Drill holes provide valuable information about palaeoecological interactions in fossil ecosystems, but the Jurassic drill‐hole record is scarce. We report circular drill holes in the infaunal bivalve Eothyasira antiqua(Münster in Goldfuss) from the Pliensbachian grey shales of the Amaltheenton Formation of Franconia, southern Germany. The outcrop of the Amaltheenton Formation at Buttenheim yields a rich bivalve fauna (57 species), which represents a typical soft‐bottom community. Eothyasira antiqua, the yet oldest known member of the family Thyasiridae, represents only 1% of the total bivalve specimens from Buttenheim, but shows an exceptionally high frequency of drill holes. With a drilling rate of 81% of the well‐preserved articulated specimens, this occurence is unique compared with other drilled bivalve records from the Mesozoic and even from Recent assemblages. The drill holes resemble those of modern naticids with a larger outer opening and are assigned to the ichnospecies Oichnus paraboloides Bromley. Statistical methods show a non‐random distribution of the drill holes over the shell surface with a concentration on the central flank. The drill‐hole producer was highly efficient in drilling and exhibited a remarkable prey and site‐selective behaviour. The drill holes on the moderately deep infaunal Eothyasira suggest that the predator was also infaunal for at least parts of its life and could cope with poorly oxygenated substrate conditions occurring temporarily in the Amaltheenton environment. Drill‐hole characteristics point to a gastropod as producer. None of the about 50 gastropod taxa of the Amaltheenton Formation can be associated with the drill holes with certainty, but Hayamia reticulata (Münster) seems to be the most likely candidate. The results of this study support the opinion that drill holes are generally a scarce phenomenon in the Early Jurassic generated by rare, probably highly specialised predators. Preservational biases are considered to have been less important.

中文翻译：

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来自南德国下侏罗统最古老的裂谷双壳类动物中的掠食性钻孔

钻孔提供了有关化石生态系统中古生态相互作用的有价值的信息，但是侏罗纪的钻孔记录却很少。我们报告了德国南部弗兰肯行政区Amaltheenton组的Pliensbachian灰色页岩中不常见的双壳类Eothyasira antiqua（Goldfuss的Münster）中的圆形钻孔。布滕海姆Amaltheenton组的露头产生了丰富的双壳动物区系（57种），代表了一个典型的软底群落。Eothyasira Antiqua甲虫科（Thyasiridae）中最古老的成员，仅占Buttenheim的双壳类标本总数的1％，但钻孔的频率异常高。与保存良好的铰接标本的钻孔率达到81％相比，这种情况与中生代甚至最近的组合中的其他双壳类钻具记录相比是独一无二的。钻孔类似于现代螺线虫的钻孔，具有较大的外部开口，并被分配给鱼类物种，Oichnus paraboloides布罗姆利。统计方法显示，钻孔在壳体表面上非随机分布，并且集中在中央侧面。钻孔生产者的钻孔效率很高，并且表现出出色的猎物和现场选择性行为。在中等深度的臭椿Eothyasira上钻孔表明，该捕食者至少在其生命的一部分时间内也没有臭臭，并且可以应对在Amaltheenton环境中暂时发生的含氧较弱的底物条件。钻孔特征表明腹足动物是生产者。Amaltheenton组的大约50个腹足动物类群中的任何一个都不能与钻孔相关联，但是Hayamia reticulata（明斯特）似乎是最有可能的人选。这项研究的结果支持以下观点：在侏罗纪早期，钻孔通常是由稀有的，可能是高度专业化的捕食者所产生的稀缺现象。保存偏见被认为不太重要。