Abstract Luancaia igen. nov. and its two new ichnospecies, L. candasensis and L. elongata, from the Middle Devonian Naranco Formation of Asturias, northern Spain, record infaunal molting. The new ichnogenus has an elongate to oblong outline, and displays a distinctly trilobate appearance that includes an axial longitudinal lobe characterized by a distinctive ridge flanked by lateral lobes at each side. Well-defined transverse ridges convey a metameric-like appearance consisting of up to nine distinct segments. The anterior-most part is more variable, but consistently features a pair of oval strongly convex, or a subtriangular fan-like ridge in well-preserved specimens. Luancaia is similar to Rusophycus in its general segmented appearance, suggesting a euarthropod producer, but differs in the presence of a distinctive axial ridge and in the absence of scratch imprints. Luancaia closely resembles the dorsal side of the enigmatic Carboniferous oniscid-like euarthropod Camptophyllia. We propose that Luancaia records supine (i.e. upside-down) infaunal molting of a euarthropod with a dorsal exoskeletal morphology similar to Camptophyllia, in which exuviation was facilitated by dorsal anchoring on a firm muddy substrate. The Naranco Formation records sedimentation in a shallow- and marginal-marine setting that at times was affected by fluvial discharge most likely during storm floods. In particular, Luancaia is preserved in storm-flood beds that accumulated in relative proximity to a river mouth. These latter deposits consist of sparsely bioturbated sandstone and mudstone that reflect deposition under stressful conditions, such as salinity stress, erosion and by pass high sedimentation rate, and turbidity. By burrowing into the sediment, the producer avoided the stressed physical conditions of the sediment surface. Marginal-marine settings, where competition and predation pressures were significantly lower than in adjacent fully marine environments, may have served as safe molting sites during the mid-Paleozoic marine radiation.

中文翻译：

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泥盆纪边缘海洋环境中新的踪迹化石记录下动物群蜕皮的古生态学和古环境影响

摘要 Luancaia igen。十一月 及其两个新的鱼类物种 L. candasensis 和 L. elongata，来自西班牙北部阿斯图里亚斯的中泥盆纪 Naranco 组，记录了底栖动物的蜕皮。新的鱼属有一个细长到椭圆形的轮廓，并显示出明显的三叶形外观，包括一个轴向纵向裂片，其特征是一个独特的脊，两侧各有侧裂片。明确定义的横向脊传达由多达九个不同部分组成的同色异谱样外观。最前面的部分变化更大，但在保存完好的标本中始终具有一对椭圆形的强凸状或亚三角形扇状脊。Luancaia 的一般分段外观与 Rusophycus 相似，表明它是真节肢动物的生产者，但不同之处在于存在独特的轴向脊和没有划痕印记。Luancaia 与神秘的石炭纪 Oniscid-like euarthropod Camptophyllia 的背侧非常相似。我们建议 Luancaia 记录了一种真节肢动物仰卧（即倒置）的 infaunal 蜕皮，其背侧外骨骼形态类似于 Camptophyllia，其中背侧锚定在坚固的泥泞基质上促进了蜕皮。Naranco 组记录了浅层和边缘海洋环境中的沉积作用，有时在风暴洪水期间最有可能受到河流排放的影响。特别是，Luancaia 保存在相对靠近河口的风暴洪水床中。后者的沉积物由稀疏的生物扰动砂岩和泥岩组成，反映了压力条件下的沉积物，如盐度胁迫、侵蚀和旁路高沉降率和浊度。通过钻入沉积物，生产商避免了沉积物表面的压力物理条件。在中古生代海洋辐射期间，竞争和捕食压力明显低于相邻的完全海洋环境的边缘海洋环境可能是安全的蜕皮地点。