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