Abstract The ichnofossil Sanctum laurentiensis from the Late Ordovician (Cincinnatian) of Laurentia is a domichnium tunneled into live colonies of ramose and frondose trepostome Bryozoa. A preferred entrance location was chosen by the trace-making endoskeletozoan. The organism chose to tunnel in positions near growing tips of branches where one of two conditions prevailed. At stereotypical sites, here considered “determinate”, domicile entrances were made where a trepostome branch was in the growth process of bifurcation; sites considered “indeterminate” were chosen where one blade or branch was impinging on another, or on some other nearby substrate, thus interfering with normal colony growth in a random, or non-ontogenetic, manner. This stereotypy is a rare example of demonstrable entrance-siting behavior by an unknown invertebrate organism. A skeleto-structural condition was present at both determinate and indeterminate locations on ramose trepostome colonies. Stereotypical entrance-site choices included a location where bryozoan freewall membrane was compromised or thinned and exozone was incompletely developed. Sanctum producers preferred incomplete exozone in order to access the endozone for excavation to form a domichnium. Middle and Late Ordovician diversification of ramose bryozoan forms stimulated escalation of bioeroder and symbiont taxa in living zoaria thus encouraging further trepostome evolution.

中文翻译：

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奥陶纪 trepostomate Bryozoa 中 Domichnium Sanctum laurenentiensis 的入口轴放置的行为刻板印象和一些生态后果

摘要 Laurentia 晚奥陶世（辛辛那提）的 ichnofossil Sanctum laurentiensis 是一种通过隧道进入枝状和叶状 trepostome Bryozoa 活菌落的属。一个首选的入口位置是由追踪内骨骼动物选择的。该生物选择在靠近树枝生长尖端的位置挖洞，在那里，两种条件之一占优势。在刻板的地点，这里被认为是“确定的”，住所入口被设置在一个trepostome分支处于分叉的生长过程中；选择被认为是“不确定”的位点，其中一个叶片或树枝撞击另一个或附近的其他一些基质，从而以随机或非个体遗传的方式干扰正常的菌落生长。这种刻板印象是未知无脊椎动物生物可证明的入口选址行为的罕见例子。在分枝链节体集落的确定和不确定位置都存在骨架结构条件。刻板的入口站点选择包括苔藓动物游离壁膜受损或变薄和外带未完全发育的位置。Sanctum 生产者更喜欢不完整的外带，以便进入内带进行挖掘以形成一个 domichnium。中、晚奥陶世分枝苔藓虫形态的多样化刺激了活体动物中生物侵蚀和共生体分类群的升级，从而鼓励了进一步的trepostome进化。Sanctum 生产者更喜欢不完整的外带，以便进入内带进行挖掘以形成一个 domichnium。中、晚奥陶世分枝苔藓虫形态的多样化刺激了活体动物中生物侵蚀和共生体分类群的升级，从而鼓励了进一步的trepostome进化。Sanctum 生产者更喜欢不完整的外带，以便进入内带进行挖掘以形成一个 domichnium。中、晚奥陶世分枝苔藓虫形式的多样化刺激了活体动物中生物侵蚀和共生体分类群的升级，从而鼓励了进一步的 trepostome 进化。