History Of Life Geol 107 Exam Definitions Second Half Of Semester

Divided all Phanerozoic marine animals into three overlapping Evolutionary Faunas, of which all three date back to the Cambrian explosion and extend to present day

-Trilobites, archaic molluscs, archaic echinoderms and inarticulate brachiopods

-mainly mudgrubbers

-dominate the Cambrian, reduced in Ordovician, insignificant since then

-reflects advent of armoured filter-feeders and pelagic predators during the Ordovician Radiation

-bryozoans, brachiopods, corals, crinoids reflect ecological tiering of suspension feeders (low mobility, heavily armoured)

- cephalopods new top carnivore ("ambush" pelagic predator)

- dominate Paleozoic, but diversity was reduced by 75% by the Permian extinction event and never recovered

-gastropods, bivalves, crustaceans, echinoids, bony fish

-less armoured and more mobile than other fauna, due to predation (speed and weapons) and biological bulldozing (burrowing deeper, causing less stable sediment for filter feeders)

Major: Permian (>50% family extinction)

Intermediate: Ordovician, Devonian, Triassic, Cretaceous (10-50%)

Lesser: others (3-10%)

Areas with distinct biotas, reflecting geography and climate

Maximize diversity during periods of strong climatic gradient and maximum continental seperation

Measures degree of similarity between two biogeographic provinces

Shallow seas which covered almost all of North America during Ordovician

- supratidal and intertidal flats

- high salinity, periodic exposure and drying in hot arid environment

- abundant cyanobacterial stromatolites, some ostracods and trilobites capable of withstanding extremes

-analogous to modern fringing reef attached to shoreline

-coral rubble attracted scavengers (gastropods and trilobites). colonized by filter-feeders (bryozoans), microniches for dwellers (brachiopods and bivalves)

-ideal for animal and algae life

-trophic web includes most of the same elements of modern level-bottom shallow marine communities

Bryophytes have thin-walled, water-conducting cells but lack xylem, waxy cuticle on leaves cuts down on evaporation - only works near water and if it is small

Vascular plants have xylem, phloem, intercellular gas transport tubes, lignin

Oldest evidence for terrestrial plant life, Ordovician

Oldest vascular plant, Middle Silurian

-Earliest true vascular plants

- best known from Rhynie Chert of Scotland

-very small xylem, restricted to being near permanent water

- Psilophyton first described from Gaspe and New Brunswick

- more xylem (10%), can grow to 3m

- thickening of ends of branches weak attempt at leaves

- leaves present, but very small and narrow

- started small, but in upper Paleozoic included large trees

- Fern-like leaves

- contain secondary xylem (wood!), permitting 10m trees

- ancestors to seed-bearing trees

Earliest known true forest in Catskills of New York State

- dominated by progymnosperms and lycopods, a few ferns and horsetails

- upper story 10m high, thin leaves so abundant light for shrubs and ground cover

- floodplains due to poor root systems

- leaf litter includes primitive spiders, centipedes, millipedes and wingless insects, and fell into water leading to anoxia and encourage air breathing among fish (lungfish)

"Age of Plants"

- Lycopods dominate Carboniferous, trees up to 50m tall

- Ferns and Horsetails range from low ground cover to trees >10m high

- Seed Ferns first gymnosperms, fertilized by wind instead of water allowing uplands to be colonized

1) binding of loose sediment by plant roots permanently changed erosion and sedimentation

2) meandering river introduced due to roots

3) new rock type (coal)

4) Altered carbon cycling, end of greenhouse

5) Permanent rise in atmospheric O2 to present levels

6) Permitted origin and evolution of terrestrial animals

Burgess Shale, strikingly similar to living amphioxus and is regarded one of the oldest fossil chordates

Echinoderms that are chordate-like phyla and on the way to fish

Lagerstatten in China found early Cambrian craniates implying boneless fish arose early in Cambrian Explosion

Jawless fish, earliest type of fish

- slow, bottom grubbing fish

Jawed fish, first appear in late Silurian

-Acanthodians first jawed fish

-Chondrichthyes sharks

- Placoderms, heavy armour, dominant fish group, replace cephalopods to become top predator

- Osteichthyes jawed bony fish, includes ray fins (typical modern fish) and lobefins (very important in Devonian, almost extinct today)

