Tracking Human Evolution:
Where Do We Fit on the
Tree of Life?
Geology 230
Fossils and Evolution
Phylogenetic Classification of Humans
Life on Earth
Eukaryota
Animalia
Bilateria
Deuterostomia
Chordata
Craniata
Vertebrata
Gnathostomata
Osteichthyes
Sarcopterygii
Tetrapoda
Phylogenetic Classification of Humans
Reptiliomorpha
Amniota
Synapsida
Therapsida
Mammalia
Eutheria
Primates
Anthropoidea
Hominidae
Homo
H. sapiens
Tree of Life Web Project
http://tolweb.org/tree/phylogeny.html
Root of the Tree, Life on Earth:
http://tolweb.org/Life_on_Earth/1
Eukaryotes
http://tolweb.org/Eukaryotes/3
Animals, Metazoa
http://tolweb.org/Animals/2374
Bilateria
http://tolweb.org/Bilateria/2459
Deuterostomia
http://tolweb.org/Deuterostomia/2466
Chordata: dorsal nerve cord
http://tolweb.org/Chordata/2499
Exemplar fossil:
Yunnanozoon or
Haikouella,
Cambrian
Yunnanozoon (Haikouella), a cephalochordate from
the Lower Cambrian of China
Urochordates: Sea Squirts. Adults have a pharynx with
gill slits. Larval forms are free-swimming and have a
notochord. Chordates are thought to have evolved
from the larval form by precocious sexual maturation.
Tunicates or Sea Squirts
mobile larva
sessile adult
Cephalochordate: Branchiostoma, the lancelet
Craniata: skull
http://tolweb.org/Craniata/14826
Vertebrata: vertebrae
http://tolweb.org/Vertebrata/14829
A living jawless fish, the lamprey
Gnathostomata: jawed vertebrates
http://tolweb.org/Gnathostomata/14843
The placoderms
were the armored
fish of the
Paleozoic. Grew up
to 10 m in length.
Placoderm, Dunkleosteus, Devonian of Ohio
Placoderm, Devonian of Australia
Osteichthyes: Bone structure in fins of
ray-finned and lobe-finned fish
Fish Anatomy: Lobe-finned fish
Sarcopterygii: lobe-fins
http://tolweb.org/Sarcopterygii/14922
Sarcopterygian, lobe-finned
fish, Devonian of Scotland
An Australian lungfish with well
developed lobe fins
Coelocanth, a
living lobefinned fish
Skeleton of the coelocanth
A Coelocanth
Evolution of the tetrapod walking leg from
the lobe fin
Sauripterus,
rhipidistian, Late
Devonian,
Pennsylvania
Evolution of
tetrapod legs
from lobe fins,
late Devonian to
early
Mississippian
Evolution of
Tetrapods
Prothero, 2007
Late Devonian fin with fingers from a lobefinned fish, Pennsylvania
Tiktaalik rosea
from the Late
Devonian of
Ellsmere
Island,
Canada, 2006
Tiktaalik rosea from
the Late Devonian
of Ellsmere Island,
Canada, 2006
Tiktaalik rosea on
Colbert Report
Lobe-Fins to Tetrapoda: four legs
http://tolweb.org/Terrestrial_Vertebrates/14952
Tetrapods: Acanthostega and
Ichthyostega, Devonian of Greenland.
Lobe-Fin Fish or Tetrapods?
Skull roof of
the Late
Devonian
Ichthyostega
Acanthostega
using its legs to
lift its head out
of the stagnant
water to
breathe
Hindlimb of Ichthyostega, Devonian of Greenland
Fish with Fingers, Jenny Clack
Ichthyostega: Photographs of part and
counterpart superimposed to show seven digits
Changing Digits from the Late Devonian
to Early Mississippian
Reptiliomorpha
http://tolweb.org/Terrestrial_Vertebrates/14952
Amniota
http://tolweb.org/Amniota/14990
Crocodiles
hatching from
their amniote
eggs