Vertebrates

Which of these is most closely related to you?

Echinoderms and Chordates are the only two phyla of deuterostomes. Vertebrates

Chordata fish, amphibians, reptiles, birds, mammals Deuterostome coelomates Notochord serves as axis of body Dorsal, hollow nerve cord Tails. Human coccyx is vestigial tail. Birds & mammals = homeotherms (constant body temperature) All others are poikilotherms (cold-blooded) though some reptiles are endothermic.

Mammals class Nurse their young with milk Have hair or fur made of keratin Homeotherms Placental = develops in womb Marsupial = born early, develops in pouch Monotreme = egg-laying (duck-billed platypus and spiny anteater).

Primates order Hands with opposable thumbs Claws have become nails Eyes are in front and close together for binocular vision Nurture their young for a long time.

Chordate Characteristics

A flexible rod between the nerve cord and the digestive tube All chordates have this as embryos Most develop later into complex, jointed skeleton. Notochord Chordate Characteristics

Develops from a plate of ectoderm that rolls into a tube Unique to chordates. (Other phyla have solid, ventral nerve cords) Develops into central nervous system, spinal cord, and brain. Dorsal, hollow nerve cord Chordate Characteristics

Just posterior to the mouth Used for suspension feeding and gas exchange (gills) In land animals, they develop into parts of the ear. Pharyngeal slits or clefts Chordate Characteristics

Lost during embryonic development in many species Provides propulsion for many aquatic species. Muscular, post-anal tail Chordate Characteristics

Classes of Chordates

Tunicates Classes of Chordates

Tunicates Classes of Chordates

Tunicates Classes of Chordates

Tunicates Classes of Chordates

Lancelets Classes of Chordates

Lancelets Classes of Chordates

Hagfish Classes of Chordates Craniate (has brain and skull) No jaws No vertebrae

Hagfish Classes of Chordates

Hagfish Classes of Chordates

Hagfish Classes of Chordates

Lamprey Classes of Chordates Vertebrate (has backbone) Still no jaws

Lamprey Classes of Chordates

Lamprey Classes of Chordates

Lamprey Classes of Chordates

Sharks and Rays Classes of Chordates Gnathostomes (“jaw-mouths”) Bones have some mineralization but are still mostly cartilage Acute senses (lateral line, nostrils, black-and-white vision) Oviparous, ovoviviparous, or viviparous.

Sharks and Rays Classes of Chordates

Sharks and Rays Classes of Chordates

Sharks and Rays Classes of Chordates

Ray-Finned Fishes Classes of Chordates

Lobe-Finned Fishes Classes of Chordates

Lungfishes Classes of Chordates

Tetrapods

Classes of Tetrapods Amphibians Urodela (“tailed ones”) Salamanders Anura (“tailless ones”) Frogs and toads Apoda (“legless ones”) Caecilians

Classes of Tetrapods Amphibians Adaptations: Camouflage Poison Metamorphosis / paedomorphosis Complex social behavior Eggs lack shells, dehydrate quickly Gas exchange through moist skin

Amniotes

Amniotic egg may be laid on land. Contains extra-embryonic membrane May be calcified (birds) or leathery (reptiles) or may implant in the uterus (mammals)

Phylogeny of Amniotes Ancestral amniote Synapsidia Diapsidia Anapsidia

Phylogeny of Amniotes Mammals Turtles Lizards & Snakes Crocodiles Dinosaurs Birds Ancestral amniote Synapsidia Diapsidia Anapsidia

Phylogeny of Amniotes Mammals Turtles Lizards & Snakes Crocodiles Dinosaurs Birds Ancestral amniote Synapsidia Diapsidia Anapsidia

Reptiles Adaptations: Keratinized skin Lungs Leathery shells on eggs Ectotherms.

Birds began as feathered reptiles Adaptations: Feathers Honeycombed bones Missing some organs Gizzard instead of teeth Endothermic Four-chambered heart Good vision Relatively large brains.

Mammals diversified in the wake of the Cretaceous extinctions Adaptations: Mammary glands Hair Four-chambered heart Endothermic Placenta / live birth Large brains Differentiated teeth.

Primates and Human Evolution Adaptations: Brain size Jaw shape Bipedal posture Size difference between sexes Long-term pair bonding Long-term infant dependency.

Multiregional Hypothesis African European Asian Austalasian Homo erectus In Africa interbreeding 1-2 million years ago

Replacement Hypothesis African European Asian Austalasian Homo erectus In Africa 100,000 years ago 1-2 million years ago