GEO 211 Exam 4

Hadrosaurinae

enlarged external nares and broad snout

Lambeosaurinae

Hollow crests on top of head

Psittacosaurus

• Early cretaceous

• China, Mongolia, Russia

• Many specimens (>400 indivd, many complete skeletons)

• HAD TAIL FILAMENTS

• evidence of social behavior in juveniles

Panoplosaurus

• nodosaurid

• preserved cheeks

Mammalia

• cretaceous

• pointed teeth

• endothermic

• large brains

• suckled their young

• rear feet for grasping

Purgatorius

• earliest example of a primate or proto-primate

• Eutherian mammal

Chalks of Europe

Late Cretaceous

• region was flooded

• high rates of carbonate accumulation (shells of coccolithophores)

• 15 cm/thousand years

  • White Cliffs of Dover

  • Denmark

Cretaceous Mass Extinction

• Dinosaurs

• Ammonoids

• Mosasaurs and other marine reptiles

• reductions in gymnosperms and angiosperms (flowering plants)

• 90% calcareous nannoplanton and foraminifera went extinct

• Meteor impact

  • Striated dolomite

  • Chicxulub Crater

Tectonic Events in Western US

• Mowry Sea (Upper Cretaceous Seaway)

• Terminal Cretaceous iridium anomaly

  • Drumheller, AB

Evolution

Descent with modification

• modification must include a change in the developmental program

• evolutionary change must involve changes in the genetic basis of development

Ernst Haeckel’s Biogenetic Law

Ontogeny recapitulates phylogeny

Ernst Von Baer

Embryos diverse during ontogeny

• more general characters appear early

• less general forms develop from general forms

• embryos DIVERGE from ancestral forms during ontogeny

• Embryos of descendants only resemble embryos of ancestors

Laid the foundation for phylogenetic thinking: early splits define major groups

D’Arcy Thompson: On Growth and Form

• geometric transformation to “warp” one species form into another

• mathematical models for the nature of this change

• good descriptor of pattern, but doesn’t get at underlying mechanism

Plotted human and chimp skull similarity of form in early life, and difference late in life. humans retain a juvenile-like skull in the adult stage

Allometry

Differential rates of growth (or evolution) of two different traits

• size-dependent change in shape

• as body size increases, brain size increases

• rates of increase are not identical (not 1:1 ratio)

Curve is a classic signature of allometry

Allo = different, metry = rates (measurements)

Interspecific Allometry

• comparison across species

• uses a fixed age

• Trend line on a graph

Example of the evolution by developmental shifts

Intraspecific Allometry

• Static allometry (same age)

• ontogenetic allometry (across ages)

• Points on a graph

Positive allometry and the Irish “elk”

• interspecific allometry is positive

• antlers are “large” but exactly in line with their allometric growth trajectory

“Odd” structure may not be odd, but simply the combination of Cope’s rule (increased body size in a lineage) coupled with a developmental program that results in positive allometry.

Heterochrony

Describes changes in the timing of development

Neoteny

Retention of juvenile forms in the adult stage

Example: axolotls retaining external gills, a juvenile structure

Homeotic genes affect the specification of cell fates

• organized in gene clusters; different for different phyla

• temporal and spatial collinearity

• each specimen contains a homeobox domain

Mutations in homeotic genes seme to get told “this is thoracic segment number 2”

• transform the fate of one tissue into the fate of a different tissue

• regulate cell fate by specifying where cell is in time and space

  • cell knows what to do once it knows “where” it is

four-winged fly and mutations in the bithorax complex

Homeotic genes pattern the body

Pedomorphosis (Heterochrony)

Retention of juvenile traits by an adult organism

Peramorphosis (Heterochrony)

Descendant’s development extends beyond that of its ancestor

HOX Genes

A type of homeotic gene

• independently evolved in complex life

• “Building codes”

New mutations, new genes, or new regulation?

Mostly: new regulation

Some: new genes and mutations

Loss of eyes in some cave-dwelling species is likely a homeotic switch

Muller’s Accessory/Essential Theory

Traits with accessory functions can evolve functions essential for survival

Fetal hemoglobin

Very important to live birth

Major Transformations

1. no paired appendages (lamprey)

2. Paired appendages (sharks)

3. Limbs

How do Major Transitions (innovations) Evolve?

