| Gobihadros | |
|---|---|
 | |
| Skeletal reconstruction | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Clade: | †Ornithopoda |
| Clade: | †Hadrosauromorpha |
| Genus: | †Gobihadros Tsogtbaataret al.,2019 |
| Type species | |
| †Gobihadros mongoliensis Tsogtbaataret al., 2019 | |
Gobihadros is a genus of basalhadrosauroiddinosaur that lived inAsia during theLate Cretaceous period in what is now theBayan Shireh Formation (Cenomanian-Santonian). It contains only thetype speciesGobihadros mongoliensis. It has an estimated length of 7.5 m (25 ft).
Between 1993 and 2004, the Mongolian Palaeontological Center and the JapaneseHayashibara Museum of Natural Sciences excavated sites at Bayshin Tsav. Material was discovered of a basal hadrosauroid new to science. Tsogtbaatar treated this species in his dissertation of 2008.[1]
In 2019, thetype speciesGobihadros mongoliensis was named and described by Khishigjav Tsogtbaatar,David Bruce Weishampel, David Christopher Evans, and Mahito Watabe. The generic name combines references to theGobi Desert and theHadrosauroidea. Thespecific name refers to the provenance from Mongolia. Because the describing article appeared in anelectronic publication,Life Science Identifiers were needed to make the name valid. These were 38EE8AD7-AD50-44BF-B31D-B2675456556A for the genus and 2DB42EE7-6A64-4D64-AA19-E5D3453BF99C for the species.[1]
Theholotype,MPC-D100/746, was found in a layer of theBayan Shireh Formation dating from theCenomanian-Santonian stages. It consists of a nearly complete skeleton with a skull. While the postcranial skeleton was articulated, the skull was partly disintegrated. Numerous specimens have been referred to the species, the most important among them specimen MPC-D100/763, a complete articulated skull, with a hand. The specimens have partly been found in other sites in Mongolia. Combined, they makeGobihadros the most completely known basal hadrosauroid from Asia.[1]
Gobihadros was a medium sized hadrosauroid. The specimen MPC-D100/763, was approximately 3 m (9.8 ft) at the time of its death, it was however, an immature individual. Other specimens reached larger sizes; MPC-D100/744 has a 72.8 cm (728 mm) longfemur, indicating a length of 5.3 m (17 ft). Nevertheless, specimen ZPAL MgD-III/3 reached 7.5 m (25 ft) long, as indicated by its femur measuring 104 cm (1,040 mm). This size appears to be the top length infully grown individuals, as indicated by the advanced age of ZPAL MgD-III/3, which features areas ofbone resorption andbone remodeling on the femur andtibia.[1][2]
The describing authors indicated some distinguishing traits.Gobihadros differs from all known other non-hadrosaurid hadrosauroids in possessing a double-layered tomial edge of the premaxilla and the presence of as much as three teeth per tooth position in the lower jaw. These are typical hadrosaurid traits and were concluded to have been acquired separately by the Hadrosauridae in a process ofparallel evolution.Gobihadros differs fromBactrosaurus johnsoni,Probactrosaurus gobiensis,Eolambia caroljonesa,Claosaurus agilis andTethyshadros insularis by an undulating upper profile of the ilium and a more sidewards projecting supra-acetabular crest.Gobihadros differs fromT. insularis,Plesiohadros djadokhtaensis and the Hadrosauridae in possessing a conical spike-like claw of the first finger.[1]
Gobihadros was placed in theHadrosauroidea in 2019, in a basal position outside of theHadrosauridae. Its exact affinities were unclear as it was recovered in a polytomy with many other such forms. Its existence was seen as affirming a pattern of subsequent American hadrosauroid invasions into Asia.[1]
In 2021 Justyna Słowiak and team examined an exceptionally large individual ofGobihadros (ZPAL MgD-III/3) throughCT scans, which was found to preserve traces of abnormal calcium deposits in some bones. Thesepaleopathologies were interpreted to represent traces ofcalcium pyrophosphate deposition disease, and were found in caudal vertebrae and pedal phalanges. The presence of this disease in this individual combined with its large size—which may represent the top size limit ofGobihadros—indicates that it was a rather old animal and this disease would have been responsible for causing restriction andpain in thejoint areas of affected bones. It is likely that the disease developed in the dinosaur due to old age rather than external factors, such asphysical trauma. The team also reinforced its advanced age based on the presence of closely spacedlines of arrested growth (LAGS) andexternal fundamental system in the femur.[3]
Media related toGobihadros at Wikimedia Commons
Data related toGobihadros at Wikispecies
