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FIGURE 2
Examples of brackish-water assemblages of trace fossils. (A) Nereid (ne) and capitellid
(cp) polychaete burrows that resemble the ichnogenera
Skolithos
(
Sk
) and
Trichichnus
. Gironde
Estuary, France. (B) Resin cast of a low-diversity trace assemblage comprising
Polykladichnus
made
by nereid (ne) polychaetes. Kouchibouguac, New Brunswick, Canada. (C) Low-diversity suite of
Arenicolites
(
Ar
) and
Trichichnus
(
Tr
) from a tidally influenced bar deposit of the Fraser River delta.
(D) Comparably robust
Gyrolithes
(
Gy1
) and more gracile examples (
Gy2
) in inclined heterolithic
stratification (IHS) of the Cretaceous McMurray Formation. (E)
Skolithos
in cross-bedded sands of
the inner Ogeechee estuary, Georgia, USA. (F) Monospecific assemblage of
Arenicolites
, Bay of
Fundy, Canada. (G) Low-diversity trace assemblage comprising diminutive traces (
Pl
,
Planolites
;
Ar
,
Arenicolites
) from an upper point bar, inner estuary, Willapa Bay, Washington, USA.
Roy and Martien, 2001; Spaargaren, 1979
). Enforced diminution also
may induce shortened lifecycles, thereby promoting elevated mortality
rates. Such conditions lead to a predominance of juvenile tracemakers
(
Chapman and Brinkhurst, 1981
) that produce comparably small traces.
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