Talarurus

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Talarurus
Temporal range: Late Cretaceous, 90Ma
Talarurus plicatospineus.JPG
Skeleton
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Family: Ankylosauridae
Subfamily: Ankylosaurinae
Genus: Talarurus
Maleev, 1952
Species: † T. plicatospineus
Binomial name
Talarurus plicatospineus
Maleev, 1952

Talarurus (/ˌtæləˈrʊərəs/ TAL-ə-ROOR-əs) is an extinct genus of ankylosaurid dinosaur that lived approximately 90 million years ago during the latter part of the Cretaceous Period in what is now Mongolia. Talarurus was a hippopotamus-sized, heavily built, ground-dwelling, quadrupedal herbivore, that could grow up to an estimated 6 m (19.7 ft) long. Like other ankylosaurs it had heavy armour and a club on its tail. Along with Tsagantegia, Talarurus is the oldest known ankylosaurid from Asia and one of the better-known ankylosaurs from Mongolia.

Etymology[edit]

The genus name Talarurus, means "basket tail", and is derived from the Greek word "talaros" (ταλαρος) meaning "wicker basket", and the Latinized form "urus" of the Greek word (ουρα) meaning "tail". The genus name is 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 type and only valid species known today is Talarurus plicatospineus. The specific name "plicatospineus" is derived from the Latin words "plicatura" which means "folded" and "spineus" which means "thorny". this is a reference to the corrugated spines which are present on the surface of its armor plates.[1][2] Talarurus was described and named by Russian paleontologist Evgeny Maleev in 1952.[3]

Discovery and age[edit]

Skull

Talarurus remains have been discovered in the southeastern parts of the Gobi Desert in what is now Mongolia. The type specimen PN 557-91 was discovered in 1948 by a joint Soviet-Mongolian Paleontological Expedition expedition, and recovered from sandy, red calcareous claystone at the Bayn Shire locality of the Bayan Shireh Formation. Sediments found in this rock formation, are thought to date from the Turonian stage of the Late Cretaceous period, about 95-88 million years ago. To determine the age of these sentiments more accurately, researchers examine dinosaur remains from similar-aged rocks elsewhere are compared with dinosaur remains from the Bayan Shireh Formation. Specimen PN 557-91 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.

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 expedition in 1975 and is now reposited at the Paleontological Institute, Russian Academy of Sciences, in Moscow.[4] 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.

Talarurus is now known from five individual specimens, from various localities at the Bayan Shireh Formation. Specimen PEN AN SSR 557 consists of a dorsal vertebra with an attached rib, and a dermal scute. Another specimen referred to this genus from the Bayshin-Tsav locality is composed of an (undescribed) incomplete skull with cranial roof, occipital part and brain Case. A second undescribed specimen, collected at the Baga Tarjach locality, consists of a fragment of a maxilla with 8 teeth.

Description[edit]

Tail

The skull of Talarurus measured approximately 24 centimetres (9.4 in) in length by approximately 22 centimetres (8.7 in) wide, and its body length has been estimated at 4 to 6 metres (13 to 20 ft). This ankylosaurid had five toes on the forefoot and four on the hind foot. Additional diagnostic characteristics include dorsal vertebrae with transversely broad hypapophyses and osteoderms with furrowed ornamentation. Compared to other ankylosaurids, Talarurus was shaped more like a hippopotamus, with a barrel-shaped body, where others have the characteristic low and wide body type. Its armor was formidable, with each armor plate adorned with additional pleated spines.

