Fossils Final Flashcards
final list of terms
Agnathan
an ancient superclass of jawless fish that gave rise to all other vertebrates after diverging from chordates in the Cambrian era
age of fish
The Devonian is known as the “age of fish” due to it being a period of significant fish evolution
ammonoidea
- extinct cephalopods characterized by elaborate suture patterns and a siphuncle along the ventral periphery of their shells
- went extinct at end of cretaceous
- siphuncle along outer shell
- no modern representatives
- nektonic (actively swimming) and carnivorous predator
- ceratic ammonoids (L Permian – triassic)
amniote
monophyletic clade of tetrapod vertebrates, including reptiles, birds, and mammals, characterized by having an egg equipped with an amnion (a membrane that encloses the embryo in a fluid-filled chamber, allowing for terrestrial reproduction)
amphibian
are a paraphyletic grouping of all non-amniote tetrapods
coleoidea
subclass of cephalopod mollusks, encompassing modern squids, cuttlefish, octopuses, and extinct belemnites, characterized by an internal shell (or lack thereof) and other features like an ink sac and arm hooks
cambrian explosion
the relatively rapid diversification and appearance of many major animal phyla in the fossil record during the early Cambrian period, approximately 541 million years ago.
cambrian fauna
the diverse and distinctive assemblage of marine invertebrate fossils characteristic of the Cambrian Period, particularly those that first appeared during the “Cambrian explosion” and include trilobites, small shelly fossils, and other early marine life.
conodont
small planktonekton that are poor swimmers and have a worm-like body. lived during the Cambrian to Triassic, most prominent in the ordovician
convergence
the independent evolution of similar traits or adaptations in distantly related lineages, often in response to similar environmental pressures or ecological niches
chelicerate
a subphylum of arthropods characterized by having chelicerae (first pair of appendages modified into claw-like structures) and lacking antennae, encompassing groups like spiders, scorpions, and horseshoe crabs, as well as extinct forms like eurypterids.
chitinozoan
flask-shaped, organic-walled microfossils of unknown biological affinity, found in Ordovician to Devonian marine sedimentary rocks, often used as biostratigraphic markers.
crionoid
a marine invertebrate belonging to the class Crinoidea within the phylum Echinodermata, characterized by having a cup-shaped body with feathery arms, often referred to as sea lilies or feather stars, and are a significant component of Paleozoic shallow marine faunas.
crustacea
a subphylum of invertebrate arthropods characterized by a hard, chitinous exoskeleton, segmented bodies, and paired, jointed appendages, including crabs, lobsters, shrimps, and barnacles.
cynodont
a clade of therapsids, also known as “dog-toothed” reptiles, that evolved in the Late Permian and diversified extensively in the Triassic, with mammals evolving from advanced cynodonts during the Late Triassic.
dueterostome
a major group of animals (Deuterostomia) characterized by their embryonic development, where the anus forms before the mouth, contrasting with protostomes where the mouth forms first.
devonian nektonic revolution
the rapid and significant diversification of actively swimming (nektonic) marine animals during the Devonian period, a period also known as the “Age of Fishes”.
diapsid
a reptile characterized by having two temporal fenestrae (skull openings) on each side of its skull, a feature that distinguishes them from other groups like anapsids (no openings) and synapsids (one opening)
echinodermata
a phylum of marine invertebrates, including sea stars, sea urchins, and sea cucumbers, characterized by a spiny skin, radial symmetry (as adults), and a unique water vascular system.