Fossil Evidence

1. provides timescales: 10s to 100s of millions of years

2. NOVEL STRUCTURES

3. renovation o folder structures

4. predicted intermediates are present:

   1. Eusthenopteron

   2. Tiktaalik

   3. Ichthyostega

Predictions from Paleontology:

1. increase in genome complexity

2. renovations in developmental genes!

Fin Fold Hypothesis for Paired Fin Evolution

Predicts: strongly correlated genetic evolution or common developmental genetic basis

Same HOX genes are expressed in both pectoral & pelvic fins/limbs.

How do new forms appear in evolution?

Gene duplication!

Evolution of Major Transitions: When and in What Order?

Adaptation is the result of natural selection. ALWAYS identified post-hoc.

Ex: Terrestrial Adaptations

1. internal nares (choana)

2. Arms: humerus, ulna, radius

3. Legs: femur, tibia, fibula

4. Epiphyseal growth plates

5. Enameled teeth

Animals behaviorally exploit prior adaptations, putting themselves under new selective pressures in the process

Paleogene Life

• recovery from Cretaceous extinctions

  • fern spikes

• birds

• mammals

• 3 million years for the full marine ecosystem to recover

  • probably because so many marine predators (crustaceans, mollusks, fishes, etc.) disappeared

• sandy coasts now offer new niches

  • sand dollars evolved from sea biscuits

• development of modern plant species

  • cacti and palm trees

• first recognizably modern rainforsts

• ice-free polar regions covered with coniferous and deciduous trees

• Angiosperms coevolved with insects, grasses spread in cooler and arid climate

Paleogene: Mammals diversified

• most modern orders present by early Eocene

• a lot of the main mammal groups have origins pretty deep into the Mesozoic

Obdurodon

• extinct monotreme (platypus)

• differed from modern platypuses in that adults retained molar teeth

• twice the size of modern platypus, around 1 m long

Paleogene Bats

• present by early Eocene

• full-on bats, no intermediates found (yet)

Archicebus

• oldest Haplorrhine (non-lemur primate)

• Eocene

• small (~0.8 oz)

Aegyptopithecus

• early fossil anthropoid that predates the divergence between hominoids (a pes and humans) and cercopithecids (Old World primates)

• Eocene

• small (~75cm long)

Vulpavus

• Carnivora

  • early Eocene

• Common ancestor?

• 60-90 cm in length

Condylarths

Extinct, polyphyletic taxon of carnivorous mammals

• multiple lineages related to ungulates

• Late Cretaceous-Oligocene, 66.5-23 Ma

Arctocyon

Condylarth

• likely plantigrade

  • walked like a bear

Creodonts

extinct, polyphyletic taxon of carnivorous mammals

• paleocene

• convergent carnassials

Patrofelis

Cat-like, 1-2m in length

• Eocene

Creodont

Sarkastodon

Creodont

• estimated 3m in length

• Eocene

• known from partial skull material

Paleogene Life: Ungulates

Phenacodus

• Eocene

• one of the earliest and most primitive ungulate

Odd-toed

• horses, tapirs, rhinos

Even-toed

• cloved-hooved goats, sheep, pigs, cattle

Paleogene Life: Horses

Earliest horses by end of Paleocene

• size of small dogs

Paleogene Life: Late Eocene Elephants

Moeritherium

• earliest

• pig sized

Palaeomastodon

• twice as tall

• possessed a rudimentary trunk and tusks

Early History of Whale Evolution and Discovery

1859: Darwin, in Origin, whales arose from bears

1883: Sir William Henry Flower, solidifies theory of descendants were from terrestrial mammals based on vestigial organs

• Phil Gingerich

• Hans Thewissen

Indohyus

Pakicetus

Ambulocetus natans

Rodhocetus

Basilosaurus

Dorudon

Indohyus

• Thewissen discovers fossils dated to 60mya in Kashmir region of India

• Even toed ungulate, a form of the mammalian order Artiodactyla

• Marine lifestyle

Basal whale form

Pakicetus

• First Archaeocete

• evolved 52 mya

• Found in Pakistan by Gingerich, 1983

• Sharper teeth, more carnivorous

• deficient in hearing underwater

• narrow braincase

• ribs do not extend to hips like most reptiles

Ambulocetus natans

• found in sediment about 120m higher than Pakicetus by Thewissen

• 49 mya

• “The walking whale that swims” - made possible by stout femur

• More aquatic, similar to a sea lion

• anatomy of spinal column, swam with tail going up and down

• skull characteristics (BIG)

