I have recently watched a documentary about prehistoric animals and wondered what used to occupy this land. Did we have bus-sized moose roaming our bogs or toaster-sized chipmunks scampering about the forest? Maybe not exactly, but there were some interesting beasties eons ago across this great nation. Here are just my top ten selections:

  • Giant beavers – What is more Canadian than the humble, hard-working beaver? Castoroides was a giant beaver that lived across North America during the Pleistocene. The first time I saw a modern day beaver I was shocked at their size but these forefathers of these guys were the size of a modern black bear, making them the largest rodent to ever roam the planet. They could grow as large as 2.2 meters with a weight up to 77 kg.

The giant beaver’s body differed a little from his modern cousin with were much broader and bigger measuring to a whopping 15 cm. These teeth were not as efficient at felling trees so they did not make dams like modern beavers. They also had proportionately smaller brains so it is speculated that were not as successful within their environment.

  • Mastodon and Mammoths – The mastodon and its cousin the mammoth were shaggy elephants that once roamed across North America and Eurasia. They were similar in size but differed in a couple of ways: mastodons were probably a little smaller than mammoths with shorter legs and lower flatter heads; their respective teeth were different to reflect the different vegetation they ate. Mammoths grazed across open areas like modern elephants while mastodons lived in forests; mammoths had curved tusks and high shoulders and mastodons had straighter tusks and lower shoulders.
  • Dire wolf – Those of you that watch Game of Thrones may have heard of this beast but did you know that they actually existed 125,000-9440 years ago? They were slightly larger than modern day gray wolves making it the largest wolf ever to have existed. They had smaller feet but a substantially larger head than the gray wolf. They weighed on average 68 kg with some being larger, in comparison to the 21-55 kg of the modern canine.
  • Short-faced bear – This extinct bear once roamed across North America until approximately 11,000 years ago. They received their name from their disproportionately shorter snout (than the average bear). These bears were huge; weighing an estimated 900-957 kg and standing between 2.5-3.7 meters tall with a 4 m vertical arm reach. To give you an idea on how big that is, this guy could look a 6’ man in the eye while walking on all fours. Researchers think that these bears were less of a scavenger than modern bears but were still omnivores.
  • Harlan’s muskox – This extinct bovid’s closest relative is today’s tundra muskox that was widely distributed across North America. They even lived in warmer climes as opposed to modern day Muskox that are restricted to the arctic tundra. Harlan’s were much taller and leaner and weighed as much as 425 kg. They had a thicker skull and longer snout than their modern cousin. The horns were placed high upon the skull with a downward curve and were fused along the midline; modern muskoxen have a center medial groove.

These goliaths of the Pleistocene became extinct mostly between the Pleistocene and Holocene epoch and it has been hypothesized that it was due to the appearance of humans to North America and natural climate change. This extinction entailed the elimination of all the larger mammals over 100 kg. This was the end of the last ice age and the melting ice caps probably played a big role. This period found more mammals surviving this period than were forced over the edge. Bison, gray wolf, lynx, grizzly and black bears, and deer all survived from this time. Maybe this is good news for our current extinction event.

–Janice Willson

Photo source: Public Library of Science

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