Ediacaran fauna
a unique assemblage of soft-bodied, macroscopic fossils, representing the earliest known multicellular life forms, that lived during the Ediacaran Period (roughly 635 to 541 million years ago), predating the Cambrian explosion
eleutherozoa
a subphylum of echinoderms that includes all free-living echinoderms, excluding crinoids (sea lilies and feather stars), and characterized by a ventral mouth and a mobile, non-sessile lifestyle.
graphite
a naturally occurring form of carbon, can be used as a biomarker and paleoenvironmental indicator due to its origin from organic matter and its persistence in geological records.
great ordovician radiation
a period of intense marine diversification during the Ordovician period (485.4 to 443.4 million years ago), where the marine ecosystems saw a dramatic increase in diversity and complexity, establishing the foundation for the Paleozoic fauna.
holapsid
a developmental stage in trilobites and some other arthropods where the organism has reached its full number of body segments (specifically, thoracic segments), but it may still continue to grow in overall size
holochroal eye
o the most common type of compound eye found in trilobites, characterized by numerous, small, calcite lenses covered by a single corneal membrane, forming a kidney-shaped visual surface.
homeothermy
the ability of an organism to maintain a relatively constant internal body temperature, regardless of the environmental temperature, a characteristic often associated with “warm-blooded” animals like birds and mammals.
ichnofossil
a fossilized record of an organism’s activity, such as tracks, trails, burrows, or borings, rather than the organism’s preserved remains.
index fossil
a fossil known to have lived during a specific, relatively short period of geological time, used to identify and date the rock layers in which they are found, and to correlate rock layers across different locations.
irregular echinoid
echinoderms (like sea urchins) that have secondarily acquired bilateral symmetry, meaning their mouth and anus are shifted towards opposite sides of the body, unlike the five-fold radial symmetry of regular echinoids.
late devonian mass extinction
a major loss of biodiversity, especially in marine environments, where it wiped out a large number of reef-building organisms, brachiopods, trilobites, and other marine species. It unfolded in several pulses rather than a single catastrophic event.
lobefin fish
bony fish characterized by having paired, fleshy, lobed fins, which are articulated via a single bone and are considered ancestral to tetrapods (amphibians, reptiles, birds, and mammals).
macroevolution
major evolutionary change. The term applies mainly to the evolution of whole taxonomic groups over long periods of time - speciation
malacostraca
a large class of crustaceans characterized by compound eyes typically on stalks. includes crabs, shrimp, lobster, isopods, and amphipods
mammal
a vertebrate animal characterized by mammary glands for nourishing young, a broad neocortex region of the brain, fur or hair, and three middle ear bones, distinguishing them from reptiles and birds.
modern fauna
the dominant marine animal assemblages that emerged after the end-Permian mass extinction and are characterized by a “Mollusc-rich assemblage” including gastropods, bivalves, and various other groups
myriapods
time period of Silurian - recent. includes milipedes and centipedes
nautiloidea
- shell with smooth exterior with no ornament or ribbing
- simple suture patterns
- still around today
- siphuncle runs through center of the shell
- modern representatives like nautilus and allonautilus
- nextonic, but is a scavenger and opportunistic predator. major carnivore because of long tentacles and eyes
ontogeny
the developmental history of an individual organism from fertilization to death, encompassing all stages of growth, including morphological changes and adaptations, as distinct from the evolutionary history of a species
paedomorphocline
a series of specimens that show paedomorphic changes through time. “ontogeny recapitulates phylogeny”
paleozoic fauna
the diverse assemblage of ancient marine invertebrates, including trilobites, brachiopods, and corals, that dominated the Earth’s oceans during the Paleozoic Era (roughly 541 to 252 million years ago)
pelmatozoa
a group of stalked and sedentary echinoderms, including extinct forms like blastoids and cystoids, as well as the living crinoids (sea lilies and feather stars).
phyletic gradualism
evolution takes place in the lineages, and speciation is a side effect
phylogeny
the evolutionary history and relationships of extinct and extant organisms, visualized through phylogenetic trees (or cladograms) that depict branching patterns of descent from common ancestors.
protaspid
to the early, unsegmented larval stage of a trilobite, characterized by a non-articulated, calcified dorsal exoskeleton
protostome
a clade of animals where the mouth develops from the first opening (blastopore) during embryonic development, and they exhibit spiral and determinate cleavage, contrasting with deuterostomes where the anus develops from the blastopore.
punctuated equilibrium
most evolution is associated with ‘sudden
speciation events (cladogenesis), and lineages otherwise show little evolution (stasis).