  • NEOTANY (HETEROCHRONY) CREATES BIG HEADS

Rodhocetus

• 49-43 mya in Pakistan

• lumbar vertebrae, neural spines higher, more developed tail for swimming

• sacral vertebrae not fused, more flexibility

  • first devotee to swimming

• femur was a third shorter than that of Ambulocetus

• skull elongated

• ears pushed further back

• smaller eyes

WEIRD LOOKING

Basilosaurus

• 35-41 mya by Cope in 1868 in Egypt and Eastern US

• first complete aquatic form

• 15m long

• complete set of hind limb bones and a pelvis, but very small

• first to have a tail fluke, due to structure of vertebral proportions

• formation of blow hole, single large nostril to top of head

NOT A REPTILE

Dorudon

• found by Gingerich 1994

• ~40 mya

• very similar to Basilosaurus, however smaller in size (4-5m) and forelimbs/hindlimbs smaller

• ability to walk on land completely diminished, move from land to sea is complete

Whale Geographic Origins

• Tethys Sea

• Distribution of BAsilosaurus and Dorudon widely spread

• Ambulocetus and Rodhocetus constrained to India, Pakistan region

Cetacean (Whale) Genetic Changes Over Generations

• formation of the ear

• formation and movement of blow hole at top of the head

• vestigial organs

  • pelvis, tibia, other leg bone structures

Paleogene Life: Birds

• water birds abundant

• no songbirds

Gastornis (Diatryma)

• Terror Bird

• clawed feet and slicing beak

• anseriformes

• paleocene

Phorosrhacos

• Terror Bird

• Cariamiformes

• Miocene

Paraceratherium

• rhinocerus

• oligocene

• largest land mammal of all time

BIG LLAMA THING

Megaceratops

• brontotheres (related to horses)

• Eocene

• 43 genera

• funny dual nose horn

Paleogene Paleogeogrpahy

• Continents were in modern configuration but closer together

• Early Paleogene

  • warm climate

  • climate later cooled

Paleogene Thermal Maximum

Very warm interval (early Eocene)

• abrupt shifts in oxygen isotope ratios in plankton and benthic organisms

• rapid temperature increase

• Carbon isotopes shift to low levels

  • melting of frozen methane

Green River Basin flora shifted

Mammals migrated

• Bering Strait

Followed by Late Eocene ice age

Laramide Orogeny

Affects weather patterns with rain shadows

• thrust sheets exposed in Rockies

• easternmost and later uplift formed Black Hills

• Front range of the Rocky Mountains

  • high elevation

  • some from post-Laramide (Neogene) uplift

  • erosion kept pace with uplift

    • broad erosional surface

Chesapeake Bay

• largest estuary in the world

• rubble found just below 36 M year old fossils

Eocene impact

• circular depression

• impact crater

• shocked grains

Neogene & Holocene

• dropping temperatures and aridification because of glaciation

• Miocene = a lot of ape evolution and diversity

Neogene: Marine life

Miocene ancestral whales

• Odontocetes (whales with teeth, porpoises)

• Mysticetes (filter feeding whales)

• Miocene recovery of plankton foraminifera

Otodus megalodon

Late Cenozoic

• 18 m long

• found worldwide (teeth)

Neogene: Terrestrial life

• grasses

• herbs and weeds

• Thrive in arid climate (water trapped in glaciers = dry)

C4 Grasses

C4 plants

• incorporate more carbon 13 than C3 grasses

  • metabolic changes, more efficient with water

• five times more silica

  • wears down teeth of grazers

Why the spread?

