• The paleozoic begins with the appearance of fossils of marine animals. For the first time, ocean animals that have easily fossilized hard parts.
• The paleozoic contains the history of animal and plant diversification in the oceans and colonization of land
Crinoids

Important Paleozoic Invertebrates
• First we will examine the anatomical plans of Trilobites, Brachiopods, Molluscs
(clams, snails and cephalopods),
Echinoderms (starfish, sea urchins and especially crinoids), and Graptolites.
• Later we will look at corals and sponges

Arthropod – “jointed-leg”
Related to Horseshoe crabs
What other arthropods do you know of?
Varied niche, predators, scavengers or filter feeders. Some swam, feeding on plankton

Sessile benthic filter feeders related to bryozoans

Articulate Brachiopods
Brachiopod life positions 1
Brachiopods sort of look like a clam. However, notice that each valve is symmetrical about its middle line.

Brachiopod life positions 2
Inarticulate Brachiopod
Lingula Infaunal sessile benthic filter feeders intertidal

Clams, Scallops Individual valve is not symmetrical about a middle line

Stalked echinoderm related to starfishes, sea urchins, etc

Related to ??? Often found in black shales, deep shelf waters, no other fossils
Great index fossils

• The Paleozoic is marked by the abrupt appearance of animals with skeletons in the rock record
– a mechanism that would trigger this event is not agreed upon, but is surely due to a combination of geologic and biologic factors
– Predators prominent
– shallow water, animals must be protected from UV.

• Organisms with hard parts have many advantages
– protection against UV rays, allowing animals to move into shallower water
– helps prevent drying out in an intertidal environment
– provides protection against predators

Photos
A. Mollusk B. Sponge
Drawings
Late Proterozoic (Ediacaran) to Early Cambria, before trilobites.

Cambrian Marine Community
• Many body plans are observed in Cambrian fossils, more than in any other period
– trilobites – many niches, e.g. benthonic mobile sedimentdeposit feeders that crawled or swam across the sea floor
– brachiopods - primitive benthonic sessile suspension feeders
– archaeocyathids - benthonic sessile suspension feeders and reef builders

Invertebrates with hard parts
Brachiopods
Note how the valves have symmetry
Trilobites
Crinoids
Sponges

• Consists of a rare preservation of soft-bodied organisms – Mid Cambrian
– Some phyla near the basic stock from which some present-day invertebrates have evolved
– Other unique and without issue
– current debate centers around how many phyla arose and how many extinction events took place in the Cambrian

Charles Walcott’s Burgess Shale
middle Cambrian shale in the Rockies of western Canada

Anomalocaris
A huge predaor
Hallucigenia
Pikaia
A chordate!!!
Sidneyia
Remarkable preservation of animals’ soft tissues, plus the first predator, Anomalocaris

Artemia salina
Similar swimming mode to Anomalocaris?
Anomalocaris
A huge predaor

Marella , a trilobitomorph or “Lace Crab”
Anomalocaris and some known prey.
Bite marks on fossils

Leanchoilia--China
Leanchoilia--Burgess

Opabina

Like the modern
Peripatus, moist forests of Cameroon,
Discussion: preadaptations to land if food is present

Totally unexpected find. Cartilage but no bone.
Jawless ancestor to fish, and us.
Maori legend of Pikea, the ancestor.
Lancelets in comparative anatomy
Link to lancelet info
Pikaia – an early chordate!
from the Burgess Shale

Cambrian Trilobites
Paradoxides bohemicus
Barrande
YPM 72949
Cambrian, Etage C.
Koneprussy, Bohemia,
Czechoslovakia.

Note large Orthoceras
A Cephalopod Mollusk
• Vast epeiric seas opened new marine habitats
– bryozoans, stromatoporoids, tabulate and rugose coral reef builders
– reefs with high diversity suspension feeders
– massive extinctions end
Ordovician, glaciation in
Gondwana & falling sealevel
Cephalopods as
Index Fossils

Bryozoans
•
Possibly related to Brachiopods
• “Moss Animals”
• Filter Feeders
• Mostly marine tropical
• Make hard exoskeleton, chitin or CaCO
3

In fossils, just the exoskeleton is preserved

Stromatoporoid - Hydrozoan coral
-

Graptolite http://www.yale.edu/ypmip/
Didymograptus denticulatus Berry
YPM 20252
Early Ordovician, Marathon Ls.
Didymograptus bifidus zone, upper
Marathon, 14.5 ft below Marathon top, section XVIII, bed of Alsate Creek, 3 mi W of
Picnic Picnic Grounds & 0.1 S54W of
Marathon, Brewster Co., Texas, USA.
Collector: Berry, W.B.

• Rapid diversification and recovery followed the
Ordovician mass extinction
– reef building by tabulate and rugose corals
– NEW PREDATOR :
Eurypterids were abundant
– Ammonoids evolved quickly and are important as index fossils
– mass extinction at the end of the Devonian collapsed the
Marine “Scorpions”
Track ways in coastal sands
Probably laid eggs as horseshoe crabs do along the foreshore

Rugose Corals – individual animals
Field Trip, Stroudsburg, PA

Favosites conicus Hall
YPM 7115
Early Devonian, Oriskany Sandstone. Loc.
C6644,
Cumberland, Allegany Co., Maryland, USA.
Collector: Gordon, R.H. & Hartley, F.
Colonial

Brachiopod
Leptaena rhomboidalis (Wilkens)
YPM 19154
Early Devonian, Helderberg Grp, New Scotland Ls.
Lower Helderberg, Indian Ladder, Thatcher State
Park, near New Salem, Albany Co., New York, USA.
Collector: Beecher, C.E.

Phacops rana (Green)
YPM 6593
Middle Devonian,
Hamilton Grp.
Eighteen Mile Creek,
Erie Co., New York,
USA. Collector:
Beecher, C.E.

• Renewed diversity and recovery with adaptations mark the
Late Paleozoic marine communities
– bryozoans and crinoids reach their greatest diversity
– patch reefs replace the massive reefs of the
Devonian –TEMPS?
– fusulinid formanifera are important index fossils

Types of Staked Echinoderms 1
Cystoids
Anomalocystis cornutus
Hall
YPM 36413
Early Devonian,
Helderberg Grp. Lower
Helderberg, Jerusalem
Hill, Herkimer Co., New
York, USA.

Types of Staked Echinoderms 2
Blastoids
Pentremites sulcatus
YPM 36130
Pennsylvanian, Gaptank Fm.
Unit 7 (27 ft thick), Section 32,
1.25 mi S60W of the Brooks
Ranch House, Glass
Mountains, Pecos Co., Texas,
USA. Collector: Ross, C.A.

Barycrinus hoveyi (Hall)
YPM 34788
Early Mississippian, Edwardsville Fm.
Crawfordsville, Montgomery Co.,
Indiana, USA. Collector: Bassett, D.A.
1888.
Fragments on Field Trip
Stroudsburg PA
Types of Staked Echinoderms 3
-
Crinoids

• Chordates have, during at least part of their life, a notochord, dorsal hollow nerve chord, and gill slits
– Vertebrates have backbones and are a subphylum of chordates
– ancestors were soft-bodied and left few fossils
– a close relationship exists between echinoderms and chordates and they may have shared a common ancestor

• Fish range from the Late Cambrian to the present and consist of five classes
• Ostracoderms
• Placoderms
• Acanthodians
• Cartilaginous fish – sharks and rays
• Bony fish

Field Trip
Bony plates in Shf
Silurian High Falls at
Delaware Water Gap

Dunkleosteous (Dinichthys) a Devonian arthrodire

• Today we will examine another Placoderm
• Named Bothryolepis
• It’s armor is similar to that of modern
South American catfishes that live in shallow, fast moving, jungle streams in
South America

Climatius , a Lower Devonian acanthodian

Cartilagenous fishes: Fossil Shark http://www.exhibits.lsa.umich.edu/New/Welcome.html
Cladoselache fyleri , a 3-foot shark, was one of the top predators in the
Devonian seas.

Bony Fishes (Osteichthys)
Ray-finned (Actinopterygians) and Lobe-finned (Sarcopterygians)

(Crossopterigian)
Field Trip Catskill fm.
Bones of early Amphibians
Similar skulls, teeth,
Bones in limbs.
Fish limbs not for walking

http://www.lhup.edu/jway/rdhll/RedHill.htm

• The first vertebrates to live on land, preceded by plants, insects, and snails
• Barriers they had to deal with:
– desiccation
– reproduction
– effects of gravity
– extraction of oxygen by lungs rather than gills

Late Devonian Ichthyostega
Skull, teeth, backbone and tail are Rhiphidistian-like

Eryops, a carnivorous amphibian, named for folds in teeth
Pennsylvania to Early Permian

Middle Carboniferous - Evolution of the Reptiles
The Land is Conquered
• The evolution of the amniote egg freed reptiles from the constraint of returning to water to reproduce
– amnion - liquid filled sac surrounding the embryo
– allantois - waste sac
– a tough shell protects the developing fetus
– reptiles were able to colonize all parts of the land

Warm
• The earliest reptiles are from the Lower
Pennsylvanian
– called Captorhinomorphs, they were small, agile, and probably fed on insects
– success due to advanced egg, more advanced jaws and teeth, and speed
– Later reptiles evolved from this group by Permian
Cool

Skull structure in reptiles, temporalis muscle
Eury wide
An not, without
Syn united, together
Dia double
Early Therapsids
Function of
Temporal
Openings

herbivorous Edaphosaurus
Discussion: Sail function
Thermoregulation
Armor
Courtship carnivorous Dimetrodon

• Therapsids succeeded the pelycosaurs during the
Permian
– mammal-like reptiles that quickly evolved into herbivorous and carnivorous forms
– they displayed fewer bones in the skull, enlargement of the lower jawbone, differentiation of the teeth, and a more vertical position of their legs
– therapsids may have been endothermic, which may help explain their distribution over wide latitudes
• End Permian extinction eliminated about 66% of all amphibians and reptiles

Back to the early Paleozoic to consider plant evolution
• Plants had the same water-to-land transition problems that animals did
– vascular land plants have a tissue system to move water
– nonvascular plants do not have this system, and are usually small and live in moist environments
– seedless vascular plants such as ferns closely resemble green algae in their pigmentation, metabolism, and reproductive cycle
– green algae have also been able to make the transition from salt water to fresh water, leading some to believe that modern terrestrial land plants evolved from them

• The earliest land plants are from the Silurian
– small, simple leafless stalks with a spore-producing structure at the tip ( Rhynia drawing and modern Psilotum pictured)
– a rhizome (the underground part of the stem) transferred water from the soil to the plant and anchored it
– leaves, roots, and secondary growth all followed during the
Devonian
• The evolution of the first seed allowed land plants
(“Seed Ferns”) to spread over all parts of the land

Lepidodendron L Dev. – P enn.
A lycopod tree 90 – 100 feet tall
An important coal-former

Calamites, a huge horsetail rush
10-14 meters tall (Pennsylvanian)

Spenopsid
(Horsetail Rush)
Calamites shown
Lycopsid (club moss)
Lepidodendron shown
• Source of coal
• Seedless vascular: Need moisture to reproduce, vulnerable to insect attack
– Lycopsids to 30m branches at top; leaves similar to palm
– Sphenopsids jointed stem underground rhizomes
• First Seed Ferns Late
Devonian West Virginia seed ferns

L. Pennsylvanian – M. Permian
Floras
• Seed-bearing vascular
– Gymnosperm trees -
Cordaites , Glossopteris , and others were able to colonize large areas of land
– many of these became extinct in the Late
Permian; those that survived were able to tolerate the warmer and drier climates

Insects and other land arthropods
• Have a strong exoskeleton, impervious to water so good for osmoregulation.
• Predation on plant spores probably a strong selective pressure for seed coatings.
Petalia sp.
YPM 29867
Late Jurassic,
Kimmeridgian, Solnhofen
Ls. Solnhofen, Bavaria,
West Germany.

• The greatest recorded mass extinction to affect Earth occurred at the end of the Permian
– about 90% of all marine invertebrate species
– fusulinids, rugose and tabulate corals, many bryozoan and brachiopod orders, and trilobites did not survive the end of the Permian
– causes for this have been speculated to be:
• reduction in marine shelf as Pangaea formed
• global drop in sea level due to glaciation
• reduction in marine shelf due to regression
• climatic changes
Fusilinids, large forams

S. A. Bowring, et. al. (1998) U/Pb Zircon Geochronology and Tempo of the End-Permian Mass Extinction. SCIENCE 280 :1039-1045
• The mass extinction at the end of the Permian was the most profound in the history of life.
• U/Pb zircon data from south China place the Permian-Triassic boundary at 251 mya.
• Strata intercalated with ash beds below the boundary:
Changhsingian pulse of the end-Permian extinction (loss of 85 percent of marine species) lasted less than 1 my.
• At Meishan, a negative excursion in d
13C at the boundary had a duration of 165,000 years or less, suggesting a catastrophic addition of light carbon. GLOBAL FIRE!

d
• 12C and 13C are stable isotopes of Carbon
12C 98.89%
13C 1.11% in today’s atmosphere
Negative excursions mean 13C down or 12C up.

d
• Standard carbon in calcite from belemnites Pee
Dee Formation (abbreviated as PDB).
• The process of photosynthesis favors the lighter form of carbon
• “If you recall from the above brief discussion of the soot found in the … clay layer, it appears that a significant portion of the land plants burned; this would have released a great deal of light carbon into the atmosphere”

Extinction
Extinction
Extinction

Asteroid Impact
Asteroid Impact
Asteroid Impact
Asteroid Impact
Supposedly due to glaciation but it doesn’t line up with low water
Mention 26-30 my cycle of extinctions