Ireland was once home to deer with massive 12-foot antlers

Ireland may not be home to any snakes, but the island’s actual natural past and present is still bustling with other wildlife. It’s currently home to 40 species of land and marine mammals, 12,000 species of insects, and more than 400 bird species. Fearsome wolves used to roam the forests of Ireland, before being hunted into extinction by 1786 These wolves were likely a primary predator of one of the larger players of Irish natural history–the extinct giant deer (Megaloceros giganteus), more commonly known as the Irish elk.

Clocking in at about 6.5 feet tall and weighing upwards of 1,500 pounds, the males boasted antlers over 12 feet wide. By comparison, modern elk have antlers that are about four feet across. These enormous Ice Age mammals were the largest deer in Europe.

While they are primarily associated with Ireland, they have been found from the current western edge of the continent east towards Russia’s Lake Baikal. A 17,000 year-old cave painting in southern France depicts a deer with enormous antlers that archaeologists believed could be Megaloceros. Additional specimens have also been uncovered in Asia and Northern Africa. Megaloceros was first uncovered in a bog in Ireland and scientifically described in the 1690s, but its fossils continue to be uncovered all over the island.

[Related: Why doesn’t Ireland have snakes?]

“Despite Ireland being a tiny place, we have a lot of modern deer and a lot of giant deer deposits,” Paolo Viscardi, Keeper of Natural History at the National Museum of Ireland in Dublin tells PopSci. “The depositional environment is just perfect and the preservation of these animals is incredible. There’s just this massive constant stream of giant deer turning up here.”

Heavy heads

Despite most museums listing the animal as an elk, Megaloceros was a deer. Their antlers were made of strong bone. This sturdy bone is one reason why they are more well-preserved than animal horns that are made of keratin. This same material that makes human hair and fingernails, that withers away over time. Horns are also more permanent like the ones found on a bighorn sheep.

The earliest fossils of Megaloceros date back about 400,000 years and the most recent fossil is roughly 8,000 years old. Some Megaloceros antler fossils have been found completely detached, while others have been uncovered still connected to the skull.

Giant Irish Deer Megaloceros giganteus in National Museum of Ireland. This room is also affectionately known as the Dead Zoo. CREDIT: Paolo Viscardi, CC BY-SA 4.0.

“The anatomy is just really interesting because they’re so big,” said Viscardi. “I’ve handled quite a lot of them and when you pick them up, you realize just how much they weighed. It’s really incredible that an animal not only grew this, but then walked around with it every day, on its head, and managed to use it to fight with.”

Antlers in the rut

Like deer, they shed these antlers every year. Paleontologists believe that the males had extra thick skulls and sturdy neck vertebrae to carry these antlers. Reproduction was also the primary reason for these enormous appendages, since males used them to fight one another for mates the way modern deer and elk do.

“It was signaling to other males that you’re not to be messed with, which really helps when it comes to that in the actual nitty gritty of the fighting,” says Viscardi.

[Related: How do deer grow antlers so quickly?]

Megaloceros was likely a very opportunistic eater, grazing on whatever plants were available. While it was primarily an herbivore, they may have dined on some animal parts, since this annual competition for mates took up enormous amounts of energy.

“I would be more surprised than not if they didn’t eat bits of animal remains,” says Viscardi. “I suspect the males would have actually actively sought out bones and the leftovers from scavengers and carnivores to feed on. It’s something you see today with a lot of deer. They’ll nibble on bits of bone they find to get the nutrients and minerals out.”

The knee bone of a male Megaloceros. CREDIT: Paolo Viscardi, CC BY-SA 4.0.

While having such large antlers benefited the species as a whole for reproductive survival, it came at a high individual cost. According to Viscardi, some of the specimens that have been found with antlers intact likely died shortly after the rut because they just did not have enough food to keep going. The fossils of large groups of males have been found together in bogs and farmland throughout Europe, many of whom likely did not have a chance to get enough food before the winter set in.

A drawn out extinction

Extreme cold also likely played a role in their extinction in parts of western Europe. Their first wave of extinction began about 12,000 years ago. The giant deer began to disappear from present day Ireland and most of Europe when the climate began to cool.

“Food becoming less available and reproduction rates going down is probably what drove the extinction in Ireland,” said Viscardi. “As it gets colder, the quality of the food availability goes down.

[Related: Researchers retraced a woolly mammoth’s steps 17,000 years after it died.]

However, their extinction was not a one and done event. Some fossils uncovered in central Russia reveal that there was an enclave of giant deer alive as late as 8,000 years ago. This last population of giant deer may have gone extinct due to a water climate, unlike their counterparts in Western Europe who disappeared due to extreme cold and ice. In a warmer world, they would have had to navigate increasing forests with their huge antlers and there would have been less grassland available for them to feed on.

In some parts of Europe, they may have faced pressure from humans, as Neolithic settlements were beginning to expand when they went extinct. Humans removing a lot of vegetation could have put them under continued stress, but it was still glaciers and extreme cold that most likely led to their extinction in Ireland.

“I don’t think there’s any really good evidence that humans turned up on the scene in Ireland, and we’re hunting or anything like that,” said Viscardi. “It’s very much more about the climate getting less hospitable.”