Comparative Vertebrate Anatomy Exam One

originally made by Cade George on quizlet

Comparative Vertebrate Anatomy (CVA)

The study of functional and evolutionary similarities and differences in the anatomy and morphology of different vertebrate species.

Homology

Structures in different species that are similar because they share a common evolutionary ancestor (shared blueprint). For example, the underlying bone structure of the forelimb in mammals, birds, and reptiles.

Analogy (Convergent Evolution)

Structures that are similar in different species but are not due to a common ancestor, typically resulting from unrelated species evolving similar traits to adapt to similar environmental pressures (e.g., the streamlined body shape of a shark and a dolphin).

Ontogeny Recapitulates Phylogeny

A historical biological hypothesis that the embryonic development (ontogeny) of an organism reflects its evolutionary history (phylogeny).

Zeitgeist

The 'spirit of the time' or the intellectual/cultural climate that influences how scientific ideas are developed and accepted.

Inheritance of Acquired Characteristics (Lamarckism)

The now-disproven theory proposed by Lamarck suggesting that traits gained by an organism during its lifetime (e.g., a stretched neck) could be passed on to its offspring.

Fitness

A measure of the contribution of a given genotype to the next generation relative to that of other genotypes; defined as higher reproductive success, not just physical strength or survival.

Natural Selection

The mechanism of evolution, defined as the differential success in the reproduction of phenotypes out of an organism's interaction with the environment.

Evolution

A broad process of change in populations over time; a directional or cumulative change in characteristics from generation to generation.

Adaptation

The outcome of natural selection; any morphological, physiological, developmental, or behavioral character that enhances the survival and reproductive success of an organism.

Artificial Selection

The intentional breeding by humans for desirable traits in domesticated plants or animals over generations.

Fossilization

A rare process that occurs under specific conditions, often involving rapid burial in a low-oxygen environment, where hard parts (like bone) are best preserved.

Cast Fossil

A type of fossil formed when a mold of an organism is filled in with minerals.

Compression Fossil

A type of fossil formed when an organism is compressed, often preserving some organic material and details (like feathers or coloration).

Perimineralization

A type of fossilization where minerals infiltrate and replace the organic material of an organism over time (e.g., petrified wood).

Bioimmuration

A type of fossilization where one organism overgrows another, preserving its shape (e.g., coral reefs or bryozoans).

Stratigraphy

The study of rock layers (strata) to determine the relative age of fossils based on the principle that younger layers are deposited on top of older layers.

Radiometric Dating

A method used to determine the absolute age of fossils and rocks by measuring the decay of radioactive isotopes.

Half-life

The time it takes for half of the radioactive atoms in a sample to decay (e.g., Carbon-14 has a half-life of 5,700 years).

Coelom

An internal, fluid-filled body cavity that provides space for complex organ systems, allowing organisms to grow larger and more complex.

Stoma

A distinct body opening that was a precursor to the mouth and gut, enabling a more efficient one-way digestive system.

Protostomes

A major group of the animal kingdom (e.g., mollusks, arthropods) where the mouth develops from the first opening (blastopore).

Deuterostomes

A major group of the animal kingdom (including chordates/vertebrates) where the anus develops from the first opening (blastopore).

Notochord

One of the five defining chordate characteristics; a flexible, hydrostatic rod that provides structural support and a place for muscles to attach.

Dorsal Nerve Cord

One of the five defining chordate characteristics; a hollow tube of nerve tissue running along the back, which forms the central nervous system.

Pharyngeal Gill Slits

One of the five defining chordate characteristics; openings in the throat region, initially used for filter-feeding, later modified for gas exchange (gills) or embryonic structures.

Post-anal Tail

One of the five defining chordate characteristics; an extension of the body beyond the anus, primarily used for propulsion and locomotion.

Endostyle/Thyroid Gland

One of the five defining chordate characteristics; a groove in the pharynx of early chordates involved in filter-feeding, considered homologous to the modern vertebrate thyroid gland.

Vertebral Column

The key defining feature of true vertebrates; a more robust, segmented spinal column (of bone or cartilage) that replaces or supplements the notochord.

Cranium

The protective skull that houses a centralized brain and sophisticated sensory organs, leading to the development of a distinct head region.

Agnathans

Jawless vertebrates (Greek for 'no jaw'), including extinct groups like conodonts and ostracoderms, and extant groups like cyclostomes (hagfish and lampreys).

Gnathostomes

Jawed vertebrates (Greek for 'jaw-mouths'), the ancestors of all modern jawed vertebrates, characterized by the evolution of true jaws and paired fins.

Placoderms

An extinct group of early, heavily armored gnathostomes with hinged jaws.

