Chapter 4 Outline
CLASSIFICATION OF ORGANISMS - TAXONOMY (SEE DISCUSSION, BOX
4.1)
- KINGDOM, PHYLLUM, CLASS, ORDER, FAMILY, GENUS, SPECIES
- DEVELOPED BY C. LINNAEUS & referred to as the
Linnaean System
- GENERALLY ORGANISMS INDICATED BY TWO NAMES - GENUS (General
Group) + species (specific group)
- examples: Felis domesticus = house cat, Canis
latrans = coyote, Canis lupus = wolf, Homo sapiens
= human
| Phylum |
Chordata |
Chordata |
Chordata |
Chordata |
| Class |
Mammalia |
Mammalia |
Mammalia |
Mammalia |
| Order |
Carnivora |
Carnivora |
Carnivora |
Primate |
| Family |
Felidae |
Canidae |
Canidae |
Hominidae |
| Genus |
Felis |
Canis |
Canis |
Homo |
| species |
domesticus |
latrans |
lupus |
sapiens |
EARLY BIOTA
- LIFE IS MONOPHYLETIC
- RNA, DNA, CELL MEMBRANES, PROTEINS, AMINO ACIDS, METABOLIC
PATHWAYS, ABILITY TO REPLICATE
- ALL SHARED, DERIVED CHARACTERS
- SOME TERMINOLOGY
- PROKARYOTE - NO INTERNAL ORGANELLES OR MEMBRANE-BOUND NUCLEUS
WITH CHROMOSOMES; <10 microns
- EUKARYOTE - HAVE INTERNAL ORGANELLES (CHLOROPLASTS &
MITOCHONDRIA) & MEMBRANE-BOUND NUCLEUS WITH CHROMOSOMES;
>10 microns
- ANAEROBE - CANNOT SURVIVE IN AN ENVIRONMENT WITH FREE OXYGEN
- AEROBE - CAN SURVIVE IN AN ENVIRONMENT WITH FREE OXYGEN
- HETEROTROPH - CANNOT SYNTHESIZE FOOD (INCLUDES ALL VERTEBRATES)
- AUTOTROPH - CAN SYNTHESIZE FOOD BY FIXING CARBON
- CHEMOSYNTHESIS - USE CHEMICAL ENERGY TO FIX CARBON
- PHOTOSYNTHESIS - USE SUNLIGHT TO FIX CARBON
- FIRST ORGANISMS
- ANAEROBIC HETEROTROPHIC PROKARYOTES (PROBABLY)
- FIRST AUTOTROPHS
- CHEMOSYNTHETIC ANAEROBES (PROBABLY)
- used heat energy from MOR hot springs
- FIRST PHOTOSYNTHETIC AUTOTROPHS
- ANAEROBIC BACTERIA (PROBABLY)
- like those now found only in restricted environments
[anaerobic hot springs in Yellowstone Park]
- As old as oldest continental crust (probably)
- CARBON SPHERES IN 3.8 BY OLD ROCKS OF GREENLAND
- SECOND PHOTOSYNTHETIC AUTOTROPHS
- AEROBIC CYANOBACTERIA (BLUE-GREEN ALGAE) (PROBABLY)
- 6 CO2 + 6 H2O + energy -> C6H12O6
+ 6 O2 (lots of free oxygen)
- ~2 BILLION YEARS AGO THE ATMOSPHERE BEGAN TO BE "POLLUTED"
BY O2
- EVOLUTION OF EUKARYOTES BETWEEN 1.5 & 2 BILLION YEARS
AGO
- EUKARYOTES ARE THOUGHT TO HAVE DEVELOPED FROM SYMBIOTIC RELATIONSHIP
BETWEEN PREVIOUSLY-INDEPENDENT PROKARYOTES (ENDOSYMBIOTIC THEORY)
- some organelles have their own DNA & RNA,
cell membranes and reproductive mechanisms
- ORGANIZATION OF DNA INTO CHROMOSOMES IN NUCLEUS ALLOWED DEVELOPMENT
OF SEXUAL REPRODUCTION (GENETIC RECOMBINATION) & THE RATE
OF ORGANIC EVOLUTION INCREASED
- EVOLUTION OF MULTICELLED ORGANISMS
- MULTICELLED ALGAE EVOLVED ~1.5 BILLION YEARS AGO
- MULTICELLED ANIMALS (EDIACARA FAUNA) EVOLVED LESS THAN 600
MILLION YEARS AGO [note your text says 670 million years ago]
- soft-bodied
- found on all continents except Antarctica (Namibia,
England, Scandinavia, Russia, Siberia, China, & N. America)
- SMALL SHELLY FOSSILS REPLACE EDIACARA FAUNA - ~550 my ago
- BODY PLANS
- BODY PLANS CONSTRAINED BY LIMITS OF THE PHYSICAL WORLD (SURROUNDED
BY WATER OR AIR; SUBJECT TO GRAVITY) AND BY ANCESTRY
