A large population of Late Cretaceous Lychnothamnus tenuis holding small sized gyrogonites are described after systematically sampling the Fronteras section in the Cabullona Group (northeastern Sonora, Mexico). This discovery represents the oldest record of Lychnothamnus in North America and the first record of this genus in Mexico. The sedimentological analyses of the section suggest that Mexican L. tenuis grew in fluvial and floodplain ephemeral ponds such as their South American counterparts, Lychnothamnus barbosai (oldest known world-wide occurrence of Lychnothamnus) and L. tenuis, from the Turonian–Santonian and Santonian–lower Campanian respectively. The small sized gyrogonites (calcified fructifications of charophytes) of L. tenuis from South America was considered to represent an adaptation to stressful growth conditions since most of the fossil and extant Lychnothamnus species are mainly found in freshwater lacustrine deposits. However, this floodplain-type environment has also been described for a small population of Lychnothamnus sp. recently recovered from the lower Eocene Claron Formation (Utah, USA) and for extant Lychnothamnus barbatus found in Australia, both populations having medium to large gyrogonites. This suggests that rather than being a response to ecological parameters, the gyrogonite size of Lychnothamnus is related to the evolutionary trend of the genus, producing smaller gyrogonites when first appeared in the Upper Cretaceous. Finally, the presence of L. tenuis in Sonora (North America) suggests a south to north colonization route for L. tenuis during the Late Cretaceous.

在对Cabullona组（墨西哥北索诺拉）的Fronteras剖面进行系统采样后，描述了一大批携带小型陀螺的晚白垩世Lychnothamnus tenuis。这一发现代表了北美Lychnothamnus的最古老记录，也是墨西哥该属的第一个记录。该部分的沉积学分析表明，墨西哥L. tenuis生长在河流和洪泛临时池中，例如南美对虾，Lychnothamnus barbosai（世界上最古老的Lychnothamnus发生）和L. tenuis，分别来自Turonian-Santonian和Santonian-lower Campanian。由于大多数化石和现存的Lychnothamnus物种主要存在于淡水湖相沉积物中，因此，来自南美的L. tenuis的小型陀螺体（钙化的钙藻土的果粒化）被认为代表了对胁迫性生长条件的适应。但是，这种洪泛区类型的环境也被描述为少量的Lychnothamnus sp。最近从较低的始新世克拉隆组（美国犹他州）和现存的Lychnothamnus barbatus采出在澳大利亚发现，这两个种群都具有中到大型的陀螺。这表明，Lychnothamnus的陀螺石大小不是对生态参数的响应，而是与该属的进化趋势有关，当首次出现在上白垩统时会产生较小的陀螺石。最后，在索诺拉（Sonora）（北美）中存在Teneus L. tenuis，表明白垩纪晚期对Tenuis L.的南到北定植路线。