Zhangheotherium

Taxobox
name = "Zhangheotherium"
fossil_range = Early Cretaceous

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image_width = 250px
image_caption = "Zhangheotherium quinquecuspidens" fossil displayed in Hong Kong Science Museum.
regnum = Animalia
phylum = Chordata
classis = Mammalia
unranked_ordo = Trechnotheria
ordo = Symmetrodonta
superfamilia = Spalacotherioidea
familia = Zhangheotheriidae
genus = "Zhangheotherium"
genus_authority = Hu, Y.Q. Wang, Luo & C.K. Li, 1997
species = "Z. quinquecuspidens"
binomial = "Zhangheotherium quinquecuspidens"
binomial_authority = Hu, Wang, Luo & Li, 1997

"Zhangheotherium" is a genus of symmetrodont, an extinct order of mammals. Previously known from only the tall pointed crowned teeth, "Zhangheotherium", described from Liaoning Province, China, fossils in 1997, is the first symmetrodont known from a complete skeleton. It was dated to between 145-125 million years ago in the Cretaceous. A single species, "Zhangheotherium quinquecuspidens", is presently known.

Symmetrodonts and other archaic mammals such as multituberculates and monotremes are still being debated on their taxonomical relationships. "Zhangheotherium" has many primitive characteristics. Among them is a venomous spur at the foot, seen today in the modern platypus. In addition, it walked with a reptilian sprawl, not at all like our known mammals but instead like many Mesozoic mammals, like "Jeholodens" and "Repenomamus".

The specimen GMV 2124 of the feathered dinosaur "Sinosauropteryx prima" contained 2 jaws of "Zhangheotherium" in its stomach region (Hurum "et al." 2006). Thus, it seems to have preyed on this primitive mammal, possibly on a regular basis.

References

*Hurum, Jørn H.; Luo, Zhe-Xi & Kielan-Jaworowska, Zofia (2006): Were mammals originally venomous? "Acta Palaeontologica Polonica" 51(1): 1–11. [http://www.app.pan.pl/acta51/app51-001.pdf PDF fulltext]