“evolutionary development is marked by isolated episodes of rapid speciation between long periods of little or no change.”
radiation
a rapid and extensive diversification of a clade (a group of organisms) into a multitude of new forms, often driven by adaptation to new environmental conditions or opportunities
reptile
air-breathing, amniotic vertebrates, typically with scaly skin, who are ectothermic (cold-blooded) and lay hard-shelled eggs, though some give birth to live young
schizochroal eye
a type of compound eye found in the extinct trilobites, specifically within the suborder Phacopina, characterized by having fewer, but larger, lenses, each with its own cornea, separated by cuticular material.
spira mirabilis
(Latin for “marvelous spiral”) refers to the logarithmic spiral, also known as the equiangular spiral, a mathematical curve named by Jacob Bernoulli for its self-similar properties, which is found in various natural forms, including nautilus shells
synapsid
a group of tetrapod vertebrates characterized by having a single temporal fenestra (opening) behind the eye socket on each side of the skull
taphonomy
the study of the processes that occur to an organism’s remains from the time of death to the time of their discovery, encompassing everything from decomposition and burial to fossilization
tetrapod
a vertebrate with four limbs (or descendants of limbed ancestors) including amphibians, reptiles, birds, and mammals
evolutionary species concept
a lineage evolving separately from others and with its own unitary evolutionary roles and tendencies
what does stabilizing selection do in a relatively unchanging environment
tends to winnow out those gene combinations and mutations that are less fit, prompting stasis
what is directional selection
new gene combinations or mutations, in a changing environment, may be more fit than the norm of the population
what were the key arguments to support Darwin’s theory of the evolution of species by means of natural selection
paleontological and biogeographical evidence
copes rule
lineages tend to increase in body size over evolutionary time (e.x., browsing horses and titanotheres)
what is speciation caused by
small changes in master regulatory genes called homeotic/ “hox” genes which regulate the fundamental development of the body plan and how major organ systems develop
in what time period was arthropod gigantism a thing
carboniferous
what does the largest of the 5 mass extinctions separate
the paleozoic and modern evolutionary faunas
what is the red queen hypothesis
sexual reproduction and the resulting genetic recombination may be just enough to allow individuals of a certain species to adapt to changes in the ecological niche they occupy
what happens at the end of the Permian period
trilobites, tabulate and rugose corals, several brachiopod orders, >65% of all amphibians & reptiles, and ~33% of all insects became extinct
what does phylum Mollusca mainly consist of
coelomate bilaterians covered by a thick fleshy mantle that may secrete a calcareous shell
what is a foot (“pod) in phylum Mollusca
a modifiable muscle known as a foot that is used for creeping in gastropods, digging in bivalves, and made into tentacles for cephalopods
what was the time period for class Gastropoda
late Cambrian - recent
what is class gastropoda characterized by
- univalved
- usually coiled shell
- head with eyes and other sense organs
- muscular foot on underside for locomotion
what do several species of pulmonate gastropods have
an operculum (a “trap door” to close the aperture, preventing desiccation)
what was the time period for class bivalvia
early Cambrian to recent
what are the characteristics of class bivalvia
- twin valved
- joined along dorsal hinge line with teeth and ligamnet
- lack head and radula
- well developed foot
what is family mytilidae
muscles - attach to hard substrates using organic “threads”
what is family osteridae
a diverse group of oysters that are common in high-energy, nearshore environments, and able to tolerate brackish conditions
what is family pectinidae
various genera of scallops. they are swimmers with primitive eyespots and a large adductor muscle to snap the bilaterally symmetrical valves shut
what was the time period of class Cephalopoda
late cambrian to recent
what are the characteristics of class Cephalopoda
