Misszhouia instance of fossil taxon
Description
Misszhouia longicaudata is almost flat (dorso-ventrally). The upper (or dorsal) side of the body consists of a non-calcified headshield (cephalon) and tailshield (pygidium) without body segments between. The body is narrowed at the articulation between cephalon and pygidium. The long many-segmented antennae are directed forward. There are no eyes. The gut has a relatively small diameter, and there are four pairs of relatively small digestive sacs (or caeca) in the cephalon only, and no branches towards the edge of the cephalon (unlike Naraoia). There are 25 limb pairs with two branches on a common base, like Naraoia and trilobites. The outer branch (or exopod) has many parallel long fine flattened side branches (setae) that probably functioned as gills with a large surface area. This exopod is attached along the whole length of the base segment (coxa) and at least the proximal part of the first segment of the inner branch (endopod). The shaft of the exopod tapers gently towards its tip. The endopod is composed of seven podomeres including a terminal claw.Differences from Naraoia
The sister genus Naraoia differ from Misszhouia longicaudata in having the following characteristics:Distribution
Misszhouia has been collected from the Lower Cambrian (late Atdabanian) of China (Yu'anshan Member of the Heilinpu Formation at Maotia’shan, the classic Chengjiang locality). It has also been found in the Niutitang Formation.
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