Hallopus was a prehistoric reptile, classified by O. C. Marsh in 1881 as a dinosaur. In fact it was probably a crocodilian or possibly a more primitive crurotarsan, and may be closely related to Junggarsuchus . It was a quite small animal, reaching a length of 1 m (3.3 ft).
- A. D. Walker. A Revision of the Jurassic Reptile Hallopus victor (Marsh), with Remarks on the Classification of Crocodiles. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences Vol. 257, No. 816 (Feb. 26, 1970), pp. 323-372