Paleo Final Exam Study 🤣😝

Paleontology

Study of the history of life and ancient environments

Fossil

Any trace of an organism that lived in the past older than 12.5kya

Applications of studying fossils

Biostrat, biogeography, paleoclimate, paleoenvironment, long-term eco and evo change, modern biodiversity issues, and fossil fuel economics

Geologic timescale

system of categorizing time in geologic record, dates continually refined

Taphonomy

study of how organisms fossilize; all processes between death and discovery

Unaltered remains - soft parts

Freezing or preservation in amber usually

Unaltered remains - hard parts

tar pits (beetles, vertebrates) or shallow marine environments (shells) usually

Permineralization

pore spaces are filled via precipitation of silica, phosphate, or pyrite; retains fine detail; common for wood and bone, sometimes shell

Recrystallization

skeletal material subjected to increased temperature and pressure converts to more stable form; destroys fine detail; aragonite to calcite, amorphous silica to quartz; common for shells

Silicification

original material replaced by silica; retains fine detail; common for shells

Pyritization

original material replaced by pyrite; retains fine detail; common for shells

Mold

composed entirely of sediment; no original material; common for shells; a negative (outside, think pottery mold)

Cast

composed entirely of sediment; no original material; common for shells; a positive (think product of putting something in a mold)

Carbonization

soft parts preserved as carbon films through distillation under heat and pressure; common for leaves, sometimes insects

Altered v. unaltered

altered = denser, not original color

Aragonite

Fairly unstable, often dissolves or recrystallizes, all gastropods, some bivalves, corals, bryozoans, sponges, and algae

Calcite

More stable, brachiopods, some bivalves, corals, bryozoans, sponges, algae, trilobites, & echinoderms

Silica

Easy to distinguish, some sponges and radiolarians, common replacement mineral

Pyrite

easy to distinguish, replacement mineral only

Cellulose

found in higher plants, algae

Calcium phosphate/apatite

found in vertebrates, brachiopods, arthropods

Best chances for preservation

Mineralized skeleton, large skeletal elements, thick/dense skeletal elements, many skeletal elements, life habit/environment that increases chance of burial and decreases chance of scavenging/decay, large population size, broad geographic range, long stratigraphic range

Controls on decay

supply of oxygen (more = faster), temperature (higher = faster), pH (neutral = faster), nature of organic C (more volatile = faster)

Lagerstatten

THE MOTHER LODE; often preserve soft parts, muscles, chitin, cell impressions, color patterns; often anoxic environments or really fast deposition to get beyond the TAZ quickly

Early mineralization of soft tissues

Can happen via pyrite, phosphate, carbonate, and depends on salinity, rate of burial, and organic content; deep lagoon and sea environments have lots of sulfates for pyritization; carbonization requires high orgo content and burial rate, in low salinity creates siderite coating and and high creates calcite coating; phosphatization requires high orgo content and low burial b/c happening pre-burial

Environments of exceptional preservation: concentration

gathering together of remains by sediment transport and sorting

Environment of exceptional preservation: conservation

Fossilization of remains without scavenging, decay, or diagenesis

Taphonomically active zone

area in sediment that is below the depth of wave action and bioturbation; organisms here are more likely to be preserved

Lagerstattens: Burgess Shale

Mid Cambrian in British Columbia, one of the oldest, submarine landslide = rapid burial in anoxic environment, small organisms that are much more complex than expected, early molluscs, echinoderms, wiwaxia, anomelocaris (1st multicellular predator), hallucenigenia

Lagerstattens: Mazon Creek

Pennsylvanian in Illinois, brackish/freshwater estuary, sedimentary concretions with OM trapped in between, fernsm crayfish, clams, worms, crabs, carbonization, tully monster

Lagerstattens: Solnhofen

Upper Jurassic in Germany, shrimp, horseshoe crabs, fish, starfish, jellyfish, shallow marine shelf, archaeopteryx

Lagerstattens: Florissant

Upper Eocene in Colorado, deep lakes, fine sed, leaves, flowers, fishies, insects, arachnids

Relative Age Dating

Age based on relative position, most sed rocks and fossils

Absolute age dating

actual age based on radiometric dating; can only be used for fossils back to 50kya

Biostratigraphy

Branch of stratigraphy that focuses on correlating and assigning relative ages of rock strata using the fossil assemblages; often linked to absolute dates via volcanic ash and igneous intrusions or basalt

Faunal Succession

fossils often occur in repeatable, predictable order vertically, this order can be used to correlate layers across a region

Index fossils

Abundant, evolves quickly/short duration, wide geographic range, easy to ID, good preservation

Biozones

Basic units of biostrat; taxon range, interval, assemblage, or acme

Signor-Lipps Effect

The last occurrence of a taxon is unlikely = true extinctions, all taxon ranges are artificially truncated, common taxa have shorter gaps between occurrences

Confidence intervals

use the distribution of gaps in taxon occurrence to calculate around FO and LO; larger gaps = larger uncertainty in FO and FO

Paleobiogeography

Study of the geographic distribution of fossil organisms

Ecological biogeography

Study of modern biogeography based on climatic and ecological factors

Historical biogeography

Study relating modern distributions of organisms to geological events

Quantifying biogeography

Metrics like dice, jaccard, simple matching, and simpson coefficients; use # of taxa in common, # of taxa in each individual sample, # taxa absent from both samples

Fossils and tectonics: timing

provide critical age constraints; focuses on timing, not reset by thermal or tectonic events like radiometric dates are; ex. separation of the scotland highland border complex from the precambrian dalradian supergroup based on early ordovician fossils

Fossils and tectonics: origin of exotic blocks of crust

when >95% of peeps say accretion has taken place; where big chunks come from

Exotic terranes: Noah’s Ark

Brings species to a new area alive

Exotic terranes: Viking funeral ship

brings to fossil record of extinct organisms to a new area

Fossils and tectonics: finite strain

describe how rocks respond to tectonic forces and other forms of deformation; stress = force per unit area acting on a rock; strain = resulting deformation or change in shape of the rock; can quantify the magnitude and direction of strain

Fossils and tectonics: paleothermometer

Temperature increase during burial; conodonts, graptolites, acritarchs, pollen change color due to the burning of carbon

Latitudinal diversity gradient

higher diversity in the tropics; cradle (more origination) or museum (less extinction)?

