 Shells with a wide umbilicus are termed Evolute and
shells with a narrow umbilicus are termed Involute.
 Theumbilical Seam is where the shell wall attaches to
the preceding whorl. The Umbilical Wall is between the
umbilical shoulder and the umbilical
seam. The Umbilical Shoulder is where the shell wall
bends toward the preceding whorl.
 The Ventrolateral Shoulder is where the shell bends
toward the venter, and the Side or Flank, is between the
ventrolateral shoulder and the umbilical shoulder.

Cross section of a coiled shell showing parts and common
dimensions.


Straight shells are Orthocones, curved shells are Cyrtocones,
either of these could be long, Longiconic, or short,Breviconic. Curved
shells that make at least one volution are termed Gyrocones. Coiled
shells that touch or are just barely impressed by the preceding whorl
are Tarphycones. Serpenticones are very evolute with many
subcircular or depressed whorls. Involute to moderately involute shells
with subrectangular, compressed whorls are termed Platycones. Shells
that are involute with subtriangular, compressed whorls
are Oxycones. Discocones have involute shells with an oval whorl
section. Spherocones are subglobular with a small umbilicus and
subcircular whorls. Cadicones are subglobular with an open, angular,
umbilicus. Planorbicones are evolute with relatively few subcircular
depressed whorls. Ancylocones have open or closed, planispiral or
helical early whorls followed by a hook. Torticones have helical
whorls. Shells that form two or more straight shafts are
called Hamiticones. Irregular, worm like shells are
termed Vermicones.

IRREGULAR OR HETEROMORPHIC SHELL
SHAPES

ORNAMENTATION
 All cephalopod shells are ornamented with at least Growth
Lines, each one representing a former position of the peristome.
Ribs are usually radial folds of the shell so they are
equally apparent on internal molds, sometimes they are
thickenings of the outer part of the shell and don’t show on
internal molds. Ribs directed radially are Rectiradiate, those
inclined forward areProrsiradiate, and those inclined backward
are Rursiradiate. Ribs can be Dense, closely spaced,
or Distant, widely spaced. Sinuous ribs snake across the
flanks, Falcate ribs are sickle-shaped, Falcoid ribs are generally
falcate, Projected ribs are inclined forward on the outer
portion. Branching ribs have Secondary Ribs that branch
from Primary Ribs. Virgatotone ribshave other ribs branching
from a single inclined rib. Intercalated Ribs are ribs not
connected to other ribs. Bundled ribs are connected at one
dorsal point. Zigzag ribs are alternately connected at the dorsal
and ventral ends. Looped ribs are connected at both ends.

TYPE, DIRECTION AND SPACING OF RIB

 Constrictions are internal shell thickenings and usually only
show on the internal mold as sinuous transverse
grooves. Lirae are small, usually longitudinal, raised portions of
the shell separated by striae, small grooves. If they are strong
enough they will show on internal molds.
Tubercles and other Nodes are present on some
shells. Nodes on internal molds are commonly the bases
of Spines. Spines were usually formed hollow on the peristome
and sealed later as the shell grew. Tubercles elongated radially
are termedBullae, and those elongated longitudinally are
termed Clavi.
A raised longitudinal ridge on the venter is called
a Keel. Keels can
be Entire (smooth), Serrated or Clavate. Sometimes
a Furrow or groove can be found on each side of the keel.
A large, deep, longitudinal groove is called a Sulcus, and
can be found on the venter or in a lateral position.

Ornamentation other than ribs
Ornamentation other than ribs

MOLLUSCA: CEPHALOPODS, AMMONOIDS
Ammonoids:
Ammonoids were among the dominant
swimming invertebrates in Mesozoic seas.
Ammonoids were so abundant and varied
that the Mesozoic could be called the "Age
of Ammonoids".
 The geologic range of ammonoid
cephalopods is Devonian to Cretaceous.

 Ammonoids are useful in biostratigraphy and worldwide
correlation of Mesozoic rocks because they were abundant,
morphologically variable, widely distributed, and had short
geologic ranges (evolved rapidly).
 One of the most distinctive features of the ammonoids is the
character of the sutures seen on the outside of the fossils.
Sutures are the seam where internal partitions
called septa intersect the outside wall of the shell.
 In the ammonoid cephalopods, the septae are convoluted
or wrinkled, and the sutures make more complex patterns.

