Riches of the Roma valley: theropod and ornithischian tracks from the Early Jurassic southern Africa

The Upper Triassic – Lower Jurassic Stormberg Group, main Karoo Basin, is notably rich in diverse dinosaur trace fossils, particularly in the Roma Valley of western Lesotho. Here, we document in detail, for the first time, the Mokhosi ichnosite (Roma Valley), initially reported simply as preserving tridactyl tracks. Thirty-five pes tracks were identified, predominantly preserved as bipedal and quadrupedal trackways attributable to theropod and ornithischian trackmakers. Three distinct morphotypes consisting of pes or manus-pes pairs were assigned to Anomoepus, Eubrontes and tentatively to Kayentapus. Our Morphotype III, although comparable to Kayentapus, preserves quantitative and qualitative features distinct from other large southern African Kayentapus-like tracks, and possesses some characteristics that lean to an ornithischian affinity rather than theropod. Ultimately, the Mokhosi ichnosite contributes to the diverse ichnological record of the Roma Valley, which now includes 15 ichnosites that preserve Anomoepus, Eubrontes, Grallator, Kayentapus and Trisauropodiscus. Furthermore, this site provides essential data for refining our understanding of Early Jurassic ornithischians in Gondwana, which are minor components of the trace- and body-fossil records.

主卡鲁盆地（main Karoo Basin）内的上三叠统-下侏罗统风暴山群（Stormberg Group）产出丰富多样的恐龙遗迹化石，尤以莱索托西部的罗马谷（Roma Valley）最为富集。本研究首次详细记述了罗马谷内的莫科霍西遗迹点（Mokhosi ichnosite），该遗迹点最初仅被报道保存有三趾足迹。研究团队共识别出35处后肢足迹（pes tracks），其中多数以双足、四足足迹链（trackways）的形式保存，造迹者可归为兽脚类（theropod）与鸟臀类（ornithischian）恐龙。研究团队划分出3种不同的形态型（morphotypes），足迹类型涵盖后肢足迹或前后肢成对足迹（manus-pes pairs），分别归为Anomoepus、Eubrontes，暂归为Kayentapus。本研究中的形态型III虽与Kayentapus相似，但其定量与定性特征均区别于南非其他大型Kayentapus类足迹，且部分特征更倾向于鸟臀类亲缘关系，而非兽脚类。综上，莫科霍西遗迹点丰富了罗马谷的遗迹化石记录（ichnological record），目前罗马谷已有15处遗迹点产出Anomoepus、Eubrontes、Grallator、Kayentapus及Trisauropodiscus化石。此外，该遗迹点可为深化我们对冈瓦纳大陆（Gondwana）早侏罗世鸟臀类恐龙的认识提供关键数据，而这类恐龙在遗迹化石与实体化石记录中均属次要类群。