Ancient Brachiopod from Chengjiang Biota with Preserved Details
Brachiopoda - Heliomedusa orienta

Name: Brachiopoda; Heliomedusa orienta (Chengjiang)

Age: Early Cambrian (~525 million years ago)

Size (25.4mm=1 inch): 13 mm by 17 mm on a 25 mm by 33 mm and 65 mm by 75 mm matrix pair

Location: Quiongzhusi Section, Yu’anshan Member, Heilinpu Formation , Mao Tian Hill, Yuxi, Chengjiang County, Yunnan Province, China

Heliomedusa orientaDescription: This brachiopod is known as Heliomedusa orienta. The species is a relatively common member of the Chengjiang biota. The source of the specific name is easy to determine, but the reason is that the oval shape and redial patterning led the original describers to think it was a jellyfish.. 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 Heliomedusa orientaare known as well, some of which may have represented failed attempts at diversity that did not persist to the present day. Unlike most brachiopods, Heliomedusa lacked a pedicle, leading scientists to believe it lay upon the surface of the sediment as an epifaunal filter feeder. Notice the fringe of setae thought to have served a sensory function. Note too the dark U-shaped structure contained within the shell. This is the lophophore, the structure by which the brachiopod circulated water for respiration and to extract food. Even the growth lines in the shell are readily discerned.

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