Horridus

C. M. Sternberg made one modification, adding T. eurycephalus and suggesting that it linked the second and third lineages closer together than they were to the T. horridus lineage.

Description Size of T. prorsus (orange) and T. horridus (green) compared to a human.

In the first attempt to understand the many species, Lull found two groups, although he did not say how he distinguished them: one composed of T. horridus, T. prorsus, and T. brevicornus; the other of T. elatus and T. calicornis.

The fossils, he argued, are indistinguishable from the T. horridus specimens that were previously attributed to the defunct species T. serratus.