Sentence examples for split of agnathans from inspiring English sources
This could suggest that the central functions for MC receptors developed after the split of agnathans but prior to the split of gnathostomes.
While the MCb receptor clearly seems to belong to the rather slowly evolving MC3-4-5 clusurelyhat surely must have existed prior to the split of agnathans from the lineage of chordates, the MC1 receptor character of the MCa receptor may suggest that an ancestor to the MC1 receptor was also present at this stage in evolution.
Unlike the slitlike gills of gnathostomes, the gills of agnathans are pouchlike and open through pores.
All these evidences strongly suggest that the segmental and compartmental architecture of the vertebrate brain was already established before the divergence of agnathans and gnathostomes.
Lampreys and hagfish are the only two groups of agnathans (meaning jawless vertebrates) that have survived to date.
In particular, the machinery for myelin formation is entirely absent, so the nerves of ascidians, like those of agnathans, are unmyelinated [37].
The theoretical time of divergence of agnathans is estimated 564 MYR for molecular and 525 MYR for fossil data [ 16].
The true androgen receptor evolved only later in gnathostomes after their split from agnathans, which already show reactivity to androgens probably mediated by other receptors (Guerriero 2009 and references therein).
Interestingly, xanthophores are the evolutionary youngest pigment cell type that seems to have emerged in the gnathostome lineage after the divergence of agnathans.
To investigate the early phase of vertebrate evolution from a molecular perspective, the expression patterns of various developmental regulatory genes have been compared between the gnathostomes and the lamprey, one of the two extant groups of agnathans [ 4- 14].
Most fossils of Agnathans and some fossils of acanthodian (stem Chondrichthyes or stem osteichthyes) support the presence of multiple gill clefts [ 45], and the sea lamprey, which is in the class Petromyzontida, has seven gill clefts.
