About Ankylosaurus
| Scientific Name (Genus) | Ankylosaurus |
| Meaning of Name | Fused lizard ankylōsis (fused) [Greek] - sauros (lizard) [Greek] |
| Classification | Ornithischia, Thyreophora, Ankylosauridae |
| Total Length | Approx. 6-8m |
| Diet | Herbivorous |
| Period | Late Cretaceous (approx. 68-66 million years ago) |
| Species Name | Ankylosaurus magniventris |
| Year of Paper Publication | 1908 |
| Genus Name Publication | Brown, B.; Kaisen, P. C. (1908). The Ankylosauridae, a new family of armored dinosaurs from the Upper Cretaceous. Bulletin of the AMNH, 24. |
The Famous Yet Mysterious "Living Fortress"
Ankylosaurus is one of the most famous dinosaurs, synonymous with the term "armored dinosaur," and a hallmark of the end of the Cretaceous period. Its name means "fused lizard," derived from the heavy armor that covered its entire body.
However, contrary to its fame, a complete, fully articulated skeleton has yet to be discovered. The image we have of Ankylosaurus is a reconstruction based on fragmentary fossils such as skulls, armor, and tail clubs, supplemented by more complete fossil records of its close relatives (like Euoplocephalus).
Ankylosaurus is thought to have fed on soft, low-lying plants like ferns. Its teeth were small and weak, so it couldn't chew tough plants. Instead, it likely used its wide beak to crop vegetation and swallow it with minimal chewing. A 2017 study estimated that it needed to eat about 60 kg of ferns per day.
The defense of Ankylosaurus was thorough. Not only did it have various large and small bony plates (osteoderms) covering its back and head, but it also had bony, shutter-like armor over its eyelids. This allowed it to protect its vulnerable eyes.
Furthermore, CT scans of its skull have revealed a highly complex and convoluted nasal passage. Interesting theories suggest this structure may have functioned like an "air conditioner" to warm and moisten inhaled air, or as a "resonance chamber" to produce loud vocalizations.
A Tail Club to Crush Tyrannosaurus
The greatest weapon of Ankylosaurus was the massive bony mass at the end of its tail, commonly known as a "tail club." This club was formed from two large and one small central osteoderm, each semi-circular in shape. The bones in the latter half of the tail were fused together to form a stiff rod, acting as a "handle" for swinging the club. Meanwhile, the muscles at the base of the tail were very flexible, allowing it to swing the club with great speed and force from side to side.
According to a 2009 study, a strike from this club could reach a maximum impact of 364-718 MPa (megapascals). This is equivalent to about 50 times the pressure of a pressure washer and was powerful enough to shatter the leg bones of a contemporary Tyrannosaurus. It was truly the ultimate defensive weapon.
Paper Description and the Tail Club
The tail club was not depicted in the initial description.
Source: Brown, B.; Kaisen, P. C. (1908). The Ankylosauridae...
In 1906, an expedition from the American Museum of Natural History led by paleontologist Barnum Brown discovered fossil specimens including the top of a skull, teeth, back armor, vertebrae, and ribs in the Hell Creek Formation of Montana, USA. Based on this collection of fossils, cataloged as specimen number AMNH 5895, Ankylosaurus magniventris was described as a new genus and species in 1908.
In this paper, the characteristic tail club of Ankylosaurus was not reconstructed, as the end of the tail was unknown at the time.
In 1910, Barnum Brown discovered ribs, limbs, armor, and a tail club in the Scollard Formation in Alberta, Canada. Based on these specimens, known as AMNH 5214, the tail club (bony mass) was described for the first time.
In 1947, fossil collector Charles M. Sternberg unearthed an Ankylosaurus skull (specimen CMN 8880), which is now one of the most famous Ankylosaurus specimens, just 1 km north of Brown's 1910 discovery site.
"Anguirus" in the Godzilla Film Series
Ankylosaurus also served as the model for "Anguirus" in the Godzilla film series. In the movie's lore, Anguirus is an Ankylosaurus that was mutated and reawakened by a hydrogen bomb test. It first appeared in the 1955 film 'Godzilla Raids Again' and holds a special place in the series' history as "the first monster Godzilla ever fought on screen." Initially appearing as Godzilla's enemy, in the later Showa series, Anguirus was reintroduced as Godzilla's reliable "partner and ally," fighting alongside him for the peace of the Earth, a change that is significant to fans.
While Ankylosaurus was about 6-8 meters long, the Anguirus that first appeared in the Godzilla series was 100 meters long.
Ankylosaurus Stamp & Fossil Gallery