 The three suture patterns of the ammonoids
are goniatite, ceratite, and ammononite.
HTTP://HIGHEREDBCS.WILEY.COM/LEGACY/COLLEGE/LEVIN/0471697435/CHAP_TUT/CHAPS/CHAPTER14-04.HTML

MOLLUSCA: CEPHALOPODS, NAUTILOIDS
Nautiloids
 Unlike ammonites, some nautiloids are still alive today.
 Nautiloids are the only cephalopods with an external shell that are
still alive today. The living animal, Nautilus, is housed in a coiled
shell, exposing only its head and tentacles to the outside world.
Much of the shell is divided into chambers that are filled with gas.
By adjusting the levels of gas the animal may live in the depths of
the ocean and move to shallow water at night time to feed.
 In contrast, the nautiloid cephalopods have smoothly curved
septa.
The geologic range of nautiloid cephalopods is Cambrian to
Recent.
.

MOLLUSCA: CEPHALOPODS,
BELEMNITES
 Belemnites died out at the same time as ammonites and
dinosaurs.
 Belemnites are an extinct group of cephalopod that probably
looked like a squid.
 Unlike nautiloids and ammonites, belemnites have an internal
soild calcareous shell (which resembles a cigar in size, shape,
and color) called a rostrum. Many people will be familiar with
belemnite rostra, they are straight, and look rather like bullets.
 The front part of this shell is chambered, as in the nautiloids and
ammonoids. The rostrum is made of fibrous calcite, arranged in
concentric layers.

 Geologic range: Belemnites first appeared
about 360 million years ago. Along with
ammonites and dinosaurs, they died out at
the end of the Cretaceous period 65 million
years ago.
- all extinct.
 The belemnites were highly successful
during the Jurassic and Cretaceous.

MOLLUSCA: CEPHALOPODS,
BELEMNITES
 Apart from their shells, palaeontologists have
also found some belemnite fossils that show
their internal structure and soft parts.
 These fossils tell us a great deal about the
way these animals lived. Belemnites had
large eyes, and swam quickly using a form of
jet propulsion.

Drawing of an orthoconic cephalopod shell and internal
mold.

PHYLUM MOLLUSCA, CLASS BIVALVIA
 Bivalves (Class Bivalvia) include clams,
mussels, oysters, and scallops
 The body of bivalves is laterally compressed
(flattened sideways) and consists of 2 hinged
valves that are mirror images of one another

Phylum Mollusca Class. Bivalvia
94
Soft parts and life
cycleIn bivalves the soft parts are partially or completely
enclosed between two hinged valves. Most of the
soft parts are to be found close to the back of the
enclosed space, adjacent to the hinge.
A mantle lines both valves almost as far as their
outermost edges, and is responsible for secreting
the shell.
The body does not occupy all the space inside the
valves even when closed. The residual space is
taken up by the mantle cavity, into which hang the
respiratory gills and the muscular foot. The gill
create currents using the cilia with which they are
covered.

 Strong muscles, the adductor muscles, are
used to close the valves
 Two siphons, an incurrent and an excurrent
siphon, draw water into and out of the mantle
cavity, respectively
 Since many clams burrow into the sediment,
these siphons allow the clam to feed and
breathe
www.marinebio.net/marinescience03ecology/mfunder.htm

 Not all bivalves are burrowers; mussels
secrete strong byssal threads to attach to
rocks and other surfaces
 Oysters cement themselves to
hard substances including other
oysters!
 Scallops are unattached and can
swim for short distances by rapidly
ejecting water from the mantle
cavity and flapping their valves

In bivalves, the mantle forms a thin membrane that lines the inside surface of the
shell
This creates a mantle cavity, within which the entire body of the bivalve lies

CLASS BIVALVIA (BIVALVES)
 Body contained between 2 hinged shells (valves)
 Foot hatchet-like, modified for burrowing in
sand/mud
 Little cephalization: no head

 Adductor muscles (2 in most bivalves) close
 Cilia on gills pull water into and out of shell
through siphons. Brings oxygen, food
particles

 Importance:
human food (clams, oysters, scallops, mussels)
clams
mussels
oysters

 Importance:
jewelry (pearls)

PHYLUM MOLLUCSA , CLASS GASTROPODA
 Most diverse group (~60,000 species)
 >15,000 described fossil species
 Most extensive adaptive radiation of
any mollusc group
 Single shell, mostly right handed
sprial.
 some gastropods have lost their
shells altogether (slugs for example).
 Torsion
 Fresh and salty environments but
marine loving environment.
 Geological age (Camb.-Rec.).

