Agnatha

E89221

Agnatha is a superclass of jawless vertebrates that includes modern lampreys and hagfishes as well as numerous extinct lineages.

All labels observed (2)

Label Occurrences
Agnatha canonical 3
Cyclostomata 2

How this entity was disambiguated

Statements (46)

Predicate Object
instanceOf paraphyletic group
vertebrate superclass
bodyCovering bony armor in many extinct forms
lack of true scales in most extant forms
characterizedBy absence of jaws
absence of paired fins in most forms
cartilaginous or fibrous skeleton
persistent notochord in adults
single median nostril in many groups
circulatorySystem closed circulatory system
contrastedWith Gnathostomata
surface form: Gnathostomata (jawed vertebrates)
diversifiedIn Ordovician Period
surface form: Ordovician period
etymology from Greek a- (without) and gnathos (jaw)
evolutionaryStatus paraphyletic relative to jawed vertebrates
feedingMode filter feeding in many extinct forms
parasitism in many lampreys
scavenging in many hagfishes
firstAppearance Cambrian Period
surface form: Cambrian period
habitat freshwater environments
marine environments
hasCommonName jawless vertebrates
hasLanguageName Agnatha (Latinized scientific name)
hasSignificance key to understanding early vertebrate evolution
highDiversityIn Devonian Period
surface form: Devonian period

Silurian
surface form: Silurian period
includesExtantGroup hagfishes
lampreys
includesExtinctGroup Anaspida
Anaspida
surface form: Galeaspida

Osteostraci
Pteraspidomorphi
Thelodonti
ostracoderms
includesTaxon Cephalaspidomorphi (sensu lato)
Myxiniformes
Petromyzontidae
surface form: Petromyzontiformes
kingdom Animalia
nervousSystem well-developed brain and spinal cord
phylum Chordata
precededByInFossilRecord early chordates
reproduction external fertilization in most extant forms
respiration gills
sisterGroupOf Gnathostomata in some classifications
subphylum Vertebrata
taxonRank superclass
usedIn vertebrate phylogeny studies

How these facts were elicited

Referenced by (5)

Full triples — surface form annotated when it differs from this entity's canonical label.

Vertebrata includesTaxon Agnatha
Gnathostomata evolvedFrom Agnatha
Gnathostomata sisterGroup Agnatha
this entity surface form: Cyclostomata
Thelodonti clade Agnatha
Myxiniformes superclass Agnatha
this entity surface form: Cyclostomata