A new lepidosauromorph reptile from the Middle Triassic (Ladinian) of Germany and its phylogenetic relationships

Although lepidosaurs are by far the most diverse and widespread group of present-day nonavian reptiles, with over 10,000 formally named species, their early diversification is documented only by a handful of incomplete fossils with few diagnostic features. Recent excavations in strata of the Lower Keuper (Middle Triassic: Ladinian) of Baden-Württemberg, Germany, have yielded abundant skeletal remains of a diversity of small- to medium-sized diapsid reptiles, which include at least three taxa of lepidosauromorphs. One, here named <i>Fraxinisaura rozynekae</i>, is a small-bodied reptile characterized by (1) maxillary and dentary tooth crowns conical, with lingual striae near their apices; (2) maxilla with a dorsoventrally low facial process and long tooth-bearing portion anterior to this process; (3) jugal with a short anterior process and a very short, pointed posterior process; and (4) ilium with a tall, posterodorsally extending blade. Tooth implantation is pleurodont. Size variation in the sample sheds some light on ontogenetic changes, mainly affecting the shape of and ornamentation on cranial bones. Phylogenetic analysis recovered <i>Fraxinisaura rozynekae</i> among Lepidosauromorpha and as the sister taxon of the Middle to Late Jurassic <i>Marmoretta oxoniensis</i>. Unfortunately, currently existing character-taxon matrices do not allow confident resolution of the interrelationships of these and other early Mesozoic lepidosauromorph reptiles. http://zoobank.org/urn:lsid:zoobank.org:pub:02C69A1C-FCC8-4D0C-BA71-79BA30BC9DA7 SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Schoch, R. R., and H.-D. Sues. 2018. A new lepidosauromorph reptile from the Middle Triassic (Ladinian) of Germany and its phylogenetic relationships. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1444619.

尽管鳞龙类（lepidosaurs）是现生非鸟类爬行动物中多样性最高、分布最广的类群，目前已正式命名的物种超过10000种，但它们的早期演化辐射仅能通过少量保存残缺、鉴别特征稀少的化石得以佐证。
近期在德国巴登-符腾堡州下凯珀地层（中三叠世：拉丁阶）的发掘工作中，出土了大量中小型双弓类（diapsid）爬行动物的骨骼化石，其中至少包含3个鳞龙形类（lepidosauromorphs）类群。
其中一个新属种被命名为*Fraxinisaura rozynekae*，该类群为小型爬行动物，具有以下鉴别特征：（1）上颌骨与齿骨的齿冠呈锥形，齿冠舌面近顶端处具细纹；（2）上颌骨的面突（facial process）背腹向低矮，该突前方的牙齿承载段较长；（3）轭骨（jugal）的前突较短，后突极短且尖锐；（4）髂骨（ilium）具高耸且向背后方延伸的骨板。其牙齿着生方式为侧生齿（pleurodont）。
样本中的个体大小差异为个体发育变化提供了参考依据，这些变化主要影响头骨骨骼的形态与表面纹饰。
系统发育分析结果显示，*Fraxinisaura rozynekae*隶属于鳞龙形类（Lepidosauromorpha），且与中晚侏罗世的*Marmoretta oxoniensis*互为姊妹群。
遗憾的是，当前已有的性状-类群矩阵（character-taxon matrices）尚无法明确解析该类群与其他早中生代鳞龙形类爬行动物之间的系统发育关系。
zoobank注册号：http://zoobank.org/urn:lsid:zoobank.org:pub:02C69A1C-FCC8-4D0C-BA71-79BA30BC9DA7
补充数据：本文可免费获取补充材料，访问网址为www.tandfonline.com/UJVP
本文引用格式：Schoch, R. R. 与H.-D. Sues，2018年。《产自德国中三叠世拉丁阶的鳞龙形类爬行动物新属种及其系统发育关系》，《脊椎动物古生物学杂志》。DOI: 10.1080/02724634.2018.1444619.