In the Late Triassic the landscape NE of present-day Bristol, SW England was dominated by Carboniferous Limestone ridges and cuestas that became progressively buried by continental Mercia Mudstones and finally inundated during the Rhaetian marine transgression. Mussini et al. (2020) adopt the assertions of earlier collaborators back to Whiteside and Marshall (2008) that terrestrial vertebrate assemblages from sediments contained within karstic fissure systems in the former limestone ridges at Cromhall, Tytherington and elsewhere are restricted to the Rhaetian. We review and reject the sedimentological, stratigraphic, geomorphological and topographic arguments for this and reassert a long pre-Rhaetian (Norian) history for the vertebrate-bearing fissure systems at both Tytherington and Cromhall. We also reject the contemporaneous Rhaetian freshwater-seawater mixing zone dissolution model for the fissure systems adopted by Mussini et al. (2020) and reaffirm that the Tytherington and Cromhall fissures developed as conduit caves with a long Triassic history. Applying a new regional study of the Rhaetian transgressive surface, we also show that whilst the fissures at Cromhall remained sealed after the Norian, those at nearby Tytherington were re-exposed in the Late Rhaetian. Already partially filled with Norian sediments, the Tytherington fissures were subject to reworking on the seabed. Internal collapses, probably triggered by well documented repeated regional seismicity, led to the chaotic state of the Tytherington fills when downward moving Rhaetian marine components came to lie amongst and mix with earlier Norian terrestrial sediments. The vertebrate associations in the Tytherington fissures therefore contain a substantial Rhaetian input whilst those at Cromhall do not.

在三叠纪晚期，今天的西南英格兰布里斯托尔的景观东北部由石炭系石灰岩山脊和cuestas所主导，后来逐渐被大陆的Mercia泥岩掩埋，并在Rhatian的海侵中最终被淹没。穆西尼（Mussini）等。（2020）采用早期合作者的断言回到怀特塞德和马歇尔（Whiteside and Marshall，2008）的观点，即陆生脊椎动物的组合来自克罗姆霍尔，泰瑟灵顿和其他地方的前石灰岩山脊的岩溶裂隙系统中所含沉积物。为此，我们审查并拒绝了沉积学，地层学，地貌学和地形学的论据，并重申了泰瑟灵顿和克罗姆霍尔的带脊椎动物裂隙系统的拉脱纪前（诺里安）前的悠久历史。我们还拒绝了Mussini等人采用的裂隙系统同期的Rheatian淡水-海水混合区溶解模型。（2020年），并重申Tytherington和Cromhall裂缝是具有悠久的三叠纪历史的导管洞穴。应用对Rhaetian海侵表面的新区域研究，我们还表明，尽管在Norian之后Cromhall的裂隙仍保持封闭，但附近Tytherington的裂隙在Rhaetian后期被再次暴露。泰瑟灵顿裂缝已经部分充满了诺里亚沉积物，正在对海底进行修复。内部塌陷可能是由有据可查的反复区域地震活动引发的，当向下移动的Rhaetian海洋成分位于其中并与较早的Norian陆相沉积物混合时，导致Tytherington填充物处于混乱状态。