Acanthodians

An extinct group of early gnathostomes characterized by multiple paired fins, each supported by a prominent bony spine.

Class Chondrichthyes

The class of cartilaginous fish (sharks, rays, skates, and chimaeras), characterized by a skeleton made entirely of cartilage, placoid scales, and internal fertilization via claspers.

Placoid Scales

Pointed, tooth-like scales made of dentin that cover the skin of elasmobranchs, providing a sandpaper-like texture.

Claspers

Modified pelvic fins in male cartilaginous fish used for internal fertilization.

Serial Tooth Replacement

The continuous process by which sharks replace their teeth throughout their lives.

Fusiform Body Plan

A torpedo or bullet-shaped body plan, built for speed and minimizing drag, characteristic of many sharks.

Operculum (Gill Cover)

A skeletal flap covering the gills found in chimaeras (Holocephali) and bony fish (Osteichthyes), allowing them to pump water over the gills without having to swim constantly.

Oviparous Reproduction

An egg-laying reproductive mode where the young hatch externally from eggs (e.g., some sharks, skates, and rays).

Viviparous Reproduction

A reproductive mode involving live birth where the embryos develop inside the mother and receive nourishment directly (e.g., some sharks, mammals).

Ovoviviparous Reproduction

A reproductive mode where embryos develop in eggs that hatch inside the mother's body, and the young are then born live (e.g., some sharks).

Hermaphroditic (Monoecious)

A reproductive strategy where a single individual possesses both male and female reproductive organs (e.g., hagfish).

Parthenogenesis

Reproduction without fertilization, where an embryo develops from an unfertilized egg (an alternative reproductive strategy sometimes seen in reptiles and other vertebrates).

Internal Fertilization

The union of egg and sperm occurring inside the body of the female (characteristic of Chondrichthyes).

Osteichthyes

The class of bony fish, defined by three major innovations: ossification of the endoskeleton, a swim bladder, and bony fin rays (lepidotrichia).

Ossification of the Endoskeleton

The evolutionary development where the primary support structure of the skeleton is made of bone instead of cartilage.

Swim Bladder

A gas-filled sac used by bony fish to control buoyancy, allowing them to maintain position in the water column with less energy.

Lepidotrichia

Bony fin rays that support the fins of bony fish.

Sarcopterygii (Lobe-finned fish)

One of the two major lineages of bony fish; characterized by fleshy, muscular fins and is the direct ancestral line that gave rise to all tetrapods.

Actinopterygii (Ray-finned fish)

The other major lineage of bony fish; characterized by fins supported by bony rays (lepidotrichia) and is the most diverse group of all vertebrates.

Chondrostei

A primitive subgroup of ray-finned fish (Actinopterygii) that includes sturgeon and paddlefish.

Neopterygii

The advanced subgroup of ray-finned fish that includes most modern fish species.

Heterocercal Tail

A caudal fin where the top and bottom lobes are different sizes (as seen in sharks and primitive bony fish), often linked to those lacking a swim bladder to generate lift.

Homocercal Tail

A caudal fin with equal, symmetrical lobes, common in fish possessing a swim bladder for neutral buoyancy.

Glochidium

The parasitic larval stage of freshwater mussels that must attach to the gills of a specific fish species to complete its development.

Within the Phylum Chordata, what two defining characteristics mark the evolutionary transition from primitive chordates to true Vertebrates?

The presence of a Vertebral Column (segmented spinal column).

Further cranial development (a distinct cranium to house a centralized brain).

How are the major lineages of Class Chondrichthyes (cartilaginous fish) divided, and what is the common name for each subclass?

Subclass Elasmobranchii: Sharks, Rays, and Skates.

Subclass Holocephali: Chimaeras or "Ratfishes".

The vast majority of modern fish belong to the Class Osteichthyes (bony fish). What are the two primary subclasses that emerged from this lineage?

Subclass Actinopterygii: Ray-finned fish (the most diverse group).

Subclass Sarcopterygii: Lobe-finned fish (the ancestral group to tetrapods).

The earliest jawed vertebrates (Gnathostomes) included two major extinct groups. Name them and describe a key anatomical feature for each.

Placoderms ("Plate-skinned"): Characterized by heavy, protective bony armor plates covering the head and shoulder.

Acanthodians ("Spiny Teeth"): Characterized by multiple paired fins, each supported by a bony spine.

Which subclass of the bony fish (Osteichthyes) is considered the direct ancestral line of all Tetrapods (four-limbed vertebrates)?

Subclass Sarcopterygii (Lobe-finned fish).

The Subclass Actinopterygii (ray-finned fish) is divided into two important groups that represent a primitive and an advanced lineage. Name these two groups.