 Gastropods have a well-developed head
foot, upon which are found the eyes and a
mouth containing the radula.
 In front of and above the mantle cavity lies
the visceral mass, which contain a simple
heart, the kidneys and the gut.
 The Gut opens anteriorly at the mouth, in
which there is a rasp-like tongue bearing
sharp, inward pointing teeth. It is called
radula, and is used for grazing food
(typically algal films) off the substrate.

 Digestion takes place in an out-pouching of the
gut called the digestive gland, and waste is
expelled as discrete pellets via the anus.
 The brain consists of a nerve ring surrounding
the oesphagus, and two pairs of nerves arise
from it. One pair serves the gut and another
serves the large, muscular foot. The head is
situated anteriorly, bearing primitive eyes.
 Other sense organs include simple balancing
organ, called statocysts (in the foot) and a pairs
of osphradia, which may be sensitive to water
chemistry and monitor the sediment content of
the inhalent currents.

SHELL FORM
 Gastropods shells are mainly made of
calcium carbonate (96/) aragonite or
calcite.
 Mainly are dextral (right handed sprial,
right aperture ) but a few rare cases are
sinistral.

MAJOR CHANGES FROM GENERALIZED MOLLUSC
 Development of head
 Dorsoventral elongation
 Shell – from shield to retreat
 Torsion
 Conispiral coiling and asymmetry

TORSION
 Weight of shell over head, mantle cavity
posterior
 Torsion – 180o counterclockwise rotation
of visceral mass, shell, mantle, mantle
cavity
 Occurs in larvae not adult
 First gastropods
 Detorsion

COSTS OF CONISPIRAL SHELL
 Loss of a gill, nephridium, atrium
 Mantle cavity (anus and nephridiopore)
now anterior and near mouth
 Compensation - changes in water flow or
shell structure
 See Figure 12-20 (mantle cavity evolution)
and 12-21A (abalone)

SHELL
 Apex, whorl, columnella, aperature, siphonal
canal
 Spire, body whorl, outer lip, inner lip
 operculum

LOCOMOTION
 Most move using foot
 Most have ciliated sole and secretory
glands (mucus producing)
 Hard-bottom dwelling and terrestrial, and
large soft-bottom snails - undulating wave
of muscle contractions

FEEDING
 Most often thought of as algal scrapers
(radula)
 Deposit feeders
 Suspension feeders
 Scavengers
 Predators
 Parasites

CLASS GASTROPODA
 Three “groups” – phylogeny revision
 Prosobranchs – most common members when
think of snails
 Terrestrial, freshwater, and marine*
 Common feature – operculum
 Opisthobranchs
 Sea slugs, sea hares
 Many members lost shell
 Pulmonates
 Many terrestrial species, also freshwater, a few
marine

MARINE GASTROPODA
 Patella
 Littorina
 Buccinum
 Turritella


PATELLA
Patella is a genus of sea snails with gills,
typical true limpets, marine gastropod
mollusks in the family Patellidae, the true
limpets.
or cap like (Eocene to present ), cone like
shell, oval aperture e.g, Limpet, attached
beach rocks.

BUCCINUM
(Pliocene to
present) oval
shell shaped with
large last whorl

LITTORINA
Littorina is a genus of small sea snails, marine gastropod molluscs in the
family Littorinidae, the winkles or periwinkles.
These small snails live in the tidal zone of rocky shores.
Jurassic to
present )circular
hard shell and
rounded
aperture.

TURRITELLA
Turritella (Cretaceous to present )multi
whorls shell, shallow water environments.
Turritella is a genus of medium-sized sea
snails with an operculum, marine
gastropod mollusks in the family
Turritellidae. [2]
They have tightly coiled shells, whose
overall shape is basically that of an
elongated cone.

