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"Gus" - A Mounted Tyrannosaurus Rex Skeleton
Estimate: 20,000,000 - 30,000,000 USD
"Portrait of Gertrud Loew" - Gustav Klimt
Estimate: 20,000,000 - 30,000,000 GBP
This market resolves to the piece which sells for a higher value at their upcoming Sotheby's auction.
Note the currency conversion. Currently, 1 GBP -> 1.3 USD, so the Klimt has a meaningfully higher pre-auction estimate. However, several recent dinosaurs have sold far above their pre-auction estimates (e.g., Apex sold for $46m after a ~$5m pre-auction estimate), so I think Gus has a fighting chance.
Resolution details
Example from a past auction: This painting by Vigée Le Brun sold for 3,085,000 USD. This is the equivalent number I will use.
If it's close, I'll use the currency conversion price as of the start time for the Klimt auction.
Note that the final listed sale price typically includes the buyer's premium (and potentially other fees).
Edge cases:
If one is pulled before it is put up for auction, resolves N/A.
If one goes up for auction but fails to sell for any reason, it resolves to the other.
If they both fail to sell, resolves N/A.
"Gus" - A Mounted Tyrannosaurus Rex Skeleton

An outstanding exhibition-ready mounted skeleton, with a body length of approximately 38 feet, a skull length of 54 inches, a femur length of 50.39 inches (larger than that of Stan), and rising to 12 ½ feet tall, cementing “Gus” as one of the largest T. rex ever found. Gus is importantly a single specimen with an incredible 183 fossil bone elements, plus 30 of the 32 rarely found and rarely mounted gastralia (belly ribs, which are technically osteoderms and thus not traditionally reckoned within the formal bone count), it is approximately 61% complete by bone count, with these bones representing 75-80% of the bone mass of the animal, placing it firmly among the most complete T rex ever found. (Lot essay)
"Portrait of Gertrud Loew" - Gustav Klimt

Gustav Klimt’s beguiling representations of women have made him the most celebrated painter of the female portrait in the early twentieth century. As with Picasso’s depictions of Marie-Thérèse Walter or Modigliani’s Parisian portraits, Klimt’s women constitute the most important group of works in his œuvre and are among the truly iconic images of Modern Art.
Bildnis Gertrud Loew, painted in 1902, is an extraordinarily beautiful and captivating work from a crucial period in the artist’s career. As in many of Klimt’s most important portraits, he balances the requirements of a portrait commission with an aesthetic agenda of his own. In part, this approach was enabled by the close network of patronage and artistic endeavour that flourished in fin-de-siècle Vienna, and which is exemplified in the story of this painting. (Lot essay)