5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
- Tetrapods
350
mya
Devonian
417
mya
Radiation of the “stem tetrapods” !!!
Carboniferous
Old
friends
a fish
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
- Tetrapods
Caecilians
Salamanders
Frogs
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
The amniotic egg was a big advance
Resist desiccation
- amnion protects the embryo
- yolk sac provides nourishment
- allantoic sac holds waste produced
by embryo
Provision embryo
allows for colonization of dry
habitats
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
SYNAPSID
Amniote
ancestor
ANAPSID (turtles?)
Hylonomus
Casineria
DIAPSID
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
The Permian
Formation of Pangaea dries the
landscape; amniotes dominate
like the gymnosperms.
shelled egg and the seed
Dimetrodon – a Pelycosaur
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
The Permian
Pelycosaurs
The synapsids radiate and
dominate
Dicynodonts
Gorgonopsids
Therapsids
Cynodonts
A cynodont
Mammals
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
Mammals
- excellent transitional sequences from
cynodont ‘reptiles’
- first fossils with all mammalian
features (jaw, ear, dentition, fur) date
to ~200 mya - Morganucodontids
Radiations of
Mammals
They diversify during
the Mesozoic, but the
modern groups
radiate and dominate
in the Cenozoic
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
Mammals
- Monotremes: lay eggs, “sweat” milk
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
Mammals
- Monotremes: egg laying, “sweat” milk
- Marsupials: live birth to embryo – attaches
to nipple to complete development. Mother
does not need to abandon the nest/young to
feed.
Pygmy possum – Australia
(opossums in Western
Hemisphere)
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
Mammals
- Monotremes: egg laying, “sweat” milk
- Placentals: Longer internal development
allows for precocial behavior (independence
on birth); placental allows for direct, energyefficient transfer of nutrients between blood
systems of mother and offspring.
Each energy
transformation is
less than 100%
efficient
Milk production in
mammary glands
DIGESTION
Nutrients in
bloodstream
of mother
Placenta
- Marsupials: live birth to embryo – attaches
to nipple to complete development. Mother
does not need to abandon the nest/young to
feed.
FOOD
FOOD for
OFFSPRING
DIGESTION
Nutrients in
bloodstream
of offspring
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
Mammals
- Monotremes: egg laying, “sweat” milk
- Marsupials: live birth to embryo – attaches
to nipple to complete development. Mother
does not need to abandon the nest/young to
feed.
- Placentals: Longer internal development
allows for precocial behavior (independence
on birth); placental allows for more direct and
energy-efficient nutrient transfer
precocial
altricial
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
In the Mesozoic, the synapsids are replaced by the great diapsid radiations of
Ichthyosaurs, Pterosaurs, and Dinosaurs
Archosaurs: Dinosaurs,
Pterosaurs, Crocodilians, Birds
Lepidosaurs: Lizards, Snakes,
Sphenodonts)
Diapsida
Ichthyosaurs
Younginiformes
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
- Archosaurs
Crocodilians
Pterosaurs
Ornithiscians
Dinosaurs
Saurischians
Sauropods
Theropods
Carnosaurs
Birds
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
Birds: (derived traits)
No teeth
Feathers and endothermy
flight feathers
keeled breastbone
Clavicles united into wishbone
Pneumatic skeleton (houses air
sacs from respiratory system)
Unidirectional respiration
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
In the Mesozoic, the synapsids are replaced by the great diapsid radiations of
Ichthyosaurs, Pterosaurs, and Dinosaurs
Archosaurs: Dinosaurs,
Pterosaurs, Crocodilians, Birds
Lepidosaurs: Lizards, Snakes,
Sphenodonts)
Diapsida
Ichthyosaurs
Younginiformes
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
- Lepidosaurs
Keuhniosaurs
Squamates
Scales, moveable quadrate
(double hinged jaw),
hinged skull
Rhynchocephalians (Tuatara)
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes
Tetrapods
- Amniotes
- Lepidosaurs
- Squamates