无齿龙属（属名：Henodus）又名无盾齿龙，身长约1公尺（3呎），是种生存于晚三叠纪卡尼阶的楯齿龙类，化石发现于德国图宾根。

无齿龙外表极度类似乌龟。如同乌龟，无齿龙背上有甲壳，腹部有腹甲。甲壳由独立的角质鳞甲构成，范围向外延伸超过四肢。与乌龟相比，无齿龙的甲壳由更多鳞甲构成。甲壳固定于牠的脊椎骨，四肢位于正常的位置，而乌龟的四肢是位在胸腔以内。无齿龙的四肢结构虚弱，显示牠们很少时间处在陆地上。

无齿龙仍然有两颗牙齿，各自位于嘴的上下两侧，其他的牙齿由喙状嘴取代。这些平坦的牙齿可用来压碎住在海床上的贝类。头部前半部呈方形。无齿龙最著名的地方在于牠是唯一在非海洋冲积层中发现的楯齿龙类，显示牠们可能生活在稍微咸水或是淡水的潟湖。

Henodus chelyops ("Turtle-Faced Single Tooth") was a placodont of the Late Triassic period during the early Carnian age. Fossils of Henodus chelyops were found in Tübingen, Germany. It was around 1 metre (3.3 ft) in length.

Henodus was the placodont that had the greatest (albeit superficial) resemblance to a turtle. Like turtles, it had a shell formed from a plastron on the underside and a carapace on top. The carapace extended well beyond the limbs, and was made up of individual plates of bony scutes covered by plates of horn. However, the shell was composed of many more pieces of bone than that of turtles, forming a mosaic pattern. The armor was fused to its spine, and its limbs were situated in normal positions, unlike the turtle, where they are located inside the ribcage. The weak limbs of Henodus suggest it spent little, if any time on land.