Selkirkia elongata (Chengjiang Maotianshan
Cambrian (~525 million years ago)
(25.4mm=1 inch): 37 mm long on a 60 mm by 27 mm matrix
Quiongzhusi Section, Yu’anshan Member, Heilinpu Formation, Mao Tian
Hill, Yuxi, Chengjiang County, Yunnan Province, China
This unusual member of the Priapulida is known as Selkirkia elongata.
This one comes from the most famous location of all, Maotianshan
(Mao Tian Hill), site of the discovery of the Chengjiang Biota by
Hou Xian-guang in 1984. 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 priapulids are a group of
non-segmented works whose modern-day examples can reach 30 cm in
length, and live in both shallow and deep marine sands as carnivores.
The terminal mouth bears cone-shaped projections called scalids
by which the worm would snare its prey. Ther elongated tube which
serves as the source of the name of the species presumably was held
nearly vertically in the substrate with just the tip protruding
into the water column. This taxon is only known from Chengjiang.