ABSTRACT

The holotypic materials of the sauropod ‘Morosaurus’ agilis—a partial skull, proatlases, and first three cervical vertebrae—have been a taxonomic and phylogenetic mystery since their initial description by O. C. Marsh in 1889 and redescription by C. W. Gilmore in 1907. Although most species of Morosaurus were subsumed into Camarasaurus in 1919, ‘M.’ agilis was left in the defunct genus without a proper taxonomic assignment. Similarities have been noted between ‘M.’ agilis and other Morrison Formation sauropod taxa, including Camarasaurus, Haplocanthosaurus, Diplodocus, and Brachiosauridae, but it had yet to be included in a phylogenetic analysis. Here we present new data following additional preparation and study that suggest ‘M.’ agilis is a basally diverging member of Dicraeosauridae, along with the recently described sauropod Kaatedocus. Based upon its recovery as a distinct taxon, we propose that ‘M.’ agilis receive the new generic name Smitanosaurus, yielding the new combination Smitanosaurus agilis.

http://zoobank.org/urn:lsid:zoobank.org:pub:6977D649-EE6B-42EE-9E1C-C043A38AC2AC

摘要

自从1889年由OC Marsh首次描述并由CW Gilmore于1907年对其重新命名以来，蜥脚类恐龙“ Morosaurus ”敏捷的完整材料（部分头骨，小行星和前三个颈椎）一直是分类学和系统发育的谜。的Morosaurus被归入圆顶龙于1919年，“ M. ” AGILIS被留在被禁属没有一个适当的分类分配。相似性已“之间注意到M. ” AGILIS等莫里森形成蜥脚类类群，包括圆顶龙，简棘龙属，梁龙，和腕龙科，但尚未包括在系统发育分析中。以下额外的准备和研究在这里，我们提出了新的数据暗示“ M. ” AGILIS是叉龙科的基部分散部件，与最近描述蜥脚类一起Kaatedocus。基于其作为一个独特类群的恢复，我们建议“米” AGILIS接收新的通用名称Smitanosaurus，产生新的组合Smitanosaurus AGILIS。

http://zoobank.org/urn:lsid:zoobank.org:pub:6977D649-EE6B-42EE-9E1C-C043A38AC2AC