Chondrostei (Primitive ray-finned fish, e.g., sturgeon and paddlefish).

Neopterygii (Advanced ray-finned fish, which includes the superorder Teleostei).

What are the two extant (living) groups that make up the Agnathans (jawless fish), the modern-day descendants of early jawless chordates?

Hagfish (Myxinoidea)

Lampreys (Petromyzontoidea).

The Chondrostei contains the Order Acipenseriformes. What two well-known families of fish belong to this order?

Family Acipenseridae (Sturgeons).

Family Polyodontidae (Paddlefish).

Developed the modern system of taxonomy (binomial nomenclature, e.g., Homo sapiens) for cataloging organisms.

Carl Linnaeus: Taxonomy

Proposed the theory of Inheritance of Acquired Characteristics (later disproven) as a natural explanation for species change.

Jean-Baptiste Lamarck: Inheritance of Acquired Characteristics

Proposed the mechanism of Natural Selection based on observation and data collected during the voyage of the HMS Beagle.

Charles Darwin: Natural Selection via HMS Beagle

Independently developed the theory of evolution by Natural Selection while working in the Malay archipelago.

Alfred Russel Wallace: Independently conceived Natural Selection

A political economist whose essay described how populations grow geometrically, leading to a "struggle for existence" due to limited resources.

Thomas Malthus: Struggle for Existence/Population Dynamics

Wrote Principles of Geology, confirming that the Earth was much older than previously thought and demonstrating that gradual geological processes caused dramatic changes.

Charles Lyell: Gradual Geological Change/Old Earth

Father of Comparative Anatomy and a proponent of catastrophism, suggesting species were re-created after catastrophes and fossils represented extinctions.

Georges Cuvier: Catastrophism/Father of Comparative Anatomy

A Swiss-born naturalist and Curator of Comparative Anatomy at Harvard who worked to catalog the "manifestations of the Creator" (a prevailing pre-Darwinian view).

Louis Agassiz: Cataloging manifestations of the Creator

Define Comparative Vertebrate Anatomy (CVA) in two parts.

Comparative/Functional: It is the study of similarities and differences in structure, linking physical form to its purpose.

Vertebrate/Evolutionary: It examines the history of vertebrates from their aquatic origins to the present, focusing on evolutionary change.

Explain the distinction between Homology and Analogy and provide one example for each concept (as discussed in the lecture).

Homology: Structures are similar because they share a common evolutionary ancestor (e.g., the underlying bone blueprint of the forelimb across different vertebrate classes like humans, bats, and birds).

Analogy: Structures are similar because they perform a similar function due to convergent evolution, not a common ancestor (e.g., the similar appearance of the star-nosed mole of the U.S. and the marsupial mole of Australia).

What is the core meaning of the historical principle "Ontogeny recapitulates Phylogeny"?

It is the idea that the embryonic development (ontogeny) of an individual organism reflects or summarizes the evolutionary history (phylogeny) of its species (e.g., early developmental similarities across different vertebrates).

Briefly explain the adaptive advantage of two specific physical features of the polar bear discussed in the lecture.

Paw Pads: The unique texture of the paw pads provides superior grip on ice.

Sinus Cavities: The complex sinus cavities help to warm the frigid air before it reaches the lungs.

List the three core principles (conditions) required for Natural Selection to occur.

Variation: Individuals within a population must have variations in their traits.

Differential Fitness: Individuals with certain traits must have a higher rate of reproductive success (fitness).

Heritability: These beneficial traits must be passed down from parent to offspring.

Why is the common phrase "survival of the fittest" considered misleading in a biological context?

Fitness is defined by reproductive success (the contribution to the next generation), not simply physical strength, dominance, or survival.

Describe one of the examples provided in the lecture that illustrates that fitness is about reproductive success rather than strength (e.g., the lion or the bluegill sunfish).

"Sneaker males" successfully reproduce by mimicking females and sneaking into a breeding male's nest to fertilize eggs, despite being smaller and less dominant than the nesting males.

What was the prevailing pre-Darwinian scientific belief about species, and which major historical figure epitomized this view by developing the modern system of taxonomy?

Prevailing belief: Species were immutable (unchangeable).

Figure: Carl Linnaeus (who developed binomial nomenclature, e.g., Homo sapiens).

Describe Jean-Baptiste Lamarck's central theory of how species changed over time.

Lamarck proposed the "inheritance of acquired characteristics," where traits gained by an organism during its lifetime due to use (like a giraffe stretching its neck) could be passed on to the offspring.

Name one of the two external figures (not a direct naturalist) whose work provided Charles Darwin with a crucial conceptual framework for natural selection, and explain the concept they provided.

