Exam 1 Flashcards
Taxonomy
Branch of science concerned with classifying organisms in groups based on common ancestry
Binomial nomenclature
The Linnean system that assigns generic and species names to organisms
Linnaean ranks
Life Domain Kingdom Phylum Class Order Family Genus Species
Monophyletic group (Clade)
A taxon composed of a common ancestor and all its descendants
Paraphyletic group
Taxon that includes the common ancestor and some but not all of its descendants
Phylogenetic tree
A branching diagram showing inferred evolutionary relationships among various biological species
Derived characters
A character that as changed from its ancestral condition
Parsimony
The principle that requires the fewest changes from ancestral to derived character states
Homology
A similarity due to common ancestry
Homoplasy
Similar traits shared by a set of species but are not present in their common ancestors
Convergent evolution
The process in which organisms not monophyletic independently evolve similar traits as a result of having to adapt to similar environments or ecological niches
Polytomy
Internal node containing more than two immediate descendants
Hemichordata
Phylum of marine deuterostome animals that are distinguished by a tripartite (threefold) division of the body
Notochord
A highly turgid, flexible rod of connective tissue that provides dorsal support
Dorsal hollow nerve cord
A hollow bundle of nerve fibers derived from ectoderm that runs dorsally above the notochord and gut tract. The dorsal nerve cord is later modified in vertebrates into the central nervous system (brain and spinal cord).
Endostyle
A longitudinal, ciliated, grandular, grooved organ that secretes mucus for trapping food particles.
Postanal tail
Segmented muscular structure made up of myomeres that extends beyond the anus used for locomotion
Myomeres
Blocks of striated muscle fibers that are arranged on both sides of the body
Cephalization
The development of a head through the concentration of sensory organs and nervous tissue at the anterior end
Haikouella
An extinct chordate species from 520 mya that was a sister to craniata (vertebrata), filter feeder and underwent cephalization. It had a notochord, myomeres, and a muscular pharynx.
Splanchonocranium
The portion of the skull that consists of the gill arches and their derivatives
Chondrocranium
The portion of the skull that surrounds and protects the brain and certain sensory organs
Dermatocranium
The skull roof composed of dermal bone, as opposed to endochondral bone, that shields the brain, eyes, and nostrils
Neural crest cells
An embryonic tissue that forms portions of the brain, facial bones, and almost all of the peripheral nervous system.
Hox genes
Group of genes that control the body plan of an embryo along the anterior-posterior axis
Dermal bone
A type of bone that forms in the skin
Endochondral bone
Bone that forms in cartilage
Sesamoid bone
Bone forming in a tendon or muscle
Neural arch
A dorsal projection from the vertebral centrum that, at its base, encloses the spinal cord
Centrum
The bony portion of a vertebra that surrounds the notochord
Devonian
A geologic period of the Paleozoic era and is considered the “Age of Fishes” as it spawned a remarkable variety of fish
Ostracoderms
Armored jawless fishes present during the Devonian period. Not monophyletic Body covered in dermal bone. Cartilaginous skeletons Some had pectoral fins
Placoderms
Armored jawed fishes present during the Devonian period.
Anterior of body covered with thick, bony plates
Acanthodians
Paraphyletic class of fish that is referred to as spiny sharks due to their shark-shaped bodies and immovable bony spines supporting most fins. Their paired fins have been interpreted as remnants of fin-folds.
Devonian period