Tommotia
Encyclopedia
Tommotia is a small shelly fossil from the Early Cambrian
Period. Originally, only a cone-shaped shell was recognized, which was originally thought to be an early cephalopod
, with either squid
-like tentacles or a snail
-like foot. More recent investigation has shown that the cone is not the remains of a complete animal, but a sclerite
of a larger, soft-bodied animal that would have resembled a chiton
or a sea mouse
. The fossils called Camanella may be another type of sclerite from the same animal.
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
Period. Originally, only a cone-shaped shell was recognized, which was originally thought to be an early cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
, with either squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
-like tentacles or a snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
-like foot. More recent investigation has shown that the cone is not the remains of a complete animal, but a sclerite
Sclerite
A sclerite is a hardened body part. The term is used in various branches of biology for various structures including hardened portions of sponges, but it is most commonly used for the hardened portions of arthropod exoskeletons....
of a larger, soft-bodied animal that would have resembled a chiton
Chiton
Chitons are small to large, primitive marine molluscs in the class Polyplacophora.There are 900 to 1,000 extant species of chitons in the class, which was formerly known as Amphineura....
or a sea mouse
Sea mouse
The sea mouse, Aphrodita aculeata is a marine polychaete worm found in the North Atlantic, the North Sea, the Baltic Sea and the Mediterranean. The sea mouse normally lies buried head-first in the sand. It can live in muddy sea floors down to around 1000m.Its body is covered in a dense mat of...
. The fossils called Camanella may be another type of sclerite from the same animal.