Absolute axial growth and trunk segmentation in the early Cambrian trilobite Oryctocarella duyunensis
Absolute axial growth and trunk segmentation in the early Cambrian trilobite Oryctocarella duyunensis
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DOI：
10.1017/pab.2020.63
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发表时间：
2021-08-01
期刊：
影响因子：
2.7
通讯作者：
Fusco, Giuseppe
中科院分区：
文献类型：
--
作者：
Dai, Tao;Hughes, Nigel C.;Fusco, Giuseppe
在湘西(中国)布林附近的一小段地层中，发现了多个类似于514年前的都匀Oryctocarella三叶虫的标本。从这些标本获得的大小数据表明，从Meraspid 1度开始，度代表连续的龄期。Meraspid的生长一直持续到最后阶段，这提供了三叶虫，特别是寒武纪早期物种有确定增长的第一个例子。样本包含三种这样的终末期，被认为是Holaspids，分别有9、10或11个胸节。在梅花鱼阶段，该物种的生长速度并不是恒定的。在布林组合中看到的生长模式与在其他两个地方报道的同一物种中的生长模式略有不同，证明了这些集合之间发育模式的微进化差异。
A short stratigraphic interval near Bulin in western Hunan (China) yields multiple specimens of the similar to 514-Myr-old oryctocarine trilobite Oryctocarella duyunensis. Size data obtained from these specimens indicate that, from meraspid degree 1 onward, degrees represent successive instars. Meraspid growth persisted until a terminal stage was reached, providing the first example of determinate growth in trilobites and, notably, in an early Cambrian species. The sample contains three varieties of such terminal stages, recognized as holaspids, with 9, 10, or 11 thoracic segments, respectively. During the meraspid phase, growth rates were not constant in this species. The pattern of growth seen in the Bulin assemblage differs modestly from that reported in the same species from two other localities, attesting to microevolutionary variation in developmental patterns among these collections.