Two of three authors in Argentina of a 2002 paper purporting to show evidence of bird-like fossil footprints from the Late Triassic age have retracted it after subsequent research suggested their estimates were off.
Here’s the notice for “Bird-like fossil footprints from the Late Triassic:”
In this Letter, we considered the bird-like footprints from the former Santo Domingo Formation of northwest Argentina to be of Late Triassic age. Recent radiometric dating (1) of the sedimentary sequence containing these bird-like footprints (renamed as the Laguna Brava Formation) indicated a Late Eocene age. Further geological studies (2) suggest that the region suffered a complex deformation during the Andean orogeny, including block rotation. In consequence, our previous inferences about the possible implications of this finding for the fossil record of Aves are no longer supported. This Retraction has not been signed by J.F.G. Correspondence should be addressed to R.N.M. (email@example.com).
That first link is to a Brief Communication Arising about the paper that appeared in Nature in March and began:
Bird-like tracks from northwest Argentina have been reported as being of Late Triassic age1. They were attributed to an unknown group of theropods showing some avian characters. However, we believe that these tracks are of Late Eocene age on the basis of a new weighted mean 206Pb/238U date (isotope dilution–thermal ionization mass spectrometry method) on zircons from a tuff bed in the sedimentary succession containing the fossil tracks. In consequence, the mentioned tracks are assigned to birds and its occurrence matches the known fossil record of Aves.
Ricardo Melchor — “R.N.M.” — tells us that nothing has changed since the March Brief Communication Arising:
The original version of the retraction included the new age published in March communication arising, but Nature editorial policies indicate that no new information can be included in a retraction. So the Editor suggested putting the new age information on that note (if you read it, you will see that there we indicate that we may be wrong in 2002 but we do not state it).
In this case, what happened is that background geological information changed, and the finding must be understood in a new framework. We (several colleagues and me) conducted additional field and laboratory work aiming to confirm the age of the tracks. Unfortunately the results were different of what we expected.
But, I decided to clear the situation. It was a mistake, now corrected.
The original paper has been cited 26 times, according to Thomson Scientific’s Web of Knowledge.
We’re not sure why Jorge Genise — “J.F.G” — didn’t sign the notice, and he hasn’t responded to a request for comment.