Term List (Test 1) - Fossils Flashcards
acritarch
catchall group of various small microfossils that represent the pelagically dispensed spore cases of benthic algae
analog
a representation of an object that resembles the original
apomorphy
a new or derived characteristic that has evolved from an ancestral form
Archeocyatha
taxon of extinct, sessile, reef-building marine sponges that lived during the Cambrian period
bioturbation
a process by which living organisms move and change soil sediment
biozone
a layer of rock or sediment that contains fossils from a specific group of organisms that lived during a specific time period
brachiopoda
a phylum that is comprised of animals with two hard valves (shells) connected by a hinge
Bryozoa
a phylum of simple, aquatic invertebrate animals
Cambrian fauna
incredibly diverse and marked the first appearance of many complex life forms. Trilobites (group of armoured invertebrates) are the most popular example
choanoflagellate
a group of free-living unicellular and colonial flagellate eukaryotes
carbonization
a process that converts organic material into carbon-rich compounds through heat and a lack of Oxygen
clade
a group of organisms believed to have evolved from a common ancestor, according to the principles of cladistics
convergence
the tendency of unrelated animals and plants to evolve superficially similar characteristics under similar environmental conditions
cnidaria
phylum of aquatic invertebrate animals that comprise of the coelenterates
diploblast
the presence of two germ layers. ex. cnidarians
divergence
the process by which related species develop different traits over time which can lead to new species
ecophenotypic variation
the variation in an organisms phenotype that is caused by its environment
Ediacaran fauna
unique assemblage of soft-bodied organisms preserved as fossil impressions in sandstone. represent an important development in the evolution of life due to immediate predation of life forms in the Cambrian period
eukaryote
an organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus
Elvis taxa
a taxon that has been misidentified as having re-emerged in the fossil record after a period of presumed extinction, but is not actually a descendant of the original taxon, instead having developed a similar morphology by convergent evolution.
endosymbiosis
a symbiotic relationship where one organism lives inside another
evolutionary radiation
a rapid increase in the diversity of a group of organisms, or clade
eumetazoan
a proposed diploblastic basal animal clade as a sister group of Porifera
exotic terrane
a piece of the Earth’s crust that has been moved from its original location and joined with another landmass
Great Ordovician Radiation
an evolutionary radiation of animal life throughout the Ordovician period, 40 million years after the Cambrian explosion
Great Oxygenation Even
a period of time when oxygen levels in Earth’s atmosphere and surface oceans increased. It occurred between 2.4 and 2.1 billion years ago and was a major turning point in Earth’s history.
homolog
the similarity of genes or anatomical structures between organisms that share a common ancestor
Lagerstätten
sedimentary deposits that contain unusually well-preserved fossils
Lazarus taxa
a species or group of organisms that disappears from the fossil record and then reappears later
index fossil
a fossil that is useful for dating and correlating the strata in which it is found.
Lingulida
an order of brachiopods that includes marine animals with chitino-phosphatic shells
living fossil
a species that has remained relatively unchanged over a long period of time
lophophorate
a group of marine invertebrates characterized by the presence of a specialized feeding structure called a lophophore
Modern fauna
the animal life that exists in the present day. It includes many classes of animals, such as bivalves, gastropods, vertebrates, crustaceans, and echinoids. emerged after the end-permian mass extinction
macroevolution
The study of evolutionary processes and patterns that occur above the species level. encompasses the grandest trends and transformations in evolution.
Porifera
any of the primitive multicellular aquatic animals that constitute the phylum Porifera
Paleozoic fauna
rhynchonelliform brachiopods, stony and lacy bryozoans, stromatoporoids, cephalopods, crinoids and blastoids, starfish, graptolites
parazoan
a subkingdom that includes simple, multicellular animals that lack true tissues and organs. The main group within Parazoa is the phylum Porifera, commonly known as sponges.
permineralization
a process that turns organic material into fossils by filling its pores with minerals
prokaryote
organisms whose cells lack a nucleus and other organelles.
Rugosa
an extinct order of solitary and colonial corals predominantly made of calcite and were abundant in the Middle Ordovician to the Late Permian seas
punctuated equilibrium
a theory in evolutionary biology that states that species evolve in spurts, rather than gradually
Scleractinia
Stony or hard corals are marine animals in the phylum Cnidaria that build themselves a hard skeleton. mostly made of aragonite and first appeared during the middle Triassic.
sexual dimorphism
the systematic difference in form between individuals of different sex in the same species.
septa
a wall that separates a structure or cavity into smaller one
stasis
a block of little or no evolutionary change in a species
Spiriferida
an order of extinct articulate brachiopod fossils which are known for their long hinge-line, which is often the widest part of the shell
Strophomenida
Strophomenida is a morphologically diverse extinct order of articulate brachiopods which lived from the lower Ordovician period to the mid Carboniferous period
stromatolite
calcareous mound built up of layers of lime-secreting cyanobacteria and trapped sediment, found in Precambrian rocks as the earliest known fossils
stromatoporoid
body fossils from a once living animal and a primary reef-building organism from the Middle Ordovician to the Late Devonian.
Tabulata
extinct colonial coral found as fossils in Ordovician to Jurassic marine rocks
taphonomy
the branch of paleontology that deals with the processes of fossilization
taxonomy
the branch of science concerned with classification, especially of organisms; systematics
Valves
a membranous structure that acts as a one-way gate for fluid to pass through or the name of the top and bottom shell (valve) of a bivalve mollusc
Zombie taxa
a fossil that was washed out of sediments and re-deposited in rocks and/or sediments millions of years younger.
zooxanthellae
yellowish-brown symbiotic dinoflagellate present in large numbers in the cytoplasm of many marine invertebrates.