NATICA
 Natica is a genus of small to medium-sized
predatory sea snails, marine gastropods in
the family Naticidae, the moon snails

FRESH WATER GASTROPDA:
Planorbis is a genus of air-breathing
freshwater snails, aquatic pulmonate
gastropod mollusks in the family
Planorbidae, the ram's horn snails, or
planorbids. All species in this genus have
sinistral or left-coiling shells.

ECHINODERMS (PHYLUM ECHINODERMATA)
(THE SPINY SKINNED ANIMALS)
 Echinodermata means "spiny"
(echinos) + "skin" (derma).
 Marine animals.
 Echinoderms have radial
symmetry, 5-part symmetry,
many having five or multiples of
five arms.
 They lack body segmentation.
 They have a shell, made mainly
of calcium carbonate, which is
covered by skin.

 Exclusively marine. Some are attached to
the seafloor by a stem with "roots" called
holdfasts; others are free-moving bottom
dwellers.
 Geologic range: Cambrian to Recent.

 water vascular system. Seawater is taken into
a system of canals and is used to extend the
many tube feet. These have suckers on their
tips and aid the animal in attaching itself to solid
surfaces.
 About 6,000 species — all of them marine.
 There are 5 classes of echinoderms:Sea
urchins and sand dollars (Echinoidea), Sea
lilies (Crinoidea), Sea Stars (aka "Starfish")
(Asteroidea), Brittle stars (Ophiuroidea), Sea
cucumbers (Holothuroidea)

THE DIFFERENT GROUPS OF ECHINODERMS

CLASS CRINOIDEA (CRINOIDS OR "SEA LILIES")
 Crinoids are animals which
resemble flowers - they consist of
a calyx with arms, atop a stem of
calcite disks called columnals. The
crinoid is attached to the seafloor
by root-like holdfasts. Some living
crinoids are swimmers.
 Geologic range: Middle Cambrian
to Recent. Especially abundant
during the Mesozoic.
Diagram illustrating the major body parts of
a crinoid.

Fossil Crinoidea
Modern Crinoidea

CLASS ECHINOIDEA (SAND DOLLARS AND SEA
URCHINS)
 Echinoids are disk-shaped, biscuit-shaped,
or globular.
 Have five-part symmetry.
 There are two types of echinoids, the
regulars and the irregulars.
 Geologic range: Ordovician to Recent.

 Lack arms
 eat algae or are detritus eaters
 usually have spines

ECHINODERMS:
Phylum: Echinodermata
Class: Echinoidea
(sea urchins)
Order:Regular Irregular

REGULAR ECHINOIDS
 Regular echinoids have five-fold radial
symmetry
 Mouth and periproct at opposite poles.
 Regular echinoids are mostly epifaunal
mobile grazers that sometimes occur in rocky
subtidal and intertidal environments

IRREGULAR ECHINOIDS
 Irregular echinoids have bilateral symmetry;
 Mouth toward anterior on ventral side, and
periproct in posterior interambulacral area.
 Irregular echinoids occur primarily in infaunal
environments.
 The depths at which individuals lived can
sometimes be deduced by their external
morphology

CLASS: ECHINOIDEA
 They are exclusively
marine in shallow
depths to the abyssal
planes.
MORPHOLOGY:
 They have a hard shell
which when alive is
covered by a very thin
skin and therefore they
have an
ENDOSKELETON.

ECHINOID MORPHOLOGY 2
The skeleton (TEST) is made of
calcite with tiny interlocking
plates which protect and
enclose most of the soft
parts inside.
The test is usually
hemispherical, the
interlocking plates are
arranged in 10 double
columns radiating out from
the top of the upper surface
(CORONA).
.
There are two types of plate:
AMBULACRUM
INTERAMBULACRUM

ECHINOIDS MORPHOLOGY 3
Ambulacrum: These
occur where the TUBE
FEET are positioned.
These feet are connected
to the WATER
VASCULAR SYSTEM
(system of hydraulic
tubes) through which
water is circulated
around the body and
can be used to extend
the tentacles through
the test and can act like
feet.

ECHINOID MORPHOLOGY 4
Towards the top (APEX) of the
test is the APICAL SYSTEM
which is made up of about
10 small plates that are
interconnected.

