The Irish elk (Megaloceros giganteus) is an extinct species of deer known for having the largest antlers of any known deer species.
Notes on verification
Confirmed by multiple independent, reputable sources including Britannica, Guinness World Records, and New World Encyclopedia, with consistent measurements of antler span up to 3.6-4m and weight ~40-45kg. Minor nuance from a specialist source about relative (vs absolute) antler size does not undermine the core claim.
Sources
- Biggest. Antlers. Ever. Meet the Irish Elk (smithsonianmag.com)
- https://www.guinnessworldrecords.com/world-records/70517-largest-prehistoric-antlers (guinnessworldrecords.com)
- https://www.newworldencyclopedia.org/entry/Irish_Elk (newworldencyclopedia.org)