ONTOGENY OF AN EARLY CAMBRIAN EODISCOID TRILOBITE FROM HENAN, CHINA
ONTOGENY OF AN EARLY CAMBRIAN EODISCOID TRILOBITE FROM HENAN, CHINA
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DOI：
10.1111/j.1502-3931.1989.tb01164.x
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发表时间：
1989-01-15
期刊：
影响因子：
1.5
通讯作者：
ZHANG, XG
中科院分区：
文献类型：
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作者：
ZHANG, XG
来自中国河南淅川的大量磷酸化标本可以对早寒武世始盘状三叶虫 Neocobboldia chinlinica Lee 的形态和个体发育进行详细研究。尾部伴随着生长出现了几种形态变化，通过这些变化，该物种有 13 个定量定义的阶段，可能的增长率为 1.20，以及 4 个发育时期（无原壳、后壳、长壳和全壳）。 anaprotaspis 是对 ediscoids 的第一个描述。随着逐渐成熟，它的形态发生了巨大但渐进的变化。形态测量和定性分析表明，在甲鱼时期，三个胸节有规律地形成，然后从尾部释放；并且一个阶段内可能发生多个龄期。外骨骼由保存完好的两层组成，两层都有精美的装饰，随着生长也呈现出渐变的变化。附有视觉表面的游离颊和下颌显示出 ediscoids 的许多基本特征。头盖的一些形态分化可能反映了性别二态性状况。统计和埋藏学分析表明，这些中国猪笼草标本可能代表了一个完整的种群。幼虫可能成群生活在温暖的浅水环境中。
Numerous phosphatized specimens from Xichuan, Henan, China permit a detailed study of the morphology and ontogeny of the Early Cambrian eodiscoid trilobite Neocobboldia chinlinica Lee. Several morphological changes of pygidia are seen to accompany growth, by means of which 13 quantitatively defined stages with a probable growth rate of 1.20, and 4 developmental periods (anaprotaspid, metaprotaspid, meraspid, and holaspid) have been recognized for this species. The anaprotaspis is the first description for eodiscoids. It shows great but gradual changes in morphology with progressive maturity. Morphometric and qualitative analyses indicate that three thoracic segments were formed regularly and then released from the pygidium during the meraspid period; and more than one instar might have occurred within a stage. The exoskeleton consists of two well-preserved layers, both bearing fine ornament that showed gradual change with growth as well. The free cheek with visual surface attached and the hypostoma show many of the fundamental characters of eodiscoids. Some morphological differentiation in cranidia may reflect a sexually dimorphic condition. Statistical and taphonomic analyses indicate that these specimens of N. chinlinica may represent a complete population. The larvae may have lived in swarms in a warm shallow water environment.