Mg. Mangano et al., A new ichnospecies of Nereites from Carboniferous tidal-flat facies of eastern Kansas, USA: Implications for the Nereites-neonereites debate, J PALEONTOL, 74(1), 2000, pp. 149-157
Predominantly horizontal, gently curved to slightly sinuous traces constitu
ting uniserial rows of imbricated, subspherical sediment pads occur in Penn
sylvanian tidal-flat facies of eastern Kansas. These traces exhibit a compl
ex, actively filled internal structure. The presence of a median tunnel env
eloped by overlapping pads of reworked sediment indicates that these biogen
ic structures should be included in the ichnogenus Nereites MacLeay in Murc
hison, 1839. A new ichnospecies, N. imbricata, is erected. Externally, Nere
ites imbricata differs from the other Nereites ichnospecies by the large, t
ightly packed, imbricated pads that commonly result in an annulated appeara
nce on bedding-planes. Internally, obliquely arranged, arcuate laminae enve
lope the median tunnel and tend to follow the outline of the external semis
pherical pads. Additionally, the behavioral pattern reflected by N. imbrica
ta is less specialized than that of the other Nereites ichnospecies. Eione
monoliformis Tate, 1859 resembles N. imbricata in general appearance, but l
ack the diagnostic Nereites internal structure, and is invariably preserved
as positive epireliefs. Occurrence of Nereites imbricata as both median tu
nnels surrounded by reworked sediment (Nereites preservation) and uniserial
rows of imbricated sediment pads (Neonereites preservation) supports the n
otion that Neonereites Seilacher, 1960 is a preservational variant of Nerei
tes. The ichnogenus Nereites is an eurybathic form and is a common componen
t of Paleozoic shallow-marine facies.