Flashcards BIOL 214 Exam 1 Prep Lecture 3

Fossil

Any trace left by an organism that lived in the past.

Compression fossil

Fossil formed when an organism is buried in sediment and undergoes physical compression. (uncommon for plants and animals as it leads to distortion of the fossil)

Where do compression fossils usually form?

Areas with fine sediment deposition, such as river deltas, lagoons, rivers, and ponds.

Major limitation of compression fossils

Physical compression can distort the fossil.

Mold fossil

An empty impression or space left after buried remains decay. (hole)

Cast fossil

Forms when new material fills a mold and hardens into a 3D replica. (fills the hole - think jello)

Mold vs. cast

Mold = empty impression. Cast = material that fills the impression.

What information do molds and casts preserve?

Mainly surface shape, not internal anatomy.

Organisms/structures commonly preserved as molds and casts

Hard structures such as shells, bones, teeth, exoskeletons, and tree trunks.

Permineralization

Dissolved minerals precipitate into spaces within an organism, forming internal casts. first phase of fossilization

Replacement

water containing dissolved minerals replace the original biological material, changing composition while preserving form. second phase of fossilization

Permineralization + replacement significance

Preserves original shape down to cellular detail while changing chemical composition.

Petrification

Fossilization involving extensive mineralization/replacement; wood is the most common example.

Trace fossil / Ichnofossil

Fossil that records an organism's behavior rather than its body form.

Examples of trace fossils

Footprints (where), burrows (reproduction), nests, and coprolites (diet, alone vs. together).

Coprolite

Fossilized feces; a trace fossil that reveals feeding behavior.

Body fossil vs. trace fossil

Body fossil preserves physical parts; trace fossil preserves evidence of behavior.

Unaltered remains

Organisms or body parts preserved with little or no physical change. (almost pristine account of the organism)

Examples of unaltered preservation

Freezing/permafrost, amber, preserved shells, and rare desiccation/mummification. can be very OLD

Amber preservation

Organism becomes trapped in tree resin, preserving delicate structures.

Freezing/permafrost preservation

Cold conditions preserve entire organisms or tissues with very little alteration.

Index fossil

Fossil used for dating rock layers because it characterizes a specific geologic time.

Characteristics of a good index fossil

Abundant, geographically widespread, distinctive to a time interval, and rapidly evolving.

Why are rapidly evolving organisms useful as index fossils?

Their forms change quickly, making specific forms marker of narrow geological intervals.

oxygen revolution

the accumulation of oxygen released by cyanobacteria beginning 2.5 billion years ago

earth formed when

3.8 billion years ago ish

big bang was when

13.8 billion years ago ish

desiccation/mummification

removal or loss of moisture from soft tissues

moss

prefers acidic soils, absorbs tremendous amounts of water, used to pack wounds, high acidity & antibacterial properties are good for preservation

taphonomy

the study of the fossilization process

taphos

burial/grave

geography bias

depositional areas (oceans > mountains in terms of fossils)

abundance bias

common species have better odds of preservation (ex: flower is harder than teeth)

taxonomic bias

bones and shells amenable to fossilization (shelled/skeleton)

temporal bias

earth's crust is recycled so older rocks are rarer

Evidence that the fossil record is incomplete

Geological periods may lack sedimentary formations; strata have large time gaps; new taxa continuously discovered. but, we have to go based on whatever we can find

Why are fossil species sometimes difficult to interpret?

Fossils can be crushed/fragmented, ages imprecise, and incomplete sampling makes lineages look discontinuous.

Chronospecies

A temporally distinct portion of a single lineage recognized as a separate species by morphology.

Anagenesis

Gradual evolution within one lineage, where a new form replaces the ancestral form without branching or splitting

Key feature of anagenesis

No splitting or branching. One lineage progressively changes through time.

Pseudoextinction / taxonomic extinction

A lineage changes until its original name disappears, though descendants still exist. fossil

Why can anagenesis create pseudoextinction?

Older and newer morphological forms are assigned different species names despite being one continuous lineage.

Cladogenesis

Evolution by branching/divergence, in which an ancestral lineage splits into two or more descendants.

Key feature of cladogenesis

Branching occurs, producing separate evolutionary lineages.

Real extinction

A lineage fails to leave any descendants.

Anagenesis vs. cladogenesis

Anagenesis = change without splitting. (straight line) Cladogenesis = branching into multiple lineages. (wanky lines)

STUDY THIS PIC #1

#1

Pseudoextinction vs. true extinction

Pseudoextinction: lineage continues under new name. True extinction: lineage ends with no descendants.

Cambrian

Cambrian Explosion: rapid appearance of major animal body plans and modern skeletonized marine phyla.

Ordovician

Major diversification; first land plants and jawed fishes; ends with Ordovician-Silurian mass extinction. 85% death rate

ordovician likely causes

rapid global cooling, & falling sea levels

ordovician results

costal areas destroyed, chemical reactions affected by cold

Silurian

Biodiversity recovered; bony fishes diversified; early vascular plants colonized land.

Devonian

"Age of Fishes." Vertebrates transitioned to land; tetrapods arose; ended with a mass extinction. 70% death rate

Devonian likely causes

asteroid impacts, rapid global cooling

Devonian results

local destruction from debris, ocean life affected by temperature

Carboniferous

Extensive swamp forests, high O₂, giant insects; Age of Amphibians; early reptiles/amniotes appear.

