Agnatha
E89221
Agnatha is a superclass of jawless vertebrates that includes modern lampreys and hagfishes as well as numerous extinct lineages.
Aliases (1)
- Cyclostomata ×1
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 (jawed vertebrates)
→
|
| diversifiedIn |
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
→
|
| habitat |
freshwater environments
→
marine environments → |
| hasCommonName |
jawless vertebrates
→
|
| hasLanguageName |
Agnatha (Latinized scientific name)
→
|
| hasSignificance |
key to understanding early vertebrate evolution
→
|
| highDiversityIn |
Devonian period
→
Silurian period → |
| includesExtantGroup |
hagfishes
→
lampreys → |
| includesExtinctGroup |
Anaspida
→
Galeaspida → Osteostraci → Pteraspidomorphi → Thelodonti → ostracoderms → |
| includesTaxon |
Cephalaspidomorphi (sensu lato)
→
Myxiniformes → 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
→
|
Referenced by (3)
| Subject (surface form when different) | Predicate |
|---|---|
|
Gnathostomata
→
|
evolvedFrom |
|
Vertebrata
→
|
includesTaxon |
|
Gnathostomata
("Cyclostomata")
→
|
sisterGroup |