The Origin and Evolution of Vertebrates

Flashcards covering the vocabulary of vertebrate origins and evolution based on lecture notes.

Vertebrates

Animals with a backbone; a highly successful group of animals on Earth.

Morphology

The study of the structure or form of organisms, including their specific features.

Mobility

The process of movement and locomotion of organisms, indicating how they move from one place to another.

Reproduction

The process by which organisms produce offspring, highlighting the diverse strategies and mechanisms involved.

Energy

Concerns how organisms acquire and use energy, especially the use of food and oxygen.

Opisthokonta

A lineage within Eukaryotes from which animals originated.

Choanoflagellates

The closest living relatives to animals, sharing a common ancestor approximately 900 million years ago.

Deuterostomes

Animals where the blastopore becomes the anus during early embryonic development.

Radial Symmetry

A type of symmetry where body parts are arranged around a central axis.

Bilateral Symmetry

A type of symmetry where an organism can be divided into two symmetrical halves

Predators and Prey

Important selective agents that shape the course of animal evolution through their interactions.

Vertebrate Synapomorphies

Vertebrate synapomorphies are brain, cranium, and sensory cell formation.

Pharyngeal Gill Arches

Develop into slits, then throat openings in some adult vertebrates, disappear in others.

Dorsal Hollow Nerve Cord

Projections from neurons.

Notochord

Provides flexible skeletal support during early development and disappears in many adult vertebrates.

Dorsal Hollow Nerve Cord

Runs parallel to the notochord.

Tunic

External coat of polysaccharide.

Vertebrae

Column of cartilaginous or bony structures that protects the spinal cord.

Cranium

Bony, cartilaginous, or fibrous case which protects brains and sensory organs.

Neural Crest

A developmental structure unique to vertebrates that appears along the edges of the closing neural tube.

Hagfishes and Lampreys

Clade of jawless vertebrates, the cyclostomes. Some lack a backbone, but do have rudimentary vertebrae.

Gnathostomes

Jawed vertebrates, including sharks and their relatives, ray-finned fishes, lobe-finned fishes, amphibians, reptiles (including birds), and mammals.

Chondrichthyans

Skeleton composed primarily of cartilage; streamlined body for swift swimming; internal fertilization.

Oviparous

Eggs hatch outside the mother’s body

Ovoviviparous

Eggs hatching within the uterus

Viviparous

Embryos develop in the uterus

Bony Fishes

Ray-finned and lobed fin fishes with bony skeleton enabling precision in swimming

Swim Bladder

Air pockets for buoyancy.

Operculum

Bony gill covering, displaced by water for motion.

Lateral Line System

Row of pressure detecting sensory organs for schooling behavior, predation, and orientation

Origin-of-lung Hypothesis

Lungs for aerobic respiration arose as out pockets of the esophagus.

Lobe-Fins

Muscular pelvic and pectoral fins that are supported by rod-shaped bones.

Tetrapods

Adapted to life on land, include terrestrial vertebrates:

Tetrapod Body Plan

Four limbs, feet, digits, neck for independent head movement, and fusion of pelvic girdle and backbone.

Amphibians

Both-sides-living (water and land).

Amniotic Egg

A synapomorphy of amniotes that reduced dependence on water for reproduction, important for life on land.

Amniota

Lineage that includes all tetrapods other than amphibians (Reptiles and mammals).

Ectothermic

absorb external heat rather than generating much of their own.

Birds

Feathered reptiles with body plan adaptations for flight

Endothermic

use heat generated by metabolism to maintain a warm, steady body temperature.

Mammals

Monophyletic group with mammary glands for lactation to nourish young.

Endotherms

Maintain high body temperatures with fur.

Synapsid

subset of amniotes which includes mammals, skull distinguished by a single temporal fenestra (hole behind each eye socket)

Placenta

Organ combining maternal and embryonic tissues to facilitate flow of O2 and nutrients from mother to developing embryo and remove nitrogenous wastes and CO2 from embryo.

Parental Care

Investment that improves the likelihood of offspring to survive.

Primate Lineage

The primate lineage consists of two main groups: Prosimians (before-monkeys) and Anthropoids (human-like).

Earliest Primates

Early primates were probably small tree-dwelling mammals that arose some time before 65 million years ago.

Primate Characteristics

Hands and feet that are efficient at grasping, flattened nails instead of claws, relatively large brains, color vision, complex social behavior, extensive parental care of offspring, forward-facing eyes.

Anthropoids

Group of primates that include monkeys and apes, diverging from other primates some 50 million years ago.

Great Apes (Hominids)

Relatively large bodied with long arms, short legs, and no tail.

Hominins

Monophyletic group comprising Homo sapiens and more than 20 extinct, bipedal relatives.

Bipedalism

Shared, derived character that defines hominins.

Recent Homo

Populations created art and buried their dead in an organized manner.