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New Maikhanellid Shells and Siphogonuchitid Spicule Bundles from the Cambrian Fortunian Stage of South China
Author(s) -
LIU Yunhuan,
ZHANG Yanan,
SHAO Tiequan,
TANG Hanhua,
JIANG Kaituo,
WANG Qi,
CHEN Cheng,
DONG Junyan,
LIANG Yongchun,
DAI Jun,
XUE Jiaqi
Publication year - 2016
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.12806
Subject(s) - spicule , sponge spicule , shell (structure) , paleontology , biology , morphology (biology) , geology , materials science , composite material
Abstract Maikhanellids are a distinct group of Cambrian Fortunian small shelly fossils by the cap‐shaped profiles and scaly shell ornamentation. According to the individual shell shape and ornamentation feature types of SO maikhanellids fossils which were collected from Xixiang botia, we confirmed the family Maikhanellidae content of six genera, which are Maikhanella, Ramenta, Purella, Ramentoides, Yunnannopleura and Mediata. Unlike the halkieriid animals whose shells and spicules are articulated on different body parts, maikhanellids were presumably yielded by siphogonuchitid spicules penetrating the intermediate matrix (the “spicule shell” hypothesis), and this is the reason that some researchers treated maikhanellids and co‐occurring siphogonuchitids as synonyms. The affinities of Maikhanellids and siphogonuchitids remain debatable. Here, we report three dimensionally phosphatized maikhanellid shells and siphogonuchitid spicule bundles from the Cambrian Fortunian small shell faunas of South China. They differ from all the previously reported maikhanellids and siphogonuchitids, and may represent new types. The intact and smooth surface underneath the partially preserved scales of the shells challenges the “spicule‐shell” hypothesis. The present siphogonuchitid spicules differ from the maikhanellid scales in size, morphology, and arrangement pattern, thus the spicules might not be derived from the shells. Whether the shells and spicule bundles were articulated on different body parts of the same animals remains unknown.