Geobiology

explores interactions between organisms and the physical/chemical environment on earth and elsewhere

Biological approaches to paleoenv and paleoclimatic reconstruction

relies on environmental tolerances of modern species, usually applied to congeneric species, back to upper Cenozoic

Paleobiogeochemical approaches to paleoenv and paleoclimatic reconstruction

relies on stable isotope content recorded in fossil hard parts, can be applied to almost any organisms, from any time interval; helpful because it doesn’t assume env tolerances are constant through time

Bio approaches: temperature proxies

Coral reefs (limited to tropics), amphibians (tropical to temperate), leaf margin shape, planktonic forams (varies according to coiling)

Bio approaches: oxygen proxies

increasing O2 → brittle stars & marine worms, corals, cephalopods

Bio approaches: salinity proxies

increasing salinity → freshwater mollusks, brackish mollusks, marine mollusks, coral/echinoderms, brine shrimp; ostracods, some mollusks, and diatoms are variable

Paleobiogeochemical approaches: oxygen isoptopes

more delta O18 = more O18 = lower temp because of ice volume (preferential evap of O16); useful for dinosaur warm-bloodedness, timing of pleistocene glaciations, measures of global warming, Milankovitch forcing

Paleobiogeochemical approaches: annual ocean temps

seasonality recorded in bivalve shells, periods of stop and go growth and delta O18

Paleobiogeochemical approaches: carbon isotopes

more OM = more 12C, less productivity = less delta C13; applications for identifying hydrothermal vent communities, tracking grasslands, measuring productivity through time

Paleoecology

study of relationships between organisms and their environment via the fossil record; contributes to understanding of modern ecological processes and contributes to reconstructing paleoenvironments

Community

formed by interactions among populations of living organisms at a a particular time

Quantifying communities

Rarefaction curves (species richness), # of individuals in each taxon (raw, rank, % abundance), # of individuals between taxa (evennness), density, spatial dist (uniform, random, clumped)

Examples of fossilized behavior

Symbiosis (crinoids & gastropods, inoceramids & fish), reproduction (crepidula fornicata), predation

Competition

interactions between organisms striving for the same resources (food, substrate, mates, etc.), can result in competitive exclusion or niche partitioning

Succession

regular changes that take place in a community as it becomes established and matures to a stable endpoint

Evolutionary paeloecology

study of ecological phenomena that operate at long timescales

Escalation

Evolutionary arms races thought to occur between predators and prey; example Mesozoic marine revolution - rapid adaptation to shell-crushing and drilling predation in benthic organisms throughout the Mesozoic

Offense and defense

Examples of offense - combo of rasping tongue and acidic spit in gastropods

Examples of defense - spines, apertural teeth, thickened shells, ribs, burrowing, boring, swimming

Evidence of predation - peeling, drilling, chipping

Evolution

Organisms have changed through time and are related by descent from a common ancestor ; descent with modification

Charles Darwin & On the Origin of Species

Provided a mechanism for the pattern of evolution (natural selection) and overwhelming evidence of evolution

Darwin’s Principles of Natural Selection

1. Individuals within species vary

2. Some of these variations are passed on to offpsring

3. In every generation, more offspring are produced than survive

4. The survival and reproduction of individuals are not random. Individuals who survive and reproduce the most are those with the most favorable variations

Questions posed by evolutionary biology

How does populations change through time in response to environmental change?

How do new species arise?

Microevolution

Small-scale change, usually below species level

Macroevolution

Large-scale change, usually above species level

Phyletic Gradualism

gradual transformation from one species to the next

Punctuated Equilibrium

species change very rapidly during episodes of speciation, then remain stable for long periods of time between speciation events

Direct evidence for change through time

Trilobite rib # increases through time, Chesapecten shape concavity and # of ribs

Direct evidence for transitional forms

Archaeopteryx and ambulocetus

Species selection

analogous to natural selection, but acts on species instead of individuals; species survive because they possess irreducible characters that give them an evolutionary advantage (size of range, sexual dimorphism, etc.)

Tetrapod evolution

Transition from water to land, evolved from fish, many transitional fossils with fish and tetrapod characteristics, loss of gills and scales, gain of a sturdy ribcage, lungs, a neck, and hip bones, decrease in the number of digits

Origin of flight

Evolved more than 30x in vertebrates (including gliding and powered); pterosaurs in the jurassic, bats in the eocene

Arboreal Theory

From the trees down; vertebrate flight most likely to originate via gliding stage, scarcity of arboreal dinos

Cursorial theory

Dinos are ground-dwelling, highly cursorial organisms, aerodynamically difficult to evolve flight from the ground

Systematics

Scientific study of the kinds and diversity of organisms and relationships among them

Phylogeny

evolutionary history of a group; can be visualized in a tree

Evolutionary tree

Phylogenetic tree + rates of evolution (time) + ancestors

Characters (traits)

Discrete (categorical, qualitative, composed of states) or continuous (quantitative)

Convergent character states

state that arises independently in 2 evolutionary lineages, e.g. wings

Homologous character

state that arises in 2 lineages because these lineages share a common ancestor possessing this character, e.g. vertebrate limbs

Cladistics

Relationships based on shared, derived