Paleo 202 Midterm

Homology

Similar characteristics resulting from a shared ancestry.

Traits

Features or structures

Synapomorphy

A shared (from a common ancestor), derived character

Convergent Evolution

Evolution in two unrelated lineages of a similar structure or analogue

Analogues Structures

Features with superficial resemblance, but have different origins

Vertebrata

A clade of animals containing agnathans and gnathostomes, including humans

Clade

A natural evolutionary group containing a single ancestor plus all of its descendants but no others

Chordata

A clade of animals containing vertebrates, tunicates, and cephalochordates

Cephalocordata

Lancelets- invertebrates with with chordate synapomorphies.

Tunicates

Sea Squirts- chordates with very different juvenile and adult forms

Myomeres

Muscle bundles that are visually differentiated into segments

Notochord

A hydrostatic organ found in Chordata that provides structural support for the organism; may be lost and functionally replaced in vertebrates. Fluid filled fibrous sheath.

Pharyngeal Slits

Openings in the lateral walls of the pharynx of chordates; may be modified or lost in different groups; associated with gills in adult fish

Endostyle

A groove on the ventral surface of the pharynx in tunicates and cephalochordates which produces mucous and aids in gathering food; believed to be homologous to the thyroid gland in vertebrates

Endoskeleton

The support structure of the body that lies internal to the skin

Pharynx

The region around the throat between the mouth and esophagus

Cambrian Explosion

The apparently sudden appearance of almost all modern major groups of animals in the fossil record, about 525 million years ago

Dorsal Hollow Nerve Cord

The type of sensory cord found in vertebrates in which the nerve runs along the back of the animal, and forms through a rolling up of the sides to form a hollow tube. Above notochord, sends commands to muscles. Becomes vertebral column in vertebrates.

Post-anal Tail

The continuation of the muscles and skeleton of chordates beyond the end of the digestive tract (the anus)

Vertebrata Synapomorphies

Bone, neural crest cells, distinct head/brain, cartilage

Endochondrial bone

Starts as cartilage in the embryo

Ossification

Cartilage that becomes bone

Intramembranous Ossification

Bone that does not start as cartilage

Dermal Bone

Bone formed by dermis, ex. Body armour, stegosaurus plates, spikes, shells

Neural Crest cells

Formed along dorsal hollow nerve chord, anteriorly forms skull cartilage/bone, sensory nerves/organs and dorsally forms pigment cells, nervous system, hormone organs. It’s the most important evolutionary innovation. Differs from chordates

Clasts

Pieces of worn down rocks that form clastic rocks

Terrigenous

Derived from rocks on land

Brackish Water

Saltier than freshwater but not as salty as marine water

Delta

Sedimentary Body that builds outward over time at the end of a river. Has brackish water. Ex. Nile River Delta

Estuary

At the end of a river, with no outward building sediment. Forms scoured out channels. Mix of marine and continental sediments and plant roots, marine shelly fossils. Has brackish water. Ex. Gulf of Saint Lawrence

Coarsening Outward Succession

Transition from finer carbonate marine sediments to coarser, clastic, continental, fluvial sediments at the top of a water body. Found in deltas

Sedimentary Structures

Structure from where rock was deposited, from clasts

Clastic rocks

Are terrigenous. Sandstone, mudstone, bedrock, conglomerates.

Carbonate Rocks

Made of 50% calcium carbonate and shells of marine organisms, fossils are found here. Ex. Limestone

Miguasha

Devonian Fish fossil locality. Lake, lagoon or inland sea. Has terrestrial and marine features. An ancient estuary

Cross-Bed

Rocks deposited in tidal environments with alternating inclined layers

Cross Strata

Inclined rock layers

Cross Stratification

Layers of rocks

Herringbone Cross-Stratification

Water flow alternating in 2 different directions in a delta or estuary. Has fast sediments

Water Base

Depth where surface water affects deeper water

Fair Weather Wave Base

Usually around 5-15m

Storm Wave Base

Greater depth with high energy waves (20-200m)

Ripple Marks

Show how deep the water was when sediments were deposited. Currents are angled in current direction.

Wave Ripples

In shallow water above fair weather wave base. There are no ripple below storm weather wave base

Longshore Current

Waves breaking and releasing energy. Waves run parallel to coastline and deposit and reshape sediments. Sediments create barrier islands, spits and lagoons

Lagoons

Connected to the ocean, not affected by currents and tides because of barrier islands. Usually shallow with more dissolved sediments. Saltier than the ocean. Inhospitable to life because it is anoxic. Good for preserving fossils because there are few scavengers and there is mud and fine sediments

Evaporite

Formed in lagoons when sediments evaporate. No-clastic sedimentary rock. Imbedded in mud as lagoon rise and new seawater enters. Calcite, gypsum, anhydride, halite.

Black Mud

Black because of organic material

MOTH

Man on the Hill. Deep spot in a continental shelf with finely laminated carbonate and clays. Close to shore for fine clastic sediments but far enough for carbonate. Anoxic

Carbonate Platform

Shallow carbonate shelves. Good place to fine marine invertebrate fossils.

