Erlikosaurus (Erlik’s lizard)
Erlikosaurus (Erlik's lizard)
Named By : Altangerel Perle - 1980
Diet : Herbivore / Possible Omnivore ?
Size : Estimated 3.4 meters long
Type of Dinosaur : Small Theropod
Type Species : E. andrewsi (type)
Found in : Mongolia - Bayan Shireh Formation
When it Lived : Late Cretaceous, 99-89 million years ago
Erlikosaurus, which means “Erlik’s Lizard”, is a genus that includes therizinosaurids. It lived in Asia during the Late Cretaceous period. In 1972, fossils of a skull and post-cranial fragments were discovered in the Bayan Shireh Formation in Mongolia. They date to between 96 million and 90 million years ago. Altangerel Perle, Rinchen Barsbold and others later described the remains and named the new species Erlikosaurus. It is the second taxon of therizinosaurs from this formation, along with Segnosaurus and Enigmosaurus.
Erlikosaurus, unlike other therizinosaurids was small and measured in at 3.4m (11ft) in height. It weighed 150 to 250kg (330 to 552 lb) and had a mass of about 3.4m (11ft). The snout tip had a well-developed beak and the jaws were toothed. This was used to eat herbivorous foods. Four toes made up the feet, with the first articulated at the ankle. This is in contrast to most theropods’ vestigial first foot. Erlikosaurus, like other therizinosaurids had a large stomach for food processing, strong arms that ended in elongated claws and a pelvis that was directed backwards.
Within the Therizinosauridae, Erlikosaurus has been classified as a therizinosaur. Therizinosaurs were long mysterious dinosaurs that had unclear relationships in the early years. Later studies revealed their true nature as theropodan dinosaurs and their systematic position among maniraptorans. The Erlikosaurus’ jaws and beak indicate that they used a leaf-stripping method, which was characterized by active use of their beaks with assistance from the neck. Numerous differences between the sympatric Segnosaurus and Erlikosaurus indicate that these genera are niche-partitioned.
The genus Erlikosaurus is difficult to estimate because it is only possible to measure the species from fragmentary material. This is especially true since most of the vertebral column in the holotype has disappeared. The skull of the holotype specimen is approximately 25 cm (250mm) in length, which indicates a small individual. Erlikosaurus was an average-sized therizinosaurid. It measured approximately 3.4m (11 feet) in length and had a lighter build than the more ponderous Segnosaurus. Stephan Lautenschlager, along with his colleagues, used theropod specific equations in 2012 to estimate the Erlikosaurus’s body mass. The femur of Erlikosaurus is not known so they performed bivariate regression analyses using log-transformed log-transformed data. The final results showed that the femoral length was 44.33 cm (443.3mm) and that the weight of 173.7kg (383 lb) were the result. These estimates were uncertain and they gave an overall weight range of 150 to 250 kg (330 – 550 lb). Other estimates suggested a maximum length range of 6m (20ft), a length of 4.5m and a weight of 500kg (1,100 lb). Although Erlikosaurus has no remains of its body, it is likely that Erlikosaurus was a therizinosaurid. It would have had strong arms, large claws, a bulky torso and an opisthopubic pelvis (directed backwards). Based on preserved feather impressions from Jianchangosaurus and Beipiaosaurus, it is clear that therizinosaurs are feathered animals. It is therefore likely that Erlikosaurus is feathered.
MPC-D 100/111 was the holotype specimen. It was found in layers at the Bayshin Tsav location on the Bayan Shireh Formation. The layers contained an extremely well preserved skull, an almost complete right pes, the proximal ends of metatarsals II and III, as well as a nearly complete left humerus. Some fragmentary cervical vertebrae were also found, but the number isn’t known and they weren’t illustrated. These discoveries were made in 1972 during a Soviet-Mongolian expedition to the Omnogovi province. Eight years later, the type species and genus Erlikosaurus andrewsi was described by Altangerel Perle and Rinchen Barsbold. However, Barsbold wasn’t listed as the name-giver for this species. The generic name Erlikosaurus was derived from the Erlikosaurus demon king, Turko-Mongolian mythology, and the Greek sauros (sauros meaning lizard). The name andrewsi is named in honor of Roy Chapman Andrews (American paleontologist), who led the American Asiatic Expeditions (1922-1930). Evidently, a left pes was mentioned in the original description as being part of the holotype. However, this assertion has been omitted.
In 1981, Perle named the species again as if it was new. However, he described the species in greater detail and spelled the generic name in Latin as an “Erlicosaurus”. Most authors today accept that Erlikosaurus is the original name. It was the only known therizinosaur (then known as segnosaurs). This helped to shed light on an obscure and poorly understood group of dinosaurs. It is still the best-known therizinosaurian skull.
Gregory S. Paul challenged this taxon’s validity in 2010. He argued that Enigmosaurus could be synonymous with Enigmosaurus (named 1983), as the pelvis of Erlikosaurus was unknown and the remains of Enigmosaurus were found in the same geologic formation. This would make Enigmosaurus a junior synonym to Erlikosaurus. The holotype hip from Enigmosaurus was not as similar to the Segnosaurus-like remains, and the size difference is significant. Rinchen Barsbold, paleontologist, refuted the claim of synonymy. Enigmosaurus and Erlikosaurus also have remains that can be seen at the upper and lower boundaries, respectively. Enigmosaurus is generally considered a separate genera, while Erlikosaurus is not.