Increased global trade of live fish increases the risk that gnathostomes
and other fish-borne parasites will be introduced into regions along with their introduced hosts.
Thus, it is likely that these genes have been co-opted to an earlier function in the gnathostome
lineage or have lost their early specification function in lampreys.
All modern-day gnathostomes
, from mammals to elasmobranches, have structurally and compositionally similar myelin sheaths.
Furthermore, the analysis demonstrated that all of these early members of the modern gnathostomes
are clearly separated from what now appear to be the most primitive vertebrates with jaws: a collection of armored fishes called placoderms.
Duguay et al  studied the Divergence of insulin-like growth factors I and II in the elasmobranch Squalus acanthias and observed that the prototypical IGF molecule duplicated and diverged in an ancestor of the extant gnathostomes
. According to Reinecke et al  in most bony fish species with the exception of Cottus, IGF-1 and insulin display a distinct cellular distribution, similar to that of mammals which may indicate that the branching of IGF-1 and insulin has occurred at the phylogenetic level of bony fish.
For example, humans are included in the following nested clades (using the informal names): eukaryotes, animals, deuterostomes, vertebrates, gnathostomes
, tetrapods, amniotes, mammals, eutherians, primates, monkeys, apes, and great apes (see Dawkins, 2004 for more information on the ancestry of humans).
(1995) The forebrain of gnathostomes
: in search of a morphotype.
In these jawed vertebrates (gnathostomes
), the hyomandibula played a dual role in feeding and gill ventilation.
Because they resemble later sharks so closely, the Ordovician animals qualify as the closest relatives of the gnathostomes
, or jawed vertebrates.
microRNAs reveal the interrelationships of hagfish, lampreys, and gnathostomes
and the nature of the ancestral vertebrate.
His major research area is foodborne zoonotic parasites, including echinostomes, heterophyids, and gnathostomes