Open Paleo

Alxasaurus

Russell & Dong, 1993 AHL-shah-SAWR-us /ˌɑːlʃəˈsɔːrəs/

Named after the Alxa (Alashan) Desert/region of Inner Mongolia combined with Greek 'sauros' meaning 'lizard'; meaning 'Alxa lizard'

113.2–100.5 million years ago Albian, Early Cretaceous
Early Cretaceous stages

Alxasaurus is a genus of therizinosauroid theropod dinosaurs from the Early Cretaceous (Albian age) Bayin-Gobi Formation of Inner Mongolia. It is known from five specimens, recovered from the Bayin-Gobi in 1988, as part of the China-Canada Dinosaur Project. During their preparation, paleontologists Dong Zhiming and Dale Russell noted strong similarities to Segnosaurus. In 1993, they described Alxasaurus and named its type species, A. elesitaiensis. While therizinosaurs had previously been tentatively seen as late-surviving basal sauropodomorphs, the description of Alxasaurus lent credence to the idea that they were instead highly derived coelurosaurs.

Diagnosis

  1. Dentary bears approximately 40 teeth, more than any other known therizinosauroid
  2. Symphyseal region of dentary bears teeth (no symphyseal diastema)
  3. Cervical ribs not fused to cervical centra
  4. Ligament pits well-developed on manual phalanges
  5. Ilium not greatly shortened anteroposteriorly; preacetabular ala only moderately expanded
  6. Pedal unguals shorter than or subequal to first phalanx in digits II-IV

Species

Alxasaurus elesitaiensis Russell & Dong, 1993

Type species

Named after Elesitai, a village in Inner Mongolia near which the fossil remains of Alxasaurus were located.

Holotype
IVPP RV 93001 , Institute of Vertebrate Paleontology and Paleoanthropology
Formerly
IVPP 88402 (renumbered)
Material
Largely disarticulated skeleton: dentary, cervicals, dorsals, sacrum, caudal series, scapula, coracoid, humerus, radius, ulna, carpals, metacarpals, manual phalanges, ilium, ischium, femur.
Notes
The erecting paper designates "the larger individual" of two sharing field number 88402, the smaller being referred material. Later work often writes the two as IVPP 88402a and 88402b, but no such suffixes were assigned; many elements were never marked with the accession number at all.
Horizon
Bayin-Gobi Formation, Albian, Early Cretaceous , 113.2–100.5 million years ago
Locality
Elesitai, Inner Mongolia, China Russell and Dong (1993) give the beds as "lacustrine strata of Albian age", from a fauna found near the Alxasaurus sites "suggestive of an Albian age" and from palynomorphs reported by earlier surveys.

References

  1. Russell, D. A.; Dong, Z. M. (1993). The affinities of a new theropod from the Alxa Desert, Inner Mongolia, People's Republic of China. Canadian Journal of Earth Sciences 30(10): 2107-2127. Canadian Science Publishing. doi:10.1139/e93-183 russell1993b
  2. Zhao, Q.; Xu, X.; Jia, C.; Dong, Z. (2008). Order Saurischia. The Chinese Fossil Reptiles and Their Kin (Li, J.; Wu, X.; Zhang, F., eds.) 279-335. Science Press, Beijing.

    Gives the holotype as "IVPP RV 93001 (field No 88402)", the catalog numbers the IVPP applied to the material after its description.

    zhao2008a