most advanced molluscs
- tentacles around head
- well developed sensory organs
what allowed for macrophagous predation in gastropods and cephalopods
a high degree of cephalization with well-developed sense organs
what are the evolutionary innovations in the stem arthropods
- compound eyes
- jointed limbs associated with the head
- jointed, biramous trunk limbs
- jointed body
- specialized appendages associated with the head
- specialized jointed body segments with sternites (ventral) and tergites (dorsal)
- reduction in endopodite segments
what was the time period of subphylum trilobitomorpha
Cambrian to Permian
what are the three facial sutures of phylum anthropoda
proparian - suture ends in front of genal angle
gonatoparian - suture ends at tip of genal angle
opisthoparian - suture ends at back margin of cephalon
what is the time period of subphylum Chelicerata
Cambrian to recent
what does subphylum Chelicerata include
mites, spiders, horseshoe crabs, scorpions, eurypterids (sea scorpions)
what is the time period of subphylum crustacea
cambrian to recent
what does subphylum crustaceans include
shrimp, crabs, lobster, crayfish, barnacles, and ostracods (the most abundant arthropod)
what are the two classes of subphylum crustacea
maxilopoda and Malacostraca
when did life speed up
542 mya with the extinction of ediacaran animals and the start of the cambrian explosion
what is thought to be the earliest chelicerate
sanctacaris from the Burgess Shale
what is another “missing link” between amphibians and amniotes
seymouria
what 4 groups underwent massive diversififcation in the phanerozoic era
marine animals, vascular alnd plants, non-marine tetrapods, and insects
what common patterns does the graph of the 4 groups that underwent diversification in the phanerozoic era show
a long initial period of low diversity, and then rapid increase since the cretaceous… particularly the non-marine tetrapods (i.e, the radiation of (placental) mammals)
what are the 5 major changes to overcome when transitioning to lands
- aqueous to atmospheric gas exchange
- reproduction in dry environment
- osmoregulation that promotes water retention
- no protection from uv radiaton outisde of water
- sensory structures tat function on land
what is the body plan of chelicerates
a body divided into an anterior prosome (head, usually with eyes, and a thorax) with 6 segments and a posterios opisthoma with at most 12 segments plus a postsegmental telson
what does the oldest peracarid crustacean reveal
a late evonian freshwater colonisation by isopod relatives
what is included in class maxilopoda
barnacles and ostracods
what are the 6 characteristics of class Asteroidea
- ambulacral ossicles & ampullae
- madreporite
- stone canal
- pyloric carcae
- rectal glands
- gonads
what is the time range of class Crinoidea (sea lilies)
early ordovician - recent, most abundant in the paleozoic
what are characteristics of subphylum eleutherozoa
- mobile
- stellate
- discoidal, globular, or elongate
- mouth directed downwards or to side
- no branchioles
what was the time period of class asteroidea (sea stars)
Early ordovician to recent, more prominent recently
what was the time period of class holothuroidea (sea cucumber)
Middle cambrian to recent
what was the time period of class ophiuroidea (brittle sea stars)
early ordovician to recent, most prominent recently
what was the time period of class echinoidea (urchins and sand dollars)
late ordovician - recent, most prominent in cenozoic
what was the time period of class crinoidea
ordovician to recent
what is the time period of class blastoidea
Middle ordovician to upper permian, most prominent in Mississippian
what is the time period of class edrioasteroidea
ediacaran/ cambrian to permian
what is the time period of class rhombifera
late ordovician to upper devonian
what is the time period of class diploporita (cystoids)
late ordovician to late devonian
what is the classification of condontophores
phylum chordata, subphylum vertebrata, class agnatha
what are the two classes within superclass Osteichthyes
class actinopterygii (ray-finned fish) & class sarcopterygii (lobe-finned fish)
what are the two extant diapsid subclasses
archosauria (crocodilliansa and dinosaurs) and lepidosauria (lizards and snakes)
what is saurischia
lizard-hipped dinosaurs