One plate has a special
function: it is porous and
allows sea water into the
body = MADREPORITE.
 This water then passes
through the RADIAL
CANALS and into the tube
feet.

ORDERS OF ECHINOIDS:
 Echinoidea are divided into 2
orders which can be
achieved by looking at their
symmetry:
REGULAR ECHINOIDS:
 They are usually circular
when viewed from above.
 They show a 5-fold
symmetry. Therefore they
have a regular pattern.
 The apical system is
situated on the top and
contains the anus in the
centre surrounded by the
PERIPROCT (membrane).

REGULAR ECHINOIDS 2
 The mouth is situated
on the underside
(ORAL SURFACE)
usually in the centre.
 JAWS are present
although they are rarely
preserved.
 The upper surface is
called the ABORAL
SURFACE.

IRREGULAR ECHINOIDS:
 Look at Page 190
(Black) Micraster and
copy the diagram.
 These are not circular
but are either flattened
or heart shaped.
They still have 5 rows of
ambulacrum and
interambulacrum plates
but instead of 5-fold
symmetry they show a
bilateral symmetry.

IRREGULAR ECHINOIDS 2
The ANUS is not enclosed
within the apical system.
Instead it lies either:
1) On the aboral side half way
up the side (Posterior).
Sometimes in a groove.
2) On the oral surface towards
the posterior.
The MOUTH is found on the
oral surface either:
1) In the centre with jaws.
2) Closer to the front (anterior)
without jaws.
Therefore it is easier to define
anterior and posterior.

Frequently the two rows of pores
within the double ambulacrum
plate can diverge from each
other and then converge lower
down the test forming a
distinctive pattern called
PETALS or PETALOID.
Sometimes the posterior
interambulacrum area can
extend down across the oral
surface, this usually occurs when
the mouth is posterior closer to
the anterior end.
This forms a flatish ridge on the oral
surface called the PLASTRON.
This may project like a lip across
part of the mouth: LABRUM.

ECHINOIDS’ MODE OF LIFE
Varies depending on
whether the echinoid
is regular or irregular.
All are benthonic, can
move and are
gregarious.

REGULAR ECHINOIDS
 They are usually mobile, moving about
looking for food and protection.
 Many are capable of living on hard rocks:
anchor themselves to the rocks via tube
feet even in relatively shallow water.
 Common between the sub littoral zone
down to 100 m.
 Can also use the tube feet to climb steep
rock surfaces.
 On sand they use their spines to support
them and move themselves using the
spines on the oral surface and low down
on the aboral.
 Could move in any direction.
 They eat sea weed but also partly
carnivorous: bryozoa and sponges in
particular.
 Have strong jaws e.g. Echinus lives on
rocks.

IRREGULAR ECHINOIDS MODE OF
LIFE
A) FLATTENED TEST:
 Clypeaster lived
partially or completely
buried in loose
sediment and moved
forward by moving
spines to plough
through soft sediment.
 The tube feet extract
organic matter from
sediment and transfer
to food tubes.
 Lives in shallow water
0.5 - 5 m.

B) HEART SHAPED:
 Micraster and Echinocardium which could be
completely buried.
 Common down to 50 m but can survive down
to 200 m below sea level.
 Lived in burrows of soft sediment (Micraster in
fine lime mud).
 .
 Burrows forwards using spines and tube feet
(Mucus can be secreted to help stabilise the
sediment to stop collapsing.

 Sand etc. is pushed aside and backwards.
 Organic matter is extracted from the
sediment and the waste disposed behind.
 Some food is also obtained from the sea
water via a FUNNEL which extends from the
burrow.
 The tube feet in the upper areas extend out
of the burrow.
 Water is drawn into the animal and CILIA
help waft it into the tube feet respiratory
system.
 All are gregarious.

ECHINOID HISTORY
 Upper Ordovician to Recent:
 Began in the Upper Ordovician but only a small
number.
 In the Carboniferous the numbers peaked briefly but
reduced during the Permian.
 During the Mesozoic (Triassic) the numbers increased
again with new species due to a major adaptive
radiation after the Permian extinction provided new
niches.
 They are very rarely found as Palaeozoic fossils as
they did not burrow and plates of test not well fused
therefore broke up.
 Those preserved are usually found in limestone.

