The assemblages of the Middle Devonian psammosteid agnathans
from the eastern part of the Main Devonian Field.
Earlier invertebrate species do not possess either gene, and thus these two aqp genes, which are derived from aqp4, likely originated in an agnathan
In 1975 a palaeontological expedition from Gottingen and Cologne universities (Germany) visited Arctic Canada (Langenstrassen & Schultze 1996) and inter alia collected agnathans
and gnathostomes in Lower Devonian localities on the northern part of Prince of Wales Island (Fig.
Novel molecular mechanisms of receptor diversification are beginning to be found in a variety of invertebrate phyla and agnathan
elegans was exhausted and later no articulated agnathan
specimens have been found apart from a few Tremataspis mammillata Patten and Dartmuthia gemmifera Patten shields.
Isolation of Dlx and Emx gene cognates in an agnathan
species, Lampetra japonica, and their expression patterns during embryonic and larval development: conserved and diversified regulatory patterns of homeobox genes in vertebrate head evolution.
The diverse agnathan
and fish remains include the psammosteids Pycnosteus tuberculatus (Rohon), Pycnosteus sp.
In Scotland, the associated faunal list includes the protochordate Ainiktozoon loganense Scourfield and the agnathan
Jamoytius kerwoodi White in addition to L.
Sostav i rasprostranenie beschelyustnykh i ryb v silurijskikh i devonskikh otlozheniyakh Latvii [Composition and distribution of agnathan
and vertebrate assemblages in the Silurian and Devonian deposits of Latvia].
zones include mainly these of the psammosteid heterostracans.
For example, the width of ridges and grooves on agnathan
thelodont scales is 20-200 [micro]m, while the length may coincide with the length of the scale (up to 3.
vertebrates from the Lower Silurian of Gotland, Sweden.
dentata and compare them with those of other tessellated agnathan