Permian

Pangaea present; diversification of terrestrial vertebrates; ended with the largest mass extinction. 95% death rate

Permian causes

volcanic activity, increase in methane and CO2, rapid global warming

Permian Results

oxygen removed from oceans, desertification of land

age estimation of a fossil

imprecisely by their location in strata

Triassic

Mesozoic. After Permian, before Jurassic. Age of Ammonites, 1st dinosaurs, 1st mammals, Pangaea breaks. 76% death rate

Triassic causes

increase in methane and CO2, rapid global warming

Triassic results

desertification of land, frequent heat waves

K-T

a global catastrophe 66 million years ago caused by an asteroid impact that wiped out about 80% of Earth's species, including all non-avian dinosaurs

K-T causes

asteroid impact, volcanic activity, falling sea levels

K-T results

widespread fires, plants disrupted by global ash cloud, "nuclear winter"

Silurian

plants diversify on land, first solid fossil evidence (443-419 MYA)

devonian

fish out of water, 1st simple vascular plants began to grow by lakes (419-358 MYA)

carboniferous

age of amphibians that evolve into amniote mammals, birds, reptiles, etc.

Geologic Time Scale

System used to organize Earth's history into progressively smaller units based on major geological and biological events.

Largest → smallest geologic time units

Eon → Era → Period → Epoch

Precambrian

Informal name for the enormous span of Earth's history before the Phanerozoic Eon. It includes the Hadean, Archean, and Proterozoic eons.

Three eons of the Precambrian

Hadean → Archean → Proterozoic

Hadean Eon

Earliest portion of Earth's history, beginning with Earth's formation. Conditions were initially extreme and there is essentially no conventional fossil record from this interval.

Archean Eon

Eon associated with Earth's earliest established life, dominated by simple microbial organisms.

Proterozoic Eon

longest eon, after the Archean and immediately before the Phanerozoic; major developments include increasing atmospheric oxygen, evolution/diversification of eukaryotes, and eventually multicellular organisms. plate tectonics very active, first table continents appear, first abundant fossil evidence

Ediacaran Period

Last period of the Proterozoic Eon, immediately preceding the Cambrian. It contains important fossils of early large, complex, soft-bodied organisms. fossils found world wise, lots of diversity in form but do not resemble modern life, confirmed presence of cholesterols

Ediacaran biota

Diverse group of mostly soft-bodied organisms found in Ediacaran rocks; they represent some of the earliest large, complex multicellular organisms in the fossil record. (animal like)

Why is the Ediacaran important?

It documents complex multicellular life before the Cambrian Explosion. its indicative of animals

Phanerozoic Eon

Eon following the Proterozoic characterized by abundant, readily observable animal and plant fossils; it includes the Paleozoic, Mesozoic, and Cenozoic eras. burst of diversity, groups evolved, more complex ecosystems

Three eras of the Phanerozoic

Paleozoic → Mesozoic → Cenozoic

Paleozoic Era

First era of the Phanerozoic. Begins with the Cambrian and contains major diversification of marine life and later colonization of land. first land plants and first jawed fish, ended with ordovician-silurian extinction

Paleozoic periods in order

Cambrian → Ordovician → Silurian → Devonian → Carboniferous → Permian

Mesozoic Era

Second era of the Phanerozoic; often called the Age of Reptiles.

Mesozoic periods in order

Triassic → Jurassic → Cretaceous

Cenozoic Era

Current and most recent era of the Phanerozoic; follows the K-Pg mass extinction and includes major diversification of mammals and birds.

Cambrian Period

First period of the Paleozoic Era and therefore the first period of the Phanerozoic Eon.

Cambrian Explosion

Relatively rapid diversification and appearance in the fossil record of many major animal body plans near the beginning of the Phanerozoic.

Ediacaran → Cambrian transition

Transition from the final period of the Proterozoic into the first period of the Phanerozoic, associated with a major change in the diversity and visibility of animal life in the fossil record.

Silurian Period

Period after the Ordovician mass extinction characterized by rapid recovery of biodiversity, warm climate, high sea levels, diversification of bony fishes, and expansion of plants onto land. first vascular plants began to grow by lakes

Major plant development in the Silurian

First solid fossil evidence of plants diversifying on land, including simple vascular plants growing near lakes.

Vascular tissue

Specialized plant tissue used to transport water, minerals, and nutrients through the plant; important because it allowed plants to grow larger and live farther from constantly wet environments.

Xylem tissue

tubes that carry materials from the roots to the leaves

Phloem

Living vascular tissue that carries sugar and organic substances throughout a plant

Why was vascular tissue important for life on land?

It helped plants transport materials internally and support larger body size, making terrestrial colonization more successful.

Devonian Period

Known as the "Age of Fishes." Major evolutionary changes occurred as vertebrates began transitioning from water to land; arthropods were already terrestrial, and tetrapods appeared later in the period. they left water to escape predators or find prey

First terrestrial animals in the Devonian

Arthropods appeared on land before terrestrial vertebrates.

Tetrapod

A vertebrate lineage characterized by four limbs or descent from four-limbed ancestors; early tetrapods evolved from fish-like ancestors. fin to limb evolution, replacing fins with digits

Tiktaalik roseae

Important Late Devonian transitional fish-tetrapod fossil showing features associated with the transition from aquatic vertebrates to land-dwelling tetrapods.