ECHINOID HISTORY 2
 Irregular appear in the Upper Jurassic and increase
quickly in numbers.
 They increase so quickly because they were more efficient
food grazers and had improved sanitation with anus
removed from the apical system.
 Common in limestone particularly chalk.
 Still abundant today.
 Micraster was a very important fossil as it evolved quite
quickly and palaeontologists were able to show it
changing its mouth and anus positions over time.
 This added proof to Darwin’s theory of evolution.

STARFISH (ASTEROIDEA)
 Carnivores – clams,
mussels, bivalves
 Motile by way of
tube feet
 endoskeleton made
of calcareous plates
(ie. Calcium
carbonate)
 breathes through
dermal “skin gills”

STARFISH ARM
 Each arm contains a digestive gland and
gonads
 The top of the tube feet are called ampulla,
like a medicine dropper that is squeezed to
create pressure

STARFISH
 The eye of the starfish is at the end of the
arms. (It is often red coloured)
 The anus of the starfish is on the top (aboral
side)
 The mouth piece of the starfish is called
“Aristotle’s Lantern”.

STAR FISH
The water vascular
system’s opening is
called a
madreporite. It
opens into a radial
canal. The radial
canal then goes out
to the arms in radial
canals. The radial
canals then feed
water to the tube
feet.

Ring Canal
Digestive Gland in Arm
Anus

TRILOBITES: ARTHROPODS PHYLUM
Trilobites are remarkable, hard-shelled,
segmented creatures that existed over 520
million years ago in the Earth's ancient seas

TRILOBITES: INTRODUCTION
Trilobites first evolved in the
Lower Cambrian and became
extinct by the end of the
Permian.
They are most common during
the Cambrian, Ordovician and
Silurian.
Therefore they have no modern
equivalents and an
understanding of their soft
parts has to be based on
modern day arthropods that
show some similarity i.e.
crustaceans.
They are marine animals.

THE NAME "TRILOBITE,"
WHICH MEANS "THREE
LOBED,"
all trilobites bear a long central axial lobe,
flanked on each side by right and
left pleural lobes (pleura = side, rib).
These three lobes that run from the
cephalon to the pygidium are what give
trilobites their name, and are common to all
trilobites despite their great diversity of size
and form.

The main body parts:
a cephalon (head), a
segmented thorax, and
a pygidium (tail piece).

The body can be divided into
segments:
Laterally:
A central or axial segment.
Bounded by two lateral
segments.
Transversely into three regions:
Cephalon - “head” area.
Thorax - “body” with hinged
segments.
Pygidium - “tail” with fused
segments.

PALEOECOLOGY AND LIFE HABITS
 Trilobites are very common in marine limestones and
shales of the early Paleozoic, especially from the Cambrian
Period.
 Most trilobites were epifaunal crawlers.
 Although they occupy a wide variety of exclusively marine
habitats, specific life habits are difficult to discern by
morphology alone.
 Nonetheless, several aspects of trilobite morphology can
indeed provide some clue as to the life habit or activity.
 Examples include the elongated cephalic shield of the
example which may have aided in ploughing through
sediments.
 Although most trilobites are considered to have been
benthic, the small size and non-descript morphology of
agnostid trilobites suggests that these (along with some
others) may have been nektonic or nekto-benthic.
 Enrolling of trilobites may certainly have been a defensive
mechanism.

TAXONOMY
 According to some texts, trilobites are considered to have
phylum status and are divided into eight Orders. A less radical
classification treats trilobites as a Superclass or Class with two
orders: the Polymerida and the Agnostida.
 The Polymerida are by far the most diverse of the two in
regards to species diversity and also morphologic and ecologic
types.
 The Polymerids can be identified by their larger size, a well
defined cephalic region with eyes and facial sutures, and a
large number of thoraxic segments. An easier way to identify
Polymerids is by default; if its not a agnostid (easy to identify)
then it's a Polymerid. All of the images you have seen thus far
are Polymerids, here is another example from this diverse
group.
 Agnostid trilobites are easily recognizable by their small size,
few thoraxic segments (usually around two), and a cephalon
without eyes which is superficially similar in morphology to the
pygidium. Furthermore, agnostids lack facial sutures.

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