The fossilized remains of a 5.3cm specimen.

Specimen from trilobite beds on Mount Stephen. Displayed in the Royal Ontario Museum, photo taken by Jean-Bernard Caron.[1]

Zacanthoides is an extinct genus of benthic carnivorous trilobite from the Cambrian era. The genus' type species is Z. romingeri, named after the discoverer of the creature.


In 1887 Carl Rominger published an engraving of a nearly complete and markedly spiny trilobite and named it Embolimus spinosa. In 1908 Charles Walcott introduced the combination Zacanthoides spinosus for the Mount Stephen species and for a similar trilobite from Nevada. The next change came in 1942, when Charles Resser at the United States National Museum asserted that the Mount Stephen species was sufficiently distinct that it required a new name. Resser chose to honor the man who first formally described many of the common Mount Stephen trilobites, and Zacanthoides romingeri remains the combination in use today.

  1. Caron, J. B. (n.d.). [Photograph]. Royal Ontario Museum, Toronto, Canada. https://burgess-shale.rom.on.ca/fossils/zacanthoides-romingeri/