Vickaryous et al. (2004) note the presence of two distinct ankylosaurid clades during the Late Cretaceous, "one consisting of North American taxa and the other restricted to Asian taxa. The oldest member of the Asian clade...is Talarurus plicatospineus."[5]

Classification[edit]

Front view of skeleton

Talarurus was assigned to the ankylosauridae by Maleev in its original description in 1952. in 1978, Coombs posited that it was the same dinosaur as Euoplocephalus although subsequent study did not support this assertion.[6] Maryanska (1977) demonstrated that it differed from Euoplocephalus, citing the shape of the skull, the morphology of the palate, and the presence of four pedal digits. Recent phylogenetic analysis provides evidence for assignment to the ankylosaurinae.[7]

The following cladogram is based on the phylogenetic analysis of the Ankylosaurinae conducted by Arbour and Currie (2013):[8]

Ankylosaurinae

Scolosaurus (=Oohkotokia horneri)





Ankylosaurus




Anodontosaurus



Euoplocephalus







Dyoplosaurus



Talarurus



Tsagantegia





Minotaurasaurus



Nodocephalosaurus



Tianzhenosaurus





Pinacosaurus grangeri



Pinacosaurus mephistocephalus





Tarchia



Saichania










Distinguishing anatomical features[edit]

Skull

A diagnosis is a statement of the anatomical features of an organism (or group) that collectively distinguish it from all other organisms. Some, but not all, of the features in a diagnosis are also autapomorphies. An autapomorphy is a distinctive anatomical feature that is unique to a given organism.

According to Coombs and Maryanska (1990), Talarurus can be distinguished based on the following characteristics:[9]

  • the skull is relatively long and narrow
  • the occipital condyle is partially visible when observed from the dorsal view
  • the maxillary teeth have swollen bases cut on the labial side by W-shaped furrows
  • the presence of a pentadactyl manus, and a tetradactyl pes
  • the post-cranial bones are wide relative to their length
  • the armor plates are ribbed
  • the tail club is relatively small

As one of the oldest ankylosaurids, Talarurus possesses some primitive characters that are observed in the more primitive nodosaurids but were later lost in more advanced ankylosaurs.

Paleoecology[edit]

Existing evidence suggests that the habitat that Talarurus lived in were lowland floodplains. It shared its paleoenvironment with carnivorous dromaeosaurids, therizinosaurs, and other ankylosaurians, like Tsagantegia

Talarurus in the media[edit]

Talarurus had a small part in the beginning of the Disney computer-animated film, Dinosaur.

References[edit]

  1. ^ Liddell, Henry George and Robert Scott (1980). A Greek-English Lexicon (Abridged Edition). United Kingdom: Oxford University Press. ISBN 0-19-910207-4. 
  2. ^ Dinochecker. "Talarurus". Retrieved 23 April 2014. 
  3. ^ Maleev, Evgeny A. (1952). "Noviy ankilosavr is verchnego mela Mongolii" [A new ankylosaur from the Upper Cretaceous of Mongolia]. Doklady Akademii Nauk SSSR 87 (2): 273–276. 
  4. ^ S. M. Kurzanov and T. A. Tumanova. 1978. The structure of the endocranium in some Mongolian ankylosaurs. Paleontological Journal 1978(3):369-374.
  5. ^ Vickaryous, Maryanska, and Weishampel 2004. Chapter Seventeen: Ankylosauria. in The Dinosauria (2nd edition), Weishampel, D. B., Dodson, P., and Osmólska, H., editors. University of California Press.
  6. ^ Coombs WP Jr (1978c) The families of the ornithischian dinosaur order Ankylosauria. Palaeontology 21: 143–170.
  7. ^ Maryanska, 1977. Ankylosauridae (Dinosauria) from Mongolia. Palaeontol. Polonica 37:85-151.
  8. ^ Arbour V.M. and Currie P.J., 2013, "Euoplocephalus tutus and the Diversity of Ankylosaurid Dinosaurs in the Late Cretaceous of Alberta, Canada, and Montana, USA", PLoS ONE 8(5): e62421. doi:10.1371/journal.pone.0062421
  9. ^ Coombs, WP, Jr. & T Maryanska (1990), Ankylosauria in DB Weishampel, P Dodson, & H Osmólka (eds), The Dinosauria. Univ. Calif. Press, pp. 456-483.