-
anterior segment to
slightly pointing inwards for the
posterior segment. The
tailshield (or pygidium) is large, subtriangular, and
about ⅔-¾× as long as wide...
- (or pleurae) are furrowed, and the
articulating facets distinct. The
tailshield (or pygidium) is
always smaller than the
headshield (or cephalon), a situation...
- may have an exta
large and wide rib (a
state called macropleural). The
tailshield (or pygidium) is
small but
appears to be
composed of more than one segment...
- The
articulate middle part of the body (or thorax) has 16 segments. The
tailshield (or
pygidium has a
spatulate shape. Whittington, H. B.; et al., eds. (1997)...
- laterally. This so-called
vindicular furrow serves to lock the rim of the
tailshield to the
headshield when the
trilobite is enrolled. The
axial rings of the...
- oval or semi-circular
headshield (cephalon), and a
circular to long oval
tailshield (pygidium)
equal to or
longer than the cephalon,
without any body segments...
- China, Sweden, the
Russian Federation, and Kazakhstan. Its
headshield and
tailshield are
almost completely effaced and it has two
thorax segments. T. bituberculatus...
- Agnostida,
Weymouthia is
diminutive and the
headshield (or cephalon) and
tailshield (or pygidium) are of
approximately the same size (or isopygous) and outline...
- the body of
eodiscids is diminutive, the
headshield (or cephalon) and
tailshield (or pygidium) are of
approximately same size, with 2 or 3
thoracic segments...
-
thorax segments, a
totally effaced headshield (or cephalon),
while the
tailshield (or pygidium)
although effaced, has a
clear furrow parallel to its border...
