Daanosaurus zhangi skeletal

Daanosaurus zhangi

Etymology: "Zhang's Daano lizard"

Time horizon: Late Jurassic, Oxfordian epoch? (~160 mya)

Length: 4.5m (~15 ft.) as a juvenile. Adult length unknown, but may have been similar in size to Klamelisaurus.

Probable mass: 400kg (as a juvenile). Adult mass unknown, but likely similar to Klamelisaurus.

*Light gray bones represent material which has been recovered and prepared, but not figured in the description paper. Dark gray represents missing elements.*

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Known only from a single juvenile specimen - so young that the upper and lower components of its vertebrae are still separate bones divided by unfused neural canal sutures - Daanosaurus is the most recent-living species in the family klamelisauridae that has yet been discovered. (Or if you are from west Texas, it's how you pronounce "dinosaurs" every day). A contemporary of the some of the later mamenchisaurs in Sichuan, it has many features in the vertebrae which superficially resemble Euhelopus in profile, but unlike Euhelopus there's a complete absence of bifurcation in any of the neural spines, a feature unusually similar to all but the most basal brachiosaurs. However Daanosaurus may have evolved its single neural spines independently of them. It's not known if this animal is more derived than its older cousin Klamelisaurus (without adult remains it's complicated to tell, since sauropods do sometimes undergo substantial changes in vertebra morphs as they mature), but since the basal condition appears to be bifid neural spines in both klamelisaurs and early brachiosaurs (i.e. Atlasaurus) then it's likely Daanosaurus was at the advanced end of its clade, and independently lost all traces of bifurcation in the spines. The trait was also lost by most brachiosaurids, and all known laurasiformes and chubutisaurids... only to return with a vengeance in huanghetitanids, euhelopodids, and acrofornicans... and then disappear again in the majority of titanosaurs... and appear yet again in Opisthocoelicaudia!

As a juvenile the neck proportions of Daanosaurus were generally similar to those of young Klamelisaurus specimens (aka. "Bellusaurus sui"). And as an adult it probably also took on the same far more elongated "mamenchisaur-mimic" neck proportions as adult Klamelisaurus. Of course this will not be known for sure unless older individuals of Daanosaurus are discovered, since we only know of this species (and of the fact that its family survived into the Late Jurassic, if just barely) through the swift death and burial of a baby.


References:

Y. Ye, Y.-H. Gao, and S. Jiang. 2005. A new genus of sauropod from Zigong, Sichuan. Vertebrata PalAsiatica 43(3):175-181