Your Daily Fossil

Saichania

Mounted specimen on display at Dinosaur Kingdom, in Nakasato, Japan 

Reconstruction by Andrey Atuchin

When: Late Cretaceous (~83 to 70 million years ago)

Where: Mongolia 

What: Saichania was an armored plant eating dinosaur that roamed the deserts of Mongolia in the late Cretaceous. It was about 22 ft (~6 meters) long and heavily built. It was more fearsome looking than most armored dinosaurs as it did not just have flat armor plates on its body, but rather was covered with spikes. These dinosaurs were armored all over, there is even evidence of armored eyelids! This suit of armor would have protected Saichania from predators in the late Mesozoic mongolian desert. Fossils are typically found in deserts and badlands worldwide, but typically these areas were very different environments when the species represented by the fossils were alive. The ancient Gobi Desert was much closer to the harsh modern environment than most. Saichania was well adapted for desert life, with its stocky body and teeth designed for grinding the toughest of the desert plants. 

Saichania falls within Ankylosauridae, a group of armored dinosaurs found almost worldwide. It is one of the last and most derived of the ankylosaurids. One good way to differentiate the deserved ankylosaurids from their armored close relatives is the presence of a tail club. Saichania did not have the most massive club known, but it was still a significant feature. Ankylosaurids were one of the dinosaur groups that made it right up to the end of the Cretaceous period, vanishing with the rest of the non-avian dinosaurs. 

Doedicurus 

Skeleton on display at the Museo Histórico Nacional in Buenos Aires, Argentina. 

When: Pleistocene (2 million to 11,000 years ago)

Where: South America

What: Doedicurus is a glyptodont. The Glyptodontidae were a subclade of armadillos that ranged throughout South America (and North after the land bridge reappeared). Doedicurus was one of the largest glyptodons, coming in at about 12 feet (~3.6 meters) long. Its shell was gigantic, a grown person can crawl inside one of these structures, and there has been some theories that ancient peoples could have used these shells for shelter.  The shell of Doedicurus, like all glyptodonts, was different from that of the living armadillos. The carapaces were thicker and in one solid piece, unlike the several segments present in armadillos that allow them to curl into a ball. Doedicurus had a highly domed shell, that connected to its pelvis posteriorly, but was separated from its shoulder girdle. It has been speculated that glyptodons with this type of shell stored fat in this space above the shoulders, such as a modern camel stores fat in its hump. Doedicurus also had an armored skull cap, which you can see in the fossil image but sadly has been omitted from the reconstruction. 

One of the most distinctive features of Doedicurus is its spiked tail club. In most of these entries when I present something cool that you can imagine being used in intraspecific competition I have to say ‘but it was just for display or protection’. NOT THIS TIME. There is a great amount of evidence for the hypothesis that these spiked tail clubs were used in battles between males. Not all specimens of Doedicurus have a well developed pedestal for the spikes, leading researchers to conclude this was only present in males. It is very unlikely this would have been anymore of a deterrent for predators than the large shell in the first place, and just as unlikely that Doedicurus would have been agile enough to defend itself from a swift carnivorous attacker with this club. Most compelling of all, several Doedicurus specimens have been found with healed wounds in their carapaces that match the predicted impact from a rival’s tail club. 

Doedicurus, like all of the remaining glyptodonts, went extinct about 11-10,000 years ago, at the end of the last major glaciation.