Supplementary Table 3 from Pendraig milnerae, a new small-sized coelophysoid theropod from the Late Triassic of Wales

We describe a new small-bodied coelophysoid theropod dinosaur, Pendraig milnerae gen. et sp. nov, from the Late Triassic fissure fill deposits of Pant-y-ffynnon in southern Wales. The species is represented by the holotype, consisting of an articulated pelvic girdle, sacrum and posterior dorsal vertebrae, and an associated left femur, and by two referred specimens, comprising an isolated dorsal vertebra and a partial left ischium. Our phylogenetic analysis recovers P. milnerae as a non-coelophysid coelophysoid theropod, representing the first-named unambiguous theropod from the Triassic of the UK. Recently, it has been suggested that Pant-y-ffynnon and other nearby Late Triassic to Early Jurassic fissure fill faunas might have been subjected to insular dwarfism. To test this hypothesis for P. milnerae, we performed an ancestral state reconstruction analysis of body size in early neotheropods. Although our results indicate that a reduced body size is autapomorphic for P. milnerae, some other coelophysoid taxa show a similar size reduction, and there is, therefore, ambiguous evidence to indicate that this species was subjected to dwarfism. Our analyses further indicate that, in contrast with averostran-line neotheropods, which increased in body size during the Triassic, coelophysoids underwent a small body size decrease early in their evolution.

我们记述了产自威尔士南部潘特芬农（Pant-y-ffynnon）晚三叠世裂隙充填沉积物中的一种新型小型腔骨龙类（coelophysoid）兽脚类（theropod）恐龙：彭德拉伊格·米尔纳（Pendraig milnerae），新属新种（gen. et sp. nov.）。该物种的标本包括正模标本（holotype），由关节连接的腰带骨（pelvic girdle）、荐椎（sacrum）与后部背椎，以及伴生的左侧股骨（left femur）构成；另有两件归入标本（referred specimens），分别为一枚孤立的背椎与一段部分左侧坐骨（left ischium）。我们的系统发育分析（phylogenetic analysis）显示，P. milnerae属于非腔骨龙科（non-coelophysid）的腔骨龙类兽脚类，是英国三叠纪地层中首个正式命名的确定性兽脚类恐龙。近期有研究提出，潘特芬农及其他邻近的晚三叠世至早侏罗世裂隙充填动物群可能曾经历岛屿矮化（insular dwarfism）。为验证该物种是否存在矮化现象，我们对早期新兽脚类（early neotheropods）的体型开展了祖先状态重建分析（ancestral state reconstruction analysis）。尽管我们的结果表明体型缩小是P. milnerae的自衍征（autapomorphic），但其他部分腔骨龙类类群（taxa）也呈现出类似的体型缩减现象，因此尚无明确证据表明该物种曾经历矮化。我们的分析进一步显示，与三叠纪体型逐渐增大的坚尾龙类（Averostra）支系新兽脚类不同，腔骨龙类在演化早期发生了小型化的体型缩减。