cyclostome
Cyclostomata latin

However, there is strong molecular evidence for cyclostome monophyly, and thus the term remains in use.

Cyclostome is a biological term (from the Greek for "round mouth") used in a few different senses:

The cyclostome bryozoans were dominant in the Mesozoic; since that era, they have decreased.

Feeding mechanisms as evidence for cyclostome monophyly.

On the lower, left valve, cyclostome and cheilostome bryozoans predominated.

Lampreys and hagfishes: Analysis of cyclostome relationships.

They have a characteristic row of stout spines running lengthwise along the foreleg tibia, and a cyclostome depression above the mandibles.

"Skeletal ultrastructure and phylogeny of cyclostome bryozoans".

At the present day cyclostome bryozoans are exclusively marine and stenohaline, with most species living subtidally on the continental shelf.

The "cyclostome hypothesis", on the other hand, holds that lampreys and hagfishes are more closely related, making cyclostomata monophyletic.

Most studies based on anatomy have supported the vertebrate hypothesis, while most molecular phylogenies have supported the cyclostome hypothesis.

These finds include but are not limited to seven species of calcareous cyclostome bryozoans as well as a soft-bodied ctenosome bryozoan.

Among cyclostome bryozoans, the calcitic skeleton is usually lamellar, consisting of tabular or lath-like crystallites stacked like tiles at a low angle to the wall surface.

This theory carries with it the implication that the cyclostome characters mentioned above were not part of the history of gnathostomes but were instead specializations restricted to lampreys and hagfishes.

In cyclostome braconids, the labrum and the lower part of the clypeus are concave with respect to the upper clypeus and the dorsal margin of the mandibles.

The embryonic development of hagfishes was once held to be drastically different from that of lampreys and gnathostomes, but recent evidence suggests that it is more similar than previously thought, which may remove an obstacle to the cyclostome hypothesis.

This theory raises the possibility that cyclostome characters such as the median nostril, complex tongue and pouch-like gills are either primitive craniate characters and are truly part of the history of gnathostomes, or are convergencies, that is, accidental similarities, developed independently in lampreys and in hagfishes.

The name Cyclostomata means "round mouths".

Cyclostomata, or Agnatha, lampreys and hagfishes.

Subclass Cyclostomata (hagfish and lampreys)

Traditionally the group was placed in a superclass Cyclostomata together with the Myxini (hagfishes).

Garra cyclostomata is a species of ray-finned fish in the genus Garra.

Cyclostomata is a group of chordates that comprises the living jawless fishes: the lampreys and hagfishes.

The Subclass Ostracodermi has been placed in the division Agnatha along with the extant Subclass Cyclostomata, which includes lampreys and hagfishes.

Cyclostomatida or Cyclostomata, are an order of stenolaemate bryozoans consisting of 7+ suborders, 59+ families, 373+ genera, 666+ species.

Phylogenetic research in 1998 and 1999 supported the idea that the hagfish and the lampreys form a natural group, the Cyclostomata, that is a sister group of the Gnathostomata.

Overall, the vertebrate fauna of the national park is represented of one species of cyclostomata, 20 species of fishes, 12 species of amphibians, 7 species of reptiles, 141 species of birds, 52 species of mammals.

The argument is that if Cyclostomata is indeed monophyletic, Vertebrata would return to its old content (Gnathostomata + Cyclostomata) and the name Craniata, being superfluous, would become a junior synonym.

In Cyclostomata it may be of two types: holoancestrula and artroancenstrula (in crisiids) The ancestrula gives rise to a second generation of zooids, which in turn gives rise to a third, and so on, in a process called astogeny.