Origin and Evolution of Vertebrates

A set of vocabulary flashcards covering the fundamental characteristics of Phylum Chordata, its subphyla, and the evolutionary milestones of vertebrates as outlined in the lecture by Dr. Elisa Cabrera-Guzmán.

Chordate

A member of Bilateria and Deuterostomata defined by a set of derived characters, some of which may only be expressed during embryonic development.

Notochord

An anterior-posterior, semirigid elongated structure of fluid-filled cells enclosed by a fibrous sheath that provides support, allows for lateral bending, and serves as an attachment site for muscles.

Dorsal hollow nerve cord

A single cord situated parallel to the digestive tract and notochord, with an anterior end that forms the brain in vertebrates and connects to the spinal cord.

Pharyngeal pouches or slits

Openings from the pharyngeal cavity to the outside that serve as a filter feeding apparatus in protochordates, give rise to gills in aquatic vertebrates, and form structures like the middle ear, tonsils, and glands in tetrapodes.

Muscular, post-anal tail

A structure probably evolved for propulsion in water; its vestige in adult humans is the coccyx.

Subphylum Urochordata

A group of chordates including tunicates and sea squirts that exhibit more chordate characteristics in the larval stage and are often sessile as adults.

Subphylum Cephalochordata

A subphylum of chordates commonly known as lancelets.

Subphylum Vertebrata

Chordates defined by a skeleton that includes a backbone comprised of vertebrae and a complex nervous system.

Neural crest cells

Embryonic cells in vertebrates that give rise to a variety of structures including teeth, some bones and cartilage of the skull, and some neurons and sensory structures.

Hox genes

$2$ or more sets of genes in vertebrates that specify body plans.

Gnathostomes

A clade of vertebrates characterized by the presence of jaws and a mineralized skeleton.

Osteichthyans

A group of vertebrates defined by the possession of lungs or lung derivatives.

Sarcopterygii

Lobe-finned fish, including those involved in the transition from water to land during the Devonian period.

Tetrapods

A group of vertebrates characterized by having limbs with digits.

Amniotes

A group of tetrapods, including reptiles and mammals, defined by the possession of an amniotic egg.

Jaws

Anatomical structures that evolved from the anterior gill arches of ancestral vertebrates.

Coccyx

The remnant of the muscular, post-anal tail found in adult humans.