The Carboniferous
Period SYNAPSIDS RULE
Continents are in collision course...
Marine Life of the Carboniferous
• See a recovery after the Late Devonian extinction of tabulatestromatoporoid reefs, extinctions of many fish, floating and
swimming animals, and many freshwater forms.
• Ammonoids rediversified quickly.
• Reefs remained poorly developed after the demise of the tabulatestromatoporoid reefs near the end of the Devonian.
• Brachiopods continued to thrive.
• Bryozoans were prominent.
• Crinoids and blastoids were common in the sea.
• Large foraminifera (fusulinids) appeared. First occur in Upper
Mississippian; most abundant in Pennsylvanian and Permian.
Ammonoids
• Ammonoids are relatives of the modern squid, as well
as the octopus and chambered Nautilus, all of which
belong to the group of animals called cephalopods.
• Ammonoids were important predators in the ancient
oceans, eating fish, crabs, and other shellfish.
• Ammonoids appeared in the fossil record during the
early part of the Devonian Period, about 400 million
years ago. They died out about 65 million years ago,
during the mass extinction at the end of the
Cretaceous Period that killed the dinosaurs and many
other kinds of land and sea animals.
The top specimen belongs to
the genus Goniatites. The
lower specimen is Schistoceras
missouriense.
Brachiopod
Fusulinid
foraminifera
Bryozoans
Crinoid
A Golden Age of Sharks
• Sharks and ray-finned fishes persisted as a diverse group of predators.
• Heavily-armored fish were replaced by more mobile forms.
•Sharks have undergone two major adaptive radiations and survived at
least five mass extinctions, with the first major shark radiation
occurred during the Carboniferous Period
• Indeed, with the exception of acanthodians (a type of placoderm), few
fishes swam in early Carboniferous seas.
• The fossil record indicates that more than 75% of fish groups alive
during the late Devonian died out before the beginning of the
Carboniferous.
• The placoderms - a once dominant group of armored fishes - survived
the devonian extinction event, but at greatly reduced diversity and
abundance.
Stethacanthids
• The misfortune of the placoderms presented a splendid
opportunity for sharks in general and one group in particular: the
stethacanthids.
• Perhaps in response to the ecological niches vacated by the
placoderms, the stethacanthids exploded into a riot of bizarre forms
and lifestyles.
• It was a kind of stethacanthid Mardi Gras - complete with
outrageously unwieldy headgear and strange but fascinating rituals.
Stethacanthus
Stethacanthus was an odd,
dogfish-sized shark of the
Carboniferous Period,
about 320 million years
ago. The brush-like dorsal
fin with enlarged denticles
on its flattened top and
corresponding denticled
patch on top of its head
have generated much
speculation about their
possible function.
Stethacanthus cont.
• It looked like a fish with a brush sticking out of its back. In
addition, male Stethacanthus had similar enlarged scales on top of
the head, making the whole contraption resemble a set of large,
bristle-toothed jaws.
• It seems likely that the dorsal brush and cranial bristles of
Stethacanthus played some role in their courtship rituals.
• Perhaps the brush and bristles were used during male-to-male
pushing matches, enabling the combatants to grapple together as
they tested each other's strength in competition for access to mating
grounds or sexually receptive females.
Falcatus
• Asmall stethacanthid inhabiting the warm, shallow seas that invaded
the American mainland during the early Carboniferous
• A female Falcatus falcatus biting the shoulder spine of a male,
possibly as a prelude to mating. Paleoichthyologist Richard Lund
actually found a pair of Falcatus preserved together in this position.
Additional Comments on Sharks
• Shark diversity during the Carboniferous Period was nothing less
than astonishing - Carboniferous boasted about 45 families of
sharks (compared with about 40 families of modern sharks).
• But at the close of the Permian Period (~250 mya), there occurred
what has been called the "Mother of All Mass Extinctions".
• In a geological instant, fully 99% of marine species were wiped
out - including the extravagant stethacanthids.
• But some shark lineages squeaked through this catastrophe, one of
which gave rise to modern sharks.
• Although modern sharks are remarkably diverse in form and
lifestyle, no shark today matches those of the Carboniferous for
sheer weirdness.
Freshwater Habitats
Ray-finned Fishes
• The modern bony fishes (class Osteichthyes) appeared in the late
Silurian or early Devonian (about 395 million years ago).
