tracking human evolution: where do we fit on the tree of...

Tracking Human Evolution:Where Do We Fit on the

Tree of Life?

Geology 230

Fossils and Evolution

Phylogenetic Classification of Humans

Life on EarthEukaryota

AnimaliaBilateria

DeuterostomiaChordata

CraniataVertebrata

GnathostomataOsteichthyes

SarcopterygiiTetrapoda

Phylogenetic Classification of Humans

ReptiliomorphaAmniota

SynapsidaTherapsida

MammaliaEutheria

PrimatesAnthropoidea

HominidaeHomo

H. sapiens

Tree of Life Web Project

Root of the Tree, Life on Earth: http://tolweb.org/Life_on_Earth/1

http://tolweb.org/tree/phylogeny.html

Eukaryoteshttp://tolweb.org/Eukaryotes/3

Animals, Metazoahttp://tolweb.org/Animals/2374

Bilateriahttp://tolweb.org/Bilateria/2459

Deuterostomiahttp://tolweb.org/Deuterostomia/2466

Chordata: dorsal nerve cordhttp://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: skullhttp://tolweb.org/Craniata/14826

Vertebrata: vertebraehttp://tolweb.org/Vertebrata/14829

A living jawless fish, the lamprey

Gnathostomata: jawed vertebrateshttp://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-finshttp://tolweb.org/Sarcopterygii/14922

Sarcopterygian, lobe-finned fish, Devonian of Scotland

An Australian lungfish with well

developed lobe fins

Coelocanth, a living lobe-finned 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 lobe-finned fish, Pennsylvania

Tiktaalik roseafrom 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 legshttp://tolweb.org/Terrestrial_Vertebrates/14952

Tetrapods: Acanthostega andIchthyostega, Devonian of Greenland.

Lobe-Fin Fish or Tetrapods?

Skull roof of

the Late

Devonian

Ichthyostega

Acanthostegausing 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

Reptiliomorphahttp://tolweb.org/Terrestrial_Vertebrates/14952

Amniotahttp://tolweb.org/Amniota/14990

Crocodiles

hatching from

their amniote

eggs

Pennsylvanian

anapsid or

stem reptile

Amniote Family Tree

Prothero, 2007

Synapsid Skull: one opening behind the orbit (eye)

Diapsid Skull: two openings behind the orbit (eye)

Synapsidahttp://tolweb.org/Synapsida/14845

Permian Synapsids, Germany

Triassic synapsid reptiles: Therapsids or

mammal-like reptiles

Therapsida, Mammals and extinct relatives http://tolweb.org/Therapsida/14973

BiarmosuchiaEotitanosuchiaDinocephaliaAnomodontiaTheriodontia

GorgonopsiaTherocephaliaCynodontia

DiviniidaeMammaliaProcynosuchidaeGalesauridaeThrinaxodontidaeCynognathidaegomphodontsChiniquodontidaeProbainognathidaeTritheledontidae (Ictidosauria)

A Gallery of

Therapsids

Carl Buell

From Synapsids to Mammals, a well documented transition series

Prothero, 2007

Prothero, 2007

Yanoconodon, Lower Cretaceous of China

Yanoconodon, Lower Cretaceous of China, retains ear bones attached to lower jaw

Morganucodon

Yanoconodon

Mammaliahttp://tolweb.org/Mammalia/15040

Class Mammalia - Late Triassic to RecentSuperorder Tricodonta - Late Triassic to Late

CretaceousSuperorder Multituberculata - Late Jurassic to

Early OligoceneSuperorder Monotremata - Early Cretaceous

to RecentSuperorder Metatheria (Marsupials) - Late

Cretaceous to RecentSuperorder Eutheria (Placentals) - Late

Cretaceous to Recent

Evolution of Mammalian Superorders

Tricodonts U

Eutheria

(Placentals)

Metatheria

(Marsupials)

Live Birth

Mammary Glands?.

.

Multituberculates U

Monotremes

..

Extinct: U

Mammals in the Age of Dinosaurs

Hadrocodium, a lower Jurassic

mammal with a “large” brain (6 mm

brain case in an 8 mm skull)

Lower Cretaceous mammal from China

Jawbones of a Cretaceous

marsupial from Mongolia

Mammal fossil

from the

Cretaceous of

Mongolia

Eutheriahttp://tolweb.org/Eutheria/15997

Primate Classification- 1980’s

Order Primates

Suborder Prosimii: tarsiers and lemurs

Suborder Anthropoidea: monkeys, apes, and hominids

Superfamily Hominoidea

Family Pongidae: great apes

Family Hominidae: Homo and hominid ancestors

Primate Classification – 2000’sOrder Primates

Suborder Prosimii: tarsiers and lemurs

Suborder Anthropoidea: monkeys, apes, and

hominids

Superfamily Hominoidea

Family Hominidae: all hominoids

except gibbons

Subfamily Ponginae: orangutans

Subfamily Homininae: gorillas, chimps,

Homo and hominin ancestors

98%

96%

95%

91%

84%

58%

100%% genetic similarity with humans

Prothero, 2007

Tarsiers, a primitive

Primate (Prosimian)

from Southeast Asia.

Tarsier sanctuary, Philippines

A Galago or bush

baby, a primitive

Primate

(Prosimian) from

Africa.

A Slow Loris, a

primitive Primate

(Prosimian) from

Southeast Asia.

Check out the

fingers.

Lemurs, primitive Primates

(Prosimians) from Madagascar.

Monkeys, such as baboons, have tails

and are not hominoids.

Proconsul, the oldest hominoid, 18 MY

Hominoids

The Orangutan, a Great Ape from Southeast Asia.

Gorillas, Great Apes from Africa.

Chimpanzees, Great Apes from Africa.

I’m cool

Neoteny in Human Evolution. Humans

resemble baby apes more than adult

apes. Humans are said to be

paedomorphic.

Chimp skull on the left, human skull on the right

Chimp

Homo sapiens

Consequences of Neoteny

• Large brain and cranium

• Small jaws and teeth with small face

• Retention of juvenile growth patterns

• Long juvenile period = extended learning

• Retardation of onset of puberty

• Longer life span

• Naked skin

Next: The Hominid Fossil Record