By Nina Larson
Zurich, Switzerland - A curator gingerly fastens a pointy claw bone with a thin metal wire, completing perhaps the world's biggest construction kit - reassembling a 67-million-year-old Tyrannosaurus-Rex called Trinity.
The huge skeleton will go under the hammer in a rare auction in Switzerland next month after being sent to Zurich from the United States in nine giant crates.
But palaeontologist Thomas Holtz - who is against the sale of such specimens - told AFP that it was "misleading" and "inappropriate... to combine multiple real bones from different individuals to create a single skeleton."
The Swiss sale comes only four months after Christie's withdrew another T-Rex skeleton days before it was to go under the hammer in Hong Kong after doubts were reported about parts of it.
Trinity, the Swiss T-Rex, is made up of bones from three dinosaurs excavated between 2008 and 2013 from the Hell Creek and Lance Creek formations in Montana and Wyoming.
The two sites are known for the discoveries of two other significant T-Rex skeletons that have gone to auction. "Sue" went under the hammer in 1997 for $8.4 million (R152 million), and "Stan", which took the world-record hammer price of $31.8 million at Christie's, in 2020.
- Not 'trophies' -
Trinity, which is being sold by an anonymous "private individual", is expected to fetch six to eight million Swiss francs ($6.5-8.7 million) when it goes under the hammer in Zurich on April 18, the Koller auction house estimates.
But Christian Link of Koller said he believed the guide price was a "pretty low" estimate.
The 3.9-metre (12.8-foot) high skeleton went on display on a red carpet under crystal chandeliers in a concert hall in the city Wednesday.
Just over half of the bone material in the skeleton comes from the three Tyrannosaurus specimens - above the 50 percent level needed for experts to consider such a skeleton as high quality.
Link insisted Koller was being transparent about the origins of the bones.
"Hence the name Trinity. We are not hiding in any way that this specimen comes from three different dig sites," he said.
Vertebrate palaeontologist Holtz, of the University of Maryland, remained sceptical, insisting that Trinity "really isn't a 'specimen' so much as it is an art installation."
He also took issue with auctions of significant dinosaur skeletons and other fossils, which have raked in tens of millions of dollars in recent years.
Experts have warned such trade could be harmful to science by putting the specimens in private hands and out of the reach of researchers.
"Fossils are not, or at least should not be, considered trophies or glorified action figures," Holtz said.
But Link stressed that 95 percent of known T-Rexes are currently in museums, and said any private collector who might buy Trinity was likely to make it available to scientists and lend it out to museums.
- 'Very, very old' -
Reassembling Trinity was no easy feat, Yolanda Schicker-Siber, a curator of Switzerland's Aathal Dinosaur Museum, told AFP as she secured another toe bone.
"The bones are very, very old. So they are brittle, they have cracks," she said.
"They are stabilised, but you never know if there is a crack that you haven't seen so far... You have to have the glue ready."
Aart Walen, a Dutch expert with 30 years' experience assembling dinosaur skeletons, agreed.
"We didn't break anything yet," he said proudly, as he and his colleagues worked on two large ischium bones, which sat near the dinosaur's pelvic area.
With a parakeet named Ethel perched on his shoulder, Walen filled in cracks using what looked like dental tools and modelling compound.
It was important for the fixes to remain visible, he said, showing the dark lines where the fissures had been.
"You have to see where it has been repaired. There are some stories about fakes out there. We don't want that," he said, referring to the aborted Christie's auction.
Knocking on different parts of the bone, he also demonstrated the different sounds made by original bone and the plastic additions used to fill out the skeleton.
- Room for a T-Rex -
Link said personally he would like to see a Swiss museum buy the skeleton, adding "it would be nice to have it here permanently."
Schicker-Siber said the dinosaur museum she runs with her father outside Zurich unfortunately could not afford to acquire Trinity.
"But if somebody buys it and doesn't know where to put it, we have a museum (with room) for a T-Rex," she said.