The Burgess Shales Hyolithid shows the living appearance
of this mollusc like animal. The Operculum is the fan shaped
protrusion on its lower left, here connected by its wing
shaped hinges.
Updated 7/12/17
Along
with many well preserved Zacanthoides trilobites from this locality,
we have also found in the same layers large numbers of well preserved
Hyolithes sp. many with fan shaped operculums still attached.
Sizes varied from around 1 cm to over 4 cm for the larger specimens.
Also, many loose operculums were in the mix. No trace of the
two external appendages - "Helens" were found. Here
we will photo document the conchs and operculums in numerous
close up and microscope images.
This
image from the book "The Fossils of the Burgess Shale"
by Briggs, Erwin and Collier is a similar genus as our finds,
and shows the still attached fan or pectin shaped operculum still
attached on the left. The Hyalithid was able to pull this shut
on a hinge to seal off the conch and protect the soft parts from
predators. The fracture line seen running longitudinally down
the conch was visible as well in many of our specimens, and may
be caused by cracking from compression during diagenesis. The
helens are very delicate and may have been made of a material
such as a scleroprotien which normally will not preserve. Notice
the "retraction" slots for the helens in the conch.
(click to enlarge to full size)
This
specimen from our collections shows the triangular cone shaped
conch pointing upward, and the attachment for the operculum on
the bottom. The red dot is 1/4" in all images. Preservation
is in a green shale that is very fine grained.
(click to enlarge to full size)
A
loose operculum is seen here. Hordes of this component were found
in direct association with the conchs on many slabs. In most
cases, they stayed within a few centimeters from the originating
conchs. Note the "wings" on the bottom where the hinge
was attached to the conchs wing flanges. Size ~ 1cm.
About these images: Most here were taken with a logitech web cam which can focus less than 1cm from the fossils. Those taken with the stereo microscope are at 10x,
and taken with a Sony digicam held to the eyepiece and set for autofocus and exposure.
Web cam image set - Conchs and Conchs with Operculums or thier attachment bases
(click to enlarge to full size)
The fracture line can be seen in this specimen
(click to enlarge to full size)
The fracture line can be seen in this specimen
(click to enlarge to full size)
(click to enlarge to full size)
Free Operculums
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Conchs without operculums:
(click to enlarge to full size)
The fracture line can be seen in this specimen
(click to enlarge to full size)
The fracture line can be seen in this specimen
(click to enlarge to full size)
The fracture line can be seen in this specimen
(click to enlarge to full size)
(click to enlarge to full size)
(click to enlarge to full size)
(click to enlarge to full size)
The fracture line can be seen in this specimen
(click to enlarge to full size)
(click to enlarge to full size)
(click to enlarge to full size)
The fracture line can be seen in this specimen
(click to enlarge to full size)
The fracture line can be seen in this specimen
(click to enlarge to full size)
(click to enlarge to full size)
The fracture line can be seen in this specimen
(click to enlarge to full size)
(click to enlarge to full size)
(click to enlarge to full size)
(click to enlarge to full size)
(click to enlarge to full size)
The fracture line can be seen in this specimen
(click to enlarge to full size)
(click to enlarge to full size)
The fracture line can be seen in this specimen
(click to enlarge to full size)
(click to enlarge to full size)
(click to enlarge to full size)
(click to enlarge to full size)
(click to enlarge to full size)
(click to enlarge to full size)
The fracture line can be seen in this specimen
The Burgess Shales Hyolithid shows the living appearance
of this mollusc like animal. The Operculum is the fan shaped
protrusion on its lower left, here connected by its wing
shaped hinges.
(click to enlarge to full size)
(click to enlarge to full size)
