LAUSR

Abstract Ethiopia preserves extensive Mesozoic non-marine sedimentary sequences, but dinosaur fossils are exceptionally rare. The record is limited to a handful of theropod and ornithischian teeth from the Upper Jurassic Mugher Mudstone of the eastern margin of the Northwest Plateau, which has otherwise produced a diverse vertebrate fossil assemblage including actinopterygians, dipnoans, testudineans, crocodyliforms, and mammaliaforms. Here, we report the discovery of the first confirmed sauropod dinosaur from Ethiopia. The tooth BST VP-1/1 comes from a fine-to medium-grained, pebble and clast-rich zone with concentrated lenses of vertebrate microfossils in the lower part of the Mugher Mudstone. BST VP-1/1 is broad crowned, complete to the root, and slightly ellipsoidal midway in cross-section proximally toward the root. The distal half of the tooth has a chisel-like appearance. BST VP-1/1 is planar lingually, convex labially, and narrows apically. These features compare closely with those of early macronarians, such as Giraffatitan brancai from the penecontemporaneous Tendaguru Formation in Tanzania. This specimen demonstrates the presence of sauropods in Ethiopia for the first time, and indicates that macronarians were widespread in East Africa during the Late Jurassic Epoch.