Ichnogenus Thalassinoides Ehrenberg, 1944

Uchman, Alfred & Wetzel, Andreas, 2024, Sequestrichnia - an ethological category of marine trace fossils recording the collection and stowage of nutritional material within burrows, Comptes Rendus Palevol 23 (22), pp. 325-338 : 330

Ichnogenus Thalassinoides Ehrenberg, 1944

( Fig. 3 )

Crustaceans living in the modern deep South China Sea produce Thalassinoides- like burrows that document a sequestrichnial behaviour. Two kinds of burrows were encountered, which contained abundant foraminiferal tests stowed in greenish anoxic sediment. One burrow type contains benthic agglutinated foraminifera tests, which consist mainly of Pinatubo-1991 ash but were stowed below the ash in anoxic sediment ( Kaminski & Wetzel 2004). The other kind of Thalassinoides occurs in water depths below the CCD; it exhibits a laminated fill consisting of calcareous planktonic foraminiferal tests that are stowed and preserved in the burrow, whereas they are already dissolved in the overlying hemipelagic sediment from which they originate ( Wetzel & Unverricht 2013). The calcareous foraminiferal tests must have been stowed shortly after their deposition; otherwise they would show dissolution features. Partly truncated laminae in the burrow imply later reworking by the producer ( Fig. 3 ).

Figures

FIG. 3. — Thalassinoides Ehrenberg, 1944 filled with planktonic foraminifera tests (downward displacement marked by a yellow arrow) in a sub-CCD setting indicating rapid sequestration after deposition on the sea floor; inset showing local truncation (red lines) of laminae (yellow lines), indicating subsequent,probably multiple reworking by the producer.(RV Sonne cruise 114, core 27-1, 0-21 cm sediment depth;15°45.00’N,115°45.00’E, central South China Sea, 4220 m water depth; for details see Wetzel & Unverricht 2013). Scale bar: 1 cm.