Talarurus ( TAL-ə-ROOR-əs; meaning "basket tail" or "wicker tail") is a genus of ankylosaurid dinosaur that lived in Asia during the Late Cretaceous period, about 96 million to 89 million years ago. The first remains of Talarurus were discovered in 1948 and later described by the Russian paleontologist Evgeny Maleev with the type species T. plicatospineus. It is known from multiple yet sparse specimens, making it one of the most well known ankylosaurines, along with Pinacosaurus. Elements from the specimens consists of various bones from the body; five skulls have been discovered and assigned to the genus, although the first two were very fragmented. It was a medium-sized, heavily built, ground-dwelling, quadrupedal herbivore, that could grow up to 5–6 m (16–20 ft) long and weighed about 454 to 907 kg (1,001 to 2,000 lb), nearly a ton. Like other ankylosaurs it had heavy armour and a club on its tail, limiting its speed. Talarurus is classified as a member of the Ankylosauria, in the Ankylosaurinae, a group of derived ankylosaurs. Talarurus is known from the Bayan Shireh Formation, being likely niche partitioned with Tsagantegia, as indicated by its muzzle, which has a rectangular shape specialized for grazing. These represent the oldest known ankylosaurines from Asia, although they are not very closely related to each other. It appears that the closest relative of Talarurus was Nodocephalosaurus, an ankylosaurin with similar facial osteoderms. Most of the skeletal mounts of Talarurus are outdated by numerous issues, such as the ribs pointing downward instead of to the sides, as in most ankylosaurs; an inaccurate skull cast which is mainly based on related species and not on the available skull material; very splayed arms and legs; four digits on the feet, which in reality only had three as indicated by related ankylosaurines. All of these mistakes were made by anatomical misunderstandings since ankylosaurs were not fully known at that time, also, Talarurus is not known from a complete skeleton.
History of discovery
Talarurus remains have been discovered in the southeastern parts of the Gobi Desert in what is now Mongolia. The holotype specimen PIN 557-91 was discovered in 1948 by the Joint Soviet-Mongolian Paleontological Expedition, and unearthed from sandy, red calcareous claystone at the Baynshire locality of the Bayan Shireh Formation. Talarurus was described and named by the Russian paleontologist Evgeny Maleev in 1952. Specimen PIN 557, the original holotype designated by Maleev, included a fragmentary skull with the posterior part of the skull roof, including the occipital region and the basicranium, numerous vertebrae, several ribs, a scapulocoracoid, a humerus, a radius, an ulna, a nearly complete manus, a partial ilium, an ischium, a femur, a tibia, a fibula, a nearly complete pes, and assorted armor and scutes. The generic name, Talarurus, is derived from the Greek τάλαρος ("tálaros", meaning basket or wicker cage) and οὐρά ("ourā́", meaning rear or tail), in a reference to the club end of the tail which bears resemblance to a wicker basket, and the length of the tail which consists of interlaced bony struts, reminiscent of the weave that is employed when making wicker baskets. The specific name, "plicatospineus", is derived from the Latin plicātus (meaning folded) and spīneus (meaning thorny or spiny), in a reference to the numerous osteoderms that gave form to its armor in life. In fact it consisted of fragmentary remains of six individuals discovered at the site. In 1977, Teresa Maryańska chose PIN 557-91, a posterior rear of the skull, as the holotype, given the irregularities of the combined individuals. Also, she renamed Syrmosaurus disparoserratus into a second species: Talarurus disparoserratus. However, in 1987, this was remade into the separate genus Maleevus. Elements of all these specimens were combined into a skeletal mount exhibited at the Orlov Museum. Although very complete, in several aspects the mount is strongly inaccurate. The type and only valid species known today is Talarurus plicatospineus.
Talarurus is now known from at least a dozen individual specimens from various localities. Specimen PIN 3780/1 was collected from terrestrial sediments at the Bayshin-Tsav locality of the Bayan Shireh Formation, by a joint Soviet-Mongolian Paleontological Expedition in 1975 and is now reposited at the Paleontological Institute, Russian Academy of Sciences, in Moscow. This material was assigned to Talarurus and is also considered to date from the Turonian stage of the Cretaceous. This specimen consists of the top of a skull and a fragmentary skeleton. Since 2006, in the context of the Korea-Mongolia Joint International Dinosaur Project, numerous additional specimens have been referred to Talarurus, found at the Baynshire and Shine Us Khuduk localities. These in 2014 were still undescribed. Another specimen referred to this genus from the Bayshin Tsav locality is composed of an (undescribed) incomplete skull with cranial roof, occipital part and braincase. A second undescribed specimen, collected at the Baga Tarjach locality, consists of a fragment of a maxilla with eight teeth. Arbour have listed many of the referred and additional material for Talarurus. Even more additional material has been found. In 2007 during the Korea-Mongolia International Dinosaur Expedition, specimens MPC-D 100/1354, MPC-D 100/1355, and MPC-D 100/1356 were collected from the eastern part of the Gobi Desert, at the Bayn Shire locality in the Bayan Shireh Formation. These specimens were described on detail in 2019, consisting of three medium-preserved skulls with additional anatomical and ecological data for Talarurus. This new material is now permanently housed at the Institute of Paleontology and Geology of the Mongolian Academy of Sciences.
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