We present the oldest known occurrences of crown-group Trochodendraceae based on new material from the Palaeocene of Wyoming, USA. Two genera are recognized, Trochodendron and Eotrochion gen. nov. The fossil fruit of Trochodendron infernense sp. nov. is represented by a pedicellate, apically dehiscent capsular fruit composed of nine follicle-like units, each bearing a persistent convex style. The basal part is ornamented with numerous raised stamen scars. From the same deposits, Eotrochion is represented by infructescences, fruits and associated leaves. The infructescences are racemes of numerous apically dehiscent capsules, each with c. 14–16 styles, each with an underlying nectary and receptacles lacking stamen scars, but possessing a prominent perianth scar. A phylogenetic assessment of the modern species, plus representatives of four extinct genera of fossil Trochodendraceae based on available morphological characters, yields a favoured topology of Trochodendron(Eotrochion(Concavistylon kvacekii(C. wehrii (Pentacentron, Tetracentron)))). A parsimony analysis of currently available characters indicates that C. wehrii renders Concavistylon non-monophyletic. Accordingly, we transfer it to Paraconcavistylon gen. nov., characterized by pendent, rather than erect infructescences. We also reconsider the extinct Nordenskioeldia (Late Cretaceous to Miocene), the prior placement of which in Trochodendraceae has been challenged, and we consider it to fall outside the crown group of the family.

中文翻译：

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北半球化石和现存的绒毛纲科的形态，解剖，系统发育和分布

我们根据来自美国怀俄明州的古新世的新物质，介绍最古老的已知冠群金线菊科。公认的有两个属，Trochodendron和Eotrochion gen。十一月 Trochodendron infernense sp。的化石果实。十一月 由九个卵泡状单位组成的有花梗，顶端开裂的荚果所代表，每个单位都具有持续的凸出样式。基部饰有许多凸起的雄蕊疤痕。从相同的沉积物中，Eotrochion表现为果梗，果实和相关叶片。该果序众多顶部开裂胶囊的总状花序，每Ç。14-16种花柱，每一种都有下层蜜腺和容器，没有雄蕊疤痕，但有明显的花被疤痕。根据可用形态学特征对现代物种进行系统发育评估，再加上四个已灭绝的化石化Tro科属的代表，可以得到化化的Trochodendron（Eotrochion（Concavistylon kvacekii（C. wehrii（Pentacentron，Tetracentron））））的拓扑结构。对当前可用字符的简约分析表明，魏氏梭菌使Concavistylon具有非一元性。因此，我们将其转移到Paraconcavistylongen。十一月，以垂下而不是直立的花序为特征。我们还重新考虑了已灭绝的Nordenskioeldia（晚白垩世至中新世），其先前在Trochodendraceae中的放置受到了挑战，我们认为它不在该家族的王室成员之列。