Halichondrites
sp.
Porifera,
Demospongia, Halichondritdae
Geological
Time: Early Cambrian (~525 million years ago)
Size (25.4mm=1
inch): matrix 155 mm by 75 mm
Fossil
Site: Chengjiang Maotianshan Shale, Quiongzhusi Section, Yu’anshan
Member, Heilinpu Formation, Mafang Village, Kunming, Anning, Yunnan Province,
China
Fossil Code:
CJF911
Price: $225.00
- sold
|  Description:
This is a large member of the Demospongia, the most diverse of modern-day
sponges. Greater than 90% of the extant 5,000 known species of sponges
are desmosponges. Such a representation in the fossil record is
not maintained where less than half the known genera are of this
type, a consequence of the fact that the skeletons do not fossilize
readily. Demosponge skeletons are composed of spongin fibers and/or
siliceous spicules. Sponges are known from the late Precambrian,
with few localities contributing to the fossil record over time.
The Chengjiang Biota is one such fossil lagerstatte. The diversity
of soft-tissue fossils is astonishing: algae, medusiforms, sponges,
priapulids, annelid-like worms, echinoderms, arthropods (including
trilobites), hemichordates, chordates, and the first agnathan fish
make up just a small fraction of the total. Numerous problematic
forms are known as well, some of which may have represented failed
attempts at diversity that did not persist to the present day.
This
one is known as Halichondrites, a genus known also from the slightly
younger Burgess Shale. It was shaped like a long tube, and had numerous
long spicules that formed a hairy thatched appearance. It was one
of the largest sponges of the Cambrian. This matrix section has
numerous examples of the spicules preserved.
Also
see: Chengjiang
Biota
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