Plankton

Thrive in the photic zone, base of marine food chain, calcerous skeleton. From carbonate skeletons when dead

Bottom Dwelling Vertebrates

Eyes on top of head, mouths on underside. Ex. Osteostracans, Wobbegongs

Reefs

In shallow carbonate platforms. Full of corals

Coral

Eat plankton, in high energy environments with nutrient rich water. Form barrier ridges parallel to coastline. Protect lagoons. Sturdy at shallow water (Gogo formation in Australia with late Devonian fossils), delicate and branched in deep water (plate corals).

Bourma Sequence

Pattern of texture and sedimentary structures. Upward succession of upward sediments as flow loses energy.

Deep water

Lack of water shallow structures, slope between continental shelf is steep and unstable, affected by slumps and landslides.

Turbidities

Deep water deposits that are affected by turbidity currents. Less dense than marine flow when mixed with water.

Burgess Shale

Cambrian locality deposited by turbidity currents

Hallucigeania

Chordate worm with paired spines and appendages. Related to extant velvet worms

Odontogriphus

Chordate like a sandal. Early mollusk

Pikia

Early chordate with tentacles. Has post anal tail, myomeres, rod-like notochord. Related to cephalochordates

Metaspriggina

Early vertebrate with a edicaran form. Has notochord, eyes, brain, myomeres, cartilage and gills. Related to arthropods and annelid worms

Biota

Collection of organisms. Ex. Mistaken Point in Newfoundland, Ediacara Hill in Australia

Cloudina

Tube dwelling chordate. First to produce calcium carbonate shells. Fossils had holes in the shell to indicate competition

Kimbrella

Early bilateral chordate

Chordata Synapomorphies

Myomeres, notochord, dorsal hollow nerve chord, endostyle, pharangeal slits, post anal tail.

Pelagic

Sediments that floated before settling

Silica

Plankton skeleton remains. Forms quartz, becomes chert. Ex. Pelagic limestone. Formed below silica

Chert

Laminated rock in deep water

CDD (Calcium Compensation Depth)

Lower depth where calcium dissolves due to higher pressures (4000-5000m).

Arrectionary Prism

Pile of oceanic crust sediments are scraped off of sinking plates and attaches of leading edge of overriding plates

Obducted

Oceanic crust pushed on top of continental plate at convergent plate boundary

2 ways Paleozoic fossil can be created

On continental shelves: Accretionary prism, obducted plates

Ophiolite

Preserved oceanic crust in obducted plates

Lagerstatten

“Storage place,” areas of exceptional fossil preservation

2 Lagerstatten types

Konzentrat/concentration-lagerstatten, konservat/conservation lagetstatten

Konzentrat/concentration lagerstatten

Deposits with high concentration of disarticulated fossil parts. Deposited over a long time with poor preservation quality. Cannot assume animals are from same time period.

How Konzentrat/concentration lagerstatten is formed

slow sedimentation, flowing water moves fossil parts together (river and beach deposits), caves or pitfalls

Exception to Konzentrat/concentration lagerstatten

Bone beds and mass death layers

Konservat/Conservation Lagerstatten

Well preserved fossils, 3 categories: conservation deposits, stagnation deposits, obtrutions deposits

Conservation deposits

Mummification, freezing of ice age mammals in permafrost, insects in amber,

Konservat/Conservation Lagerstatten

Stagnation Deposits

Anoxic and low rate of decay, fine sediments, produce impressions, moulds, casts,

Konservat/Conservation Lagerstatten

Obtrution Deposits

Organisms buried so fast, there is no time for decay, steep cliff, caused by turbidity currents from a storm, produce impressions, moulds, casts, ex. Burgess Shale,

Konservat/Conservation Lagerstatten

Agnathans

Jawless fishes, a grade (non-monophyletic) of fishes

Age of Fishes

The Devonian Period; a time when most of the main groups of fossil fishes had evolved and were thriving globally

Paraphyletic Assemblage (Grade)

A group of organisms that is not united by synapomorphies; a group that excludes some descendants of the common ancestor

Haikouichthys

A Cambrian fossil vertebrate found in deposits about 525 million years old in China- swam by flexing myomeres.

Pectoral Fins

The anterior paired fins of fishes

Pelvic Fins

The posterior paired fins of fishes

Gills

Membranous structures supported on cartilage or bone that allow gas exchange between the blood and water; found in fishes and some amphibians

Anal Fin

The median fin on the ventral surface of the body; may vary from none to two fins depending on species

Dorsal Fin

A fin found on the back of a fish; there may be zero to three, depending on the species of fish

Caudal Fin

The median fin at the posterior end of an aquatic vertebrate

Cartilage

A firm, flexible connective tissue that forms skeletal elements in vertebrates; cartilage is replaced by bone in endochondral bone formation

Bone

A mineralized tissue incorporating calcium hydroxyapatite and collagen, support and muscles attachment, storage for phosphates, protection

Endochondral Bone

Embryonic elements are pre-formed in cartilage and later replaced by bone during ossification in the vertebrate skeleton

Odontoblasts

Specialized cells that produce dentine

Osteoblasts

Bone forming cells

Dentine

Calcareous material that is harder than bone but softer than ganoine/enamel; found in teeth and scales of certain vertebrates

Gnathostomata

The group of jawed vertebrates; see phylogenetic tree