Cricocosmia
jinningensis
Nematomorpha
Geological
Time: Early Cambrian (~525 million years ago)
Size: 10-25
mm long (if straightened) on a 70 mm by 80 mm matrix
Fossil
Site: Chengjiang Maotianshan Shales, Quiongzhusi Section, Yu’anshan
Member, Heilinpu Formation, Ercaicun Village, Haikou, Kunming County,
Yunnan Province, China
This
is an example of a death assemblage of the nematomorphs Maotianshania
cylindrical and Cricocosmia jinningensis. The first species is known
from numerous specimens, many of which have preserved details, with
the taxon named after, Maotianshan (Mao Tian Hill), site
of the discovery of the Chengjiang Biota by Hou Xian-guang in 1984.
The intestine is often preserved as a dark film, indicative of its
deposit-feeding lifestyle. The second is Cricocosmia jinningensis
with preserved cone-shaped sclerites seen in paired longitudinal
rows. This one was originally thought to be a priapulid worm, a
view still held by some researchers. It is only known from the Lower
Cambrian of Yunnan Province.
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. The fine example preserved here in exquisite detail makes this
a highly unique specimen of life from 525 million years ago.
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