• The early forms were freshwater fishes, for no fossil remains of
modern bony fishes have been found in marine deposits older than
Triassic time, about 230 million years ago.
• Recall that the Osteichthyes may have arisen from the
acanthodians.
• A subclass of the Osteichthyes, the ray-finned fishes (subclass
Actinopterygii), became and have remained the dominant group of
fishes throughout the world – they were certainly common in the
Carbonifierous
Freshwater Habitats cont.
• However, it was not the ray-finned fishes that led to the evolution of the
land vertebrates.
• Ancestors of the land vertebrates are found among another group of bony
fishes called the Choanichthyes or Sarcopterygii.
• Choanate fishes are characterized by internal nostrils, fleshy fins called lobe
fins, and cosmoid scales.
•The choanate fishes appeared in the
late Silurian or early Devonian, (390
mya) and possibly arose from the
acanthodians.
• Choanate fishes include a group
known as the Crossopterygii, which
has one living representative, the
coelacanth Latimeria.
• During the Devonian Period some
crossopterygian fishes of the order
Rhipidistia crawled out of the water to
become the first amphibians.
Freshwater Habitats cont.
Sharks
• Also in freshwater lakes swam lungfishes and xenacanth sharks
(descendants of Antarctilamna that persisted in freshwater
environments until the early Triassic Period, about 220 million
years ago).
• Xenacanths were almost exclusively freshwater inhabitants, and
had a long, rearward-pointing fin spine just behind the cranium (the
name xenacanth means "strange spine"), diplodont teeth, a slender,
eel-like body, an elongate dorsal fin extending along most of the
back, and a symmetrical, tapering tail.
Freshwater Xenacanth Sharks
Reconstruction of
Xenacanthus, an eelshaped shark that haunted
freshwater habitats in
what is now Europe
during the early Permian
(about 280 million years
ago).
Carboniferous Coal Forest
The Carboniferous is famed for extensive coal beds, which were
formed in swamps.
That is, coal deposits formed from plant remains in lowland swamps.
Coal represents an enormous biomass of plants.
Common coal swamp plants include: lycophytes, ferns, sphenopsids,
cordaites
Large trees with
straight trunks
are lychophytes;
tree to the left is
a horestail
Lycopod trees or club mosses
Lycopods are spore-bearing plants, and
were confined to swamps.
Some grew to about 100 ft tall and were 3
feet across at the base
The club-moss tree Lepidodendron
This tree, in size up to 40 meters, grew in the coal-swamps of the
Carboniferous.
Lepidodendron
Note leaf scars on the trunk.
(Trees grew to 30 m tall; 90 ft).
Spore-bearing ferns and seed ferns
Seed fern
Spore fern
Sphenopsids
Calamites leaves
Sphenopsids (like Calamites) were sporebearing and similar to living horsetails or
scouring rushes.
They are often interpreted as living
in moist areas, even perhaps
standing water
Calamites trunk
A Reconstruction of Calamites
Cordaites
A common seed plant of drier areas was Cordaites, a tall
gymnosperms up to 100 ft in height
Note the horizontal
ridges on this cast of
the pith cavity stem of
Cordaites, together
with a leaf attached
obliquely on the left
side. The small foliage
on the right is likely a
variety of rhodea.
Cordaites cont.
Reproductive structures of Cordaites. (A) Foliage with
fertile shoots. (B) Portion of the ovule-bearing
Cordaianthus including part of the primary axis with
ovulate secondary shoots bearing pendant ovules. (C)
Pollen-bearing Cordaianthus
Tree growth-form of Cordaites.
Carboniferous Terrestrial Invertebrates
Detritivores - land snail, millipedes, mites, and insects (roaches, earwigs)
Wings appeared by the Late Carboniferous.
Note: Insects first appeared in Devonian as wingless.
Types of wings:
• Fixed wings (ex.: dragonflies, damselflies, mayflies)
• Folding wings - many specializations develop
Predators - scorpions, arachnids (spiders, mites, etc.), centipedes, insects
Many kinds of spiders lived on the ground and from the late Carboniferous a
millepede with a length of more than 1.8 metres is known.
Gigantic dragonflies, with a wingspan of over 60 centimetres, flew among the
tree tops.
Herbivores - insects with piercing, sucking, tearing - no clear leaf-eaters,
however.
