Mongolarachne chaoyangensis

"Mongolarachne" chaoyangensis is a dubious species of crayfish discovered in the Dawangzhangzi Beds of the Yixian Formation in China, known from a single, poorly preserved specimen, that may be one of, if not, the oldest known fossil crayfish to date.^[1] If it were to be properly described as a new species, the genus name would have to be changed since it is preoccupied by an extinct spider.^[2]

According to Selden et al. (2019), "M". chaoyangensis is probably the same as Cricoidoscelosus,^[1] which is also found in the Yixian Formation, although there is the possibility that "M". chaoyangensis belonged to an entirely new genus.

Discovery and naming[]

The holotype, D3088, was initially discovered as a crayfish, probably by a farmer. D3088 was eventually vandalised and extra remains of the fossil were painted on to make the fossil seem like a spider, possibly to add value to the fossil so it could be sold on the black market. The fossil eventually made its way to the collection stored at the University of Kansas and it was described in 2019 by Cheng et al as a second species of the Jurassic spider Mongolarachne,^[3] but it was subsequently shown to be a fossil crayfish when the specimen was analysed further. The paint was subsequently removed and the fossil has been placed into storage until further research can be done.^[1]

Description[]

It was initially thought to have been a spider until it was determined to have been a hoax. The factors that gave the hoax away is that there were too many segments at the base of the legs, the sternum was absent and the eyes were too large to be those of a spider, but they were large enough to have come from a crayfish.^[1]

Classification[]

Selden et al. (2019) did not classify "M." chaoyangensis within Astacoidea, so for now it is left as a basal crayfish, likely due to the age of the specimen and the unpreparedness of the specimen at the time of publication,^[1] although if Selden et al. (2019) is correct, then "Mongolarachne" chaoyangensis is the same animal as the contemporaneous Cricoidoscelosus aethus.^[1]

References[]