TY - JOUR
T1 - A hyolithid without helens preserving the oldest hyolith muscle scars; palaeobiology of Paramicrocornus from the Shujingtuo Formation (Cambrian Series 2) of South China
AU - Zhang, Zhi liang
AU - Skovsted, Christian B.
AU - Zhang, Zhi fei
PY - 2018/1/1
Y1 - 2018/1/1
N2 - The hyolithid Paramicrocornus zhenbaensis from the lower Cambrian (Cambrian Series 2) Shuijingtuo Formation of southern Shaanxi and western Hubei provinces of the Yangtze Platform is well-preserved in three dimensions. The morphology of the conch and operculum of P. zhenbaensis shows that this species lacked helens, which are considered to be characteristic of hyolithids and hence Paramicrocornus may belong to a sister group of other hyolithids. The shell structure of P. zhenbaensis reveals close similarities to the shell structure of other hyolithids. Furthermore, the smaller size and non-radial orientation of tubules in the shell structure of the operculum also differ from that in orthothecid hyoliths, suggesting that this characteristic may be used to differentiate hyolithids and orthothecids. The phosphatized opercula of P. zhenbaensis exhibit a pair of muscle scars located close to the apex of the internal surface. These muscle scars, as well as similar structures in other hyolithids, probably served as attachment sites of muscles controlling the retraction of the tentaculate feeding organ recently discovered in hyolithids. Without helens, P. zhenbaensis may have been sessile with the conch partly buried in the sea floor.
AB - The hyolithid Paramicrocornus zhenbaensis from the lower Cambrian (Cambrian Series 2) Shuijingtuo Formation of southern Shaanxi and western Hubei provinces of the Yangtze Platform is well-preserved in three dimensions. The morphology of the conch and operculum of P. zhenbaensis shows that this species lacked helens, which are considered to be characteristic of hyolithids and hence Paramicrocornus may belong to a sister group of other hyolithids. The shell structure of P. zhenbaensis reveals close similarities to the shell structure of other hyolithids. Furthermore, the smaller size and non-radial orientation of tubules in the shell structure of the operculum also differ from that in orthothecid hyoliths, suggesting that this characteristic may be used to differentiate hyolithids and orthothecids. The phosphatized opercula of P. zhenbaensis exhibit a pair of muscle scars located close to the apex of the internal surface. These muscle scars, as well as similar structures in other hyolithids, probably served as attachment sites of muscles controlling the retraction of the tentaculate feeding organ recently discovered in hyolithids. Without helens, P. zhenbaensis may have been sessile with the conch partly buried in the sea floor.
KW - operculum
KW - Hyolithida
KW - tentaculate feeding organ
KW - functional morphology
KW - shell structure
KW - Yangtze Platform
UR - http://www.scopus.com/inward/record.url?scp=85031086265&partnerID=8YFLogxK
U2 - 10.1016/j.palaeo.2017.07.021
DO - 10.1016/j.palaeo.2017.07.021
M3 - Article
AN - SCOPUS:85031086265
VL - 489
SP - 1
EP - 14
JO - Palaeogeography, Palaeoclimatology, Palaeoecology
JF - Palaeogeography, Palaeoclimatology, Palaeoecology
SN - 0031-0182
ER -