Mannion Philip D
Department of Earth Science and Engineering, Imperial College London, London, UK.
PeerJ. 2019 Jan 24;7:e6348. doi: 10.7717/peerj.6348. eCollection 2019.
The Jurassic/Cretaceous (J/K) boundary, 145 million years ago, has long been recognised as an extinction event or faunal turnover for sauropod dinosaurs, with many 'basal' lineages disappearing. However, recently, a number of 'extinct' groups have been recognised in the Early Cretaceous, including diplodocids in Gondwana, and non-titanosauriform macronarians in Laurasia. Turiasauria, a clade of non-neosauropod eusauropods, was originally thought to have been restricted to the Late Jurassic of western Europe. However, its distribution has recently been extended to the Late Jurassic of Tanzania (), as well as to the Early Cretaceous of the USA ( and ), demonstrating the survival of another 'basal' clade across the J/K boundary. Teeth from the Middle Jurassic-Early Cretaceous of western Europe and North Africa have also tentatively been attributed to turiasaurs, whilst recent phylogenetic analyses recovered Late Jurassic taxa from Argentina and China as further members of Turiasauria. Here, an anterior dorsal centrum and neural arch (both NHMUK 1871) from the Early Cretaceous Wealden Supergroup of the UK are described for the first time. NHMUK 1871 shares several synapomorphies with Turiasauria, especially the turiasaurs and , including: (1) a strongly dorsoventrally compressed centrum; (2) the retention of prominent epipophyses; and (3) an extremely low, non-bifid neural spine. NHMUK 1871 therefore represents the first postcranial evidence for Turiasauria from European deposits of Early Cretaceous age. Although turiasaurs show clear heterodont dentition, only broad, characteristically 'heart'-shaped teeth can currently be attributed to Turiasauria with confidence. As such, several putative turiasaur occurrences based on isolated teeth from Europe, as well as the Middle Jurassic and Early Cretaceous of Africa, cannot be confidently referred to Turiasauria. Unequivocal evidence for turiasaurs is therefore restricted to the late Middle Jurassic-Early Cretaceous of western Europe, the Late Jurassic of Tanzania, and the late Early Cretaceous of the USA, although remains from elsewhere might ultimately demonstrate that the group had a near-global distribution.
侏罗纪/白垩纪(J/K)边界形成于1.45亿年前,长期以来一直被认为是蜥脚类恐龙的一次灭绝事件或动物群更替,许多“基干”谱系消失。然而,最近在早白垩世发现了一些“已灭绝”的类群,包括冈瓦纳的梁龙科,以及劳亚大陆的非泰坦龙形大鼻龙类。图里亚龙类是一类非新蜥脚类真蜥脚类恐龙,最初被认为仅分布于西欧的晚侏罗世。然而,其分布范围最近已扩展到坦桑尼亚的晚侏罗世(),以及美国的早白垩世(和),这表明另一个“基干”类群在J/K边界两侧都有生存。来自西欧和北非中侏罗世-早白垩世的牙齿也初步被归为图里亚龙类,而最近的系统发育分析将来自阿根廷和中国的晚侏罗世分类单元归为图里亚龙类的其他成员。在此,首次描述了来自英国早白垩世威尔德超群的一枚前部背椎椎体和神经弓(均为NHMUK 1871)。NHMUK 1871与图里亚龙类有几个共同衍征,特别是图里亚龙类和,包括:(1)椎体强烈背腹向压缩;(2)保留明显的上突;(3)神经棘极低且不分叉。因此,NHMUK 1871代表了早白垩世欧洲沉积物中图里亚龙类的首个颅后证据。尽管图里亚龙类显示出明显的异形齿,但目前只有宽阔的、典型的“心形”牙齿才能可靠地归为图里亚龙类。因此,一些基于欧洲以及非洲中侏罗世和早白垩世的孤立牙齿而推测的图里亚龙类出现地点,不能可靠地归为图里亚龙类。因此,图里亚龙类的确切证据仅限于西欧的中侏罗世晚期-早白垩世、坦桑尼亚的晚侏罗世以及美国的早白垩世晚期,尽管其他地方的化石最终可能表明该类群分布近乎全球。