Definition

1. Noun:
   • A type of vertebrate animal lacking jaws and paired fins or limbs: A "jawless vertebrate" is an eel-shaped vertebrate that does not possess true jaws or paired appendages (like arms, legs, or paired fins). This group includes living forms such as lampreys and hagfish (cyclostomes), as well as many extinct species.

Usage Examples

• Noun:
  • The lamprey is a well-known example of a jawless vertebrate.
  • Fossil records show that jawless vertebrates were once much more diverse.
  • Hagfish, another jawless vertebrate, produce large amounts of slime as a defense mechanism.

Advanced Usage

• In evolutionary biology: The term is used to describe the most primitive group of vertebrates, which are crucial for understanding the early evolution of the vertebrate lineage.
  • The study of jawless vertebrates provides key insights into the origin of the vertebrate immune system.

Variants and Related Words

• Agnathan (n): The formal scientific term for a jawless vertebrate.
  • Agnathans represent a paraphyletic group in vertebrate phylogeny.
• Cyclostome (n): A subgroup of living jawless vertebrates, including lampreys and hagfish.
  • Cyclostomes have a circular, sucking mouth.

Synonyms

• Agnathan: The direct scientific synonym.
• Jawless fish: A common, though less precise, synonym (as not all are traditionally considered "fish").

Related Phrases

• Jawless vertebrate fossil: A common phrase used in paleontology.
  • The museum has an impressive collection of jawless vertebrate fossils from the Silurian period.

Noun

1. eel-shaped vertebrate without jaws or paired appendages including the cyclostomes and some extinct forms