Orthrozanclus (from Greek ὄρθρος + ζᾰ́γκλον (órthros + zánklon), "dawn scythe") is a genus of sea creatures known from two species, O. reburrus from the Middle Cambrian (~505 million years ago) Burgess shale and O. elongata from Early Cambrian (~518 million years ago) Maotianshan Shales.

[4] Jean-Bernard Caron and Donald A. Jackson found a specimen in the Burgess Shale and in 2006 referred to it as "scleritomorph C" without a detailed description.

[5] In 2007 Caron and Simon Conway Morris published a description and named the fossil Orthrozanclus reburrus.

The underside was soft and unarmored, but the upward-facing surfaces were armored by: a small shell, near the front end; three zones of armor plates called "sclerites", which fitted close to the body and one of which ran all the way round the animal; 16 to 20 long, upwards-curving spines on each side of the body.

It also had finely spaced rings that indicate growth by addition of material round the edges, and coarser ridges which may indicate that the animal was metameric, in other words built out of repeated "modules".