Type of lobefin, extinct group that evolved into tetrapods and is on our direct evolutionary line

Assemblage of rocks from collision of Europe and North America, having mountains, lowlands with lakes and rivers, and shallow seas

Devonian amphibians, mainly aqueous forms with adaptations that would prove useful for terrestrial life

- entirely carnivorous, feeding on fish, insects, other invertebrates and amphibians

Reptiles, mammals and birds

-permits true colonization of the land

- semipermeable shell allows gases but not fluids to diffuse

- egg internally fertilized now, no need to return to water for reproduction

Anapsid: No fenestrae (earliest reptiles and modern turtles)

Synapsid: One fenestrae (mammal-like reptiles and mammals)

Diapsid: Two fenestrae (most modern reptiles, all dinosaurs, birds)

Earliest stem-group reptiles 350 Ma from Scotland, anapsid

Location of earliest true reptiles (300Ma), caught or lived in hollow lycopod tree, anapsids, insectivores

70% of all Early Permian reptiles

-early examples lack a sail, but best known were sail-back reptiles like Dimetrodon

-mostly carnivores, but included first tetrapod herbivores

- sail reduces time to get active temperature by 75%, giving it huge advantage

-replaced pelycosaurids in Middle Permian, dominate Late Permian

- mammal-like

- Cynodonts regarded direct ancestors of true mammals

Theraspids had bristles and common in periglacial and temperate climates, thus modifying body temperature

Terminal Permian extinction is the greatest extinction in Earth history, 57% of families and >95% of species

- greatly pronounced in marine realm, greatest losses among Paleozoic Fauna, especially filter feeders

-corals went completely extinct for next 20Ma

-coal gap marks Permian-Triassic boundary

-only mass extinction to ever affect insects

Largest volcanic deposits on Earth, massive release of CO2, rich in S and heavy metals

- oceanic anoxia, affecting immobial marine filter feeders and terrestrial respirers with low CO2 tolerance

-low biomass, low numbers, low diversity

- distaster biotas common (stromatolites and "weeds")

- no reefs until 9 Ma after extinction

-increasing biomass and diversity

- some taxa same as pre-extinction form (Lazarus Taxa) or convergent with pre-extinction taxa (Elvis)

- new evolutionary innovations appear on land (dinosaurs and mammals), sea (pleisiosaurs, modern corals) and air (pterosaurs)

- new ecological systems needed to accomodate

1) Lepidosauria (lizards and snakes)

2) Archosauria (thecodonts, crocodiles, pterosaurs and dinosaurs)

Amphibians, Paleozoic diapsids and living lizards have sprawling posture and thus cannot breathe and run at the same time.

Evolution of semi-erect and erect posture freed archosaurs from this

Stem group of archosaurs that use all three postures

Parusuchids top carnivore in freshwater

Crocodile top carnivore in terrestrial

Oldest dinosaur, early Late Triassic

Massive volcanism, eliminated direct competitors of dinosaurs, allowing dinosaurs to expand from 2-3% to >85% of reptiles

Shows how big animals moved with comparisons of weight vs. bone thickness and foot area

Shows herd behaviour, sometimes only front feet (swimming brontosaurs? no!) due to having higher weight/foot area ratios on front feet instead of back feet

-most dinosaurs traveled 0.5m/s

Dinosaur stampede in Queensland, Australia of thousands of small bipedal ornithopods and therapods trapped against water by a large carnosaur

-smaller dinosaurs running 3-5m/s, some showing speeds up to 12m/s

Argued that dinosaurs were warm-blooded in "Dinosaur Renaissance"

1) Predator-Prey Ratios shows 2-5% of dinosaurs were predatory, equal to ratio of predators in endothermic communities

2) Upright posture according to Carrier's Constant

3) Running Speeds, high speeds typical of endotherms

4) Polar Dinosaurs, very close to poles

Maintain constant body temperature, either endotherms and/or gigantotherms

Allow body temperature to vary widely depending on external factors, and are ecothermic

Produce heat to regulate internal temperature, has high energy cost but permits sustained exertion and function even in cold conditions

Large animals maintaining constant high body temperature simply by virtue of their large size