Thomas Malthus: Provided the concept of "struggle for existence," arguing that populations grow faster than resources, limiting survival and reproduction.

Animal/Pigeon Breeders: Demonstrated the power of Artificial Selection, where intentional selection of traits by humans leads to rapid morphological change.

Name and briefly describe the four primary "windows" or tools used to understand the evolutionary history of vertebrates.

Morphology: Comparing anatomical structures (e.g., homologous limbs) to identify shared ancestry.

Ontogeny: Studying embryonic development ("ontogeny recapitulates phylogeny") for similarities that suggest a shared ancestry.

Fossils: The most important tool; provides direct evidence of past life forms and evolutionary transitions.

Molecular Genetics: Modern DNA analysis, though limited to a fraction of the time scale, provides genetic evidence of relationships.

Explain the key difference between an "Ancestral" trait and a "Derived" trait in the context of the vertebrate phylogenetic tree.

Ancestral Traits: Appeared earlier in the evolutionary history of a lineage.

Derived Traits: Are more recent or specialized traits seen in modern, specialized groups.

Briefly describe the three main forms of natural selection in terms of which phenotypes are favored or disfavored, and how the population average changes over time.

Stabilizing Selection: Favors the average phenotype; reduces extreme phenotypes, keeping the population consistent.

Directional Selection: Favors phenotypes at one extreme (e.g., small or large); causes the population average to shift in that direction over time.

Disruptive Selection: Favors extreme phenotypes (both ends of the spectrum); disfavors the average, leading to a phenotypically more diverse or split population.

What is a significant challenge faced by the first vertebrates (Amphibians) when transitioning from water to land, as posed by the instructor?

Challenges include differences in oxygen availability, changes in how light is processed (vision), and changes in how sound travels and is perceived.

The lineage that includes birds, crocodiles, and snakes separated from mammals very early in evolutionary history. What is the major group that includes all of these organisms and is defined by having a specialized egg?

Amniotes (A major group evolved from a common ancestor around 375 million years ago).

Describe the unique "morphological oddity" of the Turtle, as mentioned by the instructor.

Its protective shell is unique because it is made of fused bone that grows out of the animal's internal skeleton.

What is the functional purpose of the Tuatara's unique "parietal eye" (third eye), which is linked to its pineal gland?

It is involved in regulating the reptile's circadian rhythms (sleep/wake cycles).

Describe the general conditions necessary for the rare process of fossilization to occur.

Rapid Burial: The organism must be quickly buried.

Low-Oxygen Environment: This prevents decomposition (e.g., mud at the bottom of a lake).

Hard Parts: The presence of hard parts (like bones) is necessary for good preservation.

Briefly describe the mechanism of the formation of cast fossils.

Formed when a mold (hollow impression) of an organism is filled in with minerals.

Briefly describe the mechanism of perimineralization.

Minerals infiltrate and replace the organic material of an organism over time, creating petrified remnants (e.g., petrified wood).

Briefly describe the mechanism of the formation of compression fossils.

Formed when an organism is compressed (flattened), often preserving some organic material and fine details like feathers.

Briefly describe the mechanism of bioimmuration.

Occurs when one organism overgrows another, preserving the shape of the organism that was encased (e.g., coral reefs or bryozoans overgrowing another organism).

How is a Mass Extinction Event represented on a graph tracking the history of life (Number of Families vs. Time)?

It is represented by a sharp spike in the extinction rate on the graph.

Identify the boundary layer associated with the extinction of the dinosaurs, state the approximate time this occurred, and explain the key piece of geological evidence that supports the extraterrestrial impact theory.

Boundary: Cretaceous-Tertiary (KT) boundary.

Time: Approximately 66 million years ago.

Evidence: A worldwide geological layer showing high concentrations of the element iridium, which is rare on Earth but common in meteorites.

Identify two specific radioactive isotopes and their corresponding half-lives mentioned in the lecture that are used for dating purposes, and state which one is used for dating very old geological events.

Carbon-14: Half-life of 5,700 years (used for recent organic material, up to ~60,000 years).

Uranium-238: Half-life of 4.5 billion years (used for dating very old geological events like the formation of the Earth).

Explain the principle of Relative Dating, also known as Stratigraphy.

t is the study of rock layers (strata), based on the principle that younger layers are located on top of older layers, allowing scientists to determine the relative sequence of events.

List and briefly describe the two key evolutionary innovations that emerged at the beginning of the animal kingdom, leading to the split between protostomes and deuterostomes (the lineage that includes vertebrates).

Coelom: An internal, fluid-filled body cavity that provided space for complex organ systems and allowed organisms to grow larger and more complex.

Stoma: A distinct body opening that was a precursor to the mouth and gut, enabling a more efficient one-way digestive system.