-
psammosteids include Psammosteus, and Obruchevia, two
genera of
enormous species with
dorsal shields around one
meter in diameter. The
Psammosteids were...
-
anchipteraspidids are
diagnostic of pteraspidids, and not of cyathaspidids. The
psammosteids are a
group of
pteraspidiforms that
forms the
sister taxon of Protopteraspididae...
-
Pycnosteus Mark-Kurik, E; Obruchev, D (1968). "ON THE
EVOLUTION OF THE
PSAMMOSTEIDS (HETEROSTRACI)".
Eesti NSV
Teaduste Akadeemia Toimetised. Keemia. Geoloogia...
- and
pteraspidid species were
applied to
psammosteids, but
proved not to be useful. At the time,
psammosteids were not well
characterized morphologically...
-
besides the tail or
caudal fin. In some pteraspids,
especially in the
psammosteids, the ends of the
branchial plates (the
plates that
covered the gills)...
- (and best)
known genus,
Drepanaspis from the Hunsrück lagerstätte. The
Psammosteids were the only
heterostracans that
survived the
Upper Frasnian extinction...
-
Intact specimens of
Weigeltaspis suggest a
living animal similar to
psammosteids like Drepanaspis. The
armor of
Phialaspis symmondsi (once considered...
-
suggest the
living animals were, at
least superficially,
similar to
psammosteids, some authorities, such as Tarlo,
place them
within Psammosteida. Because...
- Pteraspididae,
Gigantaspis and Protaspididae), and the
anchipteraspidids and the
Psammosteids.
Protopteraspids are
found in
Lower Devonian marine strata of the Western...
- to
those of
psammosteids.
Because of
these two traits,
species of this
genus were
originally described as
being North American psammosteids closely related...