1) Plates and Frills, filled with blood vessels, releasing excess heat

2) Oxygen isotopes, dependent on temperature are small variation implying at least partial endothermy

3) Bone microstructure, rich in vascular structures (osteons) sometimes

4) Nasal turbinates, small bones in nasal passages not found in ectotherms nor dinosaurs

5) Feathers, Sinosauropteryx discovered with feathers for insulation

NE China, fossil Lagerstatten of feathered dinosaurs

- dominated by gymnosperms

-trees up to 60m high

-early conifers, cycads and ginkgos dominant group

-Dominated by angiosperms

-strong reliance on vector pollination and seed dispersal

-consists of rudists (reef-builder, bizarre clam)

- ammonites most abundant swimming invertebrates, medium-level carnivore

- belemnites also very common

-J-Cret. acme of sauropterigians, large marine reptiles

Small, dolphin-like, agile, fish eating reptiles, gave birth to live young at sea

Largest sea-going monitor lizards, ate fish, other reptiles and ammonites, may have returned to land to lay eggs

Up to 12m long, long-necked with four paddle like fins, mainly fish-eaters that gave birth to live young at sea

Group of early stem-group mammliformes from late Triassic (225Ma), still had cynodont jaw structure but other features mostly mammalian

Fur-covered partial endotherms; milk producing but no nipples; lay eggs

-originated in Gondwana but restricted to it ever since

-most common Mesozoic mammals, named for the rows of cuspate teeth

- similar to modern rodents in size and lifestyle but much more primative

-most modern mammals

-Marsupials give birth to immature young that mature in mother's pouch

-placentals have longer gestation period and give birth to more fully formed young

-both originated in Northern continents

- Bolide impact blocked >99% of sunlight, instantaneous heat blast followed by a long, cold winter, very toxic atmosphere arsenic and cyanide

Reported an iridium anomoly at the precise point of the terminal Cretaceous extinction in Italy, also associated with shocked quartz

-Crater which bolide created, instantaneously sterilized North America by the impact

Immediately followed Cretaceous extinction, sudden appearance of massive amounts of fern spores (disaster biota)

Size: Small, nothing over 25kg

Climate: Polar biotas better than tropical and reef biotas

Evolutionary Niche: Highly specialized animals very vulnerable, generalists and burrowers less affected

- Greenhouse

- mix of marsupials, placentals and multituberculates

- herbivores were small, largest was size of rhino

- carnivores are terror birds and creodonts

- Greenhouse, early Eocene was warmest period in last 100Ma years

- essentially modern bats

- whale ancestor Pakicetus

- Ambulocetus large shoreline carnivore

- Basilosaurus and baleen whales

Extensive extinction amongst archaic mammals due to global cooling period

Convergent evolution results in similarity of form amongst species that attempt to fill these roles (actors change but play doesn't)

- Mesonychids largest carnivorous land mammal ever

- Creodonts small to mid-range ferret

Even-toes ungulates include deer, sheep, camels, cows, pigs and hippos

Odd-toes ungulate include horses, rhinos and tapirs

Titanotheres and chalicotheres large mammals

Miocene, changed through time to become larger, 3-4 toes to one hoof, and larger teeth

Evolution occurred due to these migrating, making sue of their survival and climate change ensured they were entirely grazing

-evolved in Africa, includes elephants, aardvarks, sea-cows

-evolved in South America, includes modern sloths, armadillos, anteaters

NE Australia, record of mammal evolution for past 25Ma

- connection with N.A beginning in Pliocene

-Sehelantropus - chimp-like skull and human features, extinct twig on early part of branch leading to hominins

- Ardipithecus - faculative biped

Found by Richard Dart, first find of australopithecines

World's oldest tools, used for scraping meat off bones, not for hunting

1) Homo habilis - "handy man"

2) Home erectus - Acheulean hand axes, controlled use of fire, first to leave Africa

3) Neanderthal - Mousterian tools

4) Early Homo sapiens- complex Aurignacian tools

Different populations oh H. erectus maintained some genetic interchange and eventually evolved into different races of H. sapiens

H. sapiens evolved out of Africa, causing other hominid populations to go extinct

Leaky Replacement theory is most compatible with this

Humans overkilled large mammals causing their extinction

New Zealand large bird that went extinct same time humans arrived