• global climate change

  • aridity

  • carbonates indicate CO2 increased

• c4 plants are more efficient with water, but less efficient with light (needs more light)

Neogene: Mammals

• groups of large mammals

• many adapted to open terrain

  • even-toed ungulates

  • elephants

  • carnivorous mammals

  • hominins

• new world primates

Megatherium

• osteoderms

• 6m in length

• late Neogene

• giant ground sloth

Smilodon

• up to 800lbs

• teeth for biting

• late Neogene

Glyptodon

• osteoderms

• almost same size/weight as a Volkswagen Beetle

• late Neogene

The Ice Age

• glacial maximum

• extent of continental glaciation

• 35,000-10,000 years ago

The Ice Age: Six Lines of Evidence

1. erratic boulders

2. glacial till and basins associated with glaciation

3. depression of the land

   1. Hudson Bay

4. glacial scouring

   1. lower parts of mountains of northeast US are smooth

   2. tops were not scraped by ice sheets

5. lowering of sea level

   1. exposed continental shelves

6. migration of species

   1. mammals crossed Bering Strait on land corridors

   2. vegetation changed in response to global changes

Chronology of Glaciation

• oxygen isotope ratios of foraminifera skeletons in sediments

• oceans are enriched in O18 during glaciations

Northern Hemisphere glaciation began ~3M years ago

• full Ice Age began 2.5 mya

Ocean currents changed during glaciation

Climate impacts were felt globally (Exception: Great Basin/SLC)

Great Lakes

• last glacial max (Wisconsin Stage)

• remained when ice sheets melted back

Isthmus of Panama

• formed 3.5-3 mya

• started modern circulation

  • gulf stream carried salty Atlantic north

  • cools, sinks

    • oceanic conveyor belt

  • high latitudes cool

North American Mammal Exchange

• north and south american mammals developed separately

• pliocene uplift of isthmus allowed for exchange of terrestrial fauna

Milankovitch Cycles

• changes in Earth’s orbit are linked to glacial oscillations

• precession cycle: 20,000 year period

• 41,000 year period initially

  • when tilt cycle is farthest from vertical, high latitudes are coolest

• eccentricity period to 100,000 years

Human Evolution

Miocene apes radiated in Africa and Eurasia

• most were arboreal

Adapted to climbing trees

• long curved toes and fingers

• Phalange curvature indicates how well an animal can climb. This curvature suggests that some of our ancestors were good at both walking and climbing.

Sahelanthropus

• 7 mya (Late Miocene)

• Africa

Braincase: 320 cm³ to 380 cm³

Ardipithecus ramidus

• 4.4 mya (early Pliocene)

• facultative biped

• could not walk or run for long distances

• teeth suggest omnivory, and are more generalized than those of modern apes

• Africa

Small brain: between 300 and 350 cm³

Australopithecus

• multiple speciles (africanus, afarensis, sediba)

• bipedal

• Africa

Brain: 400 to 500 cm³

LUCY (A. africanus)

Paranthropus

• 2.3 to 1.2 mya

• bipedal

• Huge teeth. Chewed grass? Yes.

• Africa

Brain: 500-550 cm³

NUTCRACKER MAN

Homo

• 2.4 mya

• larger skull

• similar thigh and pelvis bones

• stone tools

Homo erectus

• 1.6 mya

• Africa & Asia

• Shorter than modern humans

  • First evidence of human ancestor dispersal

Brain: 600 cm³

Homo Neanderthalensis

• 250 to 40 kya

• multiple genomes sequenced from Europe and central Asia

• robust, strong bodies

• larger brains than modern humans

• mousterian style tools, more sophisitcated than erectus

• burial sites (religion)

Homo heidelbergensis and H. antecessor

• 1.2 mya to 800 kya

• two may be synonymous

• spain, france, germany

• about 1.6-1.8 m tall

Brain size: 1,000-11500 cm³

MODERN HUMAN BRAINS: ~1,350 CM³

Human Evolution: Culture

Cro-Magnon culture

• european

• cave paintings of france and spain

Flores Island, Indonesia

Peter Brown and Michael Morwood 2003

H. floresiensis

• 50 kya

• 1 m tall

• no chin

• tools

Brain: 380 cm³ (similar to chimp)

Small, brain is to scale with humans. Debate on what this thing was. Island dwarfism?

 

Around when fully-sized humans are in Africa.

Denisovans

Brand new species of modern human. Rewrites human history!

• male Denisovan mandible found from Pleistocene Taiwan

  • different sea levels would have allowed land migration to Australia

Neanderthals split and become two different species (Neanderthals and later Denisovans).

Neanderthals later encounter Denisovans. Interbreed.

Modern humans leave Africa. Encounter Neanderthals. Interbreed.

Modern humans encounter Denisovans in Asia. Interbreed.

Only "pure" modern human population are those that have never left Africa.

Evidence that Denisovans met another modern human in Asia and interbred with them.