- COMPLEX MUSCULATURE, ENCEPHALIZATION, BILATERAL SYMMETRY
AND SEGMENTATION ARE FEATURES COMMON TO THE BODY PLANS OF ACTIVE
ANIMALS
- repetition of these features among distantly-related animal
groups is the result of convergence (independently
evolved)
- DIFFERENT PHYLA (phylum = singular) HAVE DIFFERENT BODY PLANS
- Chordata vs. Arthropoda vs. Mollusca
- CAMBRIAN EVOLUTIONARY EXPLOSION
- AN INITIAL "EXPERIMENTAL" DIVERSIFICATION OF BODY
PLANS
- Generally only animals with hard shells represented
in fossil record
- "CLASSICAL" CAMBRIAN FOSSIL ASSEMBLAGE
= trilobites (75%), inarticulate brachiopods (15-20%), &
archaeocyathids (~5%)
- However, there were lots of non-shelled animals around
- BURGESS SHALE (MIDDLE CAMBRIAN) OF BRITISH COLUMBIA
PRESERVES MANY SOFT-BODIED ANIMALS, INCLUDING SOME REPRESENTATIVES
OF PHYLA WITH TRULY WEIRD BODY PLANS
- PRIMITIVE CHORDATES (Pikaia gracilens ) ALSO OCCUR
IN THE BURGESS SHALE
CHORDATES
- INCLUDE Pikaia , UROCHORDATES, CEPHALOCHORDATES,
AND VERTEBRATES
- CHORDATES HAVE PHARYNGEAL GILL SLITS; A NOTOCHORD [STIFF,
ELONGATE SUPPORT STRUCTURE]; & A DORSAL, HOLLOW NERVE CORD
AT SOME STAGE OF THEIR LIFE
- UROCHORDATES = SEA SQUIRTS - LOOK LIKE CHORDATES ONLY IN
LARVAL STAGE
- CEPHALOCHORDATES = AMPHIOXUS
- characterized by segmentation of body wall muscles,
separation of upper and lower nerve and blood vessel branches,
and new hormone and enzyme systems
- VERTEBRATA
- CHARACTERIZED BY CALCIFIED SKELETAL TISSUE (BONE) DIVIDED
INTO DISCRETE PARTS CALLED ELEMENTS
- Agnatha (nonmonophyletic group) = jawless fish
(only modern jawless fish - lampreys & hagfish)
- GNATHOSTOMATA
- CHARACTERIZED BY TRUE JAWS
- Acanthodii & Placodermi = extinct archaic
jawed fish
- JAW EVOLVED FROM MODIFIED GILL ARCH
- CHONDRICHTHYES (CARTILAGINOUS FISH) = SHARKS, RAYS &
SKATES
- OSTEOICHTHYES (BONY FISH) = MOST MODERN FISH
- Actinopterygii = Ray-finned Bony Fish - Most
modern fish
- Sarcopterygii = Lobe-finned Bony Fish
- LUNGFISH, COELOCANTHS, & TETRAPODS
- CHARACTERIZED BY STURDY LOBE FINS (OR LEGS) WITH SPECIALIZED
STRUCTURES IN THE PELVIS, SHOULDER, BACKBONE & SKULL; ALSO
NOSTRILS & LUNGS
TETROPODA
- AMPHIBIA, REPTILIA, MAMMALIA & AVES
(Birds) = TRADITIONAL CLASSES
- AMPHIBIA = FROGS, SALAMANDERS AND CAECILIANS
- REPTILIA = TURTLES, LIZARDS AND SNAKES, TUATARA AND CROCODILES
- TETROPOD SKELETON
- SEE FIGS. 4-9, 4-10 & 4-11 IN YOUR TEXT, PLUS HANDOUT
- THERE IS A NICE LABELED DINOSAUR SKELETON AT
http://www.ucmp.berkeley.edu/diapsids/images/anat.gif
- AMNIOTA
- REPTILIA, MAMMALIA & AVES
- POSSESS "AMNIOTE" EGG CONTAINING A MEMBRANE CALLED
THE AMNION WHICH PROTECTS THE DEVELOPING EMBRYO FROM DRYING OUT
- A shell or skin, large yolk, and waste bladder
are also associated with the amnion
- Amniotes are not dependent on a moist environment
like Amphibians
- Amphibians are non-amniote tetrapods that
must lay eggs in water (or moist environment
on land) & larva breath via gills
- LISSAMPHIBIA = MODERN AMPHIBIANS
- MANY EXTINCT FORMS OF NON-AMNIOTE TETRAPODS IN FOSSIL RECORD
(MOST WENT EXTINT IN THE MIDDLE TO LATE MESOZOIC)
- AMNIOTES ARE UNITED BY HUNDREDS OF OTHER CHARACTERS IN ADDITION
TO THE AMNIOTE EGG
- AMNIOTES ARE DIVIDED INTO 2 GREAT CLADES
- SYNAPSIDA
- MAMMALIA & EXTINCT "MAMMAL-LIKE REPTILES"
- Characterized by a skull with a lower temporal
fenestra (an opening behind the eye)
- ALSO, COMPARED TO REPTILES, ADVANCED "MAMMAL-LIKE REPTILES"
(Therapsids) HAD FEWER BONES IN SKULL, A BETTER JOINT BETWEEN
SKULL & NECK, ENLARGED LOWER JAWS, DIFFERENTIATED TEETH,
LIMBS BENEATH THE BODY (SEE DISCUSSION, BOX 4.2) , & PROBABLY
FUR (probably were warm-blooded)
- "MAMMAL-LIKE REPTILES" DIVERGED FROM TRUE REPTILES
310-320 MILLION YEARS AGO
- "Mammal-like reptiles" (including sail-backed
forms like Dimetrodon ) were the dominant
land vertebrate during the Permian & Triassic
periods
- "Mammal-like reptiles" gave rise to mammals
in the Triassic period & went extinct during
the Jurassic period
REPTILIA
- TURTLES, LIZARDS & SNAKES, TUATARA,
CROCODILES AND BIRDS!; AS WELL AS EXTINCT DINOSAURS
AND PTEROSAURS (AND MARINE REPTILES LIKE MOSASAURS, ICHTHYOSAURS
& PLESIOSAURS)
- REPTILIA DIVIDED INTO 2 CLADES BASED ON SKULL STRUCTURE
- ANAPSIDA - NO TEMPORAL OPENINGS = TURTLES (CHELONIA)
- DIAPSIDA - TWO TEMPORAL OPENINGS = ALL NON-TURTLE REPTILES
LISTED ABOVE
- DIAPSIDA DIVIDED INTO 2 CLADES
- LEPIDOSAUROMORPHA - LIZARDS & SNAKES AND TUATARA
- ARCHOSAUROMORPHA - INCLUDES ARCHOSAURIA (CROCODILES, DINOSAURS,
PTEROSAURS, & BIRDS)
- ARCHOSAURIA INCLUDES 2 IMPORTANT CLADES
- ARCHOSAURS ARE CHARACTERIZED BY ANTORBITAL OPENING IN SKULL
- ARCHOSAURIA INCLUDES 2 IMPORTANT CLADES
- Crurotarsi = crocodiles & close relatives
- Ornithodira (bird neck) = birds & close
relatives
- ORNITHODIRA
- ORNITHODIRANS ARE CHARACTERIZED BY ERECT POSTURE
- The plane of the legs is perpendicular to
the plane of the torso
- The legs are tucked under the body
- The head of femur and the ankle joint only allows
movement of legs and feet forward and backward
within a plane parallel to the body
- ORNITHODIRA DIVIDED INTO 2 MAJOR CLADES
- Pterosauria = active flying reptiles with maneuvering
ability
- Wings were skin stretched between elongated 4th finger,
sides of the body & rear limbs
- Pterosaurs were warm-blooded - fine hair found covering
well-preserved pterosaurs
- active flyers must maintain constant high internal temperature
- Sparrow-sized to members with wingspans as large as 15.5
m !
- Dinosauria
- DINOSAURIA
- TRADITIONALLY DIVIDED INTO TWO CLADES BASED ON HIP STRUCTURE:
SAURISCHIA (lizard-hipped) & ORNITHISCHIA (bird-hipped)
MISCELLANEOUS QUESTIONS
- HOW MANY TIMES HAS "WARM-BLOODEDNESS" EVOLVED
IN THE VERTEBRATES?
- TWO OR THREE TIMES
- Once in the Synapsids
- At least once & possibly twice in the Ornithodirans
- PTEROSAURS & BIRDS
- "WARM-BLOODEDNESS" MAY BE ANCESTRAL TO ORNITHODIRANS
- HOW MANY TIMES HAS POWERED FLIGHT EVOLVED IN THE VERTEBRATES?
- THREE TIMES
- Once in the Synapsids
- Twice in the Ornithodirans
- IS A COW A FISH?
- SEE DISCUSSION IN BOX 4.3 (THE SHORT ANSWER IS YES!)
- DID ALL THE DINOSAURS BECOME EXTINCT?
- WHICH IS CLOSER TO A CROCODILE A LIZARD OR A BIRD?
- A BIRD!
- Birds & crocodiles are archosaurs, while
lizards are not