- Hyphalosaurus
Taxobox
name = "Hyphalosaurus"
fossil_range =Early Cretaceous
image_width = 200px
regnum =Animal ia
phylum =Chordata
classis =Sauropsida
ordo =Choristodera
familia =Hyphalosauridae Gao and Fox 2005
genus = "Hyphalosaurus"
genus_authority = Gao, et al.1999
subdivision_ranks = Species
subdivision =
*"H. lingyuanensis" (type)
*"H. baitaigouensis""Hyphalosaurus" is an extinct
genus from the OrderChoristodera , found in theEarly Cretaceous Jehol group inChina (around 130-120 million years ago). It contains two species, "H. lingyuanensis" from theYixian Formation , and "H. baitaigouensis" from theJiufotang Formation .The slab and counterslab of the
holotype were given to different groups of researchers. Each described the taxon and published their results independently, giving the animal two different names. It was quickly recognized that "Sinohydrosaurus" and "Hyphalosaurus" were mirror images of one another and in fact represented the same specimen. "Sinohydrosaurus" is a juniorsynonym of "Hyphalosaurus", as the latter name appeared in publication before the former."Hyphalosaurus" fossils are relatively widespread in the Yixian beds. Entire growth series are known, from embryos in eggs to fully-grown adults. This animal achieved an adult body size of about 0.8 meters.
This animal was aquatic, a lifestyle reflected by its elongate neck and tail and relatively reduced limbs. Superficially, it resembles a small
nothosaur . This resemblance arose convergently and does not reflect evolutionary relatedness."Hyphalosaurus" is related to the large, crocodile-like "
Champsosaurus " and the smaller, lizard-like "Monjurosuchus ". Its closest relative was the similarly built species, "Shokawa ikoi", from the Early Cretaceous of Japan. The choristoderes were aclade of aquatic reptiles that survived the end-Cretaceous extinction along withcrocodilian s,turtle s,lizard s andsnake s. The choristoderes became extinct by theMiocene .A fossil of "Hyphalosaurus" dating 120 million years ago was found in 2007 with two heads [Buffetaut et al. (2006) "A two-headed reptile from the Cretaceous of China" Biology Letters [http://journals.royalsociety.org/content/08427xp462431367/fulltext.html Early Online] (DOI: 10.1098/rsbl.2006.0580)] , marking the oldest known case of
polycephaly .Gallery
References
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