A more than 30-year mystery over the discovery of a bizarre extinct species of deer has been solved. In labs across the country, researchers have found a reason to be optimistic. They discovered Torontoceros hypogaeus, the “Toronto subway deer,” when digging the new subway extension Toronto in 1976. This important discovery has since added to our knowledge of ancient cervids and their evolutionary relationship to modern species.
As a result, the subway construction uncovered antlers with unusual, rather flat, thick beams that horizontally extended outward, which really piqued the interest of paleontologists. Recently named from the Greek for “horned Toronto deer from underground,” Torontoceros hypogaeus has puzzled scientists for decades. Recent research by Dr. Aaron Shafer and Dr. Camille Kessler shows just how evolutionary important this saltwater intrusion problem is. Their findings further underscore its connection to today’s deer.
Research Findings
The researchers conducted a large-scale study. They sequenced DNA from about two dozen ancient cervid specimens, including ancestors of today’s deer, elk, moose, and caribou. Then they compared the DNA of Torontoceros hypogaeus to these samples. This phylogenetic analysis showed a strong affinity of Torontoceros with mule deer and white-tailed deer.
EcoHealth Alliance’s Dr. Aaron Shafer was enthusiastic about this finding, calling it “like their grandparent.” It’s a great analogy, because by studying this long-extinct species, we can learn much about how the deer we are all familiar with today evolved.
The full research has been recently published in the journal Biology Letters. It’s available on the bioRxiv preprint server, where it has DOI 10.1101/2025.09.15.676284.
Significance of the Discovery
With Torontoceros hypogaeus now added to the list of extinct Ice Age megafauna, its study aims to broaden the understanding of how modern deer species might respond to ongoing environmental changes. The implications of these prehistoric discoveries go far beyond understanding ancient ecosystems — they offer a glimpse into biodiversity to come.
Today, one of the first described Torontoceros hypogaeus specimens resides at the Royal Ontario Museum in Toronto, Canada. Researchers examining the evolutionary history of cervids are equally fascinated by this exceptional specimen.
Implications for Future Research
The ramifications of this study go beyond just historical interest. As climate change poses new challenges for wildlife, studying how ancestral species adapted to their environments could inform conservation efforts for current deer populations.
Anatomical data from Torontoceros hypogaeus can have important bearing on efforts to protect existing taxa of cervids. That’s how we’ll succeed in safeguarding their survival in our increasingly fast-paced, technologically enhanced world.