|
AN
EXCEPTIONAL PRESERVATION OF CHITONS (MOLLUSCA, POLYPLACOPHORA)
IN THE ITALIAN PLIOCENETHE
|
Bruno
Dell’Angelo, Hans Gallorini and Marco Taviani |
Polyplacophora
are extremely prone to
post-mortem disarticulation of their 8-plate shells kept
together by the perinotus, a chitinous girdle with very low
preservation potential. As a consequence, most fossil chitons
are only known
from loose plates in sedimentary rocks.
Exceptions to this rule are extremely rare and refer to
Paleozoic
and Cenozoic articulated chitons hosted within
fine-grained sediments deposited low-energy environments. A
single specimen of a still articulated Craspedochiton
altavillensis (Seguenza, 1876) has been discovered in Lower
Pliocene shallow marine deposits of Tuscany, Italy. The specimen
laid attached to the internal side of the large pectinid Chlamys
latissima (Brocchi, 1814) buried in a sandy matrix. We
suspect that the chiton lived in a high-energetic environment
but embedded in semi-sciaphilic, partially reduced sands and
this habitat permitted to escape post-mortem disarticulation. |