Fossil Insects
Dragonfly reconstruction,
Pennsylvanian coal swamp
• Paleodictyoptera: Dunbaria fasciipennis
Tillyard in Dunbar & Tillyard 1924.
• This insect, with its beautifully-patterned
wings and long cerci (the "tails"), had a
wingspan of about 37 mm.
• It flew some 260 million years or so ago
over what are today the prairies of central
Kansas.
Carboniferous Tetrapods
• During the Carboniferous and the Permian the basic groups of
tetrapods (amphibian-like animals) evolved that would populate the
post-paleozoic world.
• The early tetrapods were, like early land plants, tied to the water by
their reproductive mechanisms.
• Like most "fish" they had external fertilization in water and laid eggs
in water which developed into aquatic larvae.
• The larvae metamorphosed into land-living adults. Living
"amphibians" have inherited this primitive mode of reproduction.
Revisiting the Devonian Tetrapods
Neoceratodus
Lepidosiren
Protopterus
Tetrapod Phylogeny
Amphibians-like
tetrapods
diversified
dramatically
during the
Carboniferous,
and came to
dominate
terrestrial and
aquatic habitats
Amphibian-like Tetrapods
Temnospondyls - had a rounded, crocodile-like snout. They were
diverse fish eaters in both water and on land.
They gave rise to the modern amphibians (frogs, toads, etc.).
Amphibian-like Tetrapods cont.
Aistopods - Legless, snake-like animals with large eyes and light
skulls.
They ate insects and fish. Probably aquatic.
An Aistopod or lepospondyls skull
Amphibian-like Tetrapods cont.
Nectridians - Newt-like, aquatic, medium-sized animals.
Many had bizarre horns on the back of their heads. They probably ate
fish.
Microsaurs - Lizard-like bodies, short teeth perhaps for puncturing
arthropod cuticles. Both aquatic and terrestrial forms
Reptile-like amphibians
Seymoriamorphs - Large (>2m) reptile-like animals with long
snouts.
The Carboniferous forms were aquatic, fish eaters. In the Permian,
they became more fully terrestrial.
Diadectomorphs: Large (>2m) reptile-like animals with short, deep
skulls, massive limbs, and peg-like teeth. Fully terrestrial. These
animals were the first tetrapod herbivores
The Amniotic Egg
• Sometime during the
Carboniferous, one group of
tetrapods developed the
amniotic egg.
• Primitively, the amniotic
egg has a shell hardened by
calcium carbonate which is
impermeable to water but
allows gases to be transpired.
• The embryo lies floating in
the amniotic fluid, which is
formed by the embryo.
• The shell is formed by the
mother.
Amniotic Egg cont.
• The amniotic egg is a major shared derived character for the taxa in
the Amniota, which includes us as well as the dinosaurs.
• Soon after the amniotes appeared, two distinct group are
recognizable - these are the Synapsida (which includes us) and the
Sauropsida (which includes the dinosaurs).
What is an amniotic egg, and why do we care?
• Amphibian females (like their fishy ancestors) lay a large number
of eggs in water, which the male then fertilizes externally.
• The larval amphibian emerges from the egg, and develops as a
largely aquatic organism.
• Some metamorphose into a more terrestrial form, and move onto
land. Others spend their entire life in water.
• Animals with an amniotic egg have similar stages, but they all take
place inside a well-protected egg.
• They emerge from the egg into air with an adult-like form.
Key Innovations in the Amniotic Egg
Semipermable shell: allowsO2
in and CO2 out, but retains
water.
Extra-embryonic membranes:
Amnion: encloses the embryo
with a fluid very similar to
environmental water.
Chorion: coats the inside of
shell and the yolk (nutrient
source).
Allantois: encloses a cavity for
solid wastes.
• The amniotic egg allowed tetrapods to breed away from water. It
opened up a vast new landscape that they could invade.
The boundary between Amniotes and Amphibians is hard to
define because:
• Eggs don't fossilize well.
• "Amphibians" aren't a clade (not a natural group).
• There are no novelties that are shared only by the animals we call
Amphibians. This is because we have, rather arbitrarily, decided to
call some descendents of amphibians something else. As a
consequence, the Amphibian-Amniote boudary is "fuzzy".
Westlothiana lizziae - the first amniote, is known from the early
Carboniferous.
• Despite this early appearance, Amniotes don't diversify until end
Carboniferous.
What are the main groups of amniotes?
• The primary subdivisions of amniotes are based on "holes in the
head".
• Early tetrapods had a braincase enclosed by bone, as well as outer
skull armor that was separated from this braincase.
• This interior space between the brain case and outer skull is filled
with musculature to open and close the jaws.
• Some amnniotes begin to open windows in this outer skull armor and
begin to expand jaw muscles onto the outside of the head.
• It's thought that this expansion of jaw musculature allows greater
diversity in chewing and food processing.
Main Groups of Amniotes
Anapsids - no holes in head behind the eye.
• This is the primitive state for tetrapods.
• It occurs in the earliest tetrapods and is also seen in turtles, the most
primitive reptiles.
Synapsids - one hole in head behind the eye.
• This is one of the evolutionary novelties in head holes.
• It occurs in pelycosaurs, therapsids, and mammals.
Diapsids - two holes in head behind the eye.
• This is another evolutionary novelty in head holes.
• It occurs in nearly all reptiles except turtles (i.e., lizards, snakes,
crocodiles, pterosaurs, dinosaurs and birds).
Main Groups of Amniotes
Terrestrial Ecosystems of Permian Period
All the
continents had
crashed
together to
form the
supercontinent,
Pangea.
The swamps of tropical Europe and America were drying out.
Evaporites (salt deposits) and red beds (indicating dry soils) were more
common.
Early Permian tetrapods are only known from the equatorial zone.
Permian Plants
• Drying of the swamps took a long time; spanning from Late
Carboniferous through the late Permian.
• Seed plants came to dominate lowlands.
• Wet areas with spore-bearing plants persisted, but were
increasingly rare.
Permian Tetrapods
Amphibian diversity drops, but some groups persist and become
better adapted for life in the air.
The decline is tied to:
• Drying of swamps. Amphibian reproduction is tied to water.
• Competition and/or Predation by amniotes.
Amniotes were free to breed and feed away from water. Drying
wasn't a problem.
Synapsid amniotes (one hole) dominate landscapes in the Permian.
There were two main synapsid groups in the Permian: Pelycosaurs
and Therapsids
Permian Pelycosaurs
• Dominated in the late Permian.
• Pelycosaur communities of the early Permian only occur in the
tropical zone.
Carnivorous pelycosaurs: up to 2 meters and 200 kg, big heads &
eyes, long snouts, strong jaws, pointy teeth with some differentiation
from front-to-back.
They ate fish & amphibians.
Some had sails; Sprawling front & hind legs, but vertebral spines
prevented lateral undulation during locomotion.
Dimetrodon
(carnivorous)
Popularly known as the 'finback' because of the large sail on its back supported by elongated
spines from the vertebrae . This sail may have helped control temperature by acting as a radiator,
or may have been used for display. It was a formidable predator , with huge canine teeth
Herbivorous pelycosaurs: medium to large (3 m, 300 kg), small
heads, blunt undifferentiated teeth, large gut cavity, some had sails.
The same sprawling posture as in carnivorous pelycosaurs.
Edaphosaurus
(herbivorous)
This pelycosaur also featured a sail. Like Dimetrodon, this may have been used
for heat exchange or display. Unlike Dimetrodon, its teeth show it to have been a
herbivore .
Permian Therapsids
This is an artist's representation of the possible appearance of a
therapsid. Therapsids, now extinct, were reptilians which were
descended from the stem reptiles. They are presumed to be the
ancestors of the mammals. "Non-reptilian" characteristics of members
of this group were thoracic and pelvic skeletal features which permitted
the legs to be positioned directly underneath the body.
Herbivory among the Tetrapods
• Plant eating arose many times in tetrapods.
• Plant feeding animals use two different strategies for dealing with this
problem.
• Be small and picky - avoid cellulose-rich plant parts; only eat nutrient-rich
plant parts (fruits & nuts). There is only enough high-nutrient food to support
small animals with this strategy.
• Be big and indiscriminate - eat everything that you can. Pack your gut with
microbes and let them ferment this low quality food. Eat the microbes and the
waste products they exude. Must be large to fit the massive, fermentingchamber gut.
• Herbivorous pelycosaurs took the big, indiscriminate route.
• They were large, and probably evolved from large carnivorous ancestors.
• They had small heads, so cellulose digestion must have come from microbes.
• They did, in fact, have big guts.