Amplectobelua
symbranchiata
Phylum Uncertain,
Anomalocarididae
Geological
Time: Early Cambrian (~525 million years ago)
Size: 15
mm long
Fossil
Site: Chengjiang Biota - Guanshan Fauna, Lower most part of Wulongqing
Formation, Caijiachong Valley, Yieyatoung, Gangtoucun Village, Xiamacun
Town, Kunming City, Yunnan Province, China
Description:
This fossil comes from what has been termed the “Guanshan
Fauna”, found in the Wulongqing Formation. The Guanshan Fauna
shares many genera with the slightly older Chengjiang Biota, but
differs at the species level. The discovery of the Chengjiang Biota
by Hou Xian-guang in 1984 opened a window onto a remarkable array
of lifeforms from what is termed the Cambrian Explosion. 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 is the grasping arm of one of the of the “Terrors
Of The Cambrian”, Amplectobelua symbranchaiata.
The
members of this group of enigmatic creatures are known from Asia,
Australia, Europe, and North America, and are thought by many to
be closely allied with the Arthropoda, a position not held by all
researchers. As of the publication of Hou’s book in 2004,
some 30 examples were known, most being grasping arms like this
one. The spiniferous grasping appendages are strongly suggestive
of its carnivorous habits; some trilobites from Utah bear evidence
of bite marks that have been attributed to its near relative Anomalocaris.
The primary distinction between the 2 genera is that the spines
of Anomalocaris are branched, while those on Amplectobelua are unbranched,
as seen here.
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