The History of Vertebrates
By Eric Przybyszewski Advanced Biology December 7, 2010
In The Book
Chapter 34Sections 34.1- 34.7With focus on 34.5 – 34.7
What is a Vertebrate?
A vertebrate: Any animal with a backboneBackbone meaning a segmented spinal column
Living examples: reptiles, fish, birds, amphibians, mammals, Humans
52,000 species of vertebrates, 1 million insect species
Largest vertebrate blue whale, at 100,000 kg Origins traced back about 540 mya
Origins of Vertebrates Chordates:
Simple bilaterally symmetrical animals Four features
Post anal tail Pharygeal gill slit Notochord Hollow dorsal nerve cord
Craniates: Chordates with a head Name derived from cranium (skull) Most well known: hagfish
Origins of Vertebrates Vertebrates: craniates with a backbone
More complex nervous system Restricted to marine environments Examples: jawless armored fish
Gnathostomes: vertebrates with a jaw Found up to 470 mya Chondrichthyans: cartilaginous fish
Sharks, rays etc. Ray-finned fish
Most common living fish Tuna, trout, bass, herring
Lobe-fins Evolved during the Devonian period Today only three lineages that survive
Tetrapods Tetrapods: gnathostomes with limbs and feet
Name: “four feet” 360 mya fins of lobe-fins evolved into limb and
feet First vertebrates to came ashore Amphibians Ancestor to all land vertebrates
Terapods 360 mya Coastal wetlands home to many lobe-finsMost were shallow, oxygen-poor, water
Caused them to use lungs and breath air Forced them to drag themselves across the floor Increasing the strength in fins and developing the
muscles that would become limbs Muddy bottom could be pushed against and so
feet developed
Terapods
These earliest tetrapods were not terrestrial The earliest confirmed is some 20 million
years laterThey may have spent very brief periods out of
water and would have used their new legs to pull their way through the mud
Marine Mammals
Not all terapods changed Some left shallow inter seas for the oceans Most evolved partially, fins, with leg bones now
were again used as fins. Examples
All whales Dolphins Manatee
So Far…
So Far…Chordates
Craniates
Vertebrates
Gnathostomes
Tetrapods
Living Tetrapods Amphibians
Oldest known land group Name means “two lives” Most common
Salamanders with 4,800 different species
Not all live in both water and on land Some strictly aquatic Some strictly terrestrial
Examples: frogs, salamanders, and caecilians
Amphibians Provide a look into prehistoric life
Locomotion Powerful hind legs (frogs) Legless, burrowing
Predation Carnivores (insectivorous), omnivores, herbivores
Defense mechanisms Mucus, distasteful of poisonous Camouflage
Metamorphosis Example-Frogs
Egg, to Larva (tadpole), to Adult Adapted climate
Organisms adaption's speak to the current climate Reproduction
External fertilization Mating behaviors
Amniotes Terpods that have a terrestrially adapted egg Late Devonian period Includes reptiles, birds and mammals The major difference is the egg
Amniotes The terrestrial egg
Hard shell Protection
Albumen Padding
Extraembryonic membranes Padding and protection
Amniotic cavity Nutrients and suspension
Yolk Main source of nutrients
Embryo Developing organism
Amniotes
The terrestrial egg allowed for
Permanent Land Dwelling Led to internal fertilization Led to the Reptiles, Dinosaurs and Birds
Without egg mammals may not be here
Amniotes
Became terrestrially adapted True lungs with a rib cage
Enough oxygen in the atmosphere Less permeable skin More elevated stance Capable of living in much drier environments Became herbivores, Carnivores, and Omnivores Grew larger in size
Early examples Little fossil evidence
Reptiles Oldest well documented amniotes Includes
Lizards, snakes, turtles, crocodilians Traced back to 350 mya Unique characteristics
Have scales (protein kertin) Waterproof and protective
Rely on lungs alone for gas exchange Not turtles
Lay hard shelled eggs on land Internal fertilization “Cold Blooded”
Ectothermic absorb heat Not birds
Reptiles The Major groups
Parareptiles First reptiles 300 mya
Diapsids Lepidosaurs
Lizards, snakes, marine reptiles (plesiosaurs and ichthyosaurs)
Archosaurs Crocodilians Petroasaurs (first tetrapods in the air) Dinosaurs
Reptiles… Reptiles
Diapsids
Archosaurs
Petroasaurs
Parareptiles
Lepidosaurs
Crocodilians DinosaursMarine
Reptiles
So Far…
So Far…Do not let itConfuse you
Reptiles
Diapsids
Archosaurs
Petroasaurs
Parareptiles
Lepidosaurs
Crocodilians DinosaursMarine
Reptiles
Chordates
Craniates
Vertebrates
Gnathostomes
Tetrapods
Amniotes Amphibians
Dinosaurs Covers many animals Ranged from the size of pigeons to
massive 45m (148ft) long quadrupeds
Two main Branches Ornithischian (bird hipped)
Herbivores, many had defenses Iguanodon, Stegosaurus, Triceratops
Saurischian (lizard hipped) Sauropods
Apatosaurus, Diplodocus, Brachiosaurus Theropods (birds later)
Allosarus, Deinonychus, T-rex, Velociraptor
Dinosaurs From 248 mya to 65 mya Dinosauria is one of the most
successful superorders in the earth’s history
9,000 different species Much debate
Extinction Mobility Parental abilities
Surviving lineages Lepidosaurs
Tuatara Squamates
Lizards and Snakes Birds
Lepidosaurs Surviving lineages
Tuatara Lizard like Traced back 220 mya
Snakes Legless, very successful Small and Carnivores Some poisonous Highly evolved sense of smell
Lizards Most numerous and diverse
reptiles, (excluding birds) alive Most are small and Carnivores Komodo Dragon
Crocodilians Alligators and Crocodiles Archosaur lineage back
to late Triassic First were small
quadrupeds with slender legs
Over time later species became more and more suited to aquatic environments and grew in size
Largest known is Super Croc.
Others 10 m or more in length
Birds Decedents of the Theropod dinosaurs Technically reptiles
Lost almost every resemblance to reptiles
8,600 different species Endothermic From Archosaurs came about during
the Jurassic Flight gives several advantages
Enhances hunting, scavenging Easy escape from predators
Several different physical characteristics that set birds apart and allow most of them to fly No urinary bladder Most only have one ovary Small gonads All living birds are toothless Light skull Hallow bones Wings, feathers (made of Kertin)
Several modern bird species
Origin of Birds From the bipedal
Saurischians Theropds
Raptors ex. Velociraptor
Archaeopteryx Earliest known bird at 150 mya Feathered with wing claws Capable of powered flight but
keep many dinosaur like features
Weak flyer but still it could fly Other fossils show similar
types birds but none are as complete
Mammals Synapsids Nonmammalian have no hair Temporal fenestra, hole behind the eye
socket on each side Large herbivores or carnivores
Amniotes, the synapsids, that produce milk Mammary glands Hair, layer of fat under the skin Live birth Larger brain Long duration of parental care Very social
Endothermic Higher metabolism rate
First appeared almost 200 mya During Jurassic Never became larger then modern day
shrews Kept hidden by reptile’s dominance
After the 65 mya mass extinction Mammals started to dominate Became large predators and
herbivores plus flying and aquatic species
Mammal Skull Example of Biarmosuchus Jaw and it make up.
Note the difference between the ears in a reptile and a mammal.
Primates Eutherians Placental mammals
Physical traits Feet and hands adapted for
grasping Opposable thumbs Large brain Short jaws, flat face
Living primates New World Monkeys
Prehensile tail Nostrils that open to the side
Old world Monkeys No perhensile tail Nostrils that open down
New World Old World
Review A vertebrate: Any animal with a backbone
Backbone meaning a segmented spinal column
Terapods: have limbs, feet, digitsAdoptions for on landAmphibians
AmniotesThe terrestrial egg: allowed for?
ReptilesDiapsids
Review Dinosaurs Ornithischian Saurischian Surviving lineages
Crocodilians Birds
From TheropdsArchaeopteryx
MammalsSkullPrimates
Life Begins
Dinosaurs
Amphibians
Life on land
First Mammals
Review
First Birds
Mass extinction
First Vertebrates
First Primates
Paleontology ends
First Reptiles
Review What is a vertebrate?
Any animal with a backboneBackbone meaning a segmented spinal column
Oldest land group? Amphibians
First bird? Archaeopteryx
Largest Crocodilian?Super Croc.
Two types of living monkeys?New and Old world
Review Chapter overview P. 707,708 Sections 34.1 - 34.7
with focus on 34.5 – 34.7 Try Self Quiz P. 708 #1-7 Paleontology
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