What is Kelmayisaurus “gigantus”?

The mounted skeleton of Klamelisaurus, the true identity of Kelmayisaurus “gigantus”, from Wikimedia Commons (Kabacchi, CC BY 2.0).

Kelmayisaurus “gigantus” is an informal name attached to a mythical giant theropod that has floated around the internet. Allegedly, it is known from a 22 m (72 ft) long vertebral column, which would make it by far the largest theropod ever discovered. This is twice the length of the other species in this genus, the type species K. petrolicus, which has been estimated to be 10-12 m (33-39ft) long (Brusatte et al. 2011). The outlandish size has led to speculation that it is not Kelmayisaurus or a theropod at all, but instead a sauropod (Mortimer, 2003; Molina-Pérez & Larramendi, 2019). I recently found an online copy of the original source, Wayne Grady’s book The Dinosaur Project (Grady, 1993). It contains some additional information that I think confirms the identity of K. “gigantus” as a sauropod.

“Then Zhao Xijin took everyone on a tour of the localities in the area, including the Wucaiwan Formation, a Middle Jurassic exposure of red mudstones intermixed with yellow-green siltstones about thirty kilometers to the northwest of camp [Jiangjunmiao]. Wucaiwan means ‘five colors’ in Chinese: the 122-m cliff faces are mainly red, but have horizontal bands of white, black, blue, and green. A few years earlier, Dale [Russell] noted in his field book, a Kelmayisaurus gigantus, a huge theropod measuring twenty-one meters from neck to tailtip (there was no skull) had been found there.”

The first thing to note is that the reported length was actually 21 m (69 ft) and not 22 m. The second, more important fact is that K. “gigantus” came from the Wucaiwan Member of the Shishugou Formation (formerly its own formation). The sauropod Klamelisaurus gobiensis is also from the Wucaiwan (Zhao, 1993; Moore et al. 2020) and its similar name could be easily confused with Kelmayisaurus. The holotype of Klamelisaurus (IVPP V9492) includes a relatively complete vertebral column lacking a skull, which fits the description of K.  “gigantus”. It was found about 35 km (22 mi) north of Jiangjunmiao, the abandoned town where Grady was camped. This matches the distance and direction to the Wucaiwan that he stated.

The dates line up as well; the trip to the Wucaiwan in Grady’s account happened in 1987, and Klamelisaurus was found there in 1982 and excavated in 1984. While Klamelisaurus was not formally named until 1993, the name had appeared earlier in print (Olshevsky, 1991) and Russell probably knew about it beforehand. The only discrepancy is the length, as Klamelisaurus was estimated to only be 17 m (56 ft) long by Zhao. However, since Grady already mixed up the names and classification it is conceivable that he also exaggerated the size. Taking all this evidence into account, I am convinced that Kelmayisaurus “gigantus” was just a mistaken recollection of Klamelisaurus gobiensis.

Addendum (4/13/2020)

Dong (1992) contains a map of the Jiangjunmiao area which is helpful for visualizing the locations discussed in this post. “Camp of CCDP 1987” is the camp where Grady stayed. Klamelisaurus came from one of the localities near “Camp of IVPP 1984”, although which one is unknown.

References

• Brusatte, S.L., Benson, R.B.J., & Xu, X. (2011). A reassessment of Kelmayisaurus petrolicus, a large theropod dinosaur from the Early Cretaceous of China. Acta Palaeontologica Polonica, 57(1), 65-72.
• Dong, Z. (1992). Dinosaurian Faunas of China. China Ocean Press & Springer-Verlag.
• Grady, W. (1993). The Dinosaur Project: The Story of the Greatest Dinosaur Expedition Ever Mounted. The Ex Terra Foundation. 
• Molina-Pérez, R., & Larramendi, A. (2019). Dinosaur Facts and Figures: The Theropods and Other Dinosauriformes. Princeton University Press.
• Moore, A.J., Upchurch, P., Barrett, P.M., Clark, J.M., & Xu, X. (2020). Osteology of Klamelisaurus gobiensis (Dinosauria, Eusauropoda) and the evolutionary history of Middle–Late Jurassic Chinese sauropods. Journal of Systematic Palaeontology, 18(16), 1299-1393.
• Mortimer, M. (2003, July 21). And the largest theropod is… Dinosaur Mailing List. http://dml.cmnh.org/2003Jul/msg00355.html
• Olshevsky, G. (1991). A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia. Mesozoic Meanderings, 2, 1-196.
• Zhao, X. (1993). A new mid-Jurassic sauropod (Klamelisaurus gobiensis gen. et sp. nov.) from Xinjiang, China. Vertebrata PalAsiatica, 31(2), 132-138.

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