■Weigeltisauridae是一种小体形的衣壳进化枝,其特征是有角的颅骨褶皱,细长的躯干和四肢,和由细长的骨棒支撑的patagium。部分骨骼和碎片仅在英格兰的上二叠纪(Lopingian)岩石中才能确定,德国,马达加斯加和俄罗斯。尽管有这些发现,很少有关于Weigeltisaurid骨骼的详细描述,许多骨骼元素的同源性-尤其是支撑patagium的杆-仍然是争议的主题。
■这里,我们提供了来自下萨克森州上二叠纪(Lopingian:Wuchiapingian)Kupferschiefer的几乎完整的Weigeltisaurusjaekeli骨架的详细描述,德国。由过去的作者简要论述,骨骼保留了一个几乎完整的头骨,颅后轴骨,阑尾骨骼,和支持。通过与现存和化石衣壳的比较,我们研究了阴囊棒同源性的假设。为了检查Weigeltisauridae的系统发育位置并表征进化枝的形态,我们将材料和其他weigeltisaurids整合到基于简约的系统发育分析中,该系统发育分析侧重于Permo-三叠纪非saurianDiapsida和早期Sauria(61个分类单元,339个字符)。
■我们在这里描述的Weigeltisaurid骨骼中认识到许多有趣的解剖特征,包括后颞叶弓上的空心角,上颌骨后部的披针形牙,没有连接眶后骨和鳞骨的骨弓,细长的指骨,类似于现存的树栖鳞茎,和盘根棒,位于腹壁篮的三分之一的表面。我们的系统发育研究恢复了单系Weigeltisauridae,包括elivensis,Weigeltisaurusjaekeli,和Rautianiaspp.进化枝被回收为Sauria(=LepidosauriaArchosauria)以外的Drepanosauromorpha的姊妹分类单元。
■我们的解剖学观察和系统发育分析显示,在此处描述的标本中,Weigeltisauridae的各种多形性衣壳特征和无性系。我们证实了这样的假设,即骨化是与轴向骨骼无关的真皮骨骼。weigeltisaurids的滑行装置是由其他已知的滑行衣壳中未知的真皮元素制成的。SMNK-PAL2882和其他weigeltisaurid标本突出了古生代衣壳在中生代早期辐射之前的高度形态差异。
BACKGROUND: Weigeltisauridae is a clade of small-bodied diapsids characterized by a horned cranial frill, slender trunk and limbs, and a patagium supported by elongated bony rods. Partial skeletons and fragments are definitively known only from upper Permian (Lopingian) rocks in England, Germany, Madagascar and Russia. Despite these discoveries, there have been few detailed descriptions of weigeltisaurid skeletons, and the homologies of many skeletal elements-especially the rods supporting the patagium-remain the subject of controversy.
METHODS: Here, we provide a detailed description of a nearly complete skeleton of Weigeltisaurus jaekeli from the upper Permian (Lopingian: Wuchiapingian) Kupferschiefer of Lower Saxony, Germany. Briefly addressed by past authors, the skeleton preserves a nearly complete skull, postcranial axial skeleton, appendicular skeleton, and patagial supports. Through comparisons with extant and fossil diapsids, we examine the hypotheses for the homologies of the patagial rods. To examine the phylogenetic position of Weigeltisauridae and characterize the morphology of the clade, we integrate the material and other weigeltisaurids into a parsimony-based phylogenetic analysis focused on Permo-Triassic non-saurian Diapsida and early Sauria (61 taxa, 339 characters).
RESULTS: We recognize a number of intriguing anatomical features in the weigeltisaurid skeleton described here, including hollow horns on the post-temporal arch, lanceolate teeth in the posterior portion of the maxilla, the absence of a bony arch connecting the postorbital and squamosal bones, elongate and slender phalanges that resemble those of extant arboreal squamates, and patagial rods that are positioned superficial to the lateral one third of the gastral basket. Our phylogenetic study recovers a monophyletic Weigeltisauridae including Coelurosauravus elivensis, Weigeltisaurus jaekeli, and Rautiania spp. The clade is recovered as the sister taxon to Drepanosauromorpha outside of Sauria (=Lepidosauria + Archosauria).
CONCLUSIONS: Our anatomical observations and phylogenetic analysis show variety of plesiomorphic diapsid characters and apomorphies of Weigeltisauridae in the specimen described here. We corroborate the hypothesis that the patagial ossifications are dermal bones unrelated to the axial skeleton. The gliding apparatus of weigeltisaurids was constructed from dermal elements unknown in other known gliding diapsids. SMNK-PAL 2882 and other weigeltisaurid specimens highlight the high morphological disparity of Paleozoic diapsids already prior to their radiation in the early Mesozoic.