Mongolarachne chaoyangensis

"Mongolarachne" chaoyangensis is a dubious species of crayfish discovered in the Yixian Formation in China, known from a single, poorly preserved specimen. 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. 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. "M". chaoyangensis is probably the same as Cricoidoscelus, which is also found in the Yixian Formation, although there is the possibility that "M". chaoyangensis belonged to an entirely new genus.

"Mongolarachne" chaoyangensis Temporal range: Early Cretaceous, Barremian–Aptian PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Malacostraca
Order:	Decapoda
Suborder:	Pleocyemata
Infraorder:	Astacidea
Superfamily:	Astacoidea
Genus:	†"Mongolarachne" Cheng et al., 2019 (preoccupied)
Binomial name
†"Mongolarachne" chaoyangensis Cheng et al., 2019

Cricoidoscelus aethus specimen, which is similar to that of "Mongolarachne" chaoyangensis

Discovery and naming

The fossil was initially discovered as a crayfish, probably by a farmer. The fossil 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[1] but it was subsequently shown to be a fossil crayfish when the specimen was analysed further. The paint was subsequently removed and the fossil placed into storage until further research can be done.[2]

References

1. Xiaodong Cheng; Sizhao Liu; Wenjuan Huang; Li Liu; Hongming Li; Yinxian Li (2019). "A new species of Mongolarachnidae from the Yixian Formation of western Liaoning, China". Acta Geologica Sinica (English Edition). 93 (1): 227–228. doi:10.1111/1755-6724.13780.
2. Paul A. Selden; Alison N. Olcott; Matt R. Downen; Dong Ren; Chungkun Shih; Xiaodong Cheng (2019). "The supposed giant spider Mongolarachne chaoyangensis, from the Cretaceous Yixian Formation of China, is a crayfish" (PDF). Palaeoentomology. 2 (5): 515–522. doi:10.11646/